taxonID	type	description	language	source
537A87CE8347FFB0FF04FEA8FE19FC23.taxon	description	Roberts (1993) provided a previously unpublished but more informative description and a watercolor of A. dialuzona by Valenciennes (fig. 25), a drawing by J. Werner based on RMNH 2707 — the type of A. dialuzona (fig. 59), and a vertebral count of 30 abdominal + 14 caudal = 44 for the type. The description and illustrations were apparently intended for, but were not included in, the Histoire naturelle des Poissons (Cuvier and Valenciennes 1846). The description included: " Compressed body and head, more pointed snout than in Cobitis. Eyes on top of head, almost touching, preceded by pointed spines. Very small mouth, very short barbels. Dorsal fin in middle of body. Long, pointed pectoral fin. Reddish back, white belly, silvery stripe along side of body, 8 – 9 darker gray oblong spots. Greenish-gray caudal fin with black dot at upper base. Dorsal-fin rays 11; pectoral-fin rays 10; pelvic-fin rays 7, anal-fin rays 6, caudal-fin rays 15. " Bleeker (1860) redescribed A. dialuzona based on additional specimens collected from Batavia [Jakarta]. The description was reproduced in English in van Oijen and Loots (2012: 76 – 77, fig. 4), along with an illustration from the Atlas Ichthyologique (Bleeker 1863 – 1864) of the original drawing of the type left in Java by van Hasselt, as noted by Roberts (1993).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8347FFB0FF04FEA8FE19FC23.taxon	diagnosis	Diagnosis. Cobitidae. Distinguished from all other genera by the erectile, bifid ‘ suborbital’ spine being far forward, approximately midway between the eye and the tip of the long snout (Fig. 5). In other genera of cobitids, the spine is located under or slightly anterior to the eye, never midway between the eye and the tip of the snout. The only other cobitid genus in mainland Southeast Asia with a similar body shape and color pattern is Aperioptus Richardson (Siebert 1991 a, Page and Tangjitjaroen 2015), which is distinguished from Acantopsis by having the suborbital spine only slightly anterior to the eye (reaching posteriorly to at least the anterior margin of the eye), 7 branched dorsal-fin rays (8 or more in Acantopsis), and the dorsal-fin origin over, slightly anterior, or slightly posterior to the pelvic-fin origin (vs. far in front of the pelvic-fin origin in Acantopsis). Although morphologically similar, molecular data indicate that Kottelatlimia may be more closely related to one of these two genera than Acantopsis and Aperioptus are to each other (Fig. 4, Šlechtová et al. 2008, Havird et al. 2010).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8347FFB0FF04FEA8FE19FC23.taxon	description	Description. Body long and slender, deepest predorsally; straight to slightly arched predorsally, tapering from origin of dorsal fin to narrow caudal peduncle. Venter flat, tapering from origin of pelvic fins, more strongly from origin of anal fin, to caudal peduncle. Dorsal-fin origin far in front of pelvic-fin origin. Head long (22 – 30 % SL); snout long (54 – 72 % HL), pointed, steeply sloped to nape. Suborbital spine bifid, medial point longest (Fig. 5), located near midpoint between eye and tip of snout. Groove containing spine ending below anterior margin of eye; spine ending well before eye. Eye round, subcutaenous, high on rear half of head; interorbital distance less than eye diameter. Window to gas bladder posterior to dorsal limb of cleithrum. Scales absent on head and breast, usually absent along midline of abdomen; rest of body covered with ctenoid scales; scales typically embedded on nape, lower side of body, and often anteriorly on side of body. Caudal fin forked in large individual, emarginated in small individual; lobes subequal. Lateral line complete, extending onto caudal fin for short distance. Branched dorsal rays 8 ½ – 11 ½; branched caudal rays 14, 7 in upper, 7 in lower lobe; branched anal rays 5 ½; pectoral rays 9 – 11; pelvic rays 7; 28 – 35 abdominal plus 10 – 14 caudal = 39 – 48 total vertebrae. One pair each of rostral, maxillary, and mandibular barbels; 0 – 3 pairs of labial barbels. Maximum SL = 212.5 mm, TL = 242.5 mm (A. spectabilis, NIFI 2456). Color. Color patterns vary inter- and intraspecifically. Variation within species, and possibly among species, appears to be related to habitat with darker patterns on individuals living on mixed sand and gravel or in clear water, and lighter patterns on those living on sand only or in turbid water. Intraspecific variation in color can be extreme and is probably in large part accountable for the taxonomic confusion that has surrounded this genus. The most conspicuous aspects of the color pattern of all species are the 1 – 2 rows of dark-brown to black spots on top of the head, continuing as a row of saddles along the dorsal midline to the origin of the caudal fin, and a row of smaller dark spots or blotches along the midside of the body from the head to the origin of the caudal