taxonID	type	description	language	source
F1956C94AA834E13883896A779048B27.taxon	diagnosis	Diagnosis. Despite the distinct ecological niche differences (see below-Distribution and habitat) between Opisthostoma and Plectostoma, it is not feasible to use this criterion in the genus identification, because information about the ecology is usually not available as most collections are made by soil sampling. After 150 years of work on Opisthostoma, it is still difficult to identify reliable apomorphic character states that can be used to distinguish between Opisthostoma and Plectostoma (Vermeulen 1991, 1994). Both share the character state of the constriction, which is a slight shrinkage in the whorl towards the end of the spire. When the animal retracts into its shell, its operculum rests at the constriction (Vermeulen 1991). It is, however, possible to make a morphological distinction between Opisthostoma and Plectostoma on the basic of the shell colouration in a fully grown adult, which is orange or pinkish in Plectostoma and white or pale yellowish in Opisthostoma. The colour differences between these two genera are very clear when comparing the living snails or freshly dead shell material (Figure 17, and Appendix 18). Some Plectostoma species have a regularly coiled tuba, and a shell form that is similar to Arinia. However, Plectostoma and Arinia can be easily distinguished by shell colour differences. The shell colour in Arinia is similar to that in Opisthostoma.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
F1956C94AA834E13883896A779048B27.taxon	description	Description. Apex. Protoconch is either slightly, moderately or distinctly convex (Figure 3). Spire. Height: 1.0 mm- 3.7 mm. Width: 0.85 mm- 2.60 mm (Figure 11). Number of whorls between 2 3 / 4 - 71 / 4. Apical spire shape: oblong or depressed conical (Figure 4). Basal spire shape: conical, ovoid or ellipsoid (Figure 5). Whorl periphery: flat, slightly, moderately or distinctly convex. Umbilicus: open, partially closed, or totally closed. Constriction. Parietal teeth: parietal side of inner constriction whorl (Figure 2) with two long lamellae (Figure 6 A), two ridges with a knob at each end (Figure 6 B), one ridge with a knob at one end (Figure 6 C), or no teeth (Figure 6 D). Basal teeth: basal side of inner constriction whorl (Figure 2) with no teeth (Figure 7 B), one ridge running parallel with the whorl growing direction, one ridge with a knob at one end running perpendicular to the whorl growing direction, or a combination of the latter two types (Figure 7 A). Tuba. Coiling direction: regular coiling (type 1, Figure 8 A) or distorted (Type 2, or 3) (Figure 8 B and C). Tuba whorl length in proportion to spire last whorl: ca. 3 / 8 - 1 1 / 2. Proportion of tuba that attaches to spire: whole to none. Aperture and peristome. Peristome: simple aperture without outer peristome (Figure 10 B), or double peristome (Figure 10 C and 10 D). Shape of outer peristome (Figure 10 A): same as inner peristome and uniformly round, or highly projected or slightly projected at either a particular side or at a several sides of anterior, poteriorior, left and right laterial (Figure 9 and 10 A). Spiral lines. Either thick or thin, or only thin lines present (Figure 12). Radial ribs. Rib density: 4 - 32 per mm on the spire's last whorl in right lateral view (Figure 13 A). Intensity: thick or thin (Figure 13 B). Shape: straight, slightly curved, distinctly curved, single humped, single looped or double looped and the shape remaining the same or changing between between the spire and the tuba (Figure 13 C, but single-looped, and double-humped not shown). Inclination: from orthoclin to prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
0E2EFF182AF60B9E969244C6085E4B0D.taxon	diagnosis	Diagnosis. Shares with Plectostoma mengaburensis and Plectostoma panhai the general shell form, in terms of apex, spire and tuba, but differs by lacking constriction teeth and having a more tightly coiled tuba (less than 1 / 4 of the tuba visible in top view).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
0E2EFF182AF60B9E969244C6085E4B0D.taxon	etymology	Etymology. This species is named after its type locality-Dinding.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
0E2EFF182AF60B9E969244C6085E4B0D.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 1.8 - 1.9 mm. Width: 1.4 - 1.5 mm. Number of whorls: 3 7 / 8 - 4 5 / 8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: partially closed by tuba. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible from back view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 3 / 4. Proportion of tuba that attaches to the spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 6 - 8 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
0E2EFF182AF60B9E969244C6085E4B0D.taxon	distribution	Distribution. Type locality. The exact location is unknown. The specimens are labeled as collected from " dinding ". It could be near Kampung Bukit Dinding, Pahang (3 ° 49 ' 41 " N, 102 ° 22 ' 3 " E). Distribution range. The species has only been recorded from the type locality (Figure 18 D).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
0E2EFF182AF60B9E969244C6085E4B0D.taxon	discussion	Discussion. See discussion under Plectostoma christae.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
EF57DB94C3BD90EB1674F500E83DA143.taxon	diagnosis	Diagnosis. Shares with Plectostoma dindingensis and Plectostoma panhai the general shell form, in the terms of apex, spire and tuba, but differs by lacking constriction teeth and having a less tightly coiled tuba (more than 1 / 4 of the tuba visible in top view).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
EF57DB94C3BD90EB1674F500E83DA143.taxon	etymology	Etymology. This species is named after its type locality-Mengabur.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
EF57DB94C3BD90EB1674F500E83DA143.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 1.9 - 2.2 mm. Width: 1.4 - 1.6 mm. Number of whorls: 3 7 / 8 - 4 1 / 2. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: open or half of the umbilicus closed by tuba. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible from back view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 7 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
EF57DB94C3BD90EB1674F500E83DA143.taxon	distribution	Distribution. Type locality. An unnamed small limestone hill in the plantation near the large Bukit Mengabur quarry (3 ° 43 ' 50 " N, 102 ° 49 ' 40 " E). Distribution range. This species only occurs in the Mengabur limestone cluster (Figure 18 D).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
EF57DB94C3BD90EB1674F500E83DA143.taxon	discussion	Discussion. See discussion under Plectostoma christae.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
6C131BFB0495BBC8A5B9AFA80B9CED57.taxon	diagnosis	Diagnosis. Shares with Plectostoma dindingensis, Plectostoma mengaburensis, Plectostoma christae, and Plectostoma panhai the general shell form, in terms of apex, apical spire and tuba, but differs by having an ellipsoid basal spire.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
6C131BFB0495BBC8A5B9AFA80B9CED57.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 1.6 - 1.9 mm. Width: 1.2 - 1.3 mm. Number of whorls: 3 - 3 3 / 4. Apical spire shape: depressed conical. Basal spire shape: ellipsoid. Whorl periphery: distinctly convex. Umbilicus: almost completely closed by tuba. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible between right lateral and back view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 3 / 4. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 9 - 10 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
6C131BFB0495BBC8A5B9AFA80B9CED57.taxon	distribution	Distribution. Type locality. Gunung Senyum, Pahang (3 ° 42 ' 35 " N, 102 ° 26 ' 3 " E). Distribution range. In addition to the type locality, this species also was found at the Jebak Puyuh limestone outcrop, which lies about 1 km east of Gunung Senyum (Figure 18 D). BOR 462 was collected in Pulau Singa Besar, which is located about 300 km from type locality. The reliability of the collection data is dubious (the same was found for BOR 463 of Plectostoma relauensis).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
