Amolops tawang, Saikia & Laskar & Dinesh & Shabnam & Sinha, 2022

Saikia, Bhaskar, Laskar, Mostaque A., Dinesh, K. P., Shabnam, A. & Sinha, Bikramjit, 2022, Description of two new species of Amolops (Anura: Ranidae) from Arunachal Pradesh, Northeast India under the morphological ‘ Viridimaculatus species group’, Records of the Zoological Survey of India 122 (3), pp. 247-266 : 254-256

Amolops tawang sp. nov.

(Tawang Cascade Frog)

Zoobank ID: urn:lsid:zoobank.org:act:0E8EF24C-3FCD-4D1C-9245-3716E44044C6

Holotype: V /A/ NERC / ZSI/1772 , adult male ( Figure 5 ), collected by Bikramjit Sinha and party on 08 March, 2018 from the Gomkyaleng village (N 25.925458; E

91.780033; alt.: 1891 m), Jang-Mukto Road , Tawang district, Arunachal Pradesh, India .

Diagnosis: Amolops tawang sp. nov. is a member of the morphological Viridimaculatus species group isolated in geographical space from its phylogenetic sister species having a distinct morphological set of characters. The new species can be diagnosed based on the following set of morphological characters: adult male size large (SVL 82.5 mm); head wider than long (HW>HL); snout rounded, snout longer than eye length (SL>EL); inter-orbital distance equals the upper eyelid width but smaller than the inter-narial distance (IUE=UEW<IN); tympanum small and extremely depressed, about 20% of eye length; finger I disk slightly dilated, all disks with circum-marginal grooves, but absent in finger I; tibia longer than femur and foot (TiL>ShL), about 2/3 rd of SVL; tibio-tarsal articulation reaches up to snout; supra-tympanic fold strong; dorso-lateral skin granular.

Description of the Holotype: Adult male (SVL 82.5 mm), body robust, head wider than long (HW>HL), flat above; snout rounded, protruding in lateral view; snout longer than the eye diameter (SL>EL); canthus rostralis distinct, loreal region depressed; inter-orbital space flat, equals the width of the eyelid, but narrower than the inter-narial distance (IUE=UEW<IN); the nostrils laterally placed, equidistant between snout and eye (NE=NS); pupil horizontal; tympanum small and extremely depressed, separated from the eye by a distance of more than twice its diameter; pineal ocellus visible; a pair of vomerine teeth situated between the choanae; tongue bilobed. The vocal sac faintly visible.

Arms meaty, forearm length shorter than the hand length; fingers free, tips ending in disk, finger I disk slightly dilated, all disks with circum-marginal grooves except finger I, relative length of fingers I<II<IV<III; sub-articular tubercles prominent, circular; prepollex oval.

Hindlimbs long and strong, tibia longer than both femur and foot (TiL>FOL>ShL); toes long, tips of all toes dilated into disks with circum-marginal grooves, toes completely webbed; sub-articular tubercles domed shaped; inner metatarsal tubercle oval shaped, outer absent.

The dorsal skin is smooth, slightly granular towards dorso-lateral sides; the supra-tympanic fold is strong; lateral and ventral skin is smooth.

Colouration of the Holotype: (in life) Dorsal color olive-green, spotted with large, irregular shaped dark-brown spots, brown spots enclosing a number of small olive-green dots; laterally same as dorsally; ventral color dark, speckled with lighter dots and dashes. Dorso-laterally granular along with white-tipped minute tubercles. Tibia banded; thighs mottled with dark brown and olive-green ( Figure 5 ). In preservative same as in live condition, except that all the olive-green colours are faded ( Figure 6 ).

Condition of the type: The type is in good condition. A ventral incision was made in the type specimen to extract liver tissue, which was used in the molecular study.

Natural history: The lone specimen of A. tawang sp. nov. was collected during the mid-day from a torrential hill stream with low water volume, which was characterised by large boulders. The specimen was resting under a boulder in a shallow trickle of water. A single specimen of Nanorana liebigii was also collected from the same habitat.

Distribution: Currently, this species is known only from its type locality in Tawang District, Arunachal Pradesh, India.

Comparisons: The new species is compared with the other species of Viridimaculatus species group.

