Limnonectes palavanensis ( Boulenger, 1894 )

Dehling, Maximilian, Neokleous, Dario N., Das, Indraneil, Grafe, Ulmar, Min, Pui Yong & Hertwig, Stefan T., 2025, Cryptic radiation within the tadpole-carrying Guardian Frogs from Borneo, Limnonectes palavanensis and L. finchi (Anura: Dicroglossidae), with the description of eight new species, Zootaxa 5650 (1), pp. 1-80 : 12-15

publication ID	https://doi.org/10.11646/zootaxa.5650.1.1
publication LSID	lsid:zoobank.org:pub:F8B8158B-26F9-4E1A-A1CF-A20A72F2D875
DOI	https://doi.org/10.5281/zenodo.15820475
persistent identifier	https://treatment.plazi.org/id/62199F50-FFEC-FFC3-FF34-FCC3FCFFF8BC
treatment provided by	Plazi
scientific name	Limnonectes palavanensis ( Boulenger, 1894 )
status

Treatment

Limnonectes palavanensis ( Boulenger, 1894) View in CoL

Rana palavanensis — Boulenger 1894: 85. Type locality: “ Palawan ”; Boulenger 1897: 230 (partim); Boulenger 1920: 59 (partim); van Kampen 1923: 182 (partim).

Rana microdisca palavanensis — Inger 1954: 299 (partim); Inger 1966: 222 (partim).

Limnonectes palavanensis View in CoL — Setiadi et al. 2011: 224; Inger et al. 2017: 87 (partim).

Lectotype (by present designation). BMNH 1947.2 .1.96, adult female, from Palawan, collected by A. Everett ( Fig. 3A View FIGURE 3 ).

Paralectotypes (by present designation). BMNH 1947.2 .1.94, 1947.2.1.95, two adult females, from Palawan, collected by A. Everett.

Referred specimens. KU 309130 , adult male, from Mt. Mantalingahan (8.7637167°, 117.6867°; 650 m), Barangay Samarinana , Municipality of Brooke’s Point, Palawan Province, Palawan Island, Philippines . KU 309129 , from Irawan Watershed (9.8368°, 118.64125°; 180 m), Barangay Irawan, Municipality of Puerto Princesa, Palawan Province, Philippines .

Diagnosis. Limnonectes palavanensis belongs to the L. palavanensis species group, showing the typical characters of the group, including small size (SVL <40 mm); odontoid processes in lower jaw low and inconspicuous in both males and females; dorsum finely shagreened, with prominent longitudinal dorsolateral glandular ridges; interorbital distance equal to or larger than upper eyelid width; toes not fully webbed; and horseshoe-shaped dermal ridge in middle of dorsum posterior to arm insertion. The species differs from all other species of the group by a unique combination of morphological characters, including toe webbing moderately extensive; supratympanic fold curved; pineal spot weakly discernible, at level of anterior upper-eyelid edge; vomer ridges long, narrowly separated from each other; postpalpebral ridges and lumbar ridges low, indistinct and interrupted; median ridge absent; size small with SVL of adult females 31.6–32.3 mm. The species differs from all other species of the group by at least 6.2% in the sequence of the 16S barcoding gene.

Description of lectotype. Adult female; SVL 31.6 mm; body moderately sturdy, widest at temporal region, slightly tapering to groin ( Fig. 3A View FIGURE 3 ); head large (HL/SVL 0.36, HW/SVL 0.35), about as wide as long (HW/HL 0.97); snout moderately long (SL/HL 0.43), subacuminate in dorsal view, truncate and slightly protruding in lateral profile, wider than long (SL/EE 0.85); canthus rostralis moderately distinct between eye and nostril, slightly concave from eye to nostril in dorsal view; loreal region oblique; nostrils rounded, directed dorsolaterally, situated about halfway between tip of snout and eye (EN/NS 0.97), separated from each other by distance much larger than distance between eye and nostril (NN/EN 1.56); eye directed anterolaterally, moderately protruding, large (ED/HL 0.33), its diameter shorter than snout (ED/SL 0.76); interorbital distance greater than upper eyelid width (IO/EW 1.22) and smaller than internarial distance (IO/NN 0.74); pineal spot weakly discernible, at level of anterior upper-eyelid edge; tympanum and its annulus distinctly and fully visible, not covered by supratympanic fold; tympanum separated from eye by little less than one-third its diameter (ET/TD 0.31); tympanum diameter smaller than eye diameter (TD/ED 0.57); upper jaw with dentition; odontoid processes in lower jaw low, inconspicuous; choanae small, rounded, located far anterolaterally at margins of roof of mouth, lateral fifth covered by palatal shelf of maxilla in ventral view; vomer processes bearing teeth, long, separated from choana by about two-thirds length of individual process and from each other by half length of individual process ( Fig. 4A View FIGURE 4 ); tongue moderately long and narrow, bilobed for about oneeighth its length, free distally for about two-fifths its length; median lingual process absent.