6C131BFB0495BBC8A5B9AFA80B9CED57.taxon	discussion	Discussion. See discussion under Plectostoma christae.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1BE68043C78E2020642B8CFD8ACA7EDE.taxon	diagnosis	Diagnosis. Shares with Plectostoma dindingensis, Plectostoma mengaburensis, and Plectostoma panhai the tuba form, but differs by having an oblong conical apical spire.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1BE68043C78E2020642B8CFD8ACA7EDE.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 2.0 - 2.3 mm. Width: 1.3 - 1.5 mm. Number of whorls: 4 5 / 8 - 4 3 / 8. Apical spire shape: oblong conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: completely open or partially closed by tuba. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible from back view. Tuba whorl length in proportion to spire last whorl: ca. 1 / 2 - 3 / 4. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 6 - 9 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1BE68043C78E2020642B8CFD8ACA7EDE.taxon	distribution	Distribution. Type locality. Limestone hill cluster named Kota Tongkat (3 ° 53 ' 28 " N, 102 ° 28 ' 23 " E). Distribution range. It is only known from the type locality. All other adjacent limestone outcrops have been sampled, but only other Plectostoma species were found (Figure 18 D).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1BE68043C78E2020642B8CFD8ACA7EDE.taxon	discussion	Discussion. See discussion under Plectostoma christae.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
D7BAA3FBD58EA8EB6AB5D1D0BD61581B.taxon	diagnosis	Diagnosis. Shares with Plectostoma christae the tuba form, but differs by having an oblong conical apical and conical basal spire.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
D7BAA3FBD58EA8EB6AB5D1D0BD61581B.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 1.9 - 2.1 mm. Width: 1.2 - 1.5 mm. Number of whorls: 4 3 / 4 - 5. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: Open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible between right lateral and back view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 8 - 1 / 2. Proportion of tuba that attaches to spire: at least 1 / 2. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 7 - 8 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
D7BAA3FBD58EA8EB6AB5D1D0BD61581B.taxon	distribution	Distribution. Type locality. Gua Siput, Taman Negara, Pahang (4 ° 26 ' 47 " N, 102 ° 14 ' 44 " E). Distribution range. Plectostoma siphonostomum has a similar distribution pattern as Plectostoma salpidomon and often occurs sympatrically with that species. It can be found in many limestone outcrops in the valley between the Titingwangsa Range, Tahan Range and Benom Range (Figure 18 D).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
D7BAA3FBD58EA8EB6AB5D1D0BD61581B.taxon	discussion	Discussion. See discussion under Plectostoma christae.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C04BFE6AD58458D838688FB7450FC29B.taxon	diagnosis	Diagnosis. Shares with Plectostoma mengaburensis and Plectostoma dindingensis the general shell form, in the terms of apex, spire and tuba, but differs by having a single parietal constriction tooth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C04BFE6AD58458D838688FB7450FC29B.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 2.1 - 2.2 mm. Width: 1.6 - 1.7 mm. Number of whorls: 4 1 / 2 - 4 5 / 8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately convex. Umbilicus: open. Constriction. Parietal teeth: one. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible from back view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 4. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 8 - 9 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C04BFE6AD58458D838688FB7450FC29B.taxon	distribution	Distribution. Type locality. Tham Krachaeng, Thailand (6 ° 12 ' 50 " N, 101 ° 12 ' 9 " E). The location description in the original publication is not completely correct " (06 ° 55 ' 022 " N, 101 ° 12 ' 160 " E) " (Maassen 2001). Distribution range. This species is only known from the type locality (Figure 18 D).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C04BFE6AD58458D838688FB7450FC29B.taxon	discussion	Discussion. See discussion under Plectostoma christae.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C3E398FF662DAAC2BA8F2373C29D1936.taxon	diagnosis	Diagnosis. Shares with Plectostoma dindingensis, Plectostoma mengaburensis, and Plectostoma panhai the general shell spire form but differs by having two parietal constriction teeth and aperture visible when shell observed in left lateral view.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C3E398FF662DAAC2BA8F2373C29D1936.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 1.9 - 2.6 mm. Width: 1.4 - 1.8 mm. Number of whorls: 3 5 / 8 - 4 1 / 2. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 1 and aperture visible from left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 8 - 5 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 5 - 6 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C3E398FF662DAAC2BA8F2373C29D1936.taxon	distribution	Distribution. Type locality. Limestone hills, 16 km west of Gua Musang (4 ° 54 ' 46 " N, 102 ° 6 ' 22 " E). Distribution range. Limestone hills along the 50 km Northeast transect between 4 ° 38 ' 51 " N, 101 ° 58 ' 58 " E and 5 ° 0 ' 13 " N, 102 ° 11 ' 59 " E (Figure 18 D).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C3E398FF662DAAC2BA8F2373C29D1936.taxon	discussion	Discussion. Plectostoma christae, together with Plectostoma dindingensis, Plectostoma mengaburensis, Plectostoma sinyumensis, Plectostoma umbilicatum, Plectostoma siphonostomum, and Plectostoma panhai represent a group of Plectostoma species that have a regulary coiled tuba (type 1 tuba). The species of this group occur only in Peninsular Malaysia and are genetically highly divergent (> 10 % differences in COI) from the others (Table 4). All of the seven species are distributed allopatrically (Figure 18 D). We synonymised Plectostoma jensi with Plectostoma christae, both of which were described from the same locality. Maassen (2001) distinguished between them by the slight difference in umbilicus opening and aperture tilting. In the material at our disposal, we recognised that these differences are intrapopulational variation. All individuals share the same diagnostic shell characters as mentioned above. In addition to the morphological evidence, the genetic variation between individuals with different shell forms is smaller than our species delimitation threshold of 10 %. Two species of this group, namely Plectostoma christae and Plectostoma siphonostomum, have a wider distribution range than other species in this group. The two species occur parapatrically on the limestone hills in the centre of Peninsular Malaysia (Figure 18 D). On the other hand, very little is known of the distribution range of Plectostoma panhai. Although this species was reported only once and only from the type locality, it might also occur at other limestone sites near the type locality. Plectostoma panhai is very similar to Plectostoma christae, but the two are separated by more than 150 km, and the limestone hills in between are occupied by three other Plectostoma species. The disjunct distribution and its single constriction tooth support the decision that Plectostoma panhai is a distinct species from Plectostoma christae. The remaining four species of this group, namely, Plectostoma sinyumensis, Plectostoma mengaburensis, Plectostoma dindingensis, and Plectostoma umbilicatum, are site endemics, occurring at each of the four small limestone clusters in the centre of Peninsular Malaysia (Figure 18 D). These clusters are each quite isolated, with no other limestone hills within a 20 km radius. Although these four species occur in adjacent limestone limestone clusters, and they have similar shell shapes, their taxonomic status are clear. The COI sequence divergence between these species is larger than 13 % and each of them has a set of diagnostic shell characters (Tables 3 and 4). This may raise the question how each species evolved in each limestone cluster and how long these four species have been isolated. For example, a neighbouring species, Plectostoma salpidomon, has a similar distribution range as the former four species, but the morphological and genetic divergence is much smaller than in these four species. Presumably, the answer lies in the details of the geomorphological evolution of the limestone outcrops, which, however, remains largely unknown.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
