Hemiphyllodactylus nilgiriensis, Agarwal & Pal & Khandekar, 2020

Agarwal, Ishan, Pal, Saunak & Khandekar, Akshay, 2020, Two more new Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) from Tamil Nadu, India, Zootaxa 4729 (2), pp. 249-265 : 251-257

Hemiphyllodactylus nilgiriensis sp. nov.

Figures 2–4 , 5A ; Table 3 .

urn:lsid:zoobank.org:act:258AD0D5-6E2C-46DF-A129-60C5A58D0258

Holotype. BNHS 2632 , SVL 32.2 mm, adult male, from near Mulli view point, Kilkunda, (11.252 N, 76.663 E; ca. 1240 m asl.), Nilgiris District , Tamil Nadu, India, collected by Saunak Pal on 11 December 2011.

Paratype. CEL 467, SVL 34.8 mm, adult female, same locality as holotype ; BNHS 2436 SVL 26.2 mm & BNHS 2437 SVL 31 mm, adult males, from near Maruthamalai , Daliyur, (11.037 N, 76.858 E; ca. 640 m asl.), Coimbatore, Tamil Nadu, India collected by Achyuthan Srikanthan on 18 March 2015 .

Etymology. The specific epithet is a toponym for the Nilgiri mountain range or Nilgiris, to which the new species is restricted.

Suggested Common Name. Nilgiris slender gecko

Diagnosis. Hemiphyllodactylus nilgiriensis sp. nov. can be diagnosed from congeners by the unique combination of snout-vent length up to 35 mm (n =2); nine or ten chin scales; postmentals not enlarged; ten or 11 supralabi- als; 9–11 infralabials; 16–19 dorsal scales and 12–15 ventral scales at midbody contained within one longitudinal eye diameter; four subdigital lamellae on the first finger and toe; lamellar formula of manus and pes 2222; males with eight or nine precloacal pores separated by 7–9 poreless scales from a series of 7–9 femoral pores on each thigh; no plate-like enlarged subcaudals; dark postorbital stripe and longitudinal markings on nape extending just past forelimb insertions; dorsal pattern of broken dark longitudinal markings and light paravertebral spots; postsacral marking with light-coloured anteriorly projecting arms indicated by spots; belly stippled with black.

Comparison with peninsular Indian congeners. Hemiphyllodactylus nilgiriensis sp. nov. can be distinguished from all other Indian congeners on the basis of the following differing or non-overlapping characters: males with eight or nine precloacal and 7–9 femoral pores (versus six or seven precloacal and 6–8 femoral pores in H. aurantiacus , eight or nine precloacal and two or three femoral pores in H. arakuensis , nine or ten precloacal and six or seven femoral pores in H. jnana , nine precloacal and eight femoral pores in H. kolliensis ); males with 7–9 poreless scales between precloacal and femoral series (versus 9–11 poreless scales between precloacal and femoral series in H. aurantiacus , 11–14 poreless scales between precloacal and femoral series in H. arakuensis , 10–12 poreless scales between precloacal and femoral series in H. jnana , five poreless scales between precloacal and femoral series in H. kolliensis ); 16–19 midbody dorsal scales in one eye diameter (versus 13–16 midbody dorsal scales in one eye diameter in H. aurantiacus and H. arakuensis , 16 midbody dorsal scales in one eye diameter in H. kolliensis ); 12–15 midbody ventral scales in one eye diameter (versus 9–13 midbody ventral scales in one eye diameter in H. aurantiacus , 7–9 midbody ventral scales in one eye diameter in H. arakuensis , 10–13 midbody ventral scales in one eye diameter in H. kolliensis ); lamellar formula of toes 2222 (versus lamellar formula of toes 2233, 2333 or 3333 in H. aurantiacus , lamellar formula of toes 2333 or 3333 in H. arakuensis ). Hemiphyllodactylus nilgiriensis sp. nov. is compared against Hemiphyllodactylus peninsularis sp. nov. after the description of the latter.

