Sunday, April 3, 2016

Spot-nosed Gecko, Gonatodes humeralis (Family Sphaerodactylidae)

A small, slender lizard, moderately long tail. Scales on snout larger than those on the back of the head. Males usually have a dark brown or red-brown dorsum; two rows of spots on flanks may be present; with some gray, black, yellow mottling; light spot of yellow, orange or gray on snout, ante-humeral bar or stripe present in both sexes. Female's dorsum brown-gray, indistinct vertebral stripe; snout pointed from above, round in profile; canthus rounded and indistinct; dorsum covered in small granular scales; ventrals larger than dorsal scales and imbricate; 16−21 lamellae on fourth toe wider than digit.

Coloration will separate this species from other Trinidad Gonatodes, but it may be most easily confused with G. ceciliae which has tiny scales in the canthal region, about 15 scales occur between the eye and the nostril, while G. humeralis has only seven or eight scales in this region.

Distributed in Venezuela, the Guianas, Trinidad and Tobago and Amazonia (Brazil, Bolivia, Ecuador, Peru).

Forest and forest edge habitats, usually low on tree trunks, rock walls, and in low vegetation as well as the canopy; male usually with several females. A diurnal, ambush predator. This lizard was studied at São Luís, Maranhão, Brazil. Its body temperature was strongly correlated with environmental temperatures (air and substrate), but air temperature had a greater effect on the males’ body temperatures after removing the effect of the substrate temperature; sexes differed in perch height, males perched higher, but the sexes did not differ in the tree trunk diameter used; both sexes use the largest tree trunks available in the environment; trunks with deeper leaf litter at the base were selected, deeper leaf litter is likely to provide a retreat from predators. It may also increase the humidity in the lizard’s microhabitat. Diet consists mostly of arthropods (isopods, spiders, pseudoscorpion, scorpions, millipedes, and insects) as well as land snails and annelid worms. Sexual maturity for both sexes is attained at 31 mm SVL. There is evidence of communal nesting in some populations with nest locations in ant nests, rotten palm trunks, rotten log, and a rotten liana; females produce a single egg per clutch and lay eggs in rapid succession, 52−110 day incubation period (longer for eggs laid in captivity).

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