Dravidoseps srivilliputhurensis, 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 srivilliputhurensis sp. nov.

Figures 8F-N , 9G , 16

Holotype.

NRC-AA-8279 (AK-R 1344), adult male, from near Ayyanar Kovil Falls (9.51294°N, 77.45183°E; elevation ca. 340 m asl.), Srivilliputhur-Megamalai Tiger Reserve (SMTR), Virudhunagar District, Tamil Nadu State, India, collected by Akshay Khandekar, Ishan Agarwal, Swapnil Pawar and team on 16th April 2022.

Paratypes (n = 19).

NRC-AA-8280 (AK-R 1343), NRC-AA-8281 (AK-R 1345), adult females, same data as holotype; NRC-AA-8283 (AK-R 1347), adult male, NRC-AA-8282 (AK-R 1346), NRC-AA-8284 (AK-R 1348), adult females, from near Sri Sastha Kovil, Settur Reserve Forest (9.40362°N, 77.37211°E; elevation ca. 340 m asl.), and NRC-AA-8285 (AK-R 1349), adult female, (9.47178°N, 77.42983°E; elevation ca. 300 m asl.), Madurai District, same collectors as holotype except collected on 17th April 2022; BNHS 2832 (AK-R 1434), BNHS 2833 (AK-R 1435), BNHS 2834 (AK-R 1436), adult females, (9.58131°N, 77.55227°E; elevation ca. 960 m asl.), and BNHS 2835 (AK-R 1455), adult female, from Shenbagathoppu (9.55173°N, 77.55445°E; elevation ca. 200 m asl.), Virudhunagar District, same collectors as holotype except collected on 20th April 2022; BNHS 2836 (AK-R 1489), BNHS 2837 (AK-R 1490), BNHS 2838 (AK-R 1491), adult females, from near Atthi Kovil (9.59990°N, 77.53374°E; elevation ca. 200 m asl.), Virudhunagar District, same collectors as holotype except collected on 25th April 2022; BNHS 2839 (AK-R 1492), ZSI-R-28616 (AK-R 1493), ZSI-R-28617 (AK-R 1516), adult females, from near Sathuragiri Falls (9.70927°N, 77.63074°E; elevation ca. 240 m asl.), Madurai District, same collectors as holotype except collected on 26th April 2022; ZSI-R-28618 (AK-R 1716), from near Chinnasurli Falls, Megamalai (9.70961°N, 77.42213°E; elevation ca. 610 m asl.), Theni District, same collectors as holotype except collected on 4th May 2022; ZSI-R-28619 (AK-R 1761), ZSI-R-28620 (AK-R 1762), subadults, from near Megamalai Viewpoint (9.72559°N, 77.41983°E; elevations ca. 1000 m asl.), Theni District, same collectors as holotype except collected on 8th May 2022; all from SMTR, Tamil Nadu State, India.

Referred material (n = 1).

AK-R-1717, same collection data as ZSI-R-28618 (AK-R 1716).

Etymology.

The specific epithet is a toponym for Srivilliputhur in Srivilliputhur-Megamalai Tiger Reserve (SMTR), Virudhunagar District of Tamil Nadu State, the type locality of the new species.

Suggested common name.

SMTR leaf-litter skink.

Diagnosis.

A medium-sized skink snout to vent length up to 56 mm (n = 20). Seven supralabials (rarely six on one of the side, n = 1/20) and six infralabials (rarely seven on one of the side, n = 1/20) up to angle of mouth; fifth supralabial elongate and below eye (rarely fourth on one of the side, n = 1/20); two post-supralabial; seven supraciliaries (rarely six or eight n = 1 each/20); one elongated nuchal on either side (rarely two, n = 3/20), in median contact behind parietal (rarely separated by one or two scales, n = 5/20); 63-66 scales in paravertebral rows; 26-28 scales around mid-body (rarely 29, n = 1/20); 62-68 ventral scales (rarely 70, n = 1/20); 8-10 enlarged precloacal scales; scales on lateral sides of tail base smooth, 19-21 scales around the tail. Subdigital lamellae unpaired, mostly smooth; five or six lamellae under digit I of manus and pes; 9-11 lamellae under digit IV of manus (rarely 12, n = 1/20); and 13-16 under digit IV of pes (rarely 12, 17; n = 1/20). Dorsum bronze-brown with black markings; thick brown stripe from rostrum to tail speckled with light spots; supralabials with white streak; males with yellow on lower parts of forebody and flanks extending onto belly; venter glossy grey-white without darker markings.

Comparisons.

