Gekko stoliczkai, Chandramouli & Gokulakrishnan & Sivaperuman & Grismer, 2021

Chandramouli, S. R., Gokulakrishnan, G., Sivaperuman, C. & Grismer, L. Lee, 2021, A new species of the genus Gekko Laurenti, 1768 (Squamata: Gekkonidae) from the Nicobar Archipelago, with an overview of congeners from the Andaman and Nicobar Islands, Amphibian & Reptile Conservation (e 276) 15 (1), pp. 108-125 : 117-123

Gekko stoliczkai sp. nov. ( Figs. 7–9 )

Gekko gecko (non Linnaeus, 1758) – Biswas and Sanyal (1977) part

Gekko smithii (non Gray, 1841) – Biswas (1984); Das (1999); Vijayakumar (2005) part

urn:lsid:zoobank.org:act:1795181F-C7AD-4195-A233-2B2F1B13826B

Holotype. ZSI / ANRC / T/6092 , an adult male collected from Makachua (7.4035ºN, 93.7134ºE, 37 m asl), Little Nicobar Island on 14 August 2018 by G. Gokulakrishnan.

Paratypes. DOSMB05020 , an adult female from Shastri Nagar (6.8065ºN, 93.8882ºE, 41 m asl), ZSI / ANRC / T/6093 an adult female, ZSI / ANRC / T/4796 and ZSI / ANRC / T/7221 , two adult males from East-West road (7.0022ºN, 93.8811ºE, 82 m asl), Great Nicobar.

Etymology. The specific epithet is a patronym honoring Dr. Ferdinand Stoliczka (1838–1874) for his early contributions to the herpetology of Andaman and Nicobar Islands. Some of his works, such as Stoliczka (1870; 1873), provided significant information on the herpetofauna of the Andaman and Nicobar Islands, which included the description of several new taxa such as Rana gracilis var. andamanensis (now Minervarya andamanensis ), Rana gracilis var. nicobariensis (now Minervarya nicobariensis ), Hylorana nicobariensis (now Bijurana nicobariensis ), Typhlops andamanensis (now Gerrhopilus andamanensis ), Ablabes nicobariensis (now Gongylosoma nicobariensis ), and Mocoa macrotymapnum (now Lipinia macrotympanum ).

Diagnosis. A large-bodied gecko ( SVL 116–128.83 mm) restricted to the southern islands of the Nicobar archipelago, characterized by: 14–17 supralabials; 12 or 13 infralabials; two elongate inner pair of postmentals in broad medial contact with each other; two smaller, separated outer pairs of postmentals; 13–15 precloacal pores in males, no femoral pores; two internasals in contact with each other; distinct ventrolateral dermal folds; 21–25 transverse rows of ventrals; 10–12 transverse rows of enlarged, rounded dorsal tubercles; three enlarged post-cloacal spurs on each side of the vent; 18–22 undivided subdigital lamellae under toe IV; presence of five legible, light-colored, creamy white, transverse bands in juveniles, subadults and adults have a pale-white to creamy yellow venter.

Description of the holotype ( ZSI / ANRC / T /6092). An adult male, measuring 118.37 mm SVL, head fairly large (HL: SVL 0.27), longer than broad (HL: HW 1.34); with a blunt, rounded snout tip. Eyes fairly large ( ED:HL 0.24) with a vertically elliptical pupil; eye slightly smaller than the snout length ( ED: ES 0.52); nostrils situated closer to the snout tip than to the eyes ( EN: ES 0.78). Trunk slightly shorter than one-half the length of the body ( AG: SVL 0.47). Overall habitus depressed. Supralabials 14 on each side, infralabials 13 on each side; two moderately enlarged postmentals in broad medial contact, followed by two pairs of enlarged scales, that are nearly as large as the post-mentals. Dorsum bearing 11 transverse rows of enlarged, rounded tubercles. Ventrals imbricate, in 22 transverse rows. Two pairs of enlarged, rounded cloacal spurs present at the base of the vent on each side. Subcaudals horizontally elongate, the midanterior scales not enlarged. Tail slightly shorter than the body ( SVL: TAL 1.12). Upper arm shorter than lower arm ( UAL: LAL 0.82); palm with enlarged, undivided subdigital lamellae; the first one with an indistinct claw; relative lengths of fingers IV> III > V >II>I. Thighs short ( FEL: SVL 0.17) and robust; with a few tubercles on the dorsal surface. Tibia shorter than thighs ( TBL: SVL 0.15); toes with entire, undivided subdigital lamellae, 21 on toe IV; relative lengths of toes IV> III > V >II>I. Fifteen undivided series of precloacal pores; the pore-bearing scales relatively smaller than those above. Fingers and toes free, lacking membranous skin flaps.

