Hemidactylus xericolus, Lajmi & Giri & Singh & Agarwal, 2020

Lajmi, Aparna, Giri, Varad B., Singh, Taneraw & Agarwal, Ishan, 2020, Two new species of yellow-tailed Hemidactylus Goldfuss, 1820 (Squamata Gekkonidae) from rocky outcrops on the Telangana Plateau, India, Zootaxa 4895 (4), pp. 483-504 : 492-500

Hemidactylus xericolus sp. nov.

Figs. 5–8 , Table 3

Holotype. National Centre for Biological Sciences (NCBS) NRC-AA-1110, adult male; collected from near Marrigudda , District Nalgonda, Telangana, India (16.96270° N, 78.85869° E, 430 m asl) on 23August 2015. Collected by Aparna Lajmi, Taneraw Singh and Maitreya Sil.

Paratypes. CES 16170 adult male, NRC-AA-1111 adult female. Collection details are same as the holotype .

Etymology. The specific epithet is a masculine adjective derived from the Greek xeros (= dry) and the Latin cola (= inhabitant of) and is descriptive of the arid, scrub habitats that the new species and many other endemic Indian Hemidactylus inhabit. The name also seeks to bring attention to the neglected and biodiverse Indian dry zone.

Suggested common name. Nalgonda yellow-tailed brookiish gecko

Diagnosis. A small sized Hemidactylus , snout-vent length up to at least 44.7 mm (n=3). Dorsal pholidosis heterogeneous composed of subcircular granular scales intermixed with moderately enlarged, circular, flattened, feebly keeled tubercles extending from occiput to tail and in 6–8 irregularly arranged longitudinal rows at midbody. Ventrolateral folds indistinct, about 21–26 scale rows across venter. Digits with slightly enlarged, divided scansors; lamellae in oblique series, seven (manus) and six or seven (pes) beneath fourth digit and four (manus and pes) beneath first digit; 15 or 16 precloacofemoral pores on each side separated by a single poreless scale in males (n=2). Original tail slightly depressed, verticillate, oval in transverse section with indistinct median dorsal furrow; dorsal tail pholidosis heterogenous with rounded, smooth, subimbricate scales intermixed with two to three enlarged, conical keeled tubercles at the base of every whorl, on either side of median dorsal furrow; subcaudals much enlarged; a pair of slightly enlarged postcloacal spurs on either side. Dorsal colouration of transversely arranged, pale grey to ashy markings on a pale, mustard-brown background; nuchal collar indicated by spots, not in contact with postorbital streak. The tail is distinctly yellow in adults of both sexes and juveniles.

Comparison with other members of the H. brookii group. Hemidactylus xericolus sp. nov. can be distinguished from many members of the H. brookii group by its small adult size (maximum SVL 44.7 mm versus 55.8 in H. brookii , 51.5 mm in H. chikhaldaraensis , 74.2 mm in H. chipkali , 56.2 mm in H. cf. gleadowi , 51.4 mm in H. kushmorensis , 65.0 mm in H. murrayi ( Lajmi et al. 2016) , 53.8 mm in H. malcolmsmithi , 52.3 mm in H. parvimaculatus ( Lajmi et al. 2016) , 62.5 mm in H. rishivalleyensis , 50.8 mm in H. sankariensis , 61.7 mm in H. subtreidroides , 70.2 mm in H. treutleri , and 61.9 mm in H. varadgirii ). Hemidactylus xericolus sp. nov. can be distinguished from the species that are less than 55 mm SVL by the presence of dorsal tubercles in 6–8 irregularly arranged rows versus 15–17 fairly regularly arranged rows in H. chikhaldaraensis ; 19 or 20 fairly regularly arranged longitudinal rows in H. kushmorensis ; 15–20 fairly regularly arranged longitudinal rows in H. malcolmsmithi ; 15–18 fairly regularly arranged longitudinal rows in H. parvimaculatus ; 15 fairly regularly arranged longitudinal rows in H. sankariensis . The new species can be easily distinguished from members of the ground dwelling clade by the presence of 15 or 16 precloacofemoral pores on each side in males (versus <8 precloacal pores in males of H. albofasciatus Grandison & Soman , H. gracilis Blanford , H. imbricatus , H. reticulatus Beddome , H. sataraensis Giri & Bauer and H. vijayraghavani Mirza ). Hemidactylus xericolus sp. nov. can be distinguished from H. gleadowi by the lower number of scales across the belly (21–26 versus 32–34) and fewer dorsal tubercle rows (6–8 versus 17 or 18). The yellow colouration of the tail in life, the dorsal colour pattern and the very low number of dorsal tubercle rows are unique among Indian Hemidactylus .

