Dravidoseps tamilnaduensis, Agarwal & Thackeray & Khandekar, 2024

Agarwal, Ishan, Thackeray, Tejas & Khandekar, Akshay, 2024, A non-adaptive radiation of viviparous skinks from the seasonal tropics of India: Systematics of Subdoluseps (Squamata: Scincidae), with description of a new genus and five cryptic new species, Vertebrate Zoology 74, pp. 23-83 : 23

Dravidoseps tamilnaduensis sp. nov.

Figures 8O , 9H , 17

Chresonymy.

Lygosoma pruthi - Ganesh and Aengals (2018)

Subdoluseps pruthi - Ganesh et al. (2021).

Holotype.

NRC-AA-8286 (AK-R 2396), adult female, from near Kambur, Pachaimalai Hills (11.31677°N, 78.60183°E; elevation ca. 850 m asl.), Tiruchirappalli District, Tamil Nadu State, India, collected by Akshay Khandekar, Ishan Agarwal, Swapnil Pawar and team on 22th September 2022.

Paratypes (n = 11).

ZSI-R-28691 (AK-R 2397), subadult, same details as holotype; NRC-AA-8287 (AK 739), adult male, same locality as holotype except collected by Akshay Khandekar, Ishan Agarwal, Swapnil Pawar, Tejas Thackeray and team on 29th May 2019; NRC-AA-8288 (AK 740), BNHS 2857 (AK 741), adult females, BNHS 2858 (AK 742), subadult, from near Pachaimalai Eco Tourism Centre, Pachaimalai Hills (11.31588°N, 78.58103°E; elevation ca. 780 m asl.), collected by Akshay Khandekar, Ishan Agarwal, Swapnil Pawar, Tejas Thackeray and team on 29th May 2019; BNHS 2859 (AK 743), adult female, ZSI-R-28621 (AK 745), adult male, BNHS 2860 (AK 744), subadult, from Pachaimalai Ghat road, Pachaimalai Hills (11.30229°N, 78.57332°E; elevation ca. 600 m asl.), collected by Akshay Khandekar, Ishan Agarwal, Swapnil Pawar, Tejas Thackeray and team on 29th May 2019; ZSI-R-28692 (AK-R 2724), ZSI-R-28693 (AK-R 2725), adult males, from Selur Reserve Forest, Kolli Hills (11.19463°N, 78.37537°E; elevation ca. 400 m asl.), Namakkal District, Tamil Nadu State, India, same collectors as holotype, collected on 12th October 2022; ZSI-R-28695 (AK-R 2734), adult female, from near Madu Falls, Yercaud (11.73881°N, 78.24985°E; elevation ca. 410 m asl.), Salem District, Tamil Nadu State, India, same collectors as holotype, collected on 13th October 2022.

Etymology.

The specific epithet is a toponym for Tamil Nadu State to which the new species is endemic.

Suggested common name.

Tamil Nadu leaf-litter skink.

Diagnosis.

A medium-sized skink snout to vent length up to 56 mm (n = 12). Seven supralabials and six (rarely seven, n = 1/12) infralabials up to angle of mouth; fifth supralabial elongate and below eye; two post-supralabials; seven or eight supraciliaries; one or two elongated nuchals on either side, in median contact behind parietal (rarely separated a single scale, n = 1/12); 66-70 scales in paravertebral rows; 28-30 scales around mid-body; 64-71 ventral scales; 10 enlarged precloacal scales; scales on lateral sides of tail base smooth, 20 or 21 scales around the tail. Subdigital lamellae unpaired, smooth on manus and smooth to weakly keeled on pes; five or six lamellae under digit I of manus and pes (rarely seven on manus n = 1/12); 9-11 lamellae under digit IV of manus; and 12-15 under digit IV of pes (rarely 16, n = 1/12). Dorsum dark bronze-brown with black markings; thick black stripe from rostrum to tail speckled with light spots; supralabials with white streak; males with yellow on lower parts of forebody and flanks; venter glossy white with numerous dark reticulations.

Comparisons.

