Microteiids

(Gymnophthalmidae)

Class Reptilia

Order Squamata

Suborder Lacertiformes

Family Gymnopthalmidae

Thumbnail description
Small, terrestrial, egg-laying lizards, usually fully limbed but some with reduced limbs, most of which are secretive inhabitants of the tropical forest floor

Size
Adults are less than 2.3 in (60 mm) in snoutvent length

Number of genera, species
36 genera; 175+ species

Habitat
Microteiids are usually found in leaf litter or under logs in tropical forests; several species live in wet areas and escape into the water

Conservation status
Not listed by IUCN

Distribution
Neotropical, ranging from southern Mexico to north-central Argentina east of the Andes, including Caribbean islands

Evolution and systematics

The Gymnopthalmidae were considered part of the family Teiidae throughout most of the twentieth century but are now considered distinct by most practicing herpetologists. The gymnophthalmids are sister group to the teiids, and these two families comprise a group called Teioidea, whose closest relatives are lizards in the family Lacertidae, which is restricted to the Old World.

There are 36 genera (or more depending on the source) in the Gymnopthalmidae and more than 175 species. The family is not well known. New forms are discovered and described regularly, and taxonomic rearrangements undertaken by experts will result in changes in the names and number of genera and species. The most speciose genera are Proctoporus (28 species), Bachia (18 species), Anadia (15 species), Ptychoglossus (15 species), Leposoma (12 species), and Neusticurus (11 species). These account for about half of all the gymnophthalmids described by 2002. Twelve genera are monotypic, containing only one described species. No subfamilies are recognized.

Physical characteristics

The gymnophthalmids are small terrestrial lizards. Most species have fully developed limbs, with the exception of two genera, Bachia and Calyptommatus, that have limbs reduced or absent, respectively. Dorsal scalation is variable; many species have small dorsal scales. Strongly keeled dorsal scales characterize the genus Arthrosaura. Gymnophthalmids have ventral scales larger than dorsal scales that can be either smooth or keeled. There are no osteoderms dorsally or ventrally. Tail length varies, and each tail vertebra has a fracture plane that allows the tail to be easily broken. Gymnophthalmids have good visual and olfactory systems. They have well-formed eyes and eyelids.

Distribution

Gymnophthalmids are strictly Neotropical lizards that occur from southern Mexico to north-central Argentina east of the Andes. Several genera and species occur on Caribbean islands, for example Gymnophthalmus spp., Tretioscincus bifasciatus, and Proctoporus spp.

Habitat

Gymnophthalmids are inhabitants of the forest floor or wet areas associated with tropical forests. They are denizens of leaf litter and detritus and can be found under logs, rocks, or other debris. In an analysis of an ecological community of Amazonian lizards, Vitt and Zani reported in 1991 that three species of gymnophthalmids were restricted to leaf litter. One species was found in relatively sunny spots whereas another was more commonly found in shade. A third, Leposoma percarinatum, was found along edges of swamps with fluctuating water levels.

Behavior

Gymnophthalmids are actively foraging lizards but secretive and hard to observe. These small lizards forage for small arthropod prey on the forest floor in leaf litter. Species of Alopoglossus and Neusticurus escape predators by diving into the water.

Feeding ecology and diet

All gymnophthalmids are insectivorous, foraging for arthropod prey found in the microhabitats where they live.

Reproductive biology

Reproductive biology is described for only a few species. All known species lay eggs, and clutch size is probably two for most species. Species of Gymnophthalmus and Leposoma are parthenogenetic, consisting only of females that produce fertile eggs.

Conservation status

No species are presently listed by the IUCN, but gymnophthalmids are susceptible to habitat alteration.

Significance to humans

The significance of the gymnophthalmids to people is not readily apparent. The ecological role these lizards play in tropical systems may never be completely understood but may be important nonetheless. Gymnophthalmids are prey to myriad predators, and themselves consume a wide variety of invertebrate prey.

Species accounts

List of Species

No common name

Bachia bresslaui

taxonomy

Apatelus bresslaui Amaral, 1935, Estado de Sao Paolo, Brazil.

other common names

None known.

physical characteristics

This gymnophthalmids has an elongated body and tail, reduced limbs, and no external ear opening. Colli and others reported information on this rare species in 1998. The largest individual in their sample had a snout-vent length of 4.2 in (10.6 cm). The tail is more than 1.5 times the body length. This species belongs to an ancestral group of Bachia, as evidenced by the presence of head shields that are lost in derived taxa.

distribution

Cerrado ecosystem of central Brazil and northeastern Paraguay, South America.

habitat

The species is known to live in sandy soils. Distributional information is lacking and it is possible the species also uses other substrate types.

behavior

Colli and others reported in 1998 that based on the presence of scorpions, ants, beetles, and other prey in the diet, the species probably forages above ground.

feeding ecology and diet

The diet of five individuals that were examined consisted of ants, beetles, beetle larvae, scorpions, and wolf spiders.

reproductive biology

The species is presumed to lay eggs, but the average clutch size is unknown.

conservation status

Not listed by the IUCN. This species may be more common and more widely distributed throughout the Cerrado ecosystem than previously thought. Threats include habitat destruction.

significance to humans

None known.