From the Indian Viridimaculatus species group, Amolops tawang sp. nov. differs from A. formosus (in parentheses) in having adult male larger (vs. smaller), tympanum small, distinct and depressed (vs. about the size of finger III disk), inner-metatarsal tubercles distinct (vs. indistinct), circum-marginal groove on finger I absent (vs. present), outer metatarsal tubercle absent (vs. present), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. bright green with large dark spots), limbs with incomplete bands (vs. uniformly banded); from A. himalayanus (in parentheses) in having larger male SVL> 82 mm (vs. smaller <74-75 mm), nostril equidistant (vs. nearer to eye), tympanum small, distinct and depressed (vs. slightly visible), visible sac faintly visible (vs. externally visible vocal sac present), tibia 2/3 rd of SVL (vs. almost equal), tibio-tarsal articulation reached up to the snout (vs. beyond the tip of the snout), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. olive with darker spots); from A. nidorbellus (in parentheses) in having larger male SVL> 82 mm (vs. smaller <77 mm), IUEUEW (vs. IUE>EUW), pineal ocellus distinct (vs. barely visible), vocal sac faintly visible (vs. externally visible vocal sacs absent), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. brown with small, irregular cobalt green spots), ventral color dark, speckled with lighter dots and dashes (vs. pale brown with scattered small, white spots); from A. viridimaculatus sensu stricto (in parentheses) in having larger male SVL> 82 mm (vs. smaller <77 mm), head wider (vs. longer), tympanum distinct (vs. indistinct), outer metatarsal tubercle absent (vs. present), limbs not distinctly banded (vs. distinctly banded), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. maroon red with large green blotches); from A. chanakya sp. nov. (in parentheses) in having larger male SVL> 82 mm (vs. smaller <77 mm), nostril equidistant (vs. nearer to the eye), IUE=UEW (vs. IUE<UEW), tympanum extremely depressed and small (vs. larger), TYD = ½TE (vs. TYD ≈ TE), external vocal sac faintly visible (vs. distinctly visible), tibio-tarsal articulation reaches up to snout (vs. nostril), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. dorsum dull brick-red, spotted with irregular cocoa-brown spots), ventral color dark, speckled with lighter dots and dashes (vs. ventral cocoa-brown).

From the Viridimaculatus species group found outside India, Amolops tawang sp. nov. differs from A. beibengensis (in parentheses) in having larger male SVL> 82 mm (vs. <76 mm), head wider than long (vs. HL=HW), tibio-tarsal articulation reached up to the snout (vs. between nose and eye), vocal sac faintly visible (vs. absent), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. dorsum brown with green spots); from A. gyirongensis (in parentheses) in having larger male SVL> 82 mm (vs. <64 mm), tibio-tarsal articulation reached up to the snout (vs. nostril), vocal sac faintly visible (vs. absent); dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. bright green with dark brown irregular large spots); from A. kaulbacki (in parentheses) in having larger male SVL> 82 mm (vs. up to 72 mm), IN>IUE=UEW (vs. IN>IUE>UEW), tibio-tarsal articulation reached up to the snout (vs. beyond snout), vocal sac faintly visible (vs. absent), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. green with black spots and marbling); from A. longimanus (in parentheses) in not having distinctive dorsolateral fold (vs. present), absence of parotid-like swelling above tympanum (vs. present); from A. medogensis (in parentheses) in having smaller male SVL of 82 mm (vs. 95 mm), vocal sac faintly visible (vs. absent), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. olive green with brown markings/dark brown with small yellow-green spots); from A. pallasitatus (in parentheses) in having tibio-tarsal articulation reached up to the snout (vs. posterior eye corner), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. yellow green with irregular dark brown blotches); from A. splendissimus (in parentheses) in having larger male SVL> 82 mm (vs. 76 mm), IUE=UWD (vs. IUE<UEW), supra-tympanic fold strong (vs. poorly developed), vocal sac faintly visible (vs. absent), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. black-brown spangled thickly with bright yellow spots); from A. wangyufani (in parentheses) in having larger male SVL> 82 mm (vs. <70 mm), tibio-tarsal articulation reached up to the snout (vs. beyond snout), dorsal color olive-green, spotted with large, irregular shaped dark-brown spots (vs. brown with sparse green patches).

Etymology: The species epithet is a toponym named after the district Tawang, from where the type was collected. Located in the westernmost part of Arunachal Pradesh, Tawang is renowned for Tawang Monastery, which is the largest in India as well as being the birthplace of the 6 th Dalai Lama, Tsangyang Gyatso. The species epithet is treated as a noun in apposition to the generic name.

Suggested Common Name: We suggest Tawang cascade frog as a common English name and तवांग झरना मढक

as a common Hindi name for this species.

Figures

Figure 5. Live colour image of holotype of Amolops tawang sp. nov. (Photo: Bikramjit Sinha).

Figure 6. Holotype image of Amolops tawang sp. nov. in preserved condition (A: dorsal view; B: ventral view).