Dorsal surfaces of head, trunk and limbs and lateral surfaces of trunk finely shagreened; small tubercles sparsely scattered on upper eyelid and on dorsum; dorsolateral dermal ridge distinct on both sides from posterior end of upper eyelid to groin; postpalpebral ridge formed by small tubercles, low, interrupted and indistinct; horseshoe-shaped dermal ridge low, in middle of back just behind level of arms; lumbar ridge indistinct, low and interrupted, from near posterior end of horseshoe-shaped ridge to supraanal region; median ridge absent; supratympanic fold thick and conspicuous, extending from posterior end of orbit to insertion of arm, curved ( Fig. 5A View FIGURE 5 ); ventral side of head smooth; transverse chest fold between arm insertions low; ventral side of trunk weakly areolate; ventral side of limbs smooth; cloaca without dermal flap.

Forelimbs moderately sturdy; hand relatively small (HND/SVL 0.24); tips of fingers rounded, slightly enlarged into disks; relative length of fingers: I = II = IV <III; subarticular tubercles rounded, well developed, numbering one on Fingers I and II, two on Fingers III and IV, proximal tubercles on Fingers III and IV larger and more prominent than distal ones; finger webbing absent; thenar tubercle distinct, oval, prominent, about one-third length of metacarpal of Finger I; inner and outer palmar tubercles fused proximally, forming large, roughly U-shaped, prominent tubercle on proximal half of Fingers II–IV.

Hindlimbs sturdy, very long (LEG /SVL 1.86); heel reaching half SL beyond tip of snout when legs adpressed forwardly to body; tibiofibula long (TFL/SVL 0.63), longer than thigh (TFL/THL 1.17); heels overlapping each other considerably when knees flexed and thighs held perpendicularly to median plane; foot shorter than tibiofibula (FOT/TFL 0.82); relative length of toes: I <II <V <III <IV; toe tips rounded, enlarged into disks; subarticular tubercles numbering one on Toes I and II, two on Toes III and V, and three on Toe IV; pedal webbing formula I 1+/2 II 1+/2.25 III 1.5/3- IV 3-/1.5 V ( Fig. 6 View FIGURE 6 ); narrow dermal ridge on preaxial side of Toe I and on postaxial side of Toe V from proximal end of metacarpus to disk; inner metatarsal tubercle prominent, elongated, about half length of metatarsus of Toe I; outer metatarsal tubercle absent.

Colouration. (from Boulenger 1894:) Dorsum brown; sides of snout below canthus blackish; temporal region light; dark cross bar between eyes; horseshoe-shaped tubercle blackish; dorsolateral folds edged with blackish laterally; limbs with regular dark cross bands; ventral side whitish. See Fig. 7A View FIGURE 7 for a photograph of a specimen in life.

In preserved state ( Fig. 3A View FIGURE 3 ), dorsum of lectotype including flaks and dorsal parts of limbs light brown; lower arm, fingers, legs, and feet with mid-brown crossbars; upper eyelids with bluish tinge; interorbital bar mid-brown; supratympanic fold and dorsolateral fold as well as area between these folds mid-brown; tympanum cream-coloured with light brown rim; sides of head mid-brown; two mid-brown blotches on dorsal side of snout; horseshoe-shaped tubercle dark brown; ventral side of head, chest, arms and legs yellowish cream-white; abdomen whitish cream-coloured; infralabial region dark brown with small white spots; throat without pattern.

Variation. The female paralectotypes match the holotype in general appearance.The state of BMNH 1947.2.1.94 does not allow it to be measured. SVL of BMNH 1947.2.1.95 is 32.3 mm. It matches the lectotype in proportions and measurements ( Table 2). Pedal webbing variation is I 1+/2 II 1+/2.25 [50], 2.5 [50] III 1.5/3- IV 3-/1.5 V ( Fig. 6 View FIGURE 6 ). Boulenger (1894, 1897) stated an SVL of 43 mm for the species, later corrected to 31–33 mm for the three type specimens ( Boulenger 1920).

Bioacoustics. The advertisement call and other vocalisations are unknown.

Distribution. The species is restricted to Palawan, Philippines where it occurs at elevations between 180 m and 650 m.

Ecology. Limnonectes palavanensis is found in swamps, seepages, and wide, slow-moving streams ( Setiadi et al. 2011). Alcala & Brown (1998) treat the species as Rana microdisca in an account together with Limnonectes parvus from Mindanao, Philippines, and the ecological data provided in that account most likely refer to the latter.

Etymology. Named after the type locality, Palawan Island in the Philippines.

Suggested English name. Palawan Guardian Frog.