E573215260DDCD0E978CA9341D22D75B.taxon	diagnosis	Diagnosis. Shares with Plectostoma sciaphilum, Plectostoma senex, and Plectostoma turriforme the tuba form, but differs by having a slightly or moderately convex apex and depressed apical spire.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
E573215260DDCD0E978CA9341D22D75B.taxon	description	Description. Apex. Shape: slightly or moderately convex. Spire. Height: 1.3 - 3.0 mm. Width: 1.2 - 1.4 mm. Number of whorls: 3 1 / 2 - 4 1 / 2. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately or distinctly convex. Umbilicus: closed by tuba (common) or partially open (rare). Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 3 and aperture visible from left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 1 / 2 - 3 / 4 Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 6 - 8 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
E573215260DDCD0E978CA9341D22D75B.taxon	distribution	Distribution. Type locality. Gua Musang (4 ° 52 ' 59 " N, 101 ° 58 ' 12 " E). Distribution range. This species mainly occurs in the limestome hills that are located between Gua Musang and as far as 30 km radius of Gua Musang. One populations exists at a limestone hill that is located about 90 km north of Gua Musang (Figure 18 A).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
E573215260DDCD0E978CA9341D22D75B.taxon	discussion	Discussion. The species is well-characterised, although it displays considerable variability in the shell shape (Appendix 6).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
368D5AC904DDED99352DFEA28B202EAB.taxon	diagnosis	Diagnosis. Shares with Plectostoma whitteni the general shell form, in terms of apex, spire and tuba, but differs by having two lamella-shaped constriction teeth and a higher spire (> 3 mm).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
368D5AC904DDED99352DFEA28B202EAB.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 3.1 - 3.8 mm. Width: 2.4 - 2.6 mm. Number of whorls: 4 3 / 4 - 4 7 / 8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: completely closed by tuba. Constriction. Parietal teeth: two lamellae. Basal teeth: none. Tuba. Coiling direction: type 3 and aperture visible in left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: simple peristome. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 6 - 7 ribs per mm. Rib intensity: thin. Shape: slightly curved to single-humped. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
368D5AC904DDED99352DFEA28B202EAB.taxon	distribution	Distribution. Type locality. " Tonkin " (Dautzenberg and Fischer 1905). The exact locality should be the limestone hill near Chau Dao. Distribution range. Limestone hills in the Province of Kien Giang (Figure 18 A).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
368D5AC904DDED99352DFEA28B202EAB.taxon	discussion	Discussion. In recent years, this species has been recorded at several limestone hills in the vicinity of Ha Tien, which is a popular tourism site. Although the type specimen cannot be located and the exact type locality cannot be determined, the shell morphology of the recent material fits well with the description in the original publication. In the original publication, Dautzenberg and Fischer (1905) mentioned that this species was collected by M. Mansuy from Tonkin (French protectorate), which was a large area that included part of Southern China, and the Northern parts of Laos and Vietnam. Dautzenberg and Fischer (1905) further provided a list of locations where most of the snails were collected. One of these was, Chau Doc, which is located about 70 km from Ha Tien. Furthermore, a recent intensive land snail survey in the Northern Provinces of Laos, namely, Hua Phan and Luang Prabang, did not discover any Plectostoma species (Muratov and Abdou 2006). Hence, Plectostoma tonkinianum probably occurs in the small limestone hill cluster in the coastal area of the Southern part of Vietnam and neighboring Cambodia.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
307342CA97B1DEAD2EDDC2A561384113.taxon	diagnosis	Diagnosis. Shares with Plectostoma tonkinianum the general shell form, in the terms of apex, spire and tuba, but differs by lacking constriction teeth and lower spire (<2 mm).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
307342CA97B1DEAD2EDDC2A561384113.taxon	etymology	Etymology. This species is named after Dr. Tony Whitten, who was senior biodiversity specialist of the World Bank between 1995 and 2010, and is currently the Regional Director for Asia-Pacific Fauna & Flora International. Dr. Whitten has been actively promoting the protection of the biodiversity that is associated with limestone and has been involved in conservation action to protect limestone habitats.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
307342CA97B1DEAD2EDDC2A561384113.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 1.7 - 1.9 mm. Width: 1.4 - 1.6 mm. Number of whorls: 3 7 / 8 - 4 1 / 4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: completely closed by tuba. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 3 and aperture visible in left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 1 / 2 - 5 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 6 - 7 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
307342CA97B1DEAD2EDDC2A561384113.taxon	distribution	Distribution. Type locality. Gua Taat, Tasik Kenyir (4 ° 51 ' 3 " N, 102 ° 43 ' 21 " E). Distribution range. This species only occurs in Gua Taat, Tasik Kenyir (Figure 18 A).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
307342CA97B1DEAD2EDDC2A561384113.taxon	discussion	Discussion. The general shell form of Plectostoma whitteni is similar to Plectostoma tonkinianum. There is no genetic information for Plectostoma tonkinianum, but Plectostoma whitteni is genetically closer to Plectostoma tohchinyawi than to any of the other 18 species. Nevertheless, Plectostoma whitteni is considered a distinct species as compared to Plectostoma tonkinianum and Plectostoma tohchinyawi because of the lack of constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C0E1BB78FE859889D28375353F2B924E.taxon	diagnosis	Diagnosis. Shares with Plectostoma senex and Plectostoma turriforme the tuba form, but differs by lacking basal constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C0E1BB78FE859889D28375353F2B924E.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.6 - 2.9 mm. Width: 1.5 - 1.6 mm. Number of whorls: 4 1 / 4 - 5 1 / 2. Apical spire shape: oblong conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: completely closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 3 and aperture visible in left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 6 - 8 ribs per mm. Rib intensity: thin. Shape: slightly curved.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C0E1BB78FE859889D28375353F2B924E.taxon	distribution	Distribution. Type locality. Bukit Panching, Pahang (3 ° 53 ' 28 " N, 103 ° 8 ' 26 " E). Distribution range. Endemic to Bukit Panching (not seen in Figure 18 A because its symbol overlaps with Plectostoma senex).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C0E1BB78FE859889D28375353F2B924E.taxon	discussion	Discussion. See under Plectostoma turriforme.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
