Raorchestes narpuhensis, Boruah & Deepak & Das, 2025

Boruah, Bitupan, Deepak, V. & Das, Abhijit, 2025, Revision of bush frogs, Raorchestes and Philautus (Amphibia: Anura: Rhacophoridae) from the northeast Indian biodiversity hotspot with description of thirteen new species, Vertebrate Zoology 75, pp. 517-625 : 517-625

Raorchestes narpuhensis sp. nov.

Figure 30; Tables 1, 2, S 12

Holotype.

WII-ADA 1509 , an adult male collected by BB, VJ and AD on 29 May 2022 from Narpuh Wildlife Sanctuary ( 25.11062°N, 92.37215°E, elevation 70 m a. s. l.), Sonapur, East Jaintia Hills District, Meghalaya, India .

Paratypes.

Four adult males ( WII-ADA 1510 , WII-ADA 1518 , WII-ADA 1519 , WII-ADA 1521 ) and one adult female ( WII-ADA 1517 ). Collection details are the same as the holotype ; two adult males ( WII-ADA 1525 – WII-ADA 1526 ) collected by BB and AD on 30 May 2022 from Narpuh Wildlife Sanctuary ( 25.10995°N, 92.37159°E, elevation 80 m a. s. l.), East Jaintia Hills District, Meghalaya .

Referred material.

Seven adult males ( WII-ADA 1939 , WII-ADA 1940 , WII-ADA 1994 , WII-ADA 1995 , WII-ADA 1997 , WII-ADA 1998 , WII-ADA 2000 ) collected by BB on 19 July 2016 from Riwai village ( 25.20469°N, 91.89818°E, elevation 520 m a. s. l.), East Khasi Hills District, Meghalaya .

Diagnosis.

Small sized Raorchestes, SVL 18.0– 21.1 mm in adult males and adult female at least 23.1 mm; head length equal to or slightly greater than width; nuptial pad present on first finger in males; spinules on dorsal aspect of head, upper eyelid, dorsum, flank and limb; groin, axilla, and lateral side of thigh pale yellowish; slightly dark “) (“ marking on the dorsum; slightly dark brown and broad crossbar on forearm, thigh, and tibia; dark streak below eye.

Description of the holotype.

Holotype is in good condition, an incision on underside of right thigh; adult male with vocal sac, SVL 21.2 mm; head length and width equal; snout sub-ovoid in dorsal view and protruding in lateral view, slightly protruding in ventral view, slightly concave on internarial region; snout length slightly longer than eye length ( EL / SL = 0.94); nostril small, oval in shape, oblique and laterally positioned, closer to snout tip than eye ( NS / EN = 0.81); narial region protruding; internarial distance less than inter-upper eyelid space ( IN / IUE = 0.81) and greater than upper eyelid width ( UEW / IN = 0.77); tympanum rounded, indistinct, one fifth of the eye length; canthus rostralis distinct, rounded and oblique; loreal region concave; vomerine teeth absent; choanae round; pair of internal slit like openings on lower jaw; an external subgular vocal sac present.

Forelimbs slender, forearm shorter than hand length ( FAL / HAL = 0.91); relative length of fingers = I <II <IV <III; finger with rounded disc, disc on finger III is largest, disc width of the finger II, III and IV greater than tympanic diameter; circum-marginal groove present on each disc; palmar tubercles barely visible; subarticular tubercles large and round; number of subarticular tubercles on fingers I: II: III: IV = 1: 1: 2: 2.

Hindlimbs slender; thigh length greater than tibia length ( TBL / TL = 0.91) and foot length ( FOL / TL = 0.75); tibia length greater than foot length ( FOL / TBL = 0.82); relative length of toes = I <II <III <V <IV; toe with rounded disc; circum-marginal groove present on each disc; disc width of fourth toe slightly smaller than that of third finger; elliptical shaped inner metatarsal tubercle present, outer one absent; subarticular tubercles distinct, rounded, I: II: III: IV: V = 1: 1: 2: 3: 2.