Hemidactylus xericolus sp. nov. is most closely related to its sister species, Hemidactylus flavicaudus sp. nov. but is genetically deeply divergent ( Table 2) and can be diagnosed from based on fewer dorsal tubercle rows at midbody (6–8 versus 11–14) as well as in dorsal colour pattern (upper preorbital streaks on each side almost meeting at rostral versus meeting at rostral; nuchal collar indicated by spots and usually not meeting postorbital streak laterally versus complete nuchal collar meeting postorbital streak laterally.

Holotype description. The holotype is generally in good condition with some minor exceptions; all artifacts of preservation: the body shape is somewhat dorsoventrally flattened, tail partly regenerated, is curved in a sigmoid manner towards the right. Head short (HL/ SVL 0.27), slightly elongate ( HW /HL 0.71), not strongly depressed (HH/HL 0.36), relatively broad ( HW / BW 0.83), distinct from neck. Loreal region slightly inflated, canthus rostralis not prominent. Snout short ( SE /HL 0.41); slightly longer than eye diameter ( OD / SE 0.56); scales on snout, canthus rostralis and forehead region homogeneous in shape and slightly heterogeneous in size, rounded, not flat and juxtaposed; distinctively larger than those on interorbital and occipital region; scales on interorbital and occipital region homogeneous in shape, slightly heterogeneous in size, granular, those on occipital region smallest. Eye small ( OD / HL 0.23); pupil vertical with crenate margins; supraciliaries small, mucronate, increasing in size from midorbital position with those on the anterior end of orbit largest. Ear opening oval (greatest diameter 1.20 mm); eye to ear distance greater than diameter of eye ( EE / OD 1.34). Rostral wider (1.9 mm) than deep (1.1 mm), completely divided dorsally by weakly developed rostral groove; two enlarged internasals in contact medially, one supranasal on each side which is half the size of internasal; two postnasals on either side, slightly smaller than supranasal; both postnasals on right side are of similar size; rostral in contact with nasal, supralabial I and internasal; nostrils large, slightly oval, directed upwards, covering most of the nasal scale; nasal on either side surrounded by supranasal, internasal, rostral, supralabial I and postnasals. Mental almost equal in length (1.9 mm) and width (1.8 mm) triangular, two well-developed postmentals, the inner pair slightly shorter (1.5 mm) than mental and not in contact with each other behind mental, outer twice in length (1.5 mm) than the inner pair (0.7 mm), separated from each other by inner pair. Inner postmentals bordered by mental, infralabial I, slightly infralabial II, outer postmental and two gular scales; outer postmental bordered by inner postmental, infralabial II, and four gular scales. Infralabials bordered by a single row of enlarged and elongated scales starting from centre of infralabial III to infralabial VI on right and from below infralabial III to infralabial VII on left. Eight supralabials (to midorbital position) on either side; 10 supralabials (to angle of jaw) on either side; seven infralabials (to angle of jaw) on the right and eight on the left side.

Body slender, trunk not elongate ( TRL / SVL 0.48), with indistinct ventrolateral folds without denticulate scales. Dorsal pholidosis heterogeneous, composed of conical, granular scales intermixed with irregularly arranged, longitudinal rows of 6–8 slightly larger, rounded, feebly keeled, indistinct tubercles at midbody, extending from shoulder to tail; those on parasagittal rows slightly smaller, gradually increasing in size laterally, being slightly larger on flanks; roughly two to three times longer than adjacent granules, surrounded by a rosette of 6–8 small granules, 2–6 granules between two adjacent enlarged tubercles. Ventral scales much larger than granular scales on dorsum, roughly hexagonal, smooth, imbricate, more or less similar in size; midbody scale rows across belly 24 or 25; gular region with still smaller, smooth, rounded, subimbricate scales, increasing in size anteriolaterally, those below mental, postmentals and infralabials are largest.

Femoral and precloacal pores 16 on each side, separated by a single non-pored scale. Scales on the palm and sole smooth, granular, rounded; scales on forelimb homogeneous, dorsal aspect with rounded, smooth, subimbricate scales which are slightly smaller than largest enlarged tubercles on dorsum, those on ventral portion are smaller and granular; scales on hindlimbs heterogenous in size and shape, dorsal part of thigh and shank are similar like dorsum, with granular scales, intermixed with scattered, enlarged, rounded, slightly conical, feebly keeled tubercles, which are denser on shank than thigh, anterior portion of thighs and ventral aspect of hindlimbs with much enlarged, smooth, imbricate scales. Fore- and hind limbs relatively slender; forearm short ( FL / SVL 0.13); tibia short (CL/ SVL 0.15); digits moderately long, strongly clawed; terminal phalanx of all digits curved, arising angularly from distal portion of expanded lamellar pad, half or more than half as long as associated toepad; scansors beneath each toe in oblique series divided, except a distal and one or two basal scansors in all digits single; scansors from proximalmost at least twice the diameter of palmar scales to distalmost single scansor: 4-6-7-7-6 (left manus) 4-6-7-7-6 (right manus), 4-6-7-7-6 (left pes) 4-7-7-6-6 (right pes). The first digit on all limbs shorter, slightly less than half the length of second digit. Relative length of digits (measurements in mm in parentheses): III(3.4)> IV(3.2)> V (3.1)> II(2.8)> I(1.9) (left manus); IV(4.1)> V (3.8)> III(3.2)> II(3.0)> I(2.1) (left pes).