BC7AE61FB9D97AA5F02C73E6CF107B80.taxon	diagnosis	Diagnosis. Shares with Plectostoma sciaphilum and Plectostoma turriforme the tuba form, but differs by having two knob-shaped constriction teeth and fewer than 6 whorls.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
BC7AE61FB9D97AA5F02C73E6CF107B80.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.6 - 3.1 mm. Width: 1.6 - 1.7 mm. Number of whorls: 5 1 / 8 - 5 5 / 8. Apical spire shape: oblong conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: completely closed by tuba. Constriction. Parietal teeth: two. Basal teeth: one transverse tooth. Tuba. Coiling direction: type 3 and aperture visible in left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 4 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
BC7AE61FB9D97AA5F02C73E6CF107B80.taxon	distribution	Distribution. Type locality. Gua Charas, limestone hill near Sungai Lembing in the state of Pahang, Malaysia (3 ° 54 ' 27 " N, 103 ° 8 ' 47 " E). Distribution range. In addition to the type locality, this species had been recorded from Bukit Panching (Figure 18 A).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
BC7AE61FB9D97AA5F02C73E6CF107B80.taxon	discussion	Discussion. See discussion under Plectostoma turriforme.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
833DD0C1B007C492AFC16F0D21043D01.taxon	diagnosis	Diagnosis. Shares with Plectostoma sciaphilum and Plectostoma senex the tuba form, but differs by having two lamella-shaped constriction teeth and having more than 6 whorls.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
833DD0C1B007C492AFC16F0D21043D01.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 3.2 mm. Width: 1.6 mm. Number of whorls: 7. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: completely closed by tuba. Constriction. Parietal teeth: two. Basal teeth: two. Tuba. Coiling direction: type 3 and aperture visible in left lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 5 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
833DD0C1B007C492AFC16F0D21043D01.taxon	distribution	Distribution. Type locality. Bukit Tenggek, Pahang (4 ° 0 ' 51 " N, 103 ° 9 ' 34 " E). Distribution range. In addition to the type locality, this species can be found at nearby Bukit Sagu (Figure 18 A).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
833DD0C1B007C492AFC16F0D21043D01.taxon	discussion	Discussion. Plectostoma turriforme, Plectostoma sciaphilum, and Plectostoma senex are three very similar species than occur in the four lenticular easternmost limestone hills in Peninsular Malaysia (Figure 18 A). These four hills, namely, Bukit Panching, Bukit Charas, Bukit Sagu, and Bukit Tenggek are located along a 15 km longitudinal transect. Plectostoma turriforme occurs at the two former sites and Plectostoma senex at the two latter sites. Plectostoma sciaphilum occurs sympatrically with Plectostoma turriforme in Bukit Panching. These four hills (and thus the three species) are among the most isolated limestone outcrops in Peninsular Malaysia.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
F91AD6E4755B9C83932314E8DB6B01DB.taxon	diagnosis	Diagnosis. Shares with Plectostoma retrovertens the spire and tuba form, but differs by having spire height between 1.6 - 1.9 mm.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
F91AD6E4755B9C83932314E8DB6B01DB.taxon	description	Description. Apex. Shape: slightly convex. Spire. Height: 1.6 - 1.9 mm. Width: 1.1 - 1.3 mm. Number of whorls: 3 3 / 4 - 4 1 / 4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: partially or completely closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible between right lateral and back view; the tuba coils upward until the first teleconch whorl of the spire. Tuba whorl length similar to that of the last whorl of the spire. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similer to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 7 - 8 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
F91AD6E4755B9C83932314E8DB6B01DB.taxon	distribution	Distribution. Type locality. Bukit Serdam, Pahang (3 ° 49 ' 47 " N, 101 ° 55 ' 36 " E). Distribution range. To date, this species has been recorded from three limestone hills, namely Bukit Serdam, Gua Kechil and a small hill nearby (Figure 18 C).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
F91AD6E4755B9C83932314E8DB6B01DB.taxon	discussion	Discussion. See discussion under Plectostoma retrovertens.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A2D51D045BA52515849E8C1BE65CD31D.taxon	diagnosis	Diagnosis. Shares with Plectostoma palinhelix the spire and tuba form, but differs by having spire height between 2.3 - 2.6 mm.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A2D51D045BA52515849E8C1BE65CD31D.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 2.3 - 2.6 mm. Width: 1.5 - 1.7 mm. Number of whorls: 4 5 / 8 - 5. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: distinctly convex. Umbilicus: partially or completely closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible between right lateral and back view; the tuba coils upward until the first teleconch whorl of the spire. Tuba whorl length similar to the length of the last whorl of the spire. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similer to inner peristome, projected all around, except the posterior part, where two lateral sides are slightly more projected than the anterior side. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 7 - 9 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A2D51D045BA52515849E8C1BE65CD31D.taxon	distribution	Distribution. Type locality. Bukit Chintamanis, Pahang (3 ° 26 ' 45 " N, 102 ° 0 ' 51 " E). Distribution range. Endemic to the type locality (Figure 18 C).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A2D51D045BA52515849E8C1BE65CD31D.taxon	discussion	Discussion. Plectostoma retrovertens and Plectostoma palinhelix are very distinct from other Plectostoma by having a very long tuba in relation to their spire. In fact, a preliminary phylogenetic analysis suggests that these two are basal species for all Peninsular Malaysia's Plectostoma. These two species are located more 40 km apart on outcrops that belong to the same limestone facies (Figure 18 C). The two species are very similar in their shell shape, but Plectostoma retrovertens is about one-third larger than Plectostoma palinhelix. Furthermore, the genetic divergence between the two species is 10 %.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1EF0F7EEC8BBC5F068DE5443D1918DEB.taxon	etymology	Etymology. This species is named after its type locality-Gua Ikan.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1EF0F7EEC8BBC5F068DE5443D1918DEB.taxon	diagnosis	Diagnosis. Shares with Plectostoma kayiani the general shell form, in terms of spire and tuba shape, but differs by having both thick and thin spiral lines.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1EF0F7EEC8BBC5F068DE5443D1918DEB.taxon	distribution	Distribution. Type locality. Gua Ikan in the State of Kelantan (5 ° 21 ' 9 " N, 102 ° 1 ' 34 " E). Distribution range. In addition to the type location, this species also occurs at nearby limestone hills as far as 30 km away (Figure 18 C).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
1EF0F7EEC8BBC5F068DE5443D1918DEB.taxon	discussion	Discussion. The two forms of Plectostoma ikanensis were found in the type locality at two different parts of the hill that within a distance of 100 m. The overall shell appearances of these two forms are very different, especially in terms of tuba coiling direction and spire shape. Interestingly, one of the Plectostoma ikanensis forms (i. e. BOR 5507) is very similar to Plectostoma davisoni on the basis of these two shell characters. In most of the other Plectostoma species examined in this study, tuba coiling direction and spire shape are rather stable characters within a species. Nevertheless, both Plectostoma ikanensis forms lack a constriction which unite them and distinguish them from other similar species (see Diagnosis). In addition to the morphological evidence, we found that the genetic divergence of these two forms is smaller than 1 % (Table 4), and our preliminary phylogenetic analysis shows that the two forms are reciprocally monophyletic. We therefore conclude that they be classified as the same species.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