Dravidoseps srivilliputhurensis sp. nov. can be diagnosed from known congeners based on the following characters: 27.8 ± 0.79 (26-29) RBS (versus 31.0 ± 1.41 (30-32) in D. gingeeensis sp. nov. and D. jawadhuensis sp. nov., 28.1 ± 0.86 (26-30) in D. nilgiriensis comb. nov., 30.0 ± 0.00 (30) in D. pruthi comb. nov., and 29.0 ± 1.00 (28-30) in D. goaensis comb. nov.); 14.8 ± 0.97 (13-17) 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., and 13.4 ± 0.79 (13-15) in D. goaensis comb. nov.); 9.2 ± 0.77 (8-10) SPCLR (versus 10.0 ± 0.00 (10) SPCLR in D. pruthi comb. nov., and 8.3 ± 0.76 (8-10) in D. goaensis comb. nov.); 20.3 ± 0.78 (19-21) RTS (versus 21.4 ± 0.89 (21-23) in D. pruthi comb. nov.); Elo two or three (rarely one, on just one individual on one side) (versus one or two Elo in D. kalakadensis sp. nov., one Elo (rarely two in 3/22 individuals) in D. nilgiriensis comb. nov.); seven SL (rarely six on one side in 1/20 specimens) (versus six SL (seven on both sides in one specimen and on one side in three specimens) in D. kalakadensis sp. nov.); SL V elongate and below eye (rarely IV elongated and below eye, on one side in 1/ 20 individuals) (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.); presence of unkeeled scales on tail base (versus keeled scales on tail base in D. goaensis comb. nov.). Dravidoseps srivilliputhurensis sp. nov. is diagnosed against the new species described below as part of their respective descriptions.

Description of the holotype.

Adult male (SVL 44.5 mm) in good state of preservation except body bent towards right and tail curved towards left side, a 3.7 mm long incision at marginally above the mid-body ventral for liver tissue collection, and hemipenis partially everted only on right side (Fig. 16A, B )). Head short (HL/SVL 0.17), wide (HW/HL 0.67), not strongly depressed (HH/HL 0.47), indistinct from neck. Loreal region not inflated, canthus rostralis indistinct. Snout almost half head length (ES/HL 0.44), slightly more than twice eye diameter (ES/ED 2.12). Rostral twice as wide (1.8 mm) as long (0.9 mm), in broad contact with supranasals posteriorly and supralabial I and nasals on either side; supranasals in contact with each other medially, frontonasal posteriorly, nasals and anterior loreals laterally; frontonasal much wider (1.7 mm) than long (1.1 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 and first supraciliary posteriorly, anterior and posterior loreals laterally. Frontal elongate, roughly bell-shaped, widest anteriorly at the point where prefrontals and first supraciliary 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 and a single dorsal scale posteriorly, first secondary temporal laterally; a single enlarged, elongate, nuchal scale on either side, separated medially by a single dorsal scale, left nuchal scale much larger than the one on the right side (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 (0.7 mm) than tall (0.5 mm); a single small supra-preocular, an upper and lower preocular, and a single sub-preocular present only on either side (Fig. 16E ). Eye small (ED/ HL 0.21) with round pupil; lower eyelid with an enlarged, transparent central window; seven supraciliaries on either side, anterior supraciliary largest, bordered by prefrontal anteriorly, frontal and 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; four 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, last post-subocular and four 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 0.11), oval, bearing two anterior lobules on either side; tympanum deep (Fig. 16E ). Mental twice as wide (1.8 mm) as long (0.9 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 (1.4 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 same in size (1.4 mm) and shape as anterior pair, 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 (0.9 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. 16D ).

Body relatively slender (BW/AGL 0.25), elongate (AGL/SVL = 0.60); dorsal scales on body smooth, cycloid, imbricate; ventrals similar to dorsals except subequal from chest to vent, marginally larger on pectoral and precloacal region; 64 scales in paravertebral rows; 28 scales around mid-body; 66 ventral scales; 10 enlarged precloacal scales (Fig. 16A, 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, mostly smooth; lamellae series: 5-8-9-11-8 left manus (Fig. 16F ), 5-10-14-16-13 left pes (Fig. 16G ), 5-9-9-10-8 right manus, 5-10-14-15-12 right pes. Relative length of digits (measurements in mm in parentheses): IV (2.0)> III (1.7)> II (1.5)> V (1.3)> I (0.9) (left manus); IV (4.1)> III (3.3)> V (2.5)> II (2.0)> I (1.0) (left pes).