Dorsal aspect of snout smooth in middle and shagreen towards side; inter-upper eyelid space smooth, upper eyelid shagreen with blunt indistinct tubercles; indistinct dermal ridge with tubercular projection from snout to inter-upper eyelid space; supratympanic fold distinct; loreal region shagreen; few blunt tubercles behind angle of jaw; dorsum smooth, scattered spinules on dorsolateral aspect and towards flank starting above supratympanic fold; posterior part of the dorsum smooth; flank ventro-laterally granular; limbs smooth dorsally, spinules not visible in preserved condition; ventrally throat and chest smooth; lower arms granular on ventral aspect; abdomen granular; thigh granular at base; shank smooth ventrally; large indistinct flat tubercular projection on palm; webbing on hand absent; finely granular nuptial pad present on first finger; webbing on feet slight, reaching below second subarticular tubercle of fourth toe.

Colouration in life.

Head, dorsum and limb pale brown on dorsal aspect, towards flank paler; upper eyelids slightly dark brown; inverted triangular dark brown mark on head, starting on inter-upper eyelid space; dark brown stripe on loreal region to snout tip; supratympanic fold dark brown; indistinct dark brown streak ventral to eye; base of the forelimb and inner lateral aspect of lower arm pale yellow; an indistinct brown cross bar on forearm; disc of the inner two fingers yellow and on outer two brown; pair of dark brown concave stripes on dorsum, anterior and posterior ends diffused; crossbars on thigh, tibia and tarsus indistinct; some of the tubercles on upper eyelid, dorsolateral aspect of dorsum, flank, forearm, thigh, tibia and tarsus white; irregular white spots on upper lip; ventral aspect of head, abdomen and limbs flesh coloured with irregular brown flecks; axilla, groin and inner lateral aspect of thigh pale yellow.

Colouration in preservative.

Dorsally head and dorsum pale brown; slightly dark brown “) (“ mark on dorsum starting behind upper eyelids to in front of groin; slightly dark brown mark on head starting on inter-upper eyelid space to posterior part of head; upper eyelid dark brown; loreal region slightly dark brown; supratympanic fold dark brown; forelimb and hindlimb light yellowish with dense brown mottling; tibia slightly darker than thigh; single, broad, indistinct, slightly dark brown crossbar on forearm, thigh, and tibia; surrounding of vent is brown; ventrally cream coloured, anterior part of throat and towards side heavily mottled with brown; scattered brown mottling on chest and abdomen; limbs, palms and feet heavily mottled with brown; pale white blotches on abdomen.

Morphological variation.

Details of morphometric variations are given in Table S 12. Dorsal “) (” marking varied among specimens, distinct to nearly diffused; snout tip of the female paratype ( WII-ADA 1517 ) and male paratypes ( WII-ADA 1521 , WII-ADA 1525 ) more pronounced with blunt tubercular projection; indistinct mid dorsal line and similar longitudinal line present on thigh and tibia of WII-ADA 1519 .

Morphological comparison.