400AB12CDF5ED813B0593611F9AB23A0.taxon	etymology	Etymology. This species is named after Kay Arnold and Ian Mellsop from New Zealand, who have generously supported wildlife conservation work in many parts of Peninsular Malaysia, including the forests around Lake Kenyir where this species was discovered.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
400AB12CDF5ED813B0593611F9AB23A0.taxon	diagnosis	Diagnosis. Shares with Plectostoma ikanensis the general shell form, in terms of spire and tuba shape, but differs by lacking thick spiral lines.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
400AB12CDF5ED813B0593611F9AB23A0.taxon	description	Description. Apex. Shape: slightly to moderately convex. Spire. Height: 1.4 - 1.6 mm. Width: 1.2 - 1.4 mm. Number of whorls: 3 1 / 2 - 3 3 / 4. Apical spire shape: depressed conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: open. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible from front view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 3 / 4. Proportion of tuba that attaches to spire: almost whole except the part near the aperture. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similer to inner peristome, projected all around, except the posterior part, where left lateral sides are slightly more projected than the anterior and right lateral side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 8 - 10 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
400AB12CDF5ED813B0593611F9AB23A0.taxon	distribution	Distribution. Type locality. Gua Bewah, Tasik Kenyir (4 ° 51 ' 3 " N, 102 ° 43 ' 21 " E). Distribution range. To date, this species is only known to occur at two neighbouring limestone outcrops, namely, Gua Bewah and Gua Taat at the southern part of Tasik Kenyir (Figure 18 C).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
400AB12CDF5ED813B0593611F9AB23A0.taxon	discussion	Discussion. This species occurs sympatrically with Plectostoma tohchinyawi and Plectostoma whitteni.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4C8EF3AE676164E4CF054CF1CA790340.taxon	diagnosis	Diagnosis. Shares with Plectostoma relauensis the general shell form, in terms of apex, spire, and tuba shape, but differs by having two parietal constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4C8EF3AE676164E4CF054CF1CA790340.taxon	etymology	Etymology. This species is named after Dr. Geoffrey Davison, who has been involved in the conservation of limestone hills in Malaysia, and has collected a lot of snail specimens, many of which are included in this revision of Plectostoma from Malaysia.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4C8EF3AE676164E4CF054CF1CA790340.taxon	description	Description. Apex. Shape: slightly to moderately convex. Spire. Height: 1.6 - 2.0 mm. Width: 1.4 - 1.5 mm. Number of whorls: 3 5 / 8 - 4 7 / 8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in frontal view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 3 / 4. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similer to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 6 - 7 ribs per mm. Rib intensity: thin. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4C8EF3AE676164E4CF054CF1CA790340.taxon	distribution	Distribution. Type locality. Limestone hill on the right hand side of the road D 29, at km 17 when travelling from Jelawang to Gua Musang (4 ° 59 ' 4 " N, 101 ° 57 ' 53 " E). Distribution range. This species has a very large distribution range, ca. 80 km diameter. It can be found in many limestone outcrops in the central part of Peninsular Malaysia, mainly in the State of Kelantan (Figure 17 D). In addition, it can also be found in a cluster of limestone hills located at upper Sungai Keniyam Kecil in Taman Negara (ca. 60 km from Gua Musang).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4C8EF3AE676164E4CF054CF1CA790340.taxon	discussion	Discussion. This species is highly variable in the shell form (Appendix 9 and Appendix 10), and has a very wide distribution range which partly overlaps with many other Plectostoma species (Figure 18). It is very densely distributed in the State of Kelantan, parapatric with Plectostoma christae. The species becomes more sparse toward the limestone hills in Taman Negara, Pahang (Figure 18 C). In view of this, it is possible that the species actually consists of two or more cryptic species, and thus more genetic data are needed.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C8A6DEFAAB5E068C80066A0FAED95156.taxon	etymology	Etymology. This species is named after its type locality-Relau substation of Taman Negara, where Gua Gajah is located.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C8A6DEFAAB5E068C80066A0FAED95156.taxon	diagnosis	Diagnosis. Shares with Plectostoma davisoni the general shell form, in terms of apex, spire, and tuba shape, but differs by having a single parietal constriction tooth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C8A6DEFAAB5E068C80066A0FAED95156.taxon	description	Description. Apex. Shape: slightly to moderately convex. Spire. Height: 1.5 - 1.9 mm. Width: 1.5 - 1.6 mm. Number of whorls: 3 3 / 8 - 3 5 / 8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: open. Constriction. Parietal teeth: one. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in frontal view. Tuba whorl length in proportion to spire last whorl: ca. 1 / 2 - 5 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 4 - 7 ribs per mm. Rib intensity: thin. Shape: straight to slightly curved. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C8A6DEFAAB5E068C80066A0FAED95156.taxon	distribution	Distribution. Type locality. Gua Gajah in the Relau substation, Taman Negara. (4 ° 38 ' 15 " N, 102 ° 3 ' 50 " E). Distribution range. This species also occurs at a limestone hill located about 20 km north of the type locality. BOR 463 was collection in Pulau Singa Besar, which is located about 300 km from type locality. The reliability of the collection data is dubious (see also BOR 462 of Plectostoma sinyumensis).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C8A6DEFAAB5E068C80066A0FAED95156.taxon	discussion	Discussion. This species occurs sympatrically with Plectostoma siphonostomum on the same limestone hills. Despite the high density of limestone hills in the area, where many other Plectostoma species occur, Plectostoma relauensis is only found in two of these (Figure 18).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
8910F3363E1388A8409942319C14B6C6.taxon	diagnosis	Diagnosis. Shares with Plectostoma kubuensis the general shell form, in terms of apex, spire, and tuba shape, but differs by having two parietal constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
8910F3363E1388A8409942319C14B6C6.taxon	description	Description. Apex. Shape: slightly to moderately convex. Spire. Height: 1.7 - 2.1 mm. Width: 1.5 - 1.6 mm. Number of whorls: 3 3 / 4 - 4 1 / 4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: partially closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 3 / 4. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 8 - 10 ribs per mm. Rib intensity: thin. Shape: straight to slightly curved. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
8910F3363E1388A8409942319C14B6C6.taxon	distribution	Distribution. Type locality. Kaki Bukit (6 ° 38 ' 42 " N, 100 ° 12 ' 6 " E) (Figure 18 C). Distribution range. Wang Kelian limestone outcrops.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