Description of the holotype. The holotype is in good condition except for a small vertical incision (2.1 mm) on the abdomen for tissue collection.Adult male, SVL 32.2 mm. Head short (HL/SVL 0.22), slightly elongate (HW/ HL 0.72), slightly depressed (HH/HL 0.40), distinct from neck ( Figure 2A ). Prefrontal region flat; canthus rostralis smoothly rounded, snout rounded in dorsal profile ( Figure 3A ). Snout short (SE/HL 0.40); longer than eye diameter (ED/SE 0.58); scales on snout, canthus rostralis, forehead and inter-orbital region homogenous, granular; scales on the snout and canthus rostralis slightly larger and pronounced than those on occipital, forehead and inter-orbital regions, two or three rows bordering supralabials slightly larger and elongated ( Figure 3A, C ). Eye small (ED/HL 0.23); pupil vertical with crenulated margins; supraciliaries small, slightly mucronate, gradually increasing in size towards anterior of the orbit, those at the anterior end of orbit larger. Ear opening roughly circular (greatest diameter 0.5 mm); eye to ear distance slightly greater than diameter of eye (EE/ED 1.52). Rostral wider than deep (RL/RW 2.00), undivided; single large supranasal above naris on each side, separated medially by four slightly smaller internasal scales; single large postnasal, slightly smaller in size than supranasals on each side; rostral in contact with naris, supralabial I, supranasals and four small internasal scales; naris small, roughly circular; external naris surrounded by supranasal, rostral, supralabial I and single postnasals on either side ( Figure 3C ). Mental triangular, bordered laterally by infralabial I on either side and posteriorly by two chin scales; five scales touching internal edge of infralabials and mental from juncture of 2nd and 3rd infralabials on either side ( Figure 3B ). Labials gradually decrease in size posteriorly, supralabial I and infralabial I largest; supralabials (to midorbital position) nine on right and eight on left side; ten supralabials (to angle of jaw) on each side; infralabials (to angle of jaw) nine on right and ten on left side.

Body relatively stout (BW/SVL 0.14), slightly elongate (TRL/SVL 0.50), ventrolateral folds indistinct. Scales on dorsal aspect of head and neck granular, slightly smaller than those on snout and forehead, those on dorsum slightly smaller than those on snout and forehead, flat and subimbricate; 19 scales contained within one eye diameter. Ventral scales much larger than dorsals, smooth, imbricate, subcircular, gradually increasing in size posteriorly, except four or five rows above cloaca are much smaller; 13 scales contained within one eye diameter; gular region with much smaller, granular scales, becoming slightly larger, flat and juxtaposed on anterior aspect. Scales on palm and sole flat and rounded; scales on dorsal and ventral aspect of limbs flat and subimbricate, those on anteriolateral aspect of thigh largest. Fore- and hind limbs short, stout; forearm short (FL/SVL 0.8); tibia short (CL/SVL 0.11). Digits with well-developed lamellar pad; digit I vestigial, without claw; digits II–V well developed, with free terminal phalanx arising from within lamellar pad, ending in a unsheathed, recurved claw; lamellar pads of all digits with basal series of undivided, transverse lamellae, expanding into large triangular apical lamellae, which are divided/deeply notched except terminal lamella which is undivided; proximal lamellae/lamellar formula II–V: 2222 (manus and pes), basal lamellae of digits II–V: 3454 (manus) and 3464 (pes); four transversely expanded lamellae on digit I (manus and pes).

Tail regenerated, flattened ventrally, not forming caudal segments; tail shorter than snout vent length (TL/SVL 0.51); scales on dorsal and ventral aspect of tail flat, smooth and imbricate with rounded border; scales on dorsal aspect larger than those on back, gradually increasing in size ventrally ( Figure 2A ). A pair of enlarged, similar sized postcloacal spurs on both sides. Angular series of eight precloacal pores separated from a series of seven (right) and eight (left) femoral pores by seven (right) and nine (left) poreless scales ( Figure 3D ).