Raorchestes narpuhensis sp. nov. differs from R. andersoni by the absence of black patch on groin (vs. black patch with two yellow spots); differs from R. annandalii by nostril position closer to snout tip than eye (vs. nostril equidistant between eye and snout tip or closer to eye than snout tip); it differs from R. barakensis sp. nov. by absence of bony projection on humerus (vs. present), scattered tubercles on dorsum (vs. dense spinules on dorsum); it differs from R. cinerascens nov. comb. by absence of black patch on groin (vs. a dark spot partially encircled with silvery yellow tinge); it differs from R. dulongensis by absence of black patches and creamy white spots on groin and lateral aspect of thigh (vs. present), nuptial pad present on first finger of males (vs. nuptial pad absent); it differs from R. garo by presence of scattered tubercles on dorsum (vs. moderate to heavy spinules on dorsum), no marking on groin and lateral aspect of thigh (vs. dark brown patches on groin and lateral aspect of thigh or dark-brown patch with enlarged yellow spots on thigh); differs from R. hekouensis by larger body size, SVL 18.0– 21.1 mm in adult males (vs. SVL 16.1–17.5 mm in adult males), nuptial pad present only on first finger (vs. nuptial pad present on first and second finger); it differs from R. hillisi by larger body size, SVL 18.7–21.2 mm in adult males and SVL at least up to 23.1 mm in adult female (vs. SVL 14.5–17.7 mm in adult males and 17.5 in adult female), head length equal to width or slightly wider than long (vs. head longer than wide), dark brown patch on groin absent (vs. present); it differs from R. huanglianshan by dark brown patch on groin absent (vs. present), snout length being equal to or less than eye length (vs. snout length greater than eye length); it differs from R. jadoh by larger body size in adult males, SVL 18.0– 21.1 mm (vs. 13.6–14.0 mm), and inter-upper eyelid width being less than eye length (vs. inter-upper eyelid width greater than eye length); it differs from R. jakoid by snout length being less than or equal to eye length (vs. snout length greater than eye length), inter-upper eyelid width less than eye length (vs. inter-upper eyelid width greater than or equal to eye length), and thigh length being greater than or equal to tibia length (vs. thigh length less than tibia length); it differs from R. kempiae by dorsal skin, scattered tubercles present dorsum (vs. dorsal skin of dorsum with spinules and blunt tubercles), absence of marking on groin (vs. short brown strip present on groin); it differs from R. longchuanensis by inner-upper eyelid being smaller than eye length (vs. inter-upper eyelid greater than eye length); it differs from R. leiktho by larger body size in adult males, SVL 18–21.1 mm (vs. SVL 15.7–15.8 mm); it differs from R. malipoensis by its large body size, SVL 18.7–21.2 mm in adult males and SVL at least up to 23.1 mm in adult female (vs. SVL 14.6–17.7 mm in adult males and 18.3–19.3 in adult females), black patches on groin and lateral aspect of thigh absent (vs. present); it differs from R. menglaensis by head length being equal to width or slightly wider than long (vs. head longer than wide), dark brown or black blotch on groin absent (vs. present); it differs from R. mindat by absence of dark or white patches on groin (vs. enlarged black and white patches present on groin), no white patches on lateral aspect of thigh (vs. enlarged white patches on lateral aspect of thigh); it differs from R. boulengeri sp. nov. and R. mawsynramensis sp. nov. in having relative smooth skin with scattered tubercles on dorsum (vs. dense spinules on dorsal aspect of head, dorsum, and limbs), being nostril closer to snout tip than eyes (vs. nostril equidistant from eyes and snout tip in R. boulengeri sp. nov. and R. mawsynramensis sp. nov.); differs from R. orientalis sp. nov. by presence of scattered tubercles on dorsum (vs. dense spinules on dorsum), presence of broad dark brown crossbar on thigh and tibia (vs. three crossbars on thigh and tibia), presence of pair of concave stripes on dorsum (vs. a “) - (“ mark on dorsum); it differs from R. parvulus snout sub ovoid to nearly acute (vs. snout rounded), absence of marking on groin (vs. dark brown marbling enclosing a whitish blotch on groin); it differs from R. rezakhani by presence of single broad crossbar on each thigh and tibia (vs. at least three narrow dark brown crossbars on each thigh and tibia), absence of brown patch on groin (vs. a short brown streak present on groin); it differs from R. shillongensis by absence of marking on groin (vs. dark brown patch with white crown shaped mark or diffused brown patch on groin); it differs from R. tytthus nov. comb. by snout length being equal to or less than eye length (vs. snout length greater than eye length), absence of spot or marking on groin (vs. a large white spot on groin); it differs from R. yadongensis by absence of white patches on chest and abdomen (vs. present). A detailed morphological comparison is provided in Table 1.

Acoustics.

The calls of R. narpuhensis sp. nov. were recorded in Narpuh Wildlife Sanctuary, Meghalaya on 29 May 2022 between 19: 00–21: 00 hrs at an ambient temperature of 27.5 ° C. The call description is based on 40 calls from two individuals ( WII-ADA 1509 and WII-ADA 1510 ). Calls are of a single type, non-pulsatile, emitted at regular intervals and not in groups (Fig. 31 ). The mean call duration is 18.7 ± 4.02 ms (13–25 ms) with a rise time of 1 ms and a fall time of 17.68 ± 3.83 ms (12–24 ms). The mean call interval between calls is 670.17 ± 85.57 ms (544–823 ms). The dominant frequency is 3954.57 ± 165.48 Hz (3574.5–4134.4 Hz). A detailed comparison of the advertisement calls with those of the congeners is presented in Table 2.