8910F3363E1388A8409942319C14B6C6.taxon	discussion	Discussion. See discussion under Plectostoma kubuensis.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A4B5696BA6140E8A6C51AFF0EF05516A.taxon	diagnosis	Diagnosis. Shares with Plectostoma kakiense the general shell form, in terms of apex, spire, and tuba shape, but differs by lacking constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A4B5696BA6140E8A6C51AFF0EF05516A.taxon	etymology	Etymology. This species is named after its type locality-Bukit Kubu, Perlis.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A4B5696BA6140E8A6C51AFF0EF05516A.taxon	description	Description. Apex. Shape: slightly to moderately convex. Spire. Height: 1.6 - 2.0 mm. Width: 1.3 - 1.5 mm. Number of whorls: 3 5 / 8 - 4 1 / 4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: open or partially closed by tuba. Constriction. Parietal teeth: none. Basal teeth: none. Tuba. Coiling direction: type 3 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 3 / 4. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the left lateral sides are slightly more projected than the anterior and right lateral side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 10 - 11 ribs per mm. Rib intensity: thin. Shape: straight to slightly curved. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A4B5696BA6140E8A6C51AFF0EF05516A.taxon	distribution	Distribution. Type locality. Bukit Kubu (6 ° 24 ' 15 " N, 100 ° 8 ' 37 " E) (Figure 18 C). Distribution range. Endemic to the type locality.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
A4B5696BA6140E8A6C51AFF0EF05516A.taxon	discussion	Discussion. From the conchological point of view, the overall shape and size of Plectostoma kubuensis and Plectostoma kakiense is almost the same. Nevertheless, two inconspicuous but significant shell characters, namely, basal and parietal constriction teeth, mark the difference between these two species. Despite the similarity in shell form, there is a great genetic distance between the two species (16 %). The species occur at two limestone hills that lie about 30 km apart. During our survey, we could not find either species at the six limestone hills that are located between these two hills. A single Plectostoma shell was recorded by Norhanis et al. (2010) from Pulau Dayang Bunting, Langkawi, and might belong to this species.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
7617F6268D09074C814E14CA0024E587.taxon	diagnosis	Diagnosis. Shares with Plectostoma salpidomon the general shell form, in terms of apex, spire, and tuba shape, but differs by having the whole tuba attached to the spire.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
7617F6268D09074C814E14CA0024E587.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.3 - 2.7 mm. Width: 1.6 - 1.8 mm. Number of whorls: 3 1 / 8 - 4 5 / 8. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: open or partially closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 3 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 1 / 2 - 5 / 8. Proportion of tuba that attaches to spire: whole. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the left lateral sides are slightly more projected than the anterior and right lateral side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 6 - 7 ribs per mm. Rib intensity: thin. Shape: straight to slightly curved. Inclination: prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
7617F6268D09074C814E14CA0024E587.taxon	distribution	Distribution. Type locality. Batu Tai Gadjah, Ulu Keniyam Kechil, Taman Negara, Pahang Malaysia (4 ° 37 ' 0 " N, 102 ° 25 ' 14 " E) (Figure 18 B). Distribution range. This species mainly occurs in a cluster of limestone hills that are located at upper Sungai Keniyam Kecil in Taman Negara (Figure 18 B). In addition, this species has been recorded from Bukit Jereng, Blau, Kelantan, which is about 80 km west from Sungai Keniyam Kecil.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
7617F6268D09074C814E14CA0024E587.taxon	discussion	Discussion. From a conchological point of view, this species is similar to Plectostoma salpidomon; the two may be closely related. In view of biogeography, this species occurs parapatrically with Plectostoma salpidomon, which occurs in the limestone hills in between Bukit Jereng and the limestone cluster at Sungai Keniyam Kecil (Figure 18 B). Further genetic data are needed to verify the taxonomic status of Plectostoma laemodes.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
ADF2F3DA40F4851BC813CF3800E87A4A.taxon	diagnosis	Diagnosis. Shares with Plectostoma laemodes the general shell form, in terms of apex, spire, and tuba shape, but differs by having a tuba that attaches partly to the spire.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
ADF2F3DA40F4851BC813CF3800E87A4A.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.5 - 2.8 mm. Width: 1.5 - 1.7 mm. Number of whorls: 4 5 / 8 - 5 1 / 4. Apical spire shape: depressed conical. Basal spire shape: ovoid. Whorl periphery: moderately to distinctly convex. Umbilicus: completely or partially closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 4 - 7 / 8. Proportion of tuba that attaches to spire: less than 2 / 3. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 5 - 6 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
ADF2F3DA40F4851BC813CF3800E87A4A.taxon	distribution	Distribution. Type locality. Gua Bama, Pahang (4 ° 11 ' 37 " N, 101 ° 58 ' 2 " E) (Figure 18 B). Distribution range. Plectostoma salpidomon can be found in many limestone hills in the valley in between the Titiwangsa, Tahan and Benom mountain ranges (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
ADF2F3DA40F4851BC813CF3800E87A4A.taxon	discussion	Discussion. See discussion under Plectostoma laemodes.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
10D549CCDA9ACB520D567D3E19AEB32E.taxon	diagnosis	Diagnosis. Shares with Plectostoma charasense, Plectostoma tohchinyawi, and Plectostoma klongsangensis the general shell form, in terms of apex, spire, and tuba shape, but differs by lacking thick spiral lines and basal constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
10D549CCDA9ACB520D567D3E19AEB32E.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.9 - 3.0 mm. Width: 1.7 - 1.8 mm. Number of whorls: 5 5 / 8 - 5 3 / 4. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: partially closed by tuba. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 3 / 4 - 7 / 8. Proportion of tuba that attaches to spire: less than 2 / 3. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 5 - 6 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
10D549CCDA9ACB520D567D3E19AEB32E.taxon	distribution	Distribution. Type locality. Cave Pangian (local name Ngalau Pangian - 0 ° 27 ' 45 " S, 100 ° 45 ' 8 " E) Distribution range. This species was also found at a limestone hill near Kampung Desa Gadut, West Sumatra (0 ° 15 ' 36 " S, 100 ° 44 ' 16 " E). This hill is located about 20 km from the type locality. In addition, a private collector (Yansen Chen, pers. comm.) also collected the same species at Tiangko cave, about 230 km from the type locality (Figure 18 B). It therefore appears to have a wide distribution range in Sumatra. It may thus be expected that the limestone outcrops around the three hills mentioned, might support the same species.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
