Gymnophthalmus underwoodi on Tobago

The shiny lizard, Gymnophthalmus underwoodi, is one of those reptiles that is widespread and probably common,  but not particularly easy to find. It is small, lives in burrows or under objects, and is active only when the sun is shining - when it can significantly raise its body temperature. Its distribution ranges from Venezuela, the Guyanas, and Brazil northward into the Lesser Antilles. It has been reported as far north as Antigua. Humans may, at least in part, be responsible of its island distribution.The shiny lizard is frequently associated with lawns and gardens and as people transport their favorite plants from palace to place these tiny lizards may move with them. Additionally it is a unisexual species which provides the advantage of not needing a mate. In fact, G. underwoodi is one of four species in a complex of cryptic species (the others are: G. cryptus, G. leucomystax, and G. specious). Kiziran & Cole (1999) found G. cryptus is the ancestor of G. underwoodi.

Hardy (1982) commented on the lack of specimens of Gymnopthalmus underwoodi from Tobago, Cole et al did find find specimens from Tobago, nor did Murphy (1997). Yet some publications and websites have included Tobago in the distribution- the IUCN red list is an excellent example. It presence on Tobago would seem reasonable given its presence in Trinidad and Venezuela and the Antilles. However, a HerpNet search did not show any specimens from Tobago.

On 6 June 2013 Rick Lehtinen collected a single specimen of G. underwoodi in from of the Vegetable King in Castara, Tobago. Thus confirming its presence on the island. The specimen is deposited in the UWIMZ. Since that date the species has become quite abundant on the northeastern end of the island.

Literature

Cole, CJ, et al. Gymnophthalmus (Reptilia Teiidae) in the neotropics: genetics origin and systematics. American Museum Novitates (2994): 1-29

Hardy, J. D. 1982. Biogeography of Tobago, West Indies, with special reference to amphibians and reptiles, a review. Bulletin of the Maryland Herpetological Society 18(2):37–142.

Kizirian DA. Cole CJ. 1999. Origin of the Unisexual Lizard Gymnophthalmus underwoodi (Gymnophthalmidae) Inferred from Mitochondrial DNA Nucleotide Sequences. Molecular Phylogenetics and Evolution 11:394–400.

Murphy, J. C. 1997. Amphibans and reptiles of Trinidad ad Tobago. Krieger Publishing, Malabar, FL.

Shiny Lizard, Gymnophthalmus underwoodi (Family Gymnophthalmidae)

Gymnophthalmus underwoodi Grant 1958: 228. Type locality: Barbados.

Size. Adults reach 44 mm SVL, the tail 1.7x SVL, hind legs are 29% of the SVL. Diagnosis. G. underwoodi can be distinguished from all other Trinidad and Tobago lizards by having lateral scales which are only slightly smaller than the dorsal scales, it has a dorsolateral stripe that extends only to mid body, and it has 21–24 ventral scales. G. speciosus has 23–27 ventrals, a dorsolateral stripe that extends to the tail. Cole et al (1990) consider this unisexual species to have resulted from the hybridization of G. cryptus and G. speciosus. Distribution. In the Trinidad and Tobago area, this lizard occurs on Trinidad and on most of the Boca Islands with the exception of Chacachacare Island. Otherwise, it is known from Venezuela, Brazil (Amazonas), Guyana, Surinam, Barbados, Guadeloupe (incl. Les Saintes, Terre-de-Haut), St. Vincent, Martinique, Antigua, St. Kitts, Petit Cul-de-sac, Saint-Barthelme. Habits. Inhabits open, sunny areas on lawns and at the forest edge seems to prefer habitats without leaves. This is an all-female species.

Literature

Cole CJ. Dessauer HC. Markezich AL 1993 Missing Link Found: The Second Ancestor of Gymnophthalmus underwoodi (Squamata: Teiidae), A South American Unisexual Lizard of Hybrid Origin. American Museum Novitates (3055): 1-13.

Grant C. 1958. A new Gymnophthalmus (Reptilia, Teiidae) from Barbados, B.W.I. Herpetologica 14: 227-228.

Lizards of Trinidad and Tobago: 10 Facts

Leaf anole (Anolis planiceps). Photo by Renoir Auguste

Trinidad and Tobago has a spectacular diversity of lizards in the country. The field guide to the amphibians and reptiles of Trinidad and Tobago has much more information on them, but here are ten facts (at time of writing) about lizards in the country.

1. Two lizards can be legally hunted for human consumption during a stipulated time period: the green iguana (Iguana iguana) and the matte or crytpic tegu (Tupinambis cryptus).

2. The Family or group of closely related lizards with the most species on both islands is the Anoles, with at least 6 non-native introduced species, and at least one native species with a wide ranging distribution across Trinidad (Anolis planiceps). It is highly suspected that these are minimum estimates for this group, which is no surprise as Anoles are known to establish themselves across the Caribbean. In Tobago, the most widespread is the Guamangala or Richard's Anole (Anolis richardii) and on Trinidad the bronze anole (Anolis aeneus) is perhaps the most widespread of the non-native species.

3. The smallest type of lizard in the country is the Mole's dwarf gecko (Sphaerodactylus molei) which grows to less than 3 cm long fully grown.

4. The largest type of lizard in the country is the green iguana which grows to up to 2 m long.

5. There are two species of legless lizards on Trinidad: the double-headed worm lizard or white legless lizard (Amphisbaena alba) and the black and white worm lizard (Amphisbaena fuliginosa). Both are often confused for snakes or worms, but are in fact much more aligned with lizards.

Green iguana (Iguana iguana). Photo by Renoir Auguste

6. There is a shiny lizard that is all female and reproduces without the assistance of males (Gymnophthalmus underwoodi).

7. The luminous lizard (Oreosaurus shrevei) is known only from Trinidad.

8. The ocellated gecko (Gonatodes ocellatus) is known only from Tobago and its offshore islands.

Ocellated gecko (Gonatodes ocellatus). Photo by Renoir Auguste

9. Most lizards in the country are predominantly active during the day, with a few gecko species such as the turnip-tailed gecko Thecadactylus rapicauda, active at night.

10. Lizards comprise an important part of ecosystems and local human culture: they are predators to many insects we despise, and are known to be feared because of folklore tales, with one example being the "24 hour lizard, that if it falls on you, you have 24 hours left"!