Gekko nicobarensis (DAS & VIJAYAKUMAR, 2009)
Can you confirm these amateur observations of Gekko nicobarensis?
|Higher Taxa||Gekkonidae, Gekkota, Sauria, Squamata (lizards: geckos)|
|Common Names||E: Nicobar gliding gecko|
|Synonym||Ptychozoon nicobarensis DAS & VIJAYAKUMAR 2009|
Ptychozoon kuhli — DAS 1997
Ptychozoon nicbarense — GRISMER et al. 2018: 210 (in error)
Gekko (Ptychozoon) nicobarensis — WOOD et al. 2019
Gekko (Ptychozoon) nicobarensis — WOOD et al. 2020
|Distribution||India (Nicobar Islands)|
Type locality: "Nicobars" (= islands of the Nicobar Archipelago, Bay of Bengal, India)
|Types||Holotype: ZSI 2603, adult male, Major A. R. Anderson, Indian Medical Service, date of collection unknown, and collection was made presumably in the late 1800s.|
|Diagnosis||Diagnosis: A large species of Ptychozoon (reaching SVL 100.3 mm), diagnosable from congeneric species in showing the following combination of characters: dorsum with a tan vertebral stripe, lacking dark transverse bars; supranasals in contact; cutaneous expansions on sides of head; absence of predigital notch in preantebrachial cutaneous expansion; imbricate parachute support scales; four irregular rows of low, rounded enlarged scales on dorsum; 20–29 scales across widest portion of tail terminus; three indistinct chevrons on dorsum; 7–11 pairs of preanal pores; femoral pores absent; tail with an expanded terminal flap and weak lobe fusion at proximal border of tail terminus.|
Diagnosis. A medium to large-bodied (SVL 78.2–95.8 mm) species of Gekko, characterized by: presence of extensive, membranous skin flaps along the sides of the head, trunk, and tail; tail tip with an oval shaped skin flap; presence of 10–13 supralabials; 10 or 11 infralabials; two relatively small, elongate inner pairs of postmentals in broad medial contact with each other; three smaller, separated outer pairs of postmentals; 20–21 precloacal pores in males, no femoral pores; two internasals in contact with or separated by one or two small azygous scales; no ventrolateral body folds; 29–32 transverse, juxtaposed rows of ventrals; four well-spaced, transverse rows of enlarged, rounded dorsal tubercles; one enlarged post-cloacal spur on each side of the vent; 13–21 undivided subdigital lamellae on toe IV; dorsal color pattern consisting of four or five legible, dark, W-shaped, transverse bands or a light-colored vertebral stripe bounded on either side by two darker stripes, and a creamy white to light-brown venter (Chandramouli et al. 2021).
Description and variation. A medium to large-bodied species of Gekko belonging to the subgenus Ptychozoon measuring 78.42–95.86 mm SVL, head large (mean HL:SVL 0.28), much longer than broad (mean HL:HW 1.34) with a blunt, rounded snout tip. Eyes protruding, fairly large (mean ED:HL 0.25) with a vertically elliptical pupil; eye nearly half as long as the snout (mean ED:ES 0.53); nostrils situated closer to the snout tip than to the eyes (mean EN:ES 0.77). Trunk much shorter than one-half the length of the body (mean AG:SVL 0.47).
Overall habitus depressed. Supralabials 10–13 and infralabials 10–11 on each side; two moderately enlarged postmentals in broad medial contact, followed by three pairs of scales that are nearly as large as the postmentals. Dorsum bearing four transverse rows of weakly enlarged, rather indistinct tubercles. Ventrals imbricate, in 29–32 transverse rows. Sides of the body bearing a membranous flap of skin, with enlarged, rhomboidal, imbricate scales. A pair of enlarged, rounded cloacal spurs present at the base of the vent. Subcaudals not elongated horizontally, the middle row slightly enlarged. Tail with serrated dermal membranes extending along the sides, forming an oval-shaped disc at the terminus. Tail tip regenerated. Upper arm shorter than lower arm (mean UAL:LAL 0.91); palm enlarged with five fingers; the first one with an indistinct claw; relative lengths of fingers IV>III>V>II>I. Sides of upper and lower arms with extensive skin flaps. Thighs short (mean FEL:SVL 0.18) robust; with a few tuberculated scales on the dorsal surface. Tibia shorter than thighs (mean TBL:SVL 0.16); toes with entire, undivided subdigital lamellae, 14–20 under toe IV; relative lengths of toes IV>III>V>II>I. Tibia bearing lateral flaps of skin. Fingers and toes extensively webbed with membranous skin flaps extending from the base to the tip. Males have a series of 20–21 precloacal pores and lack femoral pores (Chandramouli et al. 2021).
Coloration in life. Dorsal coloration variable. Two distinct morphs recorded. One morph with a series of five or six darker brown ‘W’ shaped transverse bands on the body and five or six similar transverse bands on the tail. The other morph with a bright tan vertebral stripe bordered by darker flanks (Fig. 5). Venter uniform brown and lacking any specific pattern. Eyes with vertically elliptical pupils, a greenish yellow iris and brown reticulations (Chandramouli et al. 2021).
|Etymology||Latin implying an inhabitant of the Nicobar Islands.|
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