Dravidoseps tamilnaduensis sp. nov. can be diagnosed from known congeners based on the following characters: 29.6 ± 0.79 (28-30) RBS (versus 31.0 ± 1.41 (30-32) in D. gingeeensis sp. nov., and D. jawadhuensis sp. nov., 27.8 ± 0.79 (26-29) in D. srivilliputhurensis sp. nov.); 13.7 ± 1.07 (12-15) LAM4T (versus 17.0 ± 0.00 (17) in D. gingeeensis sp. nov., 16.5 ± 0.71 (16-17) in D. jawadhuensis sp. nov., 16.1 ± 1.20 (14-18) in D. pruthi comb. nov.); 10.0 ± 0.00 (10) SPCLR (versus 12.0 ± 0.00 (12) in D. gingeeensis sp. nov., 12.5 ± 0.71 (12-13) in D. jawadhuensis sp. nov., 8.0 ± 0.00 (8) in D. kalakadensis sp. nov., 9.2 ± 0.77 (8-10) in D. srivilliputhurensis sp. nov.); 20.8 ± 0.40 (20-21) RTS (versus 18.7 ± 0.52 (18-19) in D. kalakadensis sp. nov., 22.5 ± 0.71 (22-23) in D. jawadhuensis sp. nov., and 18.7 ± 0.52 (18-19) in D. goaensis comb. nov.); one or two Nu on either side and Sb Nu absent (present in only 1/12 specimens) (versus a single Nu on either side and three Sb Nu present in D. gingeeensis sp. nov., a single Nu on either side and two or three Sb Nu present in D. pruthi comb. nov.); seven SL (versus six SL (seven on just one specimen on either side and on three specimens on one side) in D. kalakadensis sp. nov.); SL V elongate and below eye (versus SL IV elongate and below eye (rarely SL V elongate and below eye, on just one specimen on either side and on three specimens on one side) in D. kalakadensis sp. nov.); two Elo on each side (a single on one side in 1/12 specimens) (versus a single Elo (rarely two in 3/22 individuals) in D. nilgiriensis comb. nov.); 68.0 ± 1.48 (66-70) PVR (versus 64.5 ± 1.05 (63-66) in D. srivilliputhurensis sp. nov.); presence of unkeeled scales on tail base (versus keeled scales on tail base in D. goaensis comb. nov.).

Description of the holotype.

Adult male (SVL 48.5 mm) in good state of preservation except body and tail marginally curved towards left side, and a 3.5 mm long incision in the sternal region for liver tissue collection (Fig. 17A, B ). Head short (HL/SVL 0.17), wide (HW/HL 0.73), not strongly depressed (HH/HL 0.49), indistinct from neck. Loreal region not inflated, canthus rostralis indistinct. Snout almost half head length (ES/HL 0.40), twice eye diameter (ES/ED 2.00). Rostral almost twice as wide (1.5 mm) as long (0.9 mm), in broad contact with supranasals posteriorly and supralabial I and nasals on either side; supranasals marginally in contact with each other medially, frontonasal posteriorly, nasals and anterior loreals laterally; frontonasal much wider (1.8 mm) than long (1.2 mm), in contact with supranasals anteriorly, prefrontals and frontal posteriorly, anterior loreals laterally; prefrontals relatively small, widely separated on midline, in contact with frontonasal anteriorly, frontal, first supraocular and first supraciliary posteriorly, anterior and posterior loreals laterally. Frontal elongate, roughly bell-shaped, widest anteriorly at the point where prefrontals and first supraocular connect; in contact with frontonasal anteriorly, frontoparietals posteriorly, prefrontals and first two supraoculars on either side; four supraoculars and one small post-supraocular and postocular on either side; frontoparietals in medial contact posterior to frontal, in contact with second, third, and fourth supraoculars anterolaterally and parietals and interparietal posteriorly. Interparietal large, roughly diamond-shaped, slightly projecting posteriorly, eyespot in posterior projection; postinterparietal absent; parietals large, in medial contact posterior to interparietal, in contact with frontoparietals, fourth supraocular, and post-supraocular anteriorly, two nuchal scales posteriorly, first secondary temporal laterally; a single enlarged, elongate, nuchal scale on either side in median contact posterior to parietals (Fig. 16C ). Nasals small, trapezoidal, widely separated, in contact with rostral anteriorly, supranasal dorsally, anterior loreal posteriorly, first supralabial ventrally; nostril in center of nasal; anterior loreal marginally taller (0.6 mm) than wide (0.5 mm); posterior loreal slightly larger than anterior loreal and slightly wider (0.8 mm) than tall (0.7 mm); a single small supra-preocular, an upper and lower preocular, and a single sub-preocular present only on either side (Fig. 17E ). Eye small (ED/ HL 0.20) with round pupil; lower eyelid with enlarged, transparent central window; eight supraciliaries on either side, anterior supraciliary largest, bordered by prefrontal anteriorly, first supraocular dorsally, and pre-supraocular, upper preocular and posterior loreal laterally; posterior superciliary elongate and projecting dorsomedially, bordered by fourth supraocular dorsally, post-supraocular posteriorly, and first post-subocular laterally; three post-suboculars on either side; a single primary temporal, two secondary temporals, and three tertiary temporals on either side; seven supralabials, fifth and sixth below eye; fifth supralabial elongate, in broad contact with pre-subocular and seven small scales on lower eyelid below eye on either side; two post-supralabials on either side; six infralabials on either side; two scales separating post-supralabial and external ear opening; external ear opening small (EL/HL 0.07), oval, bearing two anterior lobules on either side; tympanum deep (Fig. 17E ). Mental twice wide (1.6 mm) as long (0.8 mm); a single large postmental in contact with first and second infralabials on either side; three enlarged pairs of chin shields posterior to postmental; anterior pair large (1.3 mm), roughly rectangular, in medial contact with each other below postmental and bordered by second and third infralabials, middle pair of chin shields, and by a single median gular scale on either side; middle pair largest (1.5 mm), roughly rectangular, separated from each other by two longitudinally arranged gular scales, bordered by third and fourth infralabials, posterior pair of chin shields, and four gular scales on either side; posterior pair smallest (0.8 mm), roughly square, separated from each other by five transversely arranged gular scales, bordered by fourth and fifth infralabials and three gular scales on either side; rest of the gular scales much smaller than postmentals, cycloid and imbricate, two or three rows bordering infralabials slightly smaller and elongate (Fig. 17D ).

