Gekko rossi is one of ten currently recognized, endemic species of Gekko in the Philippines. This species is part of a unique group of island-endemic species that are distributed in the Babuyan and Batanes island groups in the extreme northern Philippines. Six unique island endemic species have been discussed in the literature; however, only three of these species are currently described (Gekko crombota, Gekko rossi, and Gekko porosus). Gekko rossi is known only from the small island of Calayan in the Babuyan Island Group in the northern Philippines.
Recent studies and increased survey efforts throughout the Philippines have resulted in a dramatic increase in the diversity of gekkonid lizards in the country. The archipelago is now known to support ten genera and at least 48 described species in the genera Cyrtodactylus (9 species), Gekko (12–13), Gehyra (1), Hemidactylus (5; including platyurus, a species formerly assigned to Cosymbotus), Hemiphyllodactylus (2), Lepidodactylus (6), Luperosaurus (8), Pseudogekko (4), and Ptychozoon (1) (Taylor, 1922a,b; Brown and Alcala, 1978; Brown and Diesmos, 2000; Brown et al., 1997, 1999, 2007, 2008, 2009, in press; Gaulke et al., 2007; Linkem et al., 2010; Welton et al., 2009, 2010a, b; Zug, 2010).
Ten species of Gekko are considered endemic to the archipelago (Brown et al., 2009; Linkem et al., 2010) and two additional species with broad geographic distributions (G. gecko, G. monarchus) are also known from the country (Taylor, 1922a, b; Brown and Alcala, 1978; Ota et al., 1989). The ten endemic Philippine species are G. athymus, G. carusadensis, G. crombota, G. ernstkelleri, G. gigante, G. mindorensis, G. palawanensis, G. porosus, G. romblon, and G. rossi. These species represent a considerable range in body size, general appearance, and ecological attributes, but all possess the following combination of morphological traits: (1) body size moderate, with relatively long, slender limbs; (2) near complete absence of interdigital webbing or cutaneous body expansions; (3) dorsal tubercles arranged in longitudinal rows on the dorsum (except for G. athymus, in which dorsal tuberculation is absent); (4) scales of dorsum between tubercle rows minute, non-imbricate; (5) scales of venter enlarged, imbricate, flat; (6) differentiated postmentals elongate; and (7) subcaudals enlarged, plate-like (Brown and Alcala, 1978; Brown et al., 2007, 2008, 2009).
From photographs by Rafe M. Brown. Dorsal ground coloration dark yellowish-brown (laterally) to dark brown (dorsally), with indistinct, irregularly scattered light gray and black blotches and small spots; dorsum with six diffuse bars light cream trilobed bars traversing the axilla-groin region, each bordered posteriorly by an accompanying set of three cream spots, one situated vertebrally, and flanked by a paravertebral pair on either side. Dorsal nuchal region and posterior portions of head similar to trunk coloration but darker and with distinct, subcircular, cream spots and black blotches; similar cream spots span a line between the orbit and auricular opening; postrictal region flat purplish gray; labial scales purplish gray with cream spots on every third labial scale; rostral and circumnasal scales dark purplish gray; interorbital region, and parietal region medium gray with white spots; infralabial region and chin gray to light gray; gular region light gray to brownish-tan. Dorsal surfaces of limbs light gray with numerous dark brown, black, and yellowishcream spots; knees and elbows flat gray; dorsal surfaces of digits dark gray, with cream spots; dorsal and lateral portions of tail banded alternating dark gray and cream (corresponding to every third or fourth tail annulus); distal autotomy regrowth dark brown to dark gray, nonbanded. Ventral body and limbs yellowish-cream with scattered gray and dark brown flecks, especially on chin and ventral surfaces of limbs; precloacalfemoral region yellow with dark orange pores, contrasting distinctly with posterior surfaces of thighs; limbs gray, fading to yellow at wrists and ankles; palmar and plantar surfaces of manus and pes yellowish with light gray distal portions and darker subdigital scansors; ventral tail yellowish, fading to cream distally, lacking transverse bars, regenerated portion solid brown; eye gold, with radiating purple lines surrounding crenulated black pupil.