Tail slightly depressed, verticillate, oval in transverse section with indistinct median dorsal furrow; dorsal tail pholidosis heterogenous with smaller, rounded, smooth, subimbricate scales, gradually increasing in size laterally, intermixed with four to six enlarged, conical, weakly keeled tubercles on every whorl, two to three on either side of median dorsal furrow; ventral scales enlarged, imbricate, median row (subcaudal plates) covering almost entire base of the tail, bordered laterally by two or three rows of larger, smooth, imbricate scales; those close to vent small, smooth, flat and imbricate ( Fig. 6 B ). A pair of slightly enlarged postcloacal spurs on either side.

Colouration in life ( Fig. 5 B ). Dorsal ground colour of head, body, limbs and tail beige with scattered indistinct lighter blotches. Two distinct dark preorbital streaks enclosing a yellow streak, upper narrower and converging from each side at rostral but not meeting, lower terminating at supralabials three and four; distinct dark postorbital streak flanked by narrow yellow markings which is broader than the lower preorbital streak and extends from behind eye until the nuchal collar with a break just after the tympanum; anterior portion of brille yellow. Head dorsum mottled and suffused with yellow, interorbital region slightly bluish, three large spots forming a transverse series on occiput in line with the end of the postorbital streak; nuchal collar indicated by three dark spots, the central largest; a large dark spot above forelimb insertions; labials with fine black spots and some yellow on anterior supralabials, rostral yellowish. Dorsum with four sets of dark markings between limb insertions; the first three consist of a central spot flanked on four corners by four smaller or subequal spots (forming the arms of an X) and the fourth has a central spot flanked by one spot on either side, the outer spots flanked by another row of similar sized spots on the flanks.

Tibia, tarsus, femur and digits with a few dark cross bars; tail suffused with saffron-yellow, five dark cross bars on original portion, regenerated portion similar to rest of tail ground colour except with less yellow. Venter offwhite, immaculate.

Variation and additional information from type series ( Fig. 8 , Table 3). There is one male and one female specimen that are very similar in SVL to the holotype (44.7. 44.5 mm). The paratypes resemble the holotype except as follows: supralabials nine on the right side of NRC-AA-1111; inner pair of postmental is in contact with each other in NRC-AA-1111; lamellae six on right side of fourth digit of pes; femoral pores 15 of left side of NRC-AA- 1110. The overall colour pattern is consistent across the type series, though the size and shape of dorsal markings is variable, there are 13 dark bands on the complete original tail of CES 16169, and the nuchal collar in CES 16169 is indicated by only two spots .

Distribution. Hemidactylus xericolus sp. nov. is known only from its type locality.

Habitat and Natural History. The type locality is surrounded by hills with rocky boulders and scrub vegetation ( Fig. 9 ). The vegetation is denser than at localities where Hemidactylus flavicaudus sp. nov. is known from and included stunted trees. The specimens were collected from horizontal surfaces of large boulders or on vertical rock surfaces at low heights of under four feet. Sympatric congeners in the rocky habitat included H. cf. treutleri , H. cf. giganteus , and an undescribed large tuberculated species (denoted by “ Hemidactylus species 2” from Lajmi & Karanth 2020). Hemidactylus cf. triedrus , H. cf. reticulatus , and H. cf. gleadowi were also seen in the adjoining scrub at the base of the hillock.

Figures

FIGURE 5. The new species in life: top, Hemidactylus flavicaudus sp. nov. (paratype, NRC-AA-1107); bottom, Hemidactylus xericolus sp. nov. (holotype, NRC-AA-1110).

FIGURE 6. Hemidactylus xericolus sp. nov. (holotype, NRC-AA-1110), dorsal view (A), ventral view (B). Scale bars 10 mm.

FIGURE 7. Hemidactylus xericolus sp. nov. (holotype, NRC-AA-1110), head in dorsal view (A), ventral view (B), lateral view (C), view of cloacal region showing femoral pores and post cloacal spurs (D), ventral view of right manus (E), and ventral view of right pes (F). Scale bars 5 mm.

FIGURE 8. The type series of Hemidactylus xericolus sp. nov.

FIGURE 9. The type locality of Hemidactylus flavicaudus sp. nov., near Guddeguda, Mahabubnagar District, Telangana.