Tail original except tip which is regenerated, entire, cylindrical, equal to snout-vent length (TL/SVL 1.02); dorsal and ventral scales cycloid, imbricate, similar to those on body dorsum except for median dorsal and subcaudal scale rows somewhat larger than surrounding scales on tail, ending in a pointed scute; scales on lateral sides of tail base smooth, 21 scales around the tail (Fig. 16A, B ).

Colouration in life (Fig. 9G).

Dorsal ground colouration of body, head and tail dull 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; limbs darker than body dorsum and with light spots; a thick dark brown stripe running from rostrum through orbit and onto flank and tail with scattered light spots bordered dorsally by a fine white stripe; yellow markings below dark stripe from throat to hindlimb insertions extending onto belly; yellow markings below dark stripe from throat to hindlimb insertions extending onto belly; supralabials with a white streak; ventral regions glossy grey-white without darker markings.

Variation and additional information.

Mensural and meristic data for the paratype series are given in Table 10 . There are 16 adult females, an adult male and two subadults. All specimens resemble the holotype male (NRC-AA-8279) in overall morphology and head scalation except for the following variation: supranasals barely in contact with each other behind rostral in ZSI-R-28618; prefrontals in contact with frontal, first supraocular, and first supraciliary posteriorly in NRC-AA-8281-8284, BNHS 2832-2836, ZSI-R-28618 and ZSI-R-28619; two supraoculars in contact with frontoparietal on either side in NRC-AA-8284, three on left and two on right side in BNHS 2834; frontal in contact with prefrontals and first two supraoculars on either side in NRC-AA-8281-8284, BNHS 2832-2836, ZSI-R-28618 and ZSI-R-28619. Eight supraciliaries present on either side in BNHS 2834, six on left and seven on right side in ZSI-R-28617; anterior supraciliary largest, bordered by only first supraocular dorsally in NRC-AA-8281-8284, BNHS 2832-2836, ZSI-R-28618 and ZSI-R-28619; three post-suboculars present on either side in ZSI-R-28618, four on left and three on right side in BNHS 2834 and ZSI-R-28617. Five paratypes - NRC-AA-8280, NRC-AA-8282, BNHS 2838, ZSI-R-28618, and ZSI-R-28620, with complete and original tail, marginally longer or shorter than body (TL/SVL 1.08, 1.08, 0.93, 0.96, and 1.01 respectively); BNHS 2833, ZSI-R-28617, and ZSI-R-28619 are either partly or completely broken tails; rest of the paratypes with either almost fully or partially regenerated tails, shorter than body. NRC-AA-8283 with partial everted hemipenis on either side. Ten gravid females - NRC-AA-8281, NRC-AA-8284, NRC-AA-8285, BNHS 2832, BNHS 2834, BNHS 2835, BNHS 2837-2839, ZSI-R-28618 with long longitudinal incision on mid-body ventral to confirm egg/developing embryos.

Distribution and natural history.

Dravidoseps srivilliputhurensis sp. nov. is known only from a few closely spaced localities (<40 km aerial distance between two farthest localities) on the eastern slopes of the Western Ghats in Srivilliputhur-Megamalai Tiger Reserve (Fig. 1 ). Dravidoseps srivilliputhurensis sp. nov. was recorded in dry and moist deciduous to semievergreen forests at elevations between 200-1000 m asl. (Fig. 11G ). At all localities (except for Chinnasurli Falls and Megamalai Viewpoint) Dravidoseps srivilliputhurensis sp. nov. was seen moving in dry leaf-litter during the day (0830-1400 hrs). At Chinnasurli Falls, a single individual was observed inactive at the base of rock surrounded by dry leaf-litter in the evening (1830 hr) and at Megamalai, Dravidoseps srivilliputhurensis sp. nov. was found in loose soil under rocks during late afternoon to evening time (1530-1830). Sympatric lizards encountered were Hemidactylus frenatus , H. leschenaultii , H. vanam Chaitanya, Lajmi & Giri, H. whitakeri , Hemiphyllodactylus sp., Cnemaspis galaxia Pal, Mirza, Dsouza & Shanker, Cn. cf. gracilis , Cn. cf. ornata , Cyrtodactylus (Geckoella) cf. collegalensis , Eutropis carinata , E. macularia , Riopa albopunctata , Calotes versicolor , and Psammophilus dorsalis .

Reproduction.

Viviparous, litter size two or three. NRC-AA-8284, BNHS 2832, BNHS 2835, with three developing embryos; NRC-AA-8281, NRC-AA-8285, BNHS 2834, BNHS 2837, BNHS 2839, ZSI-R-28618 with two developing embryos; BNHS 2838 with two eggs with embryos in early stages of development (Fig. 8F-N ).

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.