Coloration. In life, overall ground coloration dull-brown with five or six indistinct pale-white transverse crossbars on the body. Tail regenerated and uniform brown. Venter brown with small brown spots on each ventral scale. Eyes with vertically elliptical pupils and a bluish iris. In preservation, the dorsal coloration faded to a near-uniform dull brown with a pale white venter. The transverse bars barely visible and the bluish coloration of the iris faded.

Variation. Measurements and scale counts of the paratypes are given in Table 4 . Females lack precloacal pores and are nearly as large as males. Light-colored, creamy white, transverse bands are more legible in juveniles and subadults while the adults usually have feeble dorsal bands. Ventral color ranges from pale-white to creamy yellow.

Natural history. Nocturnal and found in a variety of habitats ranging from evergreen forests, semi-evergreen forests, and plantations to human habitations. Frequently observed on walls of buildings, or on tree trunks of tall trees at heights ranging from about 6 to 13 feet. Calls comprise a series of repeatedly uttered, interrupted rattling syllables of tuk…tuk…tuk…tuk advancing into high frequency syllables of tuk-tuk-tuk-tuk (also see Biswas 1984).

Comparisons. Gekko stolickzkai sp. nov. can be differentiated from G. smithii by having significantly fewer numbers of internasals and ventrals and having significantly higher numbers of infralabials and supralabials ( Tables 1–3 ; Figs. 1–2 ). It can be further separated from G. smithii by its less gracile more stout body features, in having a significantly narrower and shorter head and snout, a significantly smaller orbit, and significantly shorter limbs and trunk. From G. verreauxi , it is differentiated by the separation of nasal and rostral scales (vs. in contact in G. verreauxi ), bluish iris (vs. greenish in G. verreauxi ), and greater number of supralabials (14–17 in G. stoliczkai sp. nov. vs. 12–14 in G. verreauxi ). From Gekko nicobarensis , G. stoliczkai sp. nov. can easily be distinguished by the absence of skinflaps along the sides of the body and tail, and extensive webbing between fingers and toes (vs. present in G. nicobarensis ), and by the separation of nasal and rostral scales (vs. in contact in G. nicobarensis ). Additionally, from other members of the Gekko gecko group, the new species G. stoliczkai sp. nov. could be distinguished as follows (only opposing suite of characters mentioned): G. albofasciatus (16 precloacal pores and reddish olive dorsal coloration), G. gecko (11–15 supralabials; gray to bluish or brownish dorsal color with reddish spots), G. nutaphandi (12–14 supralabials; 17–22 precloacal pores in males; 15 subdigital lamellae under toe IV), G. reevesii (10–14 supralabials; 13–20 precloacal pores; gray-green to dark grey dorsal coloration), and G. siamensis (13–21 supralabials; 10–13 precloacal pores; grey-brown to dark green dorsal coloration) fide Rösler et al. (2011).

Distribution. Recorded during the present study from Great and Little Nicobar Islands. It has been reported from other smaller islands such as Pigeon, Pilo Milo, Menchal, and Kondul in the southern group of the Nicobar Islands ( Vijayakumar 2005) ( Fig. 10 ).

Figures

Fig. 7. Gekko stoliczkai sp. nov. in life from Great Nicobar.

Fig. 8. Holotype (ZSI/ANRC/T/6092) of Gekko stoliczkai sp. nov. in dorsal (above) and ventral (below) views.

Fig. 9. Lateral, ventral, and dorsal profiles of the head, and precloacal region of the holotype of Gekko stoliczkai sp. nov.

Fig. 1. Analyses of meristic characters. (A) First two principal components of the PCA. (B) Density curves of the first discriminant function of the DAPC. (C) Boxplots in which light-blue circles are the means and the black horizontal bars are the medians.

Fig. 2. Analyses of mensural characters. (A) First two principal components of the PCA. (B) Density curves of the first discriminant function of the DAPC. (C) Boxplots in which light-blue circles are the means and the black horizontal bars are the medians.

Fig. 10. Map of the Andaman and Nicobar Islands showing the distributions of Gekko verreauxi (red), Gekko nicobarensis (yellow), and Gekko stoliczkai sp. nov. (black).