September 9, 2015

The Galliwasps

Diploglossines – popularly called galliwasps – are an extant group of anguid lizards that inhabit South and Central America as well as the Antilles (Anguidae is the group that includes alligator lizards, slow-worms, glass lizards and kin). Most galliwasps are robust-bodied lizards with normally proportioned, complete limbs. A reduced digit count and reduced limb size is, however, present in the obscure taxa Ophiodes, Sauresia and Wetmorena. The vast majority of species are included within Celestus (with about 30 species) and Diploglossus (with about 17 species).

By Darren Naish

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

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Galliwasps are superficially skink-like and possess thin, sibcircular osteoderms that give them a shiny, streamlined appearance. The head is often robust and the jaws are powerful (especially in older males), and they can be large overall, the biggest species (the very probably extinct Jamaican giant galliwasp C. occiduus) well exceeding 30 cm in total length. Galliwasps as a whole are long-bodied, typically possessing 31-40 presacral vertebrae, though with 72-74 being present in the anguine-like, near-limbless Ophiodes (Estes 1983).

A formidable and striking appearance means that galliwasps often have some significance to local people and are sometimes wrongly regarded as venomous. Jamaican giant galliwasps apparently had some role in certain voodoo traditions. This supposed link to venomosity might explain that weird name they have, though I’ve been unable to ever find out anything specific as goes its origin. It’s said in some sources that galliwasp is actually pre-dated by a 17th century term gallivache, though the etymology of that is mysterious too.

Relatively little of known of galliwasp ecology, life history and behaviour. As a generalisation, they’re terrestrial lizards of forest, scrubby or rocky environments, though some have been collected in marshes and swamps. It’s guessed that galliwasps are capable burrowers (either in leaf litter or soft sediment) and there’s also some assumption that they’re crepuscular. A consequence of this sort of lifestyle is that they’re rarely seen and rarely encountered, and some species thought to be rare or even extinct may not be.

They seem to be adaptable and flexible as goes diet: the Jamaican giant galliwasp was reported to eat fruits and other plant parts as well as fish (Schwartz & Henderson 1991), and insects, worms, molluscs and small lizards and mammals have been listed as prey items for other species. Among the most flexible is the island endemic Malpelo or Dotted galliwasp D. millepunctatus of Malpelo Island off the coast of Colombia, a animal described as “curious and opportunistic” (Graham 1975). It eats crabs, amphipods, seabird eggs and carcasses, and seabird droppings. It also mobs seabirds that are bringing food back to their chicks and seems to respond to feeding calls made by young boobies (Kiester 1975). Incidentally, this species also forages at the edge of the sea and has been reported swimming in the sea and entering it voluntarily.

The group includes both oviparous and viviparous species. Juveniles are sometimes very differently patterned and coloured from adults, possessing bold stripes. In some places the juveniles seem to mimic locally occurring toxic millipedes (Pianka & Vitt 2003). While little good data is available, it seems that these lizards are slow to mature and long-lived, larger species maybe taking 3 or 4 years to reach maturity and then living for a few decades at least.

Several island-endemic Diploglossus and Celestus species inhabit or inhabited the Antilles, and some have become extinct in historic times due to the introduction of non-native mammals like mongooses. There’s a lot to say about these recently extinct species and I’ll have to promise to come back to them at another time (sorry, this article is intended to be a brief introduction).

There are quite a few fossil galliwasps. Diploglossus is known from the Pleistocene and Holocene of Puerto Rico and the Dominican Republic while Celestus is known from the Pleistocene and/or Holocene of the Dominican Republic and Jamaica. Fossil specimens that have been referred to extant species (including D. pleii on Puerto Rico) are somewhat larger than the biggest members of modern populations (16 cm SVL vs 11 cm) (Estes 1983). A Lower Eocene anguid from Wyoming – Eodiploglossus – has been included within this group and clearly resembles extant galliwasps in osteoderm, tooth and dentary characters. If correctly identified, Eodiploglossus suggests that diploglossines originated in North America before dispersing south to the Antilles and Central and South America.

Long-time readers of Tet Zoo – very long-time readers – might vaguely recall my promise to cover galliwasps way back in about 2007 or something (offending article is here). While this quick article is not the full, detailed review of the group I’d really like to produce, at least it’s something. I’ll return to galliwasps in time, I promise.

For previous Tet Zoo articles on anguids and other lizards, see...

Dibamids and amphisbaenians

Cambodia: now with dibamids!
Amphisbaenians and the origins of mammals (April 1st article!)
Portraits of amphisbaenians

Gekkotans

Lacertids

Iguanians

Scincomorphs

Anguimorphs

Snakes

Refs - -

Estes, R. 1983. Handbuch der Palaeoherpetologie, Teil l0a. Sauria terrestria, Amphisbaenia. Gustav Fischer Verlag, Stuttgart.

Kiester, A. R. 1975. Notes on the natural history of Diploglossus millepunctatus (Sauria: Anguidae). Smithsonian Contributions to Zoology 176, 39-43.

Graham, J. B. 1975. The biological investigation of Malpelo Island, Colombia. Smithsonian Contributions to Zoology 176, 1-8.

Pianka, E. R. & Vitt, L. J. 2003. Lizards: Windows the Evolution of Diversity. University of California Press, Berkeley.

Schwartz, A. & Henderson, R. W. 1991. Amphibians and Reptiles of the West Indies: Descriptions, Distributions, and Natural History. University of Florida Press, Gainesville.

Whitfield, P. 1983. Reptiles and Amphibians: an Authoritative and Illustrated Guide. Longman, Harlow (UK).