Colouration in life. ( Figure 4A, B ). Ground colour of dorsum, head and limbs brown. Faint dark pre-orbital stripe, two distinct dark post-orbital stripes, the lower terminating at forelimb insertions and the upper just after. Dorsum with faint dark longitudinal markings and few scattered light speckles, head dirty brown with a few darker spots and longitudinal markings. Limbs with indistinct dark reticulations and light speckles. Postsacral marking light brown to cream, chevron-shaped, flanked anteriorly by narrow black chevron; light-coloured anteriorly projecting arms indicated by scattered light cream spots. Regenerated tail orange-brown with dark reticulations, similar colouration ventrally. Throat and outside of belly strongly stippled with dark spots and numerous dark scales, underside of limbs and precloacal region strongly pigmented.

Variation and additional information from paratype. Mensural and meristic data for the type series is given in Table 3 . Colouration of female paratype ( CESL 467 ) considerably more uniform brown with a few scattered indistinct darker markings ( Figure 4B ); original portion of tail in the two male paratypes ( BNHS 2436 , 2437 ) with alternating dark and light bands. Original tail without caudal segments; dorsal and ventral scalation similar to holotype ( Figure 4C, D, E, F ).

Sequence divergence. Hemiphyllodactylus nilgiriensis sp. nov. is over 10% divergent in uncorrected pairwise ND2 sequence data from H. aurantiacus and H. kolliensis , and 6.4 % divergent from H. jnana ( Table 2 ). This species was included in Agarwal et al. (2019a) as Hemiphyllodactylus sp. IN 7. Hemiphyllodactylus nilgiriensis sp. nov. is the well supported sister to Hemiphyllodactylus peninsularis sp. nov.

Distribution and Natural history. Hemiphyllodactylus nilgiriensis sp. nov. is currently known in and around its type locality in the eastern slopes of the Nilgiris, Nilgiris District, Tamil Nadu. The holotype and paratype (CESL 467) were collected from a mud cliff along a road on the eastern side of the Nilgiris. The habitat at the type locality comprises mixed deciduous forests and open scrub patches. The specimens in Mulli were found in the early evening hours (ca. 18:00 hrs) partially hiding in a crevice ca. 1.5 m above the ground. No other geckos were observed sharing the microhabitat although Hemidactylus cf. leschenaultii Duméril & Bibron and Hemidactylus frenatus Duméril & Bibron were spotted on nearby tree trunks later in the night. Specimens collected around Maruthamalai were found curled inside loose bark on tree trunks (ca. 10:00 hrs).

Figures

FIGURE 2. Hemiphyllodactylus nilgiriensis sp. nov. (holotype, BNHS 2632): (A) dorsal view of body, (B) ventral view of body, (C) type series of Hemiphyllodactylus nilgiriensis sp. nov. Scale bars 10 mm.

FIGURE 3. Hemiphyllodactylus nilgiriensis sp. nov. (holotype, BNHS 2632): (A) dorsal view of head, (B) ventral view of head, (C) lateral view of head, (D) view of cloacal region showing precloacal and femoral pores. Scale bars 4 mm.

FIGURE 4. Hemiphyllodactylus nilgiriensis sp. nov. in life: (A) male holotype, BNHS 2632, (B) female paratype, CESL 467, (C) male paratype BNHS 2437 dorsal view, (D) male paratype BNHS 2437 ventral view, (E) male paratype BNHS 2436 dorsal view, (F) male paratype BNHS 2436 ventral view.

FIGURE 5. Habitat photos of Hemiphyllodactylus nilgiriensis sp. nov. near Mulli view point, Kilkunda, The Nilgiris District, Tamil Nadu, India (top panel) and Hemiphyllodactylus peninsularis sp. nov. near Sengaltheri, Kalakad Mundanthurai Tiger Reserve, Tirunelveli District, Tamil Nadu, India (lower panel).