fin. Spots on top of the head are in one row anterior to the nares and one or two rows posterior to the nares. Dorsal saddles and spots along the side may be faint, and the latter are often obscured by a dusky to dark line along the lateral line. Less well-defined dark spots, blotches, and reticulations may occur on the upper side, and less often on the lower side. Other dark brown to black pigment may include spots on the cheek and opercle, sometimes as 1 – 2 welldefined rows of large spots with many smaller spots above; large spots or dusky bands on the dorsal, caudal, anal, and paired fins; and a small black spot near the upper margin of the origin of the caudal fin, sometimes developed as an ocellus. The lower side of the head, breast, and belly are white. In life, large individuals have a faint yellow to reddish brown cast dorsally, are translucent white ventrally, and have a green iridescence on the side of the head. Fins are mostly clear but with dusky bands on some or all fins, black spots in the dorsal and caudal fins, and a faint yellowish cast on the paired and anal fins (Inger and Chin 1962, pers. obs.). Some species have a reddish-brown streak along the lower caudal-fin margin near the base. Smaller individuals are more translucent and have less contrasting color patterns. Sexual dimorphism. Males have a longer, ramified first branched pectoral-fin ray as noted by Inger and Chin (1962) and Siebert (1991 b, fig. 3), and a distal lobe on the first branched pectoral-fin ray in at least one species (A. dinema, Fig. 5). In some, perhaps all species males reach a smaller adult size. In the largest series of specimens examined, (UF 188116; A. dinema) males (N = 15) averaged 88.1 mm SL, and females (N = 45) averaged 99.5 mm SL. In at least some species, the medial point of the suborbital spine is longer and more curved in males (Siebert 1991 b). Interspecific and seasonal variation in sexually dimorphic characteristics, perhaps including color, remains mostly unknown in Acantopsis.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8341FFACFF04FC05FDE9FC07.taxon	description	(Fig. 6)	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8341FFACFF04FC05FDE9FC07.taxon	diagnosis	Diagnosis. Acantopsis dialuzona differs from all other species of Acantopsis (Table 4) by combination of usually 3 pairs of labial barbels, well developed ocellus on upper margin of caudal-fin base, 0 – 1 row of large spots on side of head, no large black spots on dorsal or caudal fins, rarely black specks beneath midlateral row of black spots, usually 10 ½ branched dorsal rays and 10 pectoral rays, 11 – 17 dark saddles along dorsal midline, 7 – 13 black spots along side of body, 42 – 43 total vertebrae, body depth 8.9 – 11.9 % SL, body width 6.4 – 9.1 % SL, caudal-peduncle length 12.5 – 16.2 % SL. Comparisons. Acantopsis dialuzona is distinguished from all species of Acantopsis by having a well developed ocellus on the upper margin of the caudal-fin base, and from all species except A. spectabilis by having 3 (vs. 0 – 2) pairs of labial barbels. Acantopsis dialuzona differs from A. spectabilis and A. thiemmedhi in lacking conspicuous black spots, blotches, or bands on the caudal, anal, and paired fins, and from A. thiemmedhi in lacking a large black blotch on the tip of the anterior rays of the dorsal fin. It further differs from A. dinema in having large black spots on side of head, a less deep body (8.9 – 11.9 vs. 12.0 – 14.5), and lacking many black specks beneath midlateral row of black spots. It further differs from A. spectabilis, A. rungthipae, and A. ioa by having usually 10 ½ (vs. 9 ½) branched dorsal rays, from A. ioa by having 42 – 43 (vs. 46 – 48) total vertebrae, and from A. octoactinotos by having usually 10 ½ (vs. 8 ½) branched dorsal rays, usually 10 (vs. 9) pectoral rays, large dark spots on side of head.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8341FFACFF04FC05FDE9FC07.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (22.9 – 29.7 % SL); snout long (59.5 – 71.8 % HL); 3, rarely 0 – 2, pairs of labial barbels; 10 ½, rarely 9 ½ or 11 ½, branched dorsal rays; 10, rarely 9 or 11, pectoral rays; 28 – 31 abdominal + 11 – 14 caudal = 42 – 44 total vertebrae (Table 1; Roberts 1989, 1993). Maximum SL = 183.6 mm, TL = 221.8 mm (UF 235414). Color. Dark spots in 1 or 2 rows on top of head, scattered or in 1 poorly defined row on side of head. Eleven – 17 dark saddles along dorsal midline; 7 – 13 large dark spots or blotches along lateral line from head to caudal fin; dark spots or reticulations on upper side of body. Dark pigment on lower side highly variable; usually absent, but rarely with many dark specks. Four – 5 faint bands on dorsal and caudal fins; other fins with no or faint bands; caudal fin sometimes with dark lower margin. Bold black spot in center of ocellus near upper margin of caudal-fin origin. Bleeker (1860) described A. dialuzona as having irregular, diffuse, violet-colored spots in a longitudinal row or more or less united into a stripe along the side of the body, a small black spot at the upper edge of the caudal-fin base; and 3 – 4 dusky bands on the caudal fin.