Gekko porosus 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 porosus is known only from the small islands of the Batanes 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).

Gekko porosus can be distinguished from congeners by the following combination of characters (1) medium body size (SVL 91.0–96.7 mm for adult males; 91.0–96.7 for females); (2) vertebral coloration with indistinct transverse dark bands; (3) supralabials 12 or 13; (4) preanofemorals 74–80; (5) Toe IV scansors 14–16; (6) internasals contacting rostral 1; (7) scales contacting nostril 5; (8) midbody ventral scales 35–40; (9) midbody dorsal scales 88–103; (10) midbody tubercle rows 15–17; (11) vertebral tubercles in axilla–groin distance 17–24; (12) paravertebral scales in axilla–groin distance 173–191; (13) ventral scales in axilla–groin distance 64–74.

Itbayat Island, Batanes Islands, between Luzon and Taiwan.

Gekko romblon is recognized to occur in the Batanes Island Group (Batan and Itbayat Islands) in the extreme northern Philippines.

SVL 91.0–96.7 mm for adult males; 91.0–96.7 for females

• Terrestrial