Hemiphyllodactylus minimus, Mohapatra & Khandekar & Dutta & Mahapatra & Agarwal, 2020

Mohapatra, Pratyush P., Khandekar, Akshay, Dutta, Sushil K., Mahapatra, Cuckoo & Agarwal, Ishan, 2020, A novel, diminutive Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) from a sacred grove in Odisha, eastern India, Zootaxa 4852 (4), pp. 485-499 : 488-491

Hemiphyllodactylus minimus sp. nov.

( Figures 2–5 , Table 3)

Holotype. ZSI-CZRC-7112, adult male, from Jhadeswar Shiva Temple , Humma, Ganjam District, Odisha, India (19.451242° N, 85.053831° E; 90 m asl.) collected on 18/06/2014 by Pratyush P. Mohapatra.

Paratypes. ZSI-CZRC-7113, NCBS-BH667 , BNHS 2523 , adult males, ZSI-CZRC-7114, BNHS 2520 , BNHS 2521 , NCBS-BH665 , NCBS-BH665 , BNHS 2522 , BNHS 2524 , adult females, BNHS 2522 collected on 13/05/2015 by Pratyush P. Mohapatra and S.K. Dutta; BNHS 2523 & BNHS 2524 collected on 28/02/2017 by Pratyush P. Mohapatra & Cuckoo Mahapatra; same locality data as holotype .

Referred specimen. ZSI-CZRC-7115, two days old hatchling fixed on 13/05/2015 by Pratyush P. Mohapatra.

Suggested common English name. Ganjam slender gecko.

Etymology. The specific epithet is the Latin word for smallest as this is the smallest known species of the genus Hemiphyllodactylus .

Diagnosis. Hemiphyllodactylus minimus sp. nov. can be diagnosed from congeners by the unique combination of snout-vent length up to 31.2 mm (n=11); nine or ten chin scales; postmentals not enlarged; 9–11 supralabials and infralabials; 15–18 dorsal scales and eight or nine ventral scales at mid-body contained within one longitudinal eye diameter; four subdigital lamellae on the first finger and four or five on first toe; lamellar formula of manus 2222; lamellar formula of pes 2332 and 2333; males with nine or ten precloacal pores separated by 4–6 poreless scales from a series of six or seven femoral pores on each thigh (n=4); no plate-like enlarged subcaudals; dorsum with two pairs of longitudinal stripes extending up to mid-body, the outer pair originating from behind the eye and inner pair from the nape; dorsal pattern with irregular dark lines and white spots; post sacral spot with anteriorly projecting light coloured bands; belly light speckled with dark spots.

Comparison with peninsular Indian congeners. Hemiphyllodactylus minimus sp. nov. can be distinguished from all other Indian congeners on the basis of the following differing or non-overlapping characters: males with nine or ten precloacal and six or seven femoral pores (versus males with eight or nine precloacal and two or three femoral pores in H. arakuensis , six or seven precloacal and 6–8 femoral pores in H. aurantiacus , and 11 precloacal and femoral pores in H. peninsularis ); males with 4–6 poreless scales between precloacal and femoral pores (versus 11–14 in H. arakuensis , 9–11 in H. aurantiacus , 10–12 in H. jnana , and 7–9 in H. nilgiriensis ); 15–18 mid-body dorsal scales in one eye diameter (versus 13–16 in H. arakuensis and H. aurantiacus , and 20 in H. peninsularis ); eight or nine mid-body ventral scales in one eye diameter (versus 9–13 in H. aurantiacus , 11–15 in H. jnana , 10–13 in H. kolliensis , 12–15 in H. nilgiriensis and 14 in H. peninsularis ); lamellar formula of toes 2332 or 2333 (versus 2333 or 3333 in H. arakuensis, 2233 , 2333/ 3333 in H. aurantiacus and 2222 in H. jnana , H. kolliensis , H. nilgiriensis and H. peninsularis ).

Description of the holotype. The holotype is in good condition except for a small vertical cut on the left side of the anterior tail (tail still attached to the body) and all the digits of manus on each side are bent backward. Adult male, SVL 27.3 mm. Head short (HL/SVL 0.21), slightly elongate (HW/HL 0.71), slightly depressed (HH/HL 0.44), distinct from neck ( Figure 3 ). Prefrontal region flat; canthus rostralis smoothly rounded, snout rounded in dorsal profile ( Figure 3A ). Snout short (SE/HL 0.42); longer than eye diameter (ED/SE 0.56); scales on snout, canthus rostralis, forehead and inter-orbital region homogenous in shape, granular; scales on the snout and canthus rostralis slightly larger and pronounced than those on occipital, forehead and inter-orbital regions, two 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 oval (greatest diameter 0.2 mm), eye to ear distance greater than diameter of eye (EE/ED 1.42); rostral wider than deep (RW/RH 2.00), undivided; single large supranasal above naris on each side, separated medially by two slightly smaller internasal scales; two postnasal on each side, marginally smaller in size than supranasals; rostral in contact with naris, supralabial I, supranasals and two small internasal scales; naris small, roughly circular; external naris surrounded by supranasal, rostral, supralabial I and two postnasals on either side ( Figure 3C ). Mental subtriangular, bordered laterally by infralabial I on either side and posteriorly by two slightly enlarged chin scales; five scales touching internal edge of infralabials and mental from juncture of second and third infralabials on either side ( Figure 3B ). Labials large, supralabial I and infralabial I largest, gradually decrease in size posteriorly; supralabials (to mid-orbital position) eight on right and nine on left side; ten supralabials (to angle of jaw) on each side; infralabials (to angle of jaw) 11 on right and ten on left side.