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8341FFACFF04FC05FDE9FC07.taxon	distribution	Distribution. Acantopsis dialuzona occurs in Java, Borneo, Sumatra, and the Malay Peninsula as far north as southern Thailand (Fig. 7). This distribution primarily encompasses the Southern Sumatra-Western Java and Malay Peninsula Eastern Slope ecoregions of Abell et al. (2008). It has been reported from areas of Southeast Asia outside its range, including as A. choirorhynchos (e. g., Seibert 1991 b, Sontirat 1999, and Vishwanath and Laisram 2005), because of the lack of taxonomic resolution in Acantopsis.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8341FFACFF04FC05FDE9FC07.taxon	discussion	Remarks. Cobitis choirorhynchos, treated by Kottelat (2012) and here as a synonym of A. dialuzona, was described by Bleeker (1854) based on three specimens 170 – 178 mm in total length from Sumatra. Alfred (1961 a) re-examined these specimens and designated a lectotype (RMNH 4977, Fig. 8) with a total length of 166 mm and SL of 142 mm (the shorter TL recorded by Alfred is presumably due to shrinkage). A more detailed description of C. choirorhynchos by Bleeker (1860) is reproduced in English in van Oijen and Loots (2012: 75 – 76, fig. 3) along with an illustration from the “ Atlas Ichthyologique ” (Bleeker 1863 – 1864). The only characters used by Bleeker (1854, 1860) to distinguish C. choirorhynchos from A. dialuzona was a slightly longer head, going 4 ⅔ to slightly more than 5 times in length of the body vs. 5 to 5 ⅓ times in A. dialuzona; dark spots on the head, back, and side of the body vs. no dark spots on head and back; and anal fin with 5 – 6 rays vs. 6 – 7 rays. Head length increases with standard length, and the proportionally longer head in the type of C. choirorhynchos is a function of the fact that the type of C. choirorhynchos is larger than the type of A. dialuzona (Fig. 3). Presence / absence of dark pigment on the back and side of the body is highly variable and likely related to water clarity and the color of the substrate on which specimens were collected.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835DFFAEFF04FA74FCC8FEE4.taxon	diagnosis	Diagnosis. Acantopsis spectabilis differs from all other species of Acantopsis (Table 4) by combination of 3 – 4 black spots along upper lobe, 2 – 3 larger, often darker, black spots on lower lobe of caudal fin (smaller black spots in middle of fin); 1 – 2 bands on anal and paired fins; 2 – 3 pairs of labial barbels, 9 ½ branched dorsal rays; 10 pectoral rays; 9 – 12 dark saddles along dorsal midline; 9 – 15 black spots along side of body; 2 – 3 rows of large dark spots on side of head, 43 – 44 total vertebrae, body depth 9.0 – 11.6 % SL, body width 6.8 – 9.4 % SL, caudal-peduncle length 12.9 – 16.6 % SL. Comparisons. The unique color pattern on caudal fin distinguishes A. spectabilis from all other species of Acantopsis. It is most similar to A. thiemmedhi, which differs in having 1 large black blotch on each lobe of caudal fin. All other species of Acantopsis have no or dusky bands on caudal fin. It further differs from A. thiemmedhi by having 2 – 3 (vs. 1) pairs of labial barbels and in having usually 9 ½ (vs. 10 ½) branched dorsal rays and in lacking large black blotch on tip of anterior rays of dorsal fin. It further differs from A. dinema by having dark large spots on side of head, no row of black specks beneath midlateral row of black spots, usually 9 ½ (vs. 10 ½) branched dorsal rays, smaller body depth (9.0 – 11.6 vs. 12.0 – 14.5 % SL). It further differs from A. rungthipae and A. ioa by having 2 – 3 (vs. 0) pairs of labial barbels, from A. rungthipae in lacking distinct small black spot on upper margin of caudal-fin base, and from A. ioa in having 9 – 12 (vs. 15 – 23) dark saddles along dorsal midline, 9 – 15 (vs. 13 – 21) black spots along side of body, large dark spots on side of head, 43 – 44 (vs. 46 – 48) total vertebrae. It further differs from A. dialuzona by lacking a well developed ocellus on the upper margin of the caudal-fin base and having usually 9 ½ (vs. 10 ½) branched dorsal rays.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835DFFAEFF04FA74FCC8FEE4.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (21.8 – 25.7 % SL); snout long (60.1 – 70.3 % HL); 2 – 3 pairs of labial barbels; 9 ½, rarely 8 ½, branched dorsal rays; 10, rarely 11, pectoral rays; 31 – 32 abdominal + 12 caudal = 43 – 44 total vertebrae (N = 3). Maximum SL = 212.5 mm, TL = 242.5 mm (NIFI 2456). Color. Dark spots in 1 row on top of head, scattered or in 2 – 3 rows on side of head. Black line from eye to tip of snout. Nine – 12 dark saddles along dorsal midline; 9 – 15 dark spots or blotches along to slightly below lateral line from head to caudal fin, varying from large and rounded to flattened and elongate; dark spots and blotches on upper side of body, none on lower side. Two – 3 bold, irregular bands of blotches on caudal fin, darkest at extremity of lower lobe and along margins. One – 2 dark bands on anal and paired fins. Small black spot near tip of anterior rays of dorsal fin. No small black spot or ocellus near upper margin of caudal-fin origin.