Body relatively slender (BW/AGL 0.23), elongate (AGL/SVL = 0.59); dorsal scales on body smooth, cycloid, imbricate; ventrals similar to dorsals except subequal from chest to vent, marginally larger on pectoral and precloacal region; 69 scales in paravertebral rows; 30 scales around mid-body; 70 ventral scales; 10 enlarged precloacal scales (Fig. 17A, B )). Limbs, robust, short (FL/SVL = 0.06; CL/SVL = 0.08), widely separated when adpressed; dorsal scales wider and slightly larger than ventral scales; palmar scales raised; plantar scales large, raised, coarse granules; all digits short, scales on dorsal surfaces in single row, subdigital lamellae unpaired, smooth on manus and smooth to weakly keeled on pes; lamellae series: 5-7-9-10-7 left manus (Fig. 17F ), 5-9-13-14-11 left pes (Fig. 17G ), 5-8-9-10-8 right manus, 5-9-12*-14-11 right pes. Relative length of digits (measurements in mm in parentheses): IV (2.1)> III (1.9)> II (1.6)> V (1.4)> I (1.2) (left manus); IV (3.7)> III (3.2)> V (2.5)> II (1.9)> I (1.4) (left pes).

Tail original except for tip which is regenerated, entire, cylindrical, slightly shorter than snout-vent length (TL/SVL 0.88); dorsal and ventral scales cycloid, imbricate, similar to those on body dorsum except for median dorsal and subcaudal scale rows distinctly larger than surrounding scales and roughly rectangular on regenerated tip; scales on lateral sides of tail base smooth, 20 scales around the tail (Fig. 17A, B )).

Colouration in life (Fig. 9H).

Dorsal ground colouration of body, head and tail dark bronze-brown; head with scattered dark markings; dorsal scales of body and tail finely outlined by dark brown, centre of scales with black markings forming indistinct stripes, tail dark; limbs almost black, with light spots; a thick black stripe running from rostrum through orbit and onto flank and tail with scattered light spots bordered dorsally by a broken white stripe; supralabials with a white streak; ventral regions glossy white with numerous dark reticulations.

Variation and additional information.