Body relatively stout (BW/SVL 0.17), slightly elongate (TRL/SVL 0.48), ventrolateral folds indistinct ( Figure 2 ). 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, flat and subimbricate; 15 scales contained within one eye diameter. Ventral scales much larger than dorsals, smooth, subequal, imbricate, subcircular, gradually increasing in size posteriorly, except three rows above cloaca which are much smaller; eight scales contained within one eye diameter; gular region with much smaller, granular scales, becoming slightly larger, flattened and juxtaposed on anterior and lateral aspects. Scales on palm and sole flat and subcircular; scales on dorsal and ventral aspect of limbs flat and imbricate, those on anteriolateral aspect of thigh largest. Forelimbs and hindlimbs short, stout; forearm short (FL/SVL 0.08); tibia short (CL/SVL 0.10). 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 2332 (pes); basal lamellae of digits II–V: 3455 (manus) and 3445 (pes); transversely expanded lamellae on digit I: four (manus) and five (pes).

Tail original except for one-third which is regenerated, not segmented; tail slightly shorter than snout vent length (TL/SVL 0.83) ( Figure 3 ); scales on dorsal aspect of tail much larger than those on mid-body dorsum, smooth, flat, rounded and subimbricate, gradually increasing in size laterally. Scale on ventral side of the tail almost twice the size of those on tail dorsal, smooth, flat, roughly oval and subimbricate. Two distinct hemipenial bulges at tail base, clearly visible when viewed from laterally and ventrally; three enlarged, subequal postcloacal spurs on both sides. Angular series of ten precloacal pores separated from a series of seven (right) and six (left) femoral pores by four poreless scales on either side.

Colouration in life. ( Figure 4 ). Ground colour of dorsum of body, head and limbs grey-brown with scattered light and dark markings; preorbital region dark, small dark occipital spot, and digits lighter. Fine dark pre-orbital stripe, two fine discontinuous dark post-orbital stripes that extend just beyond forelimb insertions; two fine dark longitudinal markings on nape. Postsacral marking light brown to cream, chevron-shaped, flanked anteriorly by narrow black chevron; light-coloured anteriorly projecting arms extend above hindlimb insertions as a series of a few spots. Original portion of tail with indistinct band, regenerated tail grey with dark and scattered patches. Ventral side of head, neck and limbs light coloured and pigmented with dark patches. Colouration in preservative similar to life colouration except colours strongly faded with dorsal colouration light brown and most lighter dorsal markings lost.

Variation and additional information from paratypes. Mensural and meristic data for the type series is given in Table 3. There are three male and seven female specimens ranging in size from 24.3–31.3 mm. All paratypes resemble the holotype except as follows: the colouration is variable in the type series; (in preservative) ground colour varies from light brown to dull grey; a fine dorsolateral stripe formed from a series of light spots extending between postsacaral marking and post-orbital streak in BNHS 2522 ; original portion of tail with alternating dark and light bands in BNHS 2521 , NCBS-BH665 and NCBS-BH665 ( Figure 5 ). Two paratypes, NCBS-BH667 and BNHS 2522 are without tail; ZSI-CZRC-7114 with broken tail, detached from the body (TL= 5 mm); NCBS-BH666 with original and complete tail, slightly shorter than body (TL/ SVL 0.86); six paratypes, ZSI-CZRC-7113, BNHS 2521 , NCBS-BH665, BNHS 2523 and BNHS 2524 with either completely or less than half regenerated but complete tail, slightly shorter than body (TL/ SVL 0. 91, 0.79, 0.74, 0.96, 0.64 respectively); BNHS 2520 with completely regenerated tail, less than half of the body (TL/ SVL 0.47). Original tail without caudal segments; dorsal and ventral scalation similar to holotype ( Figure 5 ).

Variation in colouration. (based on unvouchered specimens). The species shows substantial ground colour and pattern variation, broadly summarized as a dark and light phase ( Figure 6 ). The extent of the postsacral marking is also variable; the original tail is orange or light orange or drab and orange ventrally, with 8–10 pairs of indistinct black crossbars posterior to postsacral marking.