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835DFFAEFF04FA74FCC8FEE4.taxon	distribution	Distribution. Acantopsis spectabilis is known from the Irrawaddy River basin of Myanmar and India, the Salween River basin of Thailand and Myanmar, and the Tenasserim provinces region (Dawei River, and presumably the Ataran River basin) of Myanmar (Fig. 10).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835EFFA8FF04FF65FD19FF53.taxon	diagnosis	Diagnosis. Acantopsis octoactinotos differs from all other species of Acantopsis (Table 4) by having usually 8 ½ branched dorsal rays. It also differs by combination of 2 pairs of labial barbels, black spot on upper margin of caudal-fin base, no black spot on tip of anterior rays of dorsal fin, no large dark spots on side of head, no row of black specks beneath midlateral row of black spots, usually 9 pectoral rays, 11 – 17 dark saddles along dorsal midline, 8 – 13 large dark spots along side of body, 40 – 44 total vertebrae, body depth 9.6 – 11.2 % SL, body width 6.8 – 7.9 % SL, caudal-peduncle length 16.1 – 17.2 % SL. Comparisons. Acantopsis octoactinotos is distinguished from all other species of Acantopsis by having 8 ½ (vs. 9 ½ or 10 ½) branched dorsal rays, and all species except A. dinema by lacking large dark spots on side of head. It differs from A. dialuzona, A. spectabilis, A. rungthipae, and A. ioa in having 9 (vs. 10) pectoral rays, and from A. spectabilis and A. thiemmedhi in having black spot on upper margin of caudal-fin base and no conspicuous black spots, blotches, or bands on caudal fin. It further differs from A. thiemmedhi in lacking large black blotch on tip of anterior rays of dorsal fin, and in having 2 (vs. 1) pairs of labial barbels, 11 – 17 (vs. 7 – 9) dark saddles along dorsal midline, longer caudal-peduncle 16.1 – 17.2 vs. 12.5 – 14.7 % SL. It further differs from A. rungthipae in having 2 (vs. 0) pairs of labial barbels; from A. ioa in having 2 (vs. 0) pairs of labial barbels, 8 – 13 (vs. 13 – 21) dark spots along side of body, 40 – 44 (vs. 46 – 48) total vertebrae; and from A. dinema in having a small black spot on upper margin of caudal-fin base, no row of black specks beneath midlateral row of black spots, smaller body depth 9.6 – 11.2 vs. 12.0 – 14.5 % SL, longer caudal-peduncle 16.1 – 17.2 vs. 12.1 – 14.3 % SL.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835EFFA8FF04FF65FD19FF53.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (22.5 – 24.6 % SL); snout long (53.7 – 58.4 % HL); 2 pairs of labial barbels; 8 ½ (rarely 7 or 9; Siebert 1991 b) branched dorsal rays; 9, rarely 10, pectoral rays; 28 – 29 abdominal + 12 – 13 caudal = 41 – 42 total vertebrae (Table 1); Siebert (1991 b) reported 40 – 44 total vertebrae. Maximum SL = 96.0 mm (FMNH 68150, caudal fin damaged). Color. Dark spots in 1 – 2 rows on top of head; no large dark spots on side of head. Black line from eye to tip of snout. Eleven – 17 dark saddles along dorsal midline to origin of caudal fin; 8 – 13 dark spots or blotches along lateral line from head to caudal fin; small dark spots and reticulations on upper side of body; no dark spots on lower side of body below midlateral row of dark spots. Dorsal and caudal fins without bands; no dark margins on caudal fin. Small bold black spot near upper margin of caudal-fin origin; faint black spot on lower margin of caudal-fin origin. Inger and Chin (1962) reported pale yellowish coloration in live A. octoactinotos. Sexual dimorphism. Males have a longer, ramified first branched pectoral-fin ray (Siebert 1991 b).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835EFFA8FF04FF65FD19FF53.taxon	distribution	Distribution. Acantopsis octoactinotos is known from the Kinabatangan River and Segama River (Martin- Smith and Tan 1998) basins, Sabah, Malaysia (Fig. 7).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8359FFAAFF04FED5FCEFFA47.taxon	diagnosis	Diagnosis. Acantopsis thiemmedhi differs from all other species of Acantopsis (Table 4) by combination of large black blotch on tip of anterior rays of dorsal fin, large black blotch on tip of each lobe of caudal fin; usually 1 pair of labial barbels, 10 ½ branched dorsal rays, and 10 pectoral rays; 7 – 9 dark saddles along dorsal midline, 6 – 10 black spots along side of body, 1 row of large dark spots on side of head, 39 – 41 total vertebrae, body depth 9.8 – 16.6 % SL, body width 5.8 – 10.3 % SL, caudal-peduncle length 12.5 – 14.7 % SL. Comparisons. Acantopsis thiemmedhi differs from all other species of Acantopsis by having large black blotch on tip of anterior rays of dorsal fin and large black blotch on each lobe of caudal fin. Acantopsis spectabilis