Gekko (Gekko) verreauxi Tytler, 1865

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 : 111-114

Gekko (Gekko) verreauxi Tytler, 1865 ( Figs. 3–4 )

Gekko verreauxi Tytler, 1865

Gekko stentor – Boulenger (1885) part

Gekko smithii – Smith (1935) part

Lectotype. NHMUK 68.4 .3.64, an adult female collected from the ‘ Andaman Islands’ by W. Theobald fide Ota et al. (1991) (photographs studied).

Paralectotype. NHMUK 1868.4 .3.65, an adult female from the same location (photographs studied) .

Material studied. ZSI / ANRC / T/4324 from Majarpahar (11.7029°N, 92.6433°E, 16 m asl), South Andaman ; ZSI / ANRC / T/3726 from Durgapur (13.2761°N, 93.0311°E, 5 m asl), North Andaman ; ZSI / ANRC / T/4566 from Rabindranagar (10.7080°N, 92.5334°E, 57 m asl), Little Andaman ; ZSI / ANRC / T/5779 from Krishna Nagar (12.0086°N, 92.9635°E, 58 m asl), Swarajdweep (formerly Havelock Island) .

Diagnosis. A large-bodied species of Gekko ( SVL 140.06– 146.48 mm) characterized by: 12–14 supralabials; 9–13 infralabials; two elongate inner pairs of postmentals in broad contact with each other; two smaller, separated outer pairs of postmentals; 11–13 precloacal pores in males; absence of femoral pores; two internasals in contact with each other; distinct ventrolateral dermal folds; 26–29 transverse rows of imbricate ventrals; 12 or 13 transverse rows of enlarged, rounded, dorsal tubercles; two to three enlarged post-cloacal spurs on each side of the vent; 18–20 undivided subdigital lamellae on toe IV; presence of five legible, dark, transverse bands in juveniles and subadults transforming into a nearly uniform dark-brown dorsal coloration in adults with a pale-white to light-brown venter.

Description and variation. A large species of Gekko , measuring 109.55–146.49 mm SVL. Head large (mean HL: SVL 0.26), longer than broad (mean HL: HW 1.19) with a blunt, rounded snout tip. Eyes moderately large (mean ED:HL 0.25) with a vertically elliptical pupil approximately one-half the length of the snout (mean ED: ES 0.53); nostrils situated closer to the snout tip than to the eyes (mean EN: ES 0.79). Trunk one-half as long as the body (mean AG: SVL 0.46). Overall habitus depressed. Supralabials 12–14 on each side; infralabials 9–13 on each side; two moderately enlarged postmentals in broad medial contact, followed by three smaller pairs of scales. Dorsum bearing 11–13 transverse rows of enlarged tubercles. Ventrals imbricate, in 27–29 transverse rows at midbody. A pair of enlarged, rounded cloacal spurs at the base of the vent. Anterior subcaudals not enlarged, posterior ones slightly enlarged. Upper arm shorter than lower arm (mean UAL: LAL 0.79); palm enlarged with five fingers; the first one with an indistinct claw; relative lengths of fingers IV> III > V >II>I. Thighs short (mean FEL: SVL 0.16), robust bearing a few tuberculated scales on the dorsal surface. Tibia as long as the thighs (mean TBL: SVL 0.16); toes with entire, undivided subdigital lamellae, 18–20 on toe IV; relative lengths of toes IV> III > V >II>I. Fingers and toes free, lacking membranous skin flaps. Males have a series of 11–13 precloacal pores and lack femoral pores.

Coloration in life. Overall dorsal coloration uniform dark- to light-brown with five to six darker transverse bands on the body and five or six on the tail. Venter uniform brown and lacking any specific pattern. Eyes with vertically elliptical pupils and a greenish yellow iris.

Distribution. Occurs throughout the Andaman Islands, and was recorded from the following islands during the present study: South, Middle, North and Little Andaman, Rutland Island, Ritchie’s archipelago (Havelock, Neil, John Lawrance, and Henry Lawrance), Kyd, Labyrynth archipelago (Tarmugli, Alexandra, Hobday, and Redskin), Interview, North Reef, Paget, Long, Guitar, and North Passage Islands ( Fig. 10 ).

Natural history. Nocturnal in habit. Found on tall trees at a height of approximately 5 m and above the ground in evergreen forests. It has also been recorded from secondary forests, human habitations, and littoral forests. Calls comprise of a series of repeatedly uttered, rattling syllables of tuk-tuk-tuk-tuk.

Remarks. Boulenger (1885) synonymized Gekko verreauxi under Gekko stentor (Cantor, 1847) , a junior synonym of Gekko smithii Gray, 1842 . Ota et al. (1991), while revalidating G. verreauxi from the synonymy of G. smithii , provided a detailed redescription of the species with measurements and scale-counts from both the lectotype and the paralectotype. Both of these specimens are females and hence, we have supplemented the available information with new specimens, including males, in order to improve our understanding of the species. The lectotype has 14 supralabials (12–14 in our material), 10 infralabials (9–13), 11 rows of dorsal tubercles at midbody (11–13), and 21 subdigital lamellae (18–20) under toe IV.

Figures

Fig. 3. Gekko verreauxi in life from South Andaman (top, middle, and bottom right: adult; bottom left: juvenile).

Fig. 4. Dorsal, ventral, and lateral views of the head and ventral view of the foot of Gekko verreauxi (ZSI ANRC T 4566).

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).