Phylogenetic relationship.

Raorchestes narpuhensis sp. nov. is sister to R. lawngtlaiensis sp. nov. ( UFB 100 , PP 1.0; Figs 2 , 3 ) with genetic divergence of 2.3–2.7 % in the 16 S, 8.1–8.2 % in the cyt b and 8.7–8.9 % in the COI genes. The closest aerial distance between type localities of these two species is 293 km. Raorchestes narpuhensis sp. nov. has genetic divergence of 5.1–10.0 % in the 16 S, 13.7–20.8 % in the cyt b and 8.7–15.7 % in the COI genes with the other members of the genus (Table S 7 A – C).

Etymology.

The specific epithet is a toponym derived from the name “ Narpuh Wildlife Sanctuary ” in Meghalaya State where the type series were collected.

Suggested common name.

Narpuh bush frog.

Distribution and natural history.

Currently Roarchestes narpuhensis sp. nov. is known from its type locality in and around Narpuh Wildlife Sanctuary, and in Riwai of Meghalaya (Fig. 19 A ). We encountered calling males and a single female at ~ 1–2 m above ground perching on shrubs and on small bamboo leaves, Zingiber sp. on hill slopes (Fig. 20 H ). Other sympatric species found with the new species were Chirixalus sp. and Polypedates cf. himalayensis .

Figures

Figure 2. A, B Maximum likelihood tree inferred from the concatenated data set (16 S, cyt b, COI and RHO) for Raorchestes species from northeast India, Indo-Burma and Indo-China. Outgroups are not shown in this tree. Numbers at the internal branches represent ultrafast bootstrap values (UFB). Values below 50 are not shown. Scale bar: substitutions per site.

Figure 3. A, B Bayesian tree inferred from the concatenated data set (16 S, cyt b, COI and RHO) for Raorchestes species from northeast India, Indo-Burma and Indochina. Outgroups are not shown in the tree. Numbers at the nodes represent posterior probability (PP) value. Values <0.5 are not shown. Scale bar: substitutions per site.

Figure 19. Distribution of Raorchestes species in northeast India. A Raorchestes garo and three others closely related new species; B Raorchestes kempiae, R. shillongensis, R. mindat and three new species. Type localities are denoted with stars.

Figure 20. Habitat at the type localities of Raorchestes species of northeast India. A Forest trail at Tura Peak, the type locality of R. garo and R. kempiae; B forest cover and adjacent lowlands of Garo Hills, from Daribokgre; C a landscape view of forest covers and D a forest trail at Namdapha TR, type localities of R. orientalis sp. nov. and R. nasuta sp. nov.; E hills at Mawsynram, near the type locality of R. mawsynramensis sp. nov.; F Nohkalikai Waterfall and forest cover at the type locality of R. boulengeri sp. nov. in Cherrapunji; G dry stream bed and vegetation in Maruwacherra, near Barail WLS, the type locality of R. barakensis sp. nov. and H forest around Jaintia Hills in Narpuh WLS, at the type locality of R. narpuhensis sp. nov.

Figure 30. Raorchestes narpuhensis sp. nov. A – C Holotype (WII-ADA 1509) in preserved condition, A dorsal view, B ventral view of head; C lateral view of head. D, E paratype (WII-ADA 1517) in preserved condition. F – K Holotype (WII-ADA 1509) in life, F dorsolateral view, G. dorsal view, H ventral view, I close-up of granules on abdomen, J groin, K posterior view of thighs. L Dorsolateral view and M ventral view of paratype (WII-ADA 1521) in life. Scale bar = 10 mm.

Figure 31. Comparative spectrograms and oscillograms illustrating representative calls of three species of Raorchestes. A, B Oscillograms, C spectrogram, D power spectrum. The call marked with an arrow on top in A is expanded in B.