has much smaller black blotch (often absent) on tip of anterior rays of dorsal fin, 2 – 3 irregular bands or blotches on caudal fin, darkest at extremity of lower lobe. Other species of Acantopsis have dusky to dark bands on dorsal fin but no conspicuous black blotch at tip of anterior rays, and dusky bands on caudal fin. Acantopsis thiemmedhi further differs from A. spectabilis in having 1 (vs. 2 – 3) pair of labial barbels, and usually 10 ½ (vs. 9 ½) branched dorsal rays. Acantopsis thiemmedhi further differs from A. dialuzona by lacking well developed ocellus on the upper margin of the caudal-fin base, and having 1 (vs. 3) pair of labial barbels, 7 – 9 (vs. 11 – 17) dark saddles along dorsal midline, and 6 – 10 (vs. 7 – 13) black spots along side of body. It further differs from A. octoactinotos by having usually 10 ½ (vs. 8 ½) branched dorsal rays, large dark spots on side of head, 1 (vs. 2) pair of labial barbels, usually 10 (vs. 9) pectoral rays, 7 – 9 (vs. 11 – 17) dark saddles along dorsal midline, shorter caudal-peduncle 12.5 – 14.7 vs. 16.1 – 17.2 % SL. It further differs from A. dinema by having 1 (vs. 2) pair of labial barbels, large dark spots on side of head, and no row of black specks beneath midlateral row of black spots. It further differs from A. rungthipae and A. ioa by having 1 (vs. 0) pair of labial barbels and usually 10 ½ (vs. 9 ½) branched dorsal rays, from A. rungthipae in lacking distinct small black spot on upper margin of caudal-fin base and in having 6 – 10 (vs. 9 – 17) black spots along side of body, and from A. ioa in having 7 – 9 (vs. 15 – 23) dark saddles along dorsal midline, 6 – 10 (vs. 13 – 21) black spots along side of body, large dark spots on side of head, 39 – 41 (vs. 46 – 48) total vertebrae.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8359FFAAFF04FED5FCEFFA47.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (22.6 – 26.8 % SL); snout long (57.5 – 68.3 % HL); 1, rarely 2, pairs of labial barbels; 10 ½, rarely 9 ½ or 11 ½, branched dorsal rays; 10, less often 9 or 11, pectoral rays; 28 – 30 abdominal + 10 – 11 caudal = 39 – 41 total vertebrae (Table 1; Sontirat 1999). Maximum SL = 153.3 mm, TL = 191.5 mm (NIFI 2974). Color. Dark spots in 1 row on top of head, in 1 – 2 often poorly defined rows on side of head. Black line from eye to tip of snout. Seven – 9 dark saddles along dorsal midline; 6 – 10 large dark spots or blotches along lateral line from head to caudal fin; dark spots and blotches on upper side of body, none on lower side. Large black blotch near tip of anterior rays of dorsal fin, separated from black band near margin of fin; large individuals with second band in middle of fin with black spot anteriorly. Large black blotch on each lobe of caudal fin, sometimes with dark band connecting blotches; often smaller black spots or bands in middle of caudal fin. Faint bands on other fins. No small bold black spot or ocellus near upper margin of caudal-fin origin. Live individuals yellowish brown dorsally, white below, with large black blotches dorsally and laterally on body; dorsal and caudal fins with black and white bands and spots, iridescent yellow on side of head and lower fins.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8359FFAAFF04FED5FCEFFA47.taxon	distribution	Distribution. Acantopsis thiemmedhi is widespread, but seemingly uncommon, in the Chao Phraya River basin, Thailand (Fig. 13). Most of the specimens examined are from the Wang River drainage.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8359FFAAFF04FED5FCEFFA47.taxon	discussion	Remarks. The holotype of Acantopsis thiemmedhi, KUMF 3131, was examined and found to differ in fin ray counts from those recorded by Sontirat (1999). It has 9 branched dorsal rays, 11 pectoral rays, and 7 pelvic rays. Pectoral-fin rays for all 21 paratypes range from 9 to 11.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835BFFA5FF04F9E6FC1FFF7F.taxon	description	(Fig. 14)	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835BFFA5FF04F9E6FC1FFF7F.taxon	materials_examined	Holotype. THNHM F 0013610, 107.4 mm SL female (ex. UF 235976), Thailand, Welu River drainage, Chanthaburi Province, Khlung District, Khen Creek, tributary of Trok Nong River, off Rt. 3277, 12.537 N, 102.244 E, 30 January 2014, Nithirojpakdee, J. et al. Paratypes. Thailand: Welu River drainage: same locality and date as holotype: UF 235976 (6, 89.9 – 119.7 mm SL); ZRC 55596 (2, 93.2 – 111.6 mm SL); NIFI 5102 (2, 94.2 – 118.0 mm SL). Tapi River drainage: ANSP 179976 (1, 119.0 mm SL), Krabi / Surat Thani Provinces, Ipan River, trib. of Tapi River, on Rt. 4035, 25 km NE of Ao Luek, 08.623 N, 98.980 E, 22 February 2001, M. H. Sabaj and M. Hardman. INHS 93550 (1, 109.0 SL) same locality and date as ANSP 179976.