Added November 2003. Extensively updated 4 September 2022.
A small genus (currently four species) of large geckos that are in fact almost giants compared to the rest of their family. Twenty years or so ago, in the early 2000s, these geckos had lately become available in the West. Today they are extremely common in the pet trade, certainly in the UK rivalling the Leopard Gecko which was once ubiquitous.
Boulenger gives the characteristics of the genus as follows: digits strongly dilated, more or less webbed, with undivided lamellae below, all furnished with a retractile claw supported by the compressed distal joint. Upper surfaces covered with juxtaposed granular scales; lower surfaces with juxtaposed granules or slightly imbricated scales. Tail prehensile. Pupil vertical. Males with preanal pores.
Two species which were formerly part of this genus (ciliatus and chahoua) have since been reclassified.
There are a variety of publications available that deal with the husbandry and reproduction of these species, including Bartlett and Bartlett, and Walls and Walls. Please note that the Crested Gecko book by Lance Jepson actually refers to a species in a different genus (Correlophus ciliatus). See Bibliography for details.
Scientific name |
Common name |
Place of origin |
Size (max) |
Notes |
Rhacodactylus |
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Knob-Headed Giant Gecko |
New Caledonia |
TL 20.5 cm: SVL 12.5 cm |
Arboreal, with slightly prehensile tail. Overall colour is pale green-brown, with longitudinal stripes of pale brown or yellow running along its flanks. The head is large and angular. Description: head subpyramidal ; snout longer than the distance between the orbit and the ear-opening, once and two thirds the diameter of the orbit, slightly swollen at the end; interorbital space and forehead deeply concave; hinder part of head with knob-like prominences, viz. one above the ear-opening, formed by the free end of the quadrate, and five others formed by the extremities of the parietal bones; the borders and sutures of the latter form prominent ridges; the ends of the postfrontal bones and mandible also prominent; ear-opening large, oval, oblique. Body and limbs moderately elongate, rather depressed ; digits not very broadly dilated, not very unequal, with a very slight rudiment of web, which is altogether absent between the two outer toes. Throat and sides of neck with a few irregular folds; a slight fold bordering the hind limb posteriorly. Scalation details: head and body covered with subequal small granular scales, flattened on the belly, smallest on the throat. Rostral quadrangular, not quite twice as broad as high, with a small notch in the middle of its upper border; nostril pierced between the rostral, the first upper labial, and seven small nasals, the anterior being much the largest; sixteen to eighteen upper and fourteen or fifteen lower labials; mental small, subtriangular, separating the inner labials; no regular chin-shields, but larger scales passing gradually into the granules of the throat. Tail cylindrical, covered with uniform small flat scales arranged in verticils. Male with an irregular patch of very numerous praeanal pores, and a sort of pouch in the integument of the thigh posteriorly, near the tibia. Coloration: yellowish grey, with darker and lighter longitudinal bands on the back ; flanks and limbs marbled, with darker; lower surfaces dirty white, with scattered blackish dots. [SOURCE: Boulenger] |
|
R. leachianus |
Leach's Giant Gecko |
New Caledonia |
12-14" |
Probably the largest living gecko species in the world. Description: head large, oviform, elongate ; forehead concave; snout longer than the distance between the orbit and the ear-opening, a little more than twice the diameter of the orbit; ear-opening narrow, horizontal. Body and limbs moderately elongate, rather depressed; digits moderately elongate, broad, not very unequal, half-webbed; limbs bordered on each side by cutaneous folds, most developed on the anterior side of the fore limbs and on the posterior side of the hind limbs; other cutaneous folds below the rami mandibulas, on the sides of the neck, and from axilla to groin; throat with a few cross folds. Scalation details: upper surface of head covered with small irregular polygonal convex scales, larger than the granules of the back, elongated and more or less distinctly keeled on the forehead and snout; rostral twice as broad as high, with more or less distinct median cleft above; nostril pierced between seven or eight small nasals and the first upper labial; upper labials seventeen or eighteen; lower labials fourteen to seventeen, anterior very high; mental narrow, elongate, wedge-shaped, about the size of the proximal labials; no regular chin-shields, but a few larger scales, passing gradually into the minute granules of the throat. Scales small, granular, smallest on the lower surfaces. Tail: cylindrical, tapering, covered with uniform small flat juxtaposed scales arranged in verticils. Coloration: grey or pinkish grey above, dotted and indistinctly marbled with brown, sometimes with large whitish spots; lower surfaces white, uniform. [SOURCE: Boulenger] |
R. trachycephalus |
? |
New Caledonia |
? |
Large and stocky species with an effective camouflage of green, brown and pink mottling over the back and tail that conceal it when resting on a lichen-covered trunk. |
R. trachyrhynchus |
Rough-Snouted Giant Gecko |
New Caledonia |
TL approx 30.5 cm: SVL approx 15 cm |
Strictly arboreal but found in a wide range of habitat, including sclerophyll forest. Description: head oviform ; snout longer than the distance between the orbit and the ear-opening, once and two thirds the diameter of the orbit; ear-opening narrow, horizontal. Body and limbs moderately elongate, rather depressed; digits broadly dilated, not very unequal, with a distinct rudiment of web, absent between the two outer toes. Sides of neck with irregular folds. Scalation details: snout and interorbital space with very large, unequal, rough tubercles confluent with the cranial ossification; hinder part of head, body and limbs with very small, equal granular scales; granules smallest on the throat. Rostral broad, quadrangular, with distinct median cleft above; nostril pierced between the first labial and five or six small nasals, the anterior being much the largest; nine to eleven upper labials; mental small, triangular; nine to eleven infralabials, gradually decreasing in size, inner pair nearly three times as high as broad, in contact behind the mental; a row of large scales behind the labials. Body covered with uniform small granular scales. Tail: strongly prehensile: cylindrical, with uniform small flat scales arranged in verticils. Male with an irregular patch of very numerous preanal pores. Coloration: head brown; the rest of the upper surfaces grey, dotted with darker; lower surfaces dirty white, with scattered grey dots. Reproduction: the only live-bearing member of the genus, or in New Caledonia. [SOURCE: Bauer & Sadlier, Boulenger] |
Gives husbandry notes for R. leachianus