No common name

Gymnophthalmus underwoodi

taxonomy

Gymnophthalmus underwoodi Grant, 1958, Barbados. Gymnophthalmus underwoodi is actually a complex of species, or independent evolutionary units. Some populations of Gymnophthalmus underwoodi are bisexual, and others are unisexual, all-female species (parthenogens). The species was described from a series of female specimens from Barbados; no males were found. It was later proved that the Caribbean populations and some South American populations are parthenogenetic, reproducing without males or sperm.

Charles J. Cole and others (1983, 1990) and Laurence M. Hardy and others (1989) showed that this species is a product of hybridization. They suggested that G. underwoodi evolved from G. speciosus and a yet-undescribed Gymnophthalmus. Cole not only predicted what the undiscovered parent species would look like, he also predicted the specific arrangement of its 22 pairs of chromosomes and the nature of 33 of the unknown species' proteins!

Later, Cole and others (1993) reported the missing ancestor of G. underwoodi to be G. cryptus, a bisexual species described in 1992 from the Orinoco River drainage in Venezuela. After it arose in the upper Orinoco River watershed, G. underwoodi dispersed throughout the Guiana region and reached islands in the West Indies. Because multiple hybridization events could have occurred, there may be other clonal lineages of G. underwoodi that exist in a complex of species. Experts presume that more cryptic species exist that have not been described by 2002.

other common names

None known.

physical characteristics

These are small microteiids with a snout-vent length of 1.4–1.7 in (3.6–4.3 cm). The tail is about 1.5 times body length. The body is cylindrical, and the dorsal and ventral scales are smooth. The limbs are fully developed but small, with four fingers and five toes. These lizards usually are shiny bronze or olive on back, darker on the flanks, with a light dorsolateral stripe. The tail may be the same color as the body or range from bluish to orange or red.

distribution

The Gymnophthalmus underwoodi species complex occurs in the Guianan region of South America and in Trinidad and other islands of the West Indies.

habitat

These lizards are found in open types of tropical forest in leaf litter or grass. They are often found in microhabitat patches exposed to direct sunlight.

behavior

Gymnophthalmus underwoodi, like almost all gymnophthalmids, is a secretive denizen of leaf litter, and its behavior has never been studied. Because their diet consists of small surface-dwelling arthropods, it is likely these lizards actively search for their prey among leaf litter and under logs and other objects. They do not obviously bask, but they do occur mostly in leaf litter receiving direct sunlight. These lizards are part of a large group of lizards that are heliothermic, the Teoidea, almost all of which are strictly diurnal and not territorial.

feeding ecology and diet

In a study of an Amazonian lizard community, Vitt and Zani (1991) documented several orders of small insects in the diet of this species, specifically dermapterans, collembolans, and dipterans.

reproductive biology

Like other microteiids, this species lays eggs. Clutch size may range from one to four with an average clutch size of two.

conservation status

Not listed by the IUCN. Lack of knowledge about the ecology of this species complex impedes fully informed decisions about conservation needs. Threats include habitat destruction, and it will be difficult to assess the importance of habitat loss to cryptic species in the G. underwoodi complex until the distributions of different forms are understood.

significance to humans

None known.

No common name

Neusticurus ecpleopus

taxonomy

Neusticurus ecpleopus Cope, 1876, Peru.

other common names

None known.

physical characteristics

The body is cylindrical and the limbs are fully formed with five fingers and five toes. The maximum snout-vent length in males is 3.3 in (8.4 cm) and the tail is 1.4–1.8 times snout-vent length. There are six longitudinal rows of tubercles along the back and tubercles along the flanks. The tail is moderately compressed with a double crest formed by tubercles. The snout is blunt and the gular region is enlarged in adult males. These lizards are brown with black and lighter spots on the dorsum and flanks. The belly is orangish to reddish. Avila-Pires (1995) reported a relatively high degree of geographical variation.

distribution

Western Amazon along the slopes of the Andes from southern Colombia south to Bolivia.

habitat

Neusticurus ecpleopus is found along the banks of forest streams living in leaf litter and using muddy stream banks.

behavior

In their study of the ecology of Neusticurus ecpleopus, Vitt and Avila-Pires in 1998 found that the species was active throughout the day and inactive at night. They do not bask in the sun. These lizards frequently enter water and swim to the bottom to escape predators. The flattened tail is thought to facilitate swimming.