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835BFFA5FF04F9E6FC1FFF7F.taxon	diagnosis	Diagnosis. Acantopsis rungthipae differs from all other species of Acantopsis (Table 4) by combination of no exposed labial barbels, usually distinct small black spot on upper margin of caudal-fin base, 0 – 1 row of large spots on side of head, no large black spots on dorsal or caudal fins, no black specks beneath midlateral row of black spots (rarely present), usually 9 ½ branched dorsal rays and 10 pectoral rays, 10 – 20 dark saddles along dorsal midline, 9 – 17 black spots along side of body, 41 – 43 total vertebrae, body depth 9.0 – 14.2 % SL, body width 5.3 – 10.3 % SL, caudal-peduncle length 11.5 – 16.1 % SL. Comparisons. Acantopsis rungthipae is distinguished from all species of Acantopsis except A. ioa by having no labial barbels. It is distinguished from A. ioa by usually having a distinct small black spot on upper margin of caudal-fin base, 9 – 17 (vs. 13 – 21) black spots along side of body, and 41 – 43 (vs. 46 – 48) total vertebrae (Fig. 15). It further differs from A. dinema by having large dark spots on side of head, usually lacking conspicuous row of black specks beneath midlateral row of black spots, having usually 9 ½ (vs. 10 ½) branched dorsal rays, a distinct small black spot (vs. no spot) on upper margin of caudal-fin base, and usually 4 – 6 faint, narrow bands (vs. no bands) on caudal fin. It further differs from A. octoactinotos by having usually 9 ½ (vs. 8 ½) branched dorsal rays, large dark spots on side of head, usually 10 pectoral rays. It differs from A. spectabilis and A. thiemmedhi in lacking conspicuous black bands on the anal and paired fins and spots or blotches on the caudal fin. It further differs from A. thiemmedhi in lacking a large black blotch on the tip of the anterior rays of the dorsal fin and in having usually 9 ½ (vs. 10 ½) branched dorsal rays, and from A. dialuzona by lacking a well developed ocellus on the margin of caudal-fin base and having usually 9 ½ (vs. usually 10 ½) branched dorsal rays.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835BFFA5FF04F9E6FC1FFF7F.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (21.6 – 25.6 % SL); snout long (54.7 – 68.7 % HL); no exposed labial barbels; 9 ½, rarely 10 ½, branched dorsal rays; 10, rarely 9 or 11, pectoral rays; 29 – 31 abdominal + 11 – 12 caudal = 41 – 43 total vertebrae. Maximum SL = 203.2 mm, TL = 241.3 mm (CAS 238293). Color. Dark spots in 1 – 2 rows on top of head, usually 1 row anteriorly, 2 posteriorly; dark spots on side of head usually in 1 row. Black line from eye to tip of snout. Ten – 20 dark saddles along dorsal midline; 9 – 17 large dark spots or blotches along lateral line from head to caudal fin; small dark spots on upper side of body; no or few dark spots on lower side of body below midlateral row of dark spots. Dorsal fin with 2 – 3 faint bands, caudal with 4 – 5 faint bands; no dark upper and lower margins on caudal fin. Small bold black spot near upper margin of caudal-fin origin. Live individuals yellowish brown dorsally, white below, with large black blotches dorsally and laterally on body; reddish brown streak on lower caudal margin; iridescent yellow on side of head and lower fins. Sexual dimorphism. Males have a longer, ramified first branched pectoral-fin ray.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835BFFA5FF04F9E6FC1FFF7F.taxon	etymology	Etymology. This species is named in honor of Rungthip Plongsesthee, who was born on 27 May 1978 and died on 16 July 2014. “ Kae ” was a dear friend, close colleague, a Ph. D. student of Dr. F. W. H. Beamish at Burapha University, Bangsaen, Thailand, and an extremely enthusiastic ichthyologist who is greatly missed by her many friends.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE835BFFA5FF04F9E6FC1FFF7F.taxon	distribution	Distribution. Acantopsis rungthipae is the most widespread and common species of Acantopsis in mainland Asia. It is known from the Tapi, Mae Khlong, Chao Phraya, Bang Pakong, and Welu River basins in Thailand, and the Mekong River basin in Thailand, Cambodia, Laos, and Vietnam (Fig. 16).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8357FFA0FF04FF65FAD0F93A.taxon	description	(Fig. 17)	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8357FFA0FF04FF65FAD0F93A.taxon	materials_examined	Holotype. THNHM F 0013611, 100.7 mm SL female (ex. UF 188225), Thailand, Mekong River drainage, Ubon Ratchathani Province, Pho Sai District, Ta Wang River on Rt. 2112, 4 km S of Rt. 2337, 15.793 N, 105.376 E, 1 February 2016, Randall, Z. et al. Paratypes. Thailand: Mekong River drainage: UF 188225 (3, 72.4 – 97.9 mm SL), same locality and date as holotype. UF 185131 (9, 71.5 – 94.3 mm SL), same locality as holotype, 3 January 2013, Singer, R. et al. ANSP 200533 (2, 89.5 – 90.9 mm SL), ex. UF 185131. NIFI 5104 (2, 81.0 – 86.9 mm SL), ex. UF 185131. UF 188116 (56, 68.1 – 117.7 mm SL), Sakon Nakhon Province, Akat Amnuai District, Songkhram River at confluence with Yam River, 17.709 N, 104.076 E, 8 January 2015, Boyd, D. et al. ZRC 55598 (3, 94.6 – 105.5 mm SL), ex. UF 188116. INHS 110606 (3, 75.8 – 107.7 mm SL), ex. UF 188116.