Mensural and meristic data for the paratype series are given in Table 11 . There are four adult males, four adult females and three subadults. All specimens resemble the holotype male (NRC-AA-8286) in overall morphology and head scalation except for the following variation: seven SC on either side in BNHS 2860, ZSI-R-28695, seven on left and eight on right side in BNHS 2857, ZSI-R-28692; three PrO on either side in NRC-AA-8287, NRC-AA-8288, BNHS 2857, two on left and three on right side in ZSI-R-28692; three PoSbO on left and four on right side in ZSI-R-28692, rest all paratypes (except for ZSI-R-28693 which matches with holotype) have four PoSbO on either side; middle postmental separated from each other below anterior postmentals by single enlarged gular scales and bordered by three gular scales on each side in NRC-AA-8287, ZSI-R-28695. Three paratypes - BNHS 2858, BNHS 2860, and ZSI-R-28621 with complete and original tail, equal to body (TL/SVL 1.01, 1.03, and 1.00 respectively); BNHS 2857, ZSI-R-28693, and ZSI-R-28695 with tail almost completely broken and lost; rest of the paratypes with partially regenerated tails, shorter than body. Three female paratypes - BNHS 2857, BNHS 2859, and ZSI-R-28695 with long longitudinal incision on mid-body ventral to confirm egg/developing embryos; ZSI-R-28621 (adult male) was dissected (12.4 mm long incision on mid-body ventral) to confirm the sex.

Distribution and natural history.

Dravidoseps tamilnaduensis sp. nov. is known from three broad localities in the broader Shevaroyan landscape, from Pachaimalai Hills in Tiruchirappalli District (type locality), Kolli Hills in Namakkal District, and southern slopes of Yercaud in Salem District, Tamil Nadu India, between elevations of 400-850 m asl. (Fig. 1 ). The two farthest localities for the species (Yercaud in north and Kolli Hills in south) are ~60 km apart from each other in aerial distance.

At the type locality, Dravidoseps tamilnaduensis sp. nov. was observed in high abundance (n =>15 hr) in a semi-evergreen forest patch with more or less closed canopy and heavy leaf-litter on the forest floor (Fig. 11H ). Individuals were found under rocks surrounded by leaf-litter or moving in the leaf-litter during the afternoon to early evening (1330-1800 hrs). At Kolli Hills and Yercaud, Dravidoseps tamilnaduensis sp. nov. was observed in dry deciduous to semi evergreen forest patches at the hill base during the morning hours (0830-1130 hrs). They were found either under rocks or in leaf-litter in well shaded areas along a stream. Sympatric lizards recorded at all three localities include Cnemaspis yercaudensis Das & Bauer, Cyrtodactylus (Geckoella) cf. collegalensis , Hemidactylus frenatus , H. cf. graniticolus , H. whitakeri , Eutropis cf. allapallensis , E. carinata , E. macularia , Riopa albopunctata , Calotes versicolor , and Psammophilus cf. blanfordanus . We found Dravidoseps nilgiriensis comb. nov. in syntopy with D. tamilnaduensis sp. nov. in Kolli Hills, the only location where two Dravidoseps species have been found in sympatry.

Reproduction.

Viviparous, litter size two (n = 1). BNHS 2859 with two almost completely developed embryos (Fig. 8O ).

Note.

Mensural and meristic data of a single unsexed adult specimen (ZSI/SRS/VRL 470; from Pachaimalai) given in Ganesh and Aengals (2018) as Lygosoma pruthi matches the type specimens of Dravidoseps tamilnaduensis sp. nov. except for the following variation: AGL 36.2 mm of ZSI/SRS/VRL 470 (versus <33.3 mm in this work n = 13); HW 6.6 mm (versus <5.7 mm); SO four or five (versus four); Elo five (versus two on each side); RBS 32 (versus 28-30). We couldn’t examine ZSI/SRS/VRL 470 to verify the counts. The measurements of AGL and HW and counts of ABS and SO given by Ganesh and Aengals (2018) are likely to be incorrect as none of the individuals (n = 13) even with same or higher SVL in the type series have such high numbers. Elo most likely include left and right combined. We however, tentatively assign this specimen to the new species pending verification of unmatched characters mentioned here.

