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 Author Chandramouli, S. R. Department of Ecology and Environmental Sciences, School of Life Sciences, Pondicherry University, Puducherry 605014, INDIA Author Gokulakrishnan, G. Zoological Survey of India, Andaman and Nicobar Region Centre, Haddo, Port Blair 744102, INDIA Author Sivaperuman, C. Zoological Survey of India, Andaman and Nicobar Region Centre, Haddo, Port Blair 744102, INDIA Author Grismer, L. Lee Herpetology Laboratory, Department of Biology, La Sierra University, 4500 Riverwalk Parkway, Riverside, California 92515, USA text Amphibian & Reptile Conservation 2021 e 276 2021-06-30 15 1 108 125 journal article 297523 10.5281/zenodo.11390026 df1730e7-64a7-4c71-bc62-f9dd375ad8f6 1525-9153 11390026 36C13E32-9F37-4D60-B309-0FC2357C50EB 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. Fig. 8. Holotype (ZSI/ANRC/T/6092) of Gekko stoliczkai sp. nov. in dorsal (above) and ventral (below) views. 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 ). Table 4. Meristic and morphometric characters of specimens examined for (A) Gekko verreauxi , (B) Gekko nicobarensis , and (C) Gekko stoliczkai sp. nov. The specimen number of the new species holotype is in bold. Table 4A. Data for Gekko verreauxi .

Species	Gekko verreauxi	Gekko verreauxi	Gekko verreauxi	Gekko verreauxi	Mean
Catalogue Number:	ZSI/ ANRC/T/3726	ZSI/ ANRC/T/5779	ZSI/ ANRC/T/4324	ZSI/ ANRC/T/4566
Island	North Andaman	Havelock	South Andaman	Little Andaman
SVL (mm)	140.06	109.55	140.62	146.49	134.18
Trunk length	67.24	41.99	69.84	66.58	61.41
Tail	93.19	105.89	142.96	127.96	117.50
Head length	33.41	31.83	36.04	38.52	34.95
Head width	25.96	27.82	32.16	31.79	29.43
Head depth	17.14	11.31	15.89	16.96	15.33
Eye diameter	8.84	9.11	8.02	8.29	8.57
Tympanum diameter	4.13	4.06	3.77	4.52	4.12
Eye-nostril	13.69	9.87	13.04	14.17	12.69
Eye-snout	16.18	13.86	15.88	18.66	16.15
Eye-tympanum	11.12	10.11	12.25	13.2	11.67
Supalabials	12	12	14	14	–
Infralabials	9	10	11	13	–
Post-mentals	2+4	2+4	2+4	2+4	–
Ventrals	28	27	28	29	–
Internarial distance	5.1	5.09	5.26	5.19	–
Upper arm length	14.35	12.31	15.53	16.23	14.61
Lower arm length	15.62	16.03	20.76	21.56	18.49
Palm length	17.93	14.79	17.44	18.98	17.29
Femur length	18.52	18.71	25.24	24.16	21.66
Tibia length	20.75	20.72	21.08	25.55	22.03
Foot length	16.82	17.41	21.38	21.1	19.18
T4 lamellae	20	18	20	20	–
Sex	M	M	F	F	–

Table 4B. Data for Gekko nicobarensis .

Species	Gekko nicobarensis	Gekko nicobarensis	Gekko nicobarensis	Mean
Catalogue Number:	DOSMB05102	ZSI/ANRC/T/5234	ZSI/ANRC/T/4235
Island	Car Nicobar	Teressa	Camorta
SVL (mm)	91.21	95.86	78.42	88.50
Trunk length	33.74	45.34	44.65	41.24
Tail	61	63.18	61.57	61.92
Head length	25.14	27.26	22.65	25.02
Head width	17.45	20.38	18.33	18.72
Head depth	10.07	12.7	11.02	11.26
Eye diameter	5.55	7.13	5.76	6.15
Tympanum diameter	1.75	3.14	2.4	2.43
Eye-nostril	8.21	9.13	8.91	8.75
Eye-snout	10.54	11.94	11.54	11.34
Eye-tympanum	7.74	8.87	6.71	7.77
Supalabials	10	13	12	–
Infralabials	10	11	10	–
Post-mentals	2+6	2+6	2+6	–

Table 4B (continued). Data for Gekko nicobarensis .

Species	Gekko nicobarensis	Gekko nicobarensis	Gekko nicobarensis	Mean
Ventrals	29	32	29	–
Internarial distance	4	4.46	3.45	–
Upper arm length	11.1	8.15	9.97	9.74
Lower arm length	10.54	10.36	11.16	10.69
Palm length	10.11	9.77	8.27	9.38
Femur length	15.74	15.8	15.1	15.55
Tibia length	14.58	15.55	13.14	14.42
Foot length	12.97	12.92	11.88	12.59
T4 lamellae	17	14	19	–
Sex	F	F	F	–

Table 4C. Data for Gekko stoliczkai sp. nov.

Species	Gekko stoliczkai sp. nov.	Gekko stoliczkai sp. nov.	Gekko stoliczkai sp. nov.	Gekko stoliczkai sp. nov.	Gekko stoliczkai sp. nov.	Mean
Catalogue Number:	ZSI/ANRC/T/6092	DOSMB05020	ZSI/ANRC/T/6093	ZSI/ANRC/T/4796	ZSI/ANRC/T/7221
Island	Little Nicobar	Great Nicobar	Great Nicobar	Great Nicobar	Great Nicobar
SVL (mm)	118.37	122	123.83	128.4	116.29	121.78
Trunk length	55.33	51.85	55.2	60.64	49.08	54.42
Tail	105.9	112	130.49	81.31	103.81	106.70
Head length	32.1	31.6	30.22	36.93	30.43	32.26
Head width	24.04	23.43	21.46	25.07	23.19	23.44
Head depth	14.17	14.28	12.93	14.54	13.69	13.92
Eye diameter	7.84	6.76	8.05	8.66	7.68	7.80
Tympanum diameter	4.3	3.12	3.29	3.93	2.63	3.45
Eye-nostril	11.77	11.16	12.15	13.94	11.54	12.11
Eye-snout	15.04	14.05	14.95	17.15	14.51	15.14
Eye-tympanum	10.76	9.76	10.22	11.16	9.96	10.37
Supalabials	14	14	14	17	15	–
Infralabials	13	12	12	13	12	–
Post-mentals	2+4	2+4	2+4	2+4	2+4	–
Ventrals	22	25	23	21	22	–
Internarial distance	3.61	3	4.47	4.75	4.39	–
Upper arm length	11.28	16.99	12.46	13.12	12.28	13.23
Lower arm length	13.84	15.9	17.68	16.02	15.71	15.83
Palm length	15.54	16.83	12.84	16.15	11.29	14.53
Femur length	19.91	20.96	18.88	20.96	21.15	20.37
Tibia length	18.19	20.06	17.78	18.32	16.51	18.17
Foot length	16.08	19.85	15.53	17.28	15.91	16.93
T4 lamellae	21	22	18	20	21	–
Sex	M	F	F	M	M	–

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