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8357FFA0FF04FF65FAD0F93A.taxon	diagnosis	Diagnosis. Acantopsis dinema differs from all other species of Acantopsis (Table 4) by combination of no large spots on side of head, many black specks beneath midlateral row of black spots from head to caudal fin, 2 pairs of labial barbels, no distinct small black spot on upper margin of caudal-fin base, no large black spots on dorsal or caudal fins, usually 10 ½ branched dorsal rays and 10 pectoral rays, 8 – 17 dark saddles along dorsal midline, 6 – 12 black spots along side of body, 41 – 42 total vertebrae, body depth 12.0 – 14.5 % SL, body width 8.0 – 10.3 % SL, caudal-peduncle length 12.1 – 14.3 % SL. Comparisons. Acantopsis dinema is distinguished from all other species of Acantopsis by having a row of black specks beneath midlateral row of black spots (specks rarely present in A. dialuzona and A. rungthipae; absent in other species of Acantopsis), and from all species except A. octoactinotos by having no dark spots on side of head (vs. usually conspicuous dark spots or specks on side of head). It further differs from A. rungthipae and A. ioa by having 2 (vs. 0) pairs of labial barbels, usually 10 ½ (vs. 9 ½) branched dorsal rays; from A. rungthipae by lacking distinct small black spot on upper margin of caudal-fin base; and from A. ioa in having 6 – 12 (vs. 13 – 21) black spots along side of body, 41 – 42 (vs. 46 – 48) total vertebrae (Fig. 15), a wider body (8.0 – 10.3 vs. 5.2 – 7.9 % SL). It further differs from A. octoactinotos in having usually 10 ½ (vs. 8 ½) branched dorsal rays, usually 10 (vs. 9) pectoral rays, no small black spot on upper margin of caudal-fin base, a shorter caudal peduncle (12.1 – 14.3 vs. 16.1 – 17.2 % SL). It further differs from A. spectabilis and A. thiemmedhi in lacking conspicuous black spots, blotches, or bands on caudal, anal, and paired fins; from A. spectabilis in having usually 10 ½ (vs. 9 ½) branched dorsal rays; and from A. thiemmedhi in having 2 (vs. 1) pairs of labial barbels, no large black blotch on tip of anterior rays of dorsal fin. It further differs from A. dialuzona in having 2 (vs. 3) pairs of labial barbels, no well developed ocellus on upper margin of caudal-fin base. It differs from A. dialuzona, A. spectabilis, A. octoactinotos, and A. ioa by having a deeper body (12.0 – 14.5 vs. 8.9 – 11.9, 9.0 – 11.6, 9.6 – 11.2, and 8.5 – 11.0 % SL, respectively).	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8357FFA0FF04FF65FAD0F93A.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (24.1 – 26.9 % SL); snout long (58.8 – 65.9 % HL); 2, rarely 3, pairs of labial barbels; 10 ½, rarely 11 ½, branched dorsal rays; 10, less often 9 or 11, pectoral rays; 29 – 31 abdominal + 10 – 13 caudal = 41 – 42 total vertebrae. Maximum SL = 116.7 mm, TL = 139.1 mm (UF 188116). Color. Dark spots in 1 or 2 rows on top of head; no or few scattered small spots on side of head; none large. Black line from eye to tip of snout. Eight – 17 dark saddles along dorsal midline to origin of caudal fin; 6 – 12 large dark spots or blotches along lateral line from head to caudal fin; many small dark spots or specks on upper side of body and on lower side of body just below midlateral row of dark spots from head to caudal fin. Fins usually without obvious bands; 2 – 3 faint bands on dorsal fin of large individuals. Dark upper and lower margins of caudal fin. No small bold black spot or ocellus near upper or lower margins of caudal-fin origin. Live individuals yellowish brown dorsally, white below, with large black blotches dorsally and laterally on body; iridescent yellow on side of head and lower fins. Sexual dimorphism. Males have a longer first branched pectoral-fin ray, ramified and with a distinctive lateral lobe on the distal end (Fig. 5). As far as is known, other species of Acantopsis do not develop the distinctive distal expansion of the first branched pectoral-fin ray. In the largest series of A. dinema examined, (UF 188116) males (N = 15) averaged 88.1 mm SL, and females (N = 45) averaged 99.5 mm SL.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8357FFA0FF04FF65FAD0F93A.taxon	etymology	Etymology. The epithet dinema, from Latin, di meaning two, and nema, for thread, refers to the usual presence of two pairs of labial barbels in this species.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8357FFA0FF04FF65FAD0F93A.taxon	distribution	Distribution. Acantopsis dinema is widespread and common in the tributaries of the Mekong River draining the Khorat Plateau and Mekong Delta ecoregions (Abell et al. 2008) in Thailand, Laos, and Cambodia (Fig. 18), from the Songkhram River in eastern Thailand to the Prek Thnot River south of Phnom Penh, Cambodia.