10D549CCDA9ACB520D567D3E19AEB32E.taxon	discussion	Discussion. There are large areas in the Northern and Western provinces of Sumatra that are covered by limestone hills (Verstappen and Genootschap 1973). Despite intensive malacological surveys in some of these areas (van Benthem Jutting 1959), no Plectostoma species was found until 1997. To date, Plectostoma kitteli is the only Plectostoma species found in Sumatra (Maassen 2002).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4BB25E27D19BFB248CDBF88981D72A0B.taxon	diagnosis	Diagnosis. Shares with Plectostoma charasense, Plectostoma tohchinyawi, and Plectostoma kitteli the general shell form, in terms of apex, spire, and tuba, but differs by having both thin and thick spiral lines, and the left lateral side of outer peristome projected more than three times the distance of the right lateral side of outer peristome. Description (estimated from figure in Panha 1996). Apex. Shape: distinctly convex. Spire. Height: 2.3 mm. Width: 1.7 mm. Number of whorls: 5 1 / 2. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: open. Constriction. Unknown. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 7 / 8. Proportion of tuba that attaches to spire: less than 2 / 3. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: different from inner peristome, the left lateral side of outer peristome is projected from inner peristome about 0.7 mm, and the right side of outer peristome about 0.1 mm, but narrowed toward the anterior part of outer peristome. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 3 ribs per mm. Rib intensity: thick. Shape: single-looped. Inclination: prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4BB25E27D19BFB248CDBF88981D72A0B.taxon	distribution	Distribution. Type locality. Khlong Saeng Wildlife Sanctuary Surat Thani Province, Thailand (8 ° 31 ' 13 " N, 98 ° 25 ' 17 " E) (Figure 18 B). Distribution range. Unknown.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4BB25E27D19BFB248CDBF88981D72A0B.taxon	discussion	Discussion. From a conchological point of view, this species appears not to be related to Plectostoma species from the Malay Peninsula and Sumatra. Instead, it is almost identical to Plectostoma mirabile, an endemic species from Gomantong Cave, Sabah, Borneo. These two species are separated by the South China Sea and located more than 2000 km apart. It remains to be determined whether this similarity is due to a disjunct distribution of closely related forms, or rather convergent shell evolution. The taxonomic status of the species remains doubtful. In the original publication, Panha (1996) compared it with Plectostoma heteropleuron (Vermeulen 1994) and Plectostoma perspectivum (Vermeulen, 1994) from Northern Borneo, but not with Plectostoma mirabile (Smith, 1893), which has an almost identical shell as Plectostoma klongsangensis. This is all the more remarkable, as Plectostoma mirabile (Smith, 1893) was treated in Vermeulen (1994), where both Plectostoma heteropleuron and Plectostoma perspectivum were originally described. In conclusion, more data are needed to verify the taxonomic status and the interesting biogeography of this species.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C99409CC25800F89FBED73CB64C0F312.taxon	diagnosis	Diagnosis. Shares with Plectostoma kitteli, Plectostoma tohchinyawi, and Plectostoma klongsangensis the general shell form, in terms of apex, spire, and tuba shape, but differs by lacking thick spiral lines and by having two basal constriction teeth.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C99409CC25800F89FBED73CB64C0F312.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 1.9 - 2.0 mm. Width: 1.3 - 1.4 mm. Number of whorls: 4 1 / 8. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: two. Tuba. Coiling direction: type 2 and aperture visible from right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 7 / 8. Proportion of tuba that attaches to spire: less than 1 / 2. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 4 ribs per mm. Rib intensity: thick. Shape: slightly curved to single-humped. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C99409CC25800F89FBED73CB64C0F312.taxon	distribution	Distribution. Type locality. Gua Charas, limestone hill near Sungai Lembing in the state of Pahang, Malaysia (3 ° 54 ' 27 " N, 103 ° 8 ' 47 " E). Distribution range. Until now, this species has been recorded from two neighbouring limestone hills, namely, Gua Charas and Bukit Panching. However, the whole hill of Bukit Panching has been lost to quarrying (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
C99409CC25800F89FBED73CB64C0F312.taxon	discussion	Discussion. The taxonomic status of this species is stable. Although the two neighbouring species, Plectostoma tohchinyawi and Plectostoma praeco, are similar to Plectostoma charasense, there are a few key shell characters that separate Plectostoma charasense from the others. See discussion under Plectostoma tohchinyawi for more discussion about the biogeography of this species.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
72C381F636EBBF533D28E77AFFEC077C.taxon	diagnosis	Diagnosis. Shares with Plectostoma charasense, Plectostoma kitteli, and Plectostoma klongsangensis the general shell form, in terms of apex, spire, and tuba shape, but differs by having both thin and thick spiral lines, and the left lateral side of outer peristome projected not more than twice the width of the right lateral side of outer peristome.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
72C381F636EBBF533D28E77AFFEC077C.taxon	etymology	Etymology. This species is named after Dato' Toh Chin Yaw, who was the Chairman of Industry, Trade and Environment Committee in the Terengganu State Government between 2008 and 2013. It is rare to find politicians working closely with the public for wildlife conservation. During his time in office, Dato' Toh was tireless in his efforts to promote and preserve Terengganu's natural heritage. One of his most influential decisions was getting the State to ban the hunting of threatened flying foxes (Pteropus vampyrus). Before he left office, he was working with scientists to gazette the Kenyir Wildlife Corridor as a protected area and was helping to secure funds to improve anti-poaching efforts in that area.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
72C381F636EBBF533D28E77AFFEC077C.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.1 - 2.4 mm. Width: 1.3 - 1.5 mm. Number of whorls: 4 7 / 8 - 5 3 / 8. Apical spire shape: oblong conical. Basal spire shape: conical. Whorl periphery: distinctly convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 7 / 8 - 8 / 8. Proportion of tuba that attaches to spire: less than 1 / 2. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the two lateral sides are distinctly more projected than the anterior side. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 4 - 6 ribs per mm. Rib intensity: thick. Shape: slightly curved to single-humped. Inclination: prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
72C381F636EBBF533D28E77AFFEC077C.taxon	distribution	Distribution. Type locality. Gua Bewah, Tasik Kenyir (4 ° 51 ' 3 " N, 102 ° 43 ' 21 " E). Distribution range. To date, this species is only known to occur at two neighbouring limestone outcrops, namely, Gua Bewah and Gua Taat at the Southern part of Tasik Kenyir (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
72C381F636EBBF533D28E77AFFEC077C.taxon	discussion	Discussion. From a conchological point of view, this species is related to Plectostoma charasense. Both are thought to be affiliated with the Plectostoma species from North Borneo. Plectostoma tohchinyawi has a high conical spire, thick and projected radial ribs, and a long detached tuba. These are the typical characteristics for dozens of Plectostoma species in North Borneo. In addition, Plectostoma tohchinyawi and Plectostoma charasense live on the five lenticular limestone outcrops that are the easternmost outcrops of the Malay Peninsula, thus closest geographically to Borneo (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
3C4AD7FA8E697208ECC45A923D55A2E5.taxon	diagnosis	Diagnosis. Shares with Plectostoma laidlawi, Plectostoma tenggekensis, and Plectostoma praeco the general shell form, in terms of spire and tuba shape, but differs by having slightly convex whorl periphery and straight ribs.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
3C4AD7FA8E697208ECC45A923D55A2E5.taxon	description	Description (estimated from figure in Sykes 1903). Apex. Shape: moderately convex. Spire. Height: 2 mm. Width: 1.3 mm. Number of whorls: 4 1 / 2. Apical spire shape: depressed conical. Basal spire shape: conical. Whorl periphery: moderately convex. Umbilicus: Open. Constriction. Unknown. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: approximately the same as the spire's last whorl length. Proportion of tuba that attaches to spire: less than 1 / 2. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: same as inner peristome and uniformly projected all around, except the posterior part. Spiral lines. Unknown Radial ribs. Rib density: 5 ribs per mm. Rib intensity: unknown. Shape: straight. Inclination: orthoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