Distribution and natural history. The species is only known from the type locality, a tiny area of 0.01 km 2 comprising ~20 large trees surrounding a temple and treated as a sacred grove ( Figure 7 ). The area is part of a flattop hillock of <300 m altitude, dominated by scrub forest and is within 15 km of the coast and Chilika Lake. The vegetation of the type locality comprises some old and relatively young mango trees ( Mangifera indica Linnaeus ), coconut palm ( Cocos nucifera Linnaeus ), areca palm (Areca catechu Linnaeus), jackfruit ( Artocarpus heterophyllus Lamarck ) and banyan trees ( Ficus benghalensis Linnaeus ). The type locality is highly modified due to anthropogenic activities and is under constant anthropogenic pressure in terms of beautification of the temple and tourist activities. The herpetofaunal diversity of Jhadeshwar sacred grove comprises 40 species of reptiles and 15 species of amphibians (Das et al.: in press).

The species has only been spotted on mango trees at the type locality and unlike other members of the Eastern Ghats clade of Hemiphyllodactylus spp., this species was never encountered on concrete walls or below rock boulders. Despite targeted searches for the species in similar micro-habitats in the hills surrounding and further away from the type locality, no other sub-populations have been found.

Other arboreal herpetofauna at the type locality include Hemidactylus frenatus Duméril & Bibron, 1836 , H. leschenaultii Duméril & Bibron , H. parvimaculatus Deraniyagala , Boiga forsteni (Duméril, Bibron & Duméril) , B. trigonata (Schneider) , Lycodon aulicus (Linnaeus) , L. gracilis (Günther) , L. nympha (Daudin) , Dendrelaphis tristis (Daudin) , and Ahaetulla nasuta (Lacépède) .

Ecological notes. During the three years of study (2014–2017), a total of 612 observations were made, with the maximum sighting of 22 individuals per survey. H. minimus sp. nov. was found to be exclusively arboreal and only found on some specific mango ( Mangifera indica L) trees in the type locality. In very few cases (3 observations) the species was found on the ground, either for foraging or to move to another tree. Random surveys conducted in the daytime resulted in finding only two individuals under the bark of mango tree within a height of 7ft from ground, which suggests that the animals prefer to stay at the upper portion of the trees. In their natural habitat, individuals were found to be actively foraging, targeting ant and termite trails (21 observations). Other observed prey species include Blattella spp. (8 observations; Figure 8 A ), unidentified beetles (3 observations) and a salticid spider (1 observation). This species lays a clutch of two eggs, glued together at the middle and free in the substrate, during April–August. The oviposition sites were at 5–7ft from ground and eggs were laid in the tree crevices or under loose bark of the mango trees ( Figure 8 B ). The eggs were rigid-shelled, oval and measured 6.1–6.6 mm in length x 4.6 mm in width (n=8). In captivity, one gravid female laid eggs on 14/06/2015 and after an incubation period of 41 days in room temperature at Berhampur, Ganjam, Odisha (average maximum and minimum temperature at the range of 31°C–26°C), the babies hatched out on 31/08/2015 ( Figure 8 C ). The two days old hatchlings were of equal size, measuring 12.4 mm SVL and 8.4 mm tail length. Juveniles have a relatively longer tail than adults (TL/SVL 0.68). absent = abs.

Figures

FIGURE 2. Hemiphyllodactylus minimus sp. nov. (holotype, ZSI-CZRC-7112): (A) dorsal view of body, (B) ventral view of body. Scale bars 10 mm.

FIGURE 3. Hemiphyllodactylus minimus sp. nov. (holotype, ZSI-CZRC-7112): (A) dorsal view of head, (B) ventral view of head, (C) lateral view of head. Scale bars 5 mm.

FIGURE 4. Holotype (ZSI-CZRC-7112) of Hemiphyllodactylus minimus sp. nov. in life.

FIGURE 5. Paratypes of Hemiphyllodactylus minimus sp. nov., from left to right, (top panel) ZSI-CZRC-7113, ZSI-CZRC- 7114, BNHS 2520, BNHS 2521, NCBS-BH665; (bottom panel) NCBS-BH666, NCBS-BH667, BNHS 2522, BNHS 2523, BNHS 2524. Scale bar 10 mm.

FIGURE 6. Colour variation in Hemiphyllodactylus minimus sp. nov. (A&B) males and (C,D,E,F) females, all from the type locality (uncollected individuals).

FIGURE 7. Habitat of Hemiphyllodactylus minimus sp. nov., at Jhadeswar Shiva Temple, Humma, Ganjam District, Odisha, India.

FIGURE 8. Natural history of Hemiphyllodactylus minimus sp. nov. (A) an uncollected female feeding on a Blattella sp., (B) a pair of eggs laid by an unvouchered female individual, (C) two- day old hatchlings.