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8351FFA3FF04F8F0FE5DFD9F.taxon	description	(Fig. 19)	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8351FFA3FF04F8F0FE5DFD9F.taxon	materials_examined	Holotype. UMMZ 250301, 128.4 mm SL (ex. UMMZ 240684), Laos, Mekong River drainage, Vientiane Province, Nam Lik, 6 km upstream of confluence with Nam Ngum River, 18.583 N, 102.500 E, 22 January 1997, W. J. Rainboth and M. Anderson. Paratypes. Laos: Mekong River drainage: UMMZ 240684 (13, 88.4 – 132.0 mm SL), same locality and date as holotype. UF 190865, 3, 96.5 – 114.9 mm SL (ex. UMMZ 240684). THNHM F 0013612, 1, 107.1 mm SL (ex. UMMZ 240684). Thailand: Mekong River drainage: UF 188135 (23, 60.6 – 98.4 mm SL), Ubon Ratchathani Province, Khong Chiam District, Mekong River at mouth of Mun River, 15.318 N, 105.513 E, 22 January 2015, D. Gridsada et al.; ANSP 200532 (2, 78.8 – 79.0 mm SL), ex. UF 188135; NIFI 5103 (2, 72.2 – 73.3 mm SL), ex. UF 188135; ZRC 55597 (2, 80.2 – 82.8 mm SL), ex. UF 188135; INHS 110605 (2, 82.7 – 83.6 mm SL), ex. UF 188135.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8351FFA3FF04F8F0FE5DFD9F.taxon	diagnosis	Diagnosis. Acantopsis ioa differs from all other species of Acantopsis (Table 4) by combination of no labial barbels, usually no distinct small black spot on upper margin of caudal-fin base, 0 – 1 row of large spots on side of head, no large black spots on dorsal or caudal fins, no row of black specks beneath midlateral row of black spots, usually 9 ½ branched dorsal rays and 10 pectoral rays, 15 – 23 narrow, blotch-like saddles along dorsal midline, 13 – 21 black spots along side of body, and 46 – 48 total vertebrae, body depth 8.5 – 11.0 % SL, body width 5.2 – 7.9 % SL, caudal-peduncle length 13.1 – 16.2 % SL. Comparisons. Acantopsis ioa is distinguished from all species of Acantopsis by having narrow blotch-like dorsal saddles, 46 – 48 (vs. <45) total vertebrae (Fig. 15), and from all other species in the genus except A. rungthipae by having no labial barbels. It is further distinguished from A. rungthipae by usually lacking a distinct small black spot on upper margin of caudal-fin base, 13 – 21 (vs. 9 – 17) black spots along side of body. It further differs from A. dinema in having no black specks beneath midlateral row of black spots, large dark spots usually present on side of head, usually 9 ½ (vs. 10 ½) branched dorsal rays, smaller body depth (8.5 – 11.0 vs. 12.0 – 14.5 % SL) and width (5.2 – 7.9 vs. 8.0 – 10.2 % SL). It further differs from A. octoactinotos in having no distinct small black spot on upper margin of caudal-fin base, large dark spots usually present on side of head, usually 9 ½ (vs. 8 ½) branched dorsal rays, usually 10 (vs. 9) pectoral rays. It further differs from A. spectabilis and A. thiemmedhi in lacking conspicuous black spots, blotches, or bands on caudal, anal, and paired fins and in having 15 – 23 (vs. <13) dark saddles along dorsal midline, from A. thiemmedhi in lacking a large black blotch on the tip of the anterior rays of the dorsal fin and in having usually 9 ½ (vs. 10 ½) branched dorsal rays, and from A. dialuzona by lacking a well developed ocellus on upper margin of caudal-fin base and having usually 9 ½ (vs. 10 ½) branched dorsal rays.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8351FFA3FF04F8F0FE5DFD9F.taxon	description	Description. As in description of genus; Tables 1, 2, 4. Head long (21.8 – 24.2 % SL); snout long (61.0 – 69.6 % HL); no exposed labial barbels; 9 ½, rarely 10 ½, branched dorsal rays; 10, less often 9 or 11, pectoral rays; 33 – 35 abdominal plus 13 – 14 caudal = 46 – 48 total vertebrae. Maximum SL = 132.0 mm, TL = 152.9 mm (UMMZ 240684). Color. Dark spots in 1 or 2 rows on top of head. Few large dark spots on side of head; if present, usually in 1 row. Faint line from eye to tip of snout. Fifteen – 23 narrow, rounded saddles along dorsal midline; 13 – 21 dark spots along lateral line from head to caudal fin; spots more discrete than in other species. Small dark spots on upper side of body; no dark spots on lower side of body. Dorsal and caudal fins with faint bands; other fins without bands. Often a dusky stripe on lower margin of caudal fin. No small bold black spot (rarely present) or ocellus near upper margin of caudal-fin origin.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8351FFA3FF04F8F0FE5DFD9F.taxon	etymology	Etymology. The epithet ioa, from Greek for an arrow or dart, refers to the relative slenderness of this species in relation to other species of Acantopsis.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
537A87CE8351FFA3FF04F8F0FE5DFD9F.taxon	distribution	Distribution. Acantopsis ioa is widespread in the mainstem Mekong River in Thailand and Laos (Fig. 20). It also is known from the Nam Lik, a large tributary of the Mekong in Laos, and the Srepok River, a large tributary of the Mekong in Cambodia.	en	Boyd, David A., Nithirojpakdee, Patchara, Deein, Gridsada, Vidthayanon, Chavalit, Grudpan, Chaiwut, Tangjitjaroen, Weerapongse, Pfeiffer, John M., Randall, Zachary S., Srisombat, Tippamas, Page, Lawrence M. (2017): Revision of the horseface loaches (Cobitidae, Acantopsis), with descriptions of three new species from Southeast Asia. Zootaxa 4341 (2): 151-192, DOI: 10.11646/zootaxa.4341.2.1