3C4AD7FA8E697208ECC45A923D55A2E5.taxon	distribution	Distribution. Type locality. This species is only known from its type locality, Jalor (Biserat). The exact location was not described in the original publication of this species. From the collectors' report (Annandale and Robinson 1913), we estimated the location and name of the limestone hill from a map in the report. This hill was named Bukit Bayu. Later, we estimated its coordinates from Google Earth (6 ° 16 ' 48 " N, 101 ° 13 ' 35 " E) (Figure 18 B). Distribution range. Unknown.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
3C4AD7FA8E697208ECC45A923D55A2E5.taxon	discussion	Discussion. This species has not been seen or collected after the original description. The type specimens cannot be located. Sykes (1903) mentioned that it is similar to Plectostoma laidlawi but he did not explain explicitly in what way. This is not unexpected, as Plectostoma laidlawi was the only one Plectostoma known from Peninsular Malaysia at the time, although more than 20 Plectostoma species had already been described from Borneo. Thus, one can assume that the statement made by Sykes was based on the geographical proximity. Interestingly, Plectostoma panhai was described from a limestone hill located just 8 km from the location where Plectostoma annandalei was found. In addition to the geographical proximity, the two neighbouring species are similar in several shell characteristics. The shell spires are very similar in terms of number of whorls, overall shape and size. On the other hand, the main difference between these two species is the tuba coiling direction (type 1 vs. type 2).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
23AC65294678C8838B54FC2249B7ED57.taxon	diagnosis	Diagnosis. Shares with Plectostoma laidlawi, Plectostoma tenggekensis, and Plectostoma annandalei the general shell form, in terms of spire and tuba shape, but differs by having slightly curved ribs.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
23AC65294678C8838B54FC2249B7ED57.taxon	description	Description. Apex. Shape: distinctly convex. Spire. Height: 2.0 - 2.2 mm. Width: 1.8 - 2.0 mm. Number of whorls: 4 1 / 4 - 4 5 / 8. Apical spire shape: depressed conical. Basal spire shape: conical. Whorl periphery: moderately to distinctly convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 7 / 8. Proportion of tuba that attaches to spire: more than 1 / 3 but less than 1 / 2. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the left lateral sides are slightly more projected than the anterior and right lateral side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 6 - 7 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
23AC65294678C8838B54FC2249B7ED57.taxon	distribution	Distribution. Type locality. Batu Che Derani, Taman Negara Pahang (4 ° 35 ' 57 " N, 102 ° 25 ' 57 " E). Distribution range. Plectostoma praeco has been recorded from four other hills at upper Sungai Keniyam Kecil, which is in the vicinity of the type locality (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
23AC65294678C8838B54FC2249B7ED57.taxon	discussion	Discussion. There is no genetic information for Plectostoma praeco. Morphological similarity suggests that Plectostoma praeco and Plectostoma tenggekensis are closely related. Each of the two species has a narrow distribution range and they are separated from each other by at least 50 km.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4620E1022FD16A8171696DF7EFB9596E.taxon	diagnosis	Diagnosis. Shares with Plectostoma laidlawi, Plectostoma annandalei, and Plectostoma praeco the general shell from, in terms of spire and tuba shape, but differs by having single-humped shaped ribs.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4620E1022FD16A8171696DF7EFB9596E.taxon	etymology	Etymology. This species is named after its type locality-Bukit Tenggek, Kuantan, Pahang.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4620E1022FD16A8171696DF7EFB9596E.taxon	description	Description. Apex. Shape: moderately convex. Spire. Height: 1.6 - 1.7 mm. Width: 1.3 - 1.4 mm. Number of whorls: 4 - 4 1 / 4. Apical spire shape: depressed. Basal spire shape: conical. Whorl periphery: moderately convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 of the spire last whorl length. Proportion of tuba that attaches to spire: less than 1 / 3. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the left lateral sides are slightly more projected than the anterior and right lateral side. Spiral lines. Thick lines: absent. Thin lines: present. Radial ribs. Rib density: 6 - 7 ribs per mm. Rib intensity: thin. Shape: slightly curved. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4620E1022FD16A8171696DF7EFB9596E.taxon	distribution	Distribution. Type locality. Bukit Tenggek, Pahang (4 ° 0 ' 51 " N, 103 ° 9 ' 34 " E). Distribution range. Endemic to type locality (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
4620E1022FD16A8171696DF7EFB9596E.taxon	discussion	Discussion. See discussion under Plectostoma praeco.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
9978D1AD2EAC81C877637BA85B4BBEA9.taxon	diagnosis	Diagnosis. Shares with Plectostoma annandalei, Plectostoma tenggekensis, and Plectostoma praeco the general shell form in terms of spire and tuba shape, but differs by having a distinctly convex whorl periphery and straight ribs.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
9978D1AD2EAC81C877637BA85B4BBEA9.taxon	description	Description. Apex. Shape: moderately to distinctly convex. Spire. Height: 1.6 - 2.3 mm. Width: 1.3 - 1.8 mm. Number of whorls: 3 5 / 8 - 4. Apical spire shape: depressed conical. Basal spire shape: conical to ovoid. Whorl periphery: distinctly convex. Umbilicus: open. Constriction. Parietal teeth: two. Basal teeth: none. Tuba. Coiling direction: type 2 and aperture visible in right lateral view. Tuba whorl length in proportion to spire last whorl: ca. 5 / 8 - 7 / 8. Proportion of tuba that attaches to spire: varies from completely attached to as much as half of the tuba detached from spire. Aperture and peristome. Peristome: double peristomes. Outer peristome shape: similar to inner peristome, projected all around, except the posterior part, where the two lateral sides are slightly more projected than the anterior side or left lateral sides slightly more projected than the anterior and right lateral side. Spiral lines. Thick lines: present. Thin lines: present. Radial ribs. Rib density: 5 - 6 ribs per mm. Rib intensity: thin. Shape: straight to slightly curved. Inclination: moderately prosoclin.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
9978D1AD2EAC81C877637BA85B4BBEA9.taxon	distribution	Distribution. Type locality. " Kelantan, Malay Peninsula ", collected by J. Waterstradt (Sykes 1902). According to Waterstradt's (1902) itinerary, he visited one of the limestone hills at Kampung Pulai. The Pulai Princess cave (4 ° 47 ' 38 " N, 101 ° 56 ' 31 " E) fits perfectly with Waterstradt's descriptions on the local population, temples and hill's topography; he also described that he and his collectors sampled shells here (Waterstradt 1902: 9 - 10). We conclude that Pulai Princess Cave must be the type locality of Plectostoma laidlawi. However, a recent survey at the highly degraded Bukit Pulai Princess cave failed to retrieve any shells of Plectostoma. Distribution range. This species occurs on the limestone hills along Berok River and Nenggiri River (Figure 18 B).	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
9978D1AD2EAC81C877637BA85B4BBEA9.taxon	discussion	Discussion. The morphology of this species is quite variable in shell size and degree of attachment of the tuba to the spire. The distribution range partially overlaps with that of Plectostoma davisoni. It is possible that the species actually consists of two or more cryptic species, and thus more genetic data are needed.	en	Liew, Thor-Seng, Vermeulen, Jaap Jan, Marzuki, Mohammad Effendi bin, Schilthuizen, Menno (2014): A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. ZooKeys 393: 1-107, DOI: http://dx.doi.org/10.3897/zookeys.393.6717, URL: http://dx.doi.org/10.3897/zookeys.393.6717