Gekko rossi differs from all other species of Philippine Gekko (i.e., G. athymus, G. crombota, G. ernstkelleri, G. gecko, G. gigante, G. mindorensis, G. monarchus, G. palawanensis, G. porosus, and G. romblon) by the following combination of characters (1) larger body size (SVL 95.5–108.2 mm for adult males; 86.8–100.0 for females); (2) dorsum brown with six diffuse transverse black bars adjacent to six transverse series of two or three cream spots; (3) high numbers of dorsal body scales (125–170 transverse midbody scales; 251–281 paravertebrals); (4) high number of sharply conical dorsal body tubercle rows (16–18 midbody; 31–37 paravertebrally); (5) 77–88 enlarged precloacal-femorals arranged in a continuous, uninterrupted series (pore bearing in males; lacking pores in females).
Gekko rossi differs from its phenotypically most similar Philippine congener, Gekko porosus (Batan and Itbayat islands, of the Batanes Island group, Fig. 1) by having dorsum brown with six diffuse transverse black bars adjacent to six transverse series of three cream spots (Fig. 3; vs. dark transverse bands and circular vertebral blotches in G. porosus, light spots absent), a greater number (125–170) of transverse midbody dorsal scales (vs. 88–103), a greater number (251–281) of paravertebral scales (vs. 173–191), the presence of sharply protuberant (vs. merely convex or slightly raised) dorsal tubercles, a greater number (31–37) of paravertebral tubercle rows (vs. 17–24), and by the absence of a modified distal femoral porebearing patch (vs. present, composed of a short series of 2 or 3 rows of pore-bearing scales [Brown et al., 2008:fig. 4C]). Finally, although body sizes of these two species overlap, adult males of G. rossi (SVL 95.5–108.2 mm) tend to be larger than G. porosus (91.0–96.7). The new species differs from the morphologically similar G. crombota (Brown et al., 2008) by three longitudinal paravertebral rows of cream spots adjacent to diffuse transverse black bars (vs. presence of trilobed cream bars) on the body trunk; a tendency toward higher midbody dorsal scale counts (125–170 vs. 107–132); a greater number (251–281) of paravertebral scales (vs. 192–226); fewer (16–18) midbody dorsal tubercle rows (vs. 18–22); precloacalfemorals arranged in a continuous series (vs. 1 or 2 scale separation between precloacals and femorals; Brown et al., 2008:fig 4B); and a greater number (77–88) of precloacal-femoral pore-bearing scales (vs. 58–74).
Gekko rossi is known only from Calayan Island in the Philippines.
Our impression is that the new species is very common in internal forested regions at the type locality, but we note that we did not find it near the island’s denuded coast. It is possible that only the forested areas of Calayan Island are optimal habitat for this species. Other gekkonids encountered on Calayan Island include Gehyra mutilate, Hemidactylus frenatus, and Lepidodactylus sp. Calayan Island is the type locality of the rare Luperosaurus macgregori, although it has not been reported on this island since the original description (Stejneger, 1907) but has recently been rediscovered on Babuyan Claro Island (Brown and Diesmos, 2000; Brown et al., 2007, 2008).
The species is named for Charles Andrew Ross in recognition of his numerous contributions to the systematics of reptiles and amphibians of the Philippines and his particular enthusiasm for the herpetofauna of the Babuyan islands. Suggested common name: Ross’ Calayan Gecko.
Gekko rossi is recognized to occur in the Babuyan Island Group of the extreme northern Philippines.
Gekko rossi has been collected low (<5 m) on trunks and buttresses of trees or on the faces of rocky outcrops and in limestone caves in primary dipterocarp forest at moderate elevations (300– 400 m) far from the island’s coast. Given the island’s geological history of isolation (McDermott et al., 1993; Yang et al., 1996; Marini et al., 2005), we consider it extremely unlikely that G. rossi will be encountered on other islands in the Babuyan island group, the Batanes island group, or mainland Luzon.
SVL 95.5–108.2 mm for adult males; 86.8–100.0 for females
Calayan Island, Babuyan Island Group, northern Philippines
Ross's Calayan gecko (Gekko rossi) is a species of lizard in the family Gekkonidae. The species is endemic to Calayan Island in the Philippines.[1]
The specific name, rossi, is in honor of herpetologist Charles Andrew "Andy" Ross.[1][2]
Males of G. rossi may attain a snout-to-vent length (SVL) of 10.8 cm (4.3 in). Females are smaller at 10.0 cm (3.9 in) maximum SVL.[1]
Ross's Calayan gecko (Gekko rossi) is a species of lizard in the family Gekkonidae. The species is endemic to Calayan Island in the Philippines.