Figures

Figure 1. Elevation map showing sampling localities from peninsular India. Stars indicate type localities (neotype locality shown for Dravidoseps goaensis comb. nov., original type locality is close to the southernmost point), light blue D. jawadhuensis sp. nov., dark blue D. srivilliputhurensis sp. nov., light green D. kalakadensis sp. nov., dark green D. pruthi comb. nov., red D. gingeeensis sp. nov., yellow D. nilgiriensis comb. nov., pink D. tamilnaduensis sp. nov., and grey, D. sp. Kalrayan (colour scheme representing species is the same as Figs 3 - 6), black squares unsampled previously known localities. The approximate extent of the Central Western Ghats (CWG), Northern Western Ghats (NWG), and Southern Western Ghats (SWG) are shown; major hill ranges and features are marked by bold white text, within the Western Ghats: AG, Agasthyamalai; AN, Anaimalai; DV, Devarmalai; N, Nilgiris; PG, Palghat Gap; PL, Palani; and outside the Western Ghats: BR, Biligirangan; J, Jawadhu; K, Kollimalai; KR, Kalrayan; mm, Male Mahadeshwara; MP, Mysore Plateau; PC, Pachaimalai; PM, Palamalai; S, Sitteri; SR, Sirumalai; T, Tirupati; V, Velikonda; Y, Yercaud; YL, Yelagiri. Inset, global distribution of Dravidoseps gen. nov. (brown) and Subdoluseps sensu stricto (green). Dravidoseps goaensis = Riopa goaensis (see main text).

Figure 8. Embryos of Dravidoseps gen. nov. at different development stages: A two pairs in D. goaensis comb. nov. in early developmental stages (neotype, BNHS 2567); B two pairs in D. gingeeensis sp. nov. in early developmental stages (holotype, NRC-AA- 8273); C - E various development stages of D. kalakadensis sp. nov. (paratypes, BNHS 2829, ZSI-R- 28613, and ZSI-R- 28615 respectively); F - N various development stages of D. srivilliputhurensis sp. nov. (paratypes, BNHS 2832, BNHS 2834, BNHS 2835, BNHS 2837 - 2839, NRC-AA- 8284, NRC-AA- 8285, ZSI-R- 28618); O two almost completely developed in D. tamilnaduensis sp. nov. (paratype, BNHS 2859). Scale bars = 5 mm; photos by Akshay Khandekar.

Figure 9. Dravidoseps gen. nov. species in life: A D. pruthi comb. nov. (neotype, NRC-AA- 1291); B D. goaensis comb. nov. (neotype, BNHS 2567); C D. nilgiriensis comb. nov. (ZSI-R- 28604); D D. gingeeensis sp. nov. (holotype, NRC-AA- 8273); E D. jawadhuensis sp. nov. (holotype, NRC-AA- 8274); F D. kalakadensis sp. nov. (holotype, NRC-AA- 8275); G D. srivilliputhurensis sp. nov. (holotype, NRC-AA- 8279); and H D. tamilnaduensis sp. nov. (holotype, NRC-AA- 8286). Photos by Akshay Khandekar (B-D, F-H) and Ishan Agarwal (A, E).

Figure 11. General habitats of all species of Dravidoseps sp. nov.: A type locality of D. pruthi comb. nov.; B neotype locality of D. goaensis comb. nov.; C habitat photo of D. nilgiriensis comb. nov., from Thamarakarai; D type locality of D. gingeeensis sp. nov.; E type locality of D. jawadhuensis sp. nov.; F type locality of D. kalakadensis sp. nov.; G paratype locality of D. srivilliputhurensis sp. nov., near Atthi Kovil Falls; and H type locality of D. tamilnaduensis sp. nov.. Photos by Akshay Khandekar (A-C, F-H), Ishan Agarwal (D), and Vinod (E).

Figure 16. Dravidoseps srivilliputhurensis sp. nov. (holotype, NRC-AA- 8279): A dorsal view of body, B ventral view of body, C dorsal view of head, D ventral view of head, E lateral right side view of head, F ventral view of left manus, and G ventral view of left pes. Scale bars: A, B = 10 mm; C-E, G = 5 mm; F = 3 mm; photos by Akshay Khandekar.

Figure 17. Dravidoseps tamilnaduensis sp. nov. (holotype, NRC-AA- 8286): A dorsal view of body, B ventral view of body, C dorsal view of head, D ventral view of head, E lateral right side view of head, F ventral view of left manus, and G ventral view of left pes. Scale bars: A, B = 10 mm; C-E, G = 5 mm; F = 3 mm; photos by Akshay Khandekar.