feeding ecology and diet

Although a variety of small insect prey are consumed, the diet information provided by Vitt and Avila-Pires (1998) showed the lizards mostly consumed fly larvae, crickets, and ants. It is likely the diet reflects the availability of small insect prey where the lizards happen to be living.

reproductive biology

Like other gymnophthalmids, Neusticurus ecpleopus lays multiple clutches in a reproductive season, most likely in clutches of two, but the exact number and frequency is unknown.

conservation status

Not listed by the IUCN. The species is not uncommon along primary forest streams within its range. Threats include habitat destruction, particularly since Neusticurus ecpleopus lives in primary forest.

significance to humans

None known.

Resources

Books

Avila-Pires, T. C. S. Lizards of Brazilian Amazonia (Reptilia: Squamata). Leiden, Germany: Zoologische Verhandelingen, 1995.

Cogger, H. G., and R. G. Zweifel, eds. Encyclopedia of Reptiles and Amphibians. 2nd ed. San Diego: Academic Press, 1998.

Dixon, J. R., and P. Soini. The Reptiles of the Upper Amazon River Basin, Iquitos Region, Peru. 2nd rev. ed. Milwaukee: Milwaukee Public Museum, 1986.

Murphy, J. C. Amphibians and Reptiles of Trinidad and Tobago. Malabar, FL: Krieger, 1997.

Pough, F. H., R. M. Andrews, J. E. Cadle, M. L. Crump, A. H. Savitzky, and K. D. Wells. Herpetology. 2nd ed. Upper Saddle River, NJ: Prentice Hall, 2001.

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

Powell, R., and R. W. Henderson, eds. Contributions to West Indian Herpetology: A Tribute to Albert Schwartz. Contributions to Herpetology, Volume 12. Ithaca, NY: Society for the Study of Amphibians and Reptiles, 1996.

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

Vitt, L. J., and S. de la Torre. A Research Guide to the Lizards of Cuyabeno. Museo de Zoologia (QCAZ) Centro de Biodiversidad y Ambiente Pontificia Universidad Catolica del Ecuador, 1996.

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

Zug, G. R., L. J. Vitt, and J. L. Caldwell. Herpetology: An Introductory Biology of Amphibians and Reptiles. 2nd ed. San Diego: Academic Press, 2001.

Periodicals

Cole, C. J. "A Lizard Foretold." Natural History 5 (1989): 12, 14–17.

——. "A Lizard Found." Natural History (August 1994): 66–69.

Cole, C. J., H. C. Dessauer, and A. L. Markezich. "Missing Link Found: The Second Ancestor of Gymnophthalmus underwoodi (Squamata: Teiidae), a South American Unisexual Lizard of Hybrid Origin." Natural History 3055 (1993): 13.

Colli, Guarino R., Mariana G. Zatz, and Helio J. daCunha. "Notes on the Ecology and Geographical Distribution of the Rare Gymnophthalmid Lizard, Bachia bresslaui." Herpetologica 54, no. 2 (1998): 169–174.

Dixon, J. R. "A Systematic Review of the Teiid Lizards, Genus Bachia, with Remarks on Heterodactylus and Anotosaura." Miscellaneous Publication of the University of Kansas Museum of Natural History 57 (1973): 1–47.

Hardy, L. M., C. J. Cole, and C. R. Townsend. "Parthenogenetic Reproduction in the Neotropical Unisexual Lizard, Gymnophthalmus underwoodi (Reptilia: Teiidae)." Journal of Morphology 201 (1989): 215–234.

Hoogmoed, M. S. "Notes on the Herpetofauna of Suriname IV. The Lizards and Amphibians of Suriname." Biogeographica 4 (1973): 1–419.

Hoogmoed, M. S., C. J. Cole, and J. Ayarzaguena. "A New Cryptic Species of Lizard (Sauria: Teiidae: Gymnophthalmus) from Venezuela." Zoologische Mededelingen (Leiden) 66 (1992): 1–8.

Kizirian, D. A. "A Review of Ecuadorian Proctoporus (Squamata: Gymnophthalmidae) with Descriptions of Nine New Species." Herpetological Monographs 10 (1996): 85–155.

Vitt, L. J., and P. A. Zani. "Ecological Relationships Among Sympatric Lizards in a Transitional Forest in the Northern Amazon of Brazil." Journal of Tropical Ecology 14 (1998): 63–86.

Vitt, L. J., and T. C. S. Avila-Pires. "Ecology of Two Sympatric Species of Neusticurus (Sauria: Gymnophthalmidae) in the Western Amazon of Brazil." Copeia no. 3 (1998): 570–582.

Lee A. Fitzgerald, PhD