Description
Oedipina uniformis is a moderately sized salamander, measuring up to 57 mm in snout-vent length and 215 mm in total length (Savage, 2002). This salamander has an extremely slender, elongated body and tail and tiny limbs, hands, and feet, giving it a worm-like appearance (Savage, 2002). Individuals are usually uniformly dark in tone and may be tan, dark brown, gray, slate, or black (Leenders, 2001). Ventrally the coloration is a less intense gray black (Savage, 2002). The head, body, and tail are all roughly the same width (Wake, 2003), with the head slightly wider than the neck (Leenders, 2001). The tail is fragile and can be twice the length of the body (Leenders, 2001). Hands and feet are tiny and are almost always syndactylous (Savage, 2002). Nineteen to twenty costal grooves are present on the sides of the body (Savage, 2002). Oedipina uniformis has relatively large eyes with black irises. It is difficult to tell Oedipina (worm salamander) species from one another because they are very similar in appearance (Leenders, 2001).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Costa Rica

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (1 records).

Oedipina uniformis occurs only in Costa Rica, on humid premontane and lower montane slopes in the region surrounding the Meseta Central, which ranges from 750-2150 m in elevation (Savage, 2002). It is most commonly found in or under rotted logs, leaf litter, and mats of moss (Savage, 2002).

Life History, Abundance, Activity, and Special Behaviors
Oedipina uniformis salamanders are semifossorial (Garcia-Paris et al., 2000). They are nocturnal and shy creatures, preferring to shelter under leaf litter, under wet moss mats, in or under decaying logs, or in old insect burrows (Leenders, 2001). When they are caught, these fast-moving salamanders engage in serpentine flipping, whipping their tails back and forth violently in order to escape the potential predator (Wake, 2003; Dodd and Brodie, 1976). If a predator grasps the tail, it breaks off (Wake, 2003). These salamanders lay large yolky eggs in cavities in the soil (Wake, 2003). The adult diet consists of small arthropods (Wake, 2003).

Trends and Threats
This species was once common but is now rarely seen due to loss of habitat from agriculture and urbanization (Wake, 2003).

Possible reasons for amphibian decline

Intensified agriculture or grazing
Urbanization

Comments
The karyotype is 2N=26, with all chromosomes having two arms, and up to eight supernumerary chromosomes present (Kezer, Sessions, and Leon, 1989; Sessions and Kezer, 1991; Green, 1991). This species has strongly heteromorphic sex chromosomes, with females being XX (Kezer, Sessions, and Leon, 1989; Sessions and Kezer, 1991).

A Spanish-language species account can be found at the website of Instituto Nacional de Biodiversidad (INBio).

References

Dodd, C. K., Jr. and Brodie, E. D., III (1976). ''Defensive mechanisms of Neotropical salamanders with an experimental analysis of immobility and the effect of temperature on immobility.'' Herpetologica, 32(3), 269-290.

García-París, M., Good., D. A., Parra-Olea, G., and Wake, D. B. (2000). ''Biodiversity of Costa Rican salamanders: implications of high levels of genetic differentiation and phylogeographic structure for species formation.'' Proceedings of the National Academy of Sciences, 97(4), 1640-1647.

Green, D. M. (1991). ''Supernumerary chromosomes in amphibians.'' Amphibian Cytogenetics and Evolution. D.M. Green and S.K. Sessions, eds., Academic Press, San Diego, California, USA.

Guyer, C., and Donnelly, M. A. (2005). Amphibians and Reptiles of La Selva, Costa Rica and the Caribbean Slope: A Comprehensive Guide. University of California Press, Berkeley.

Kezer, J., Sessions, S. K., and Leon, P. (1989). ''The meiotic structure and behavior of the strongly heteromorphic X/Y sex chromosomes of Neotropical plethodontid salamanders of the genus Oedipina.'' Chromosoma, 98, 433-442.

Leenders, T. (2001). A Guide to Amphibians And Reptiles of Costa Rica. Zona Tropical, Miami.

Sessions, S. K., and Kezer, J. (1991). ''Evolutionary cytogenetics of bolitoglossine salamanders (family Plethodontidae).'' Amphibian Cytogenetics and Evolution. D.M. Green and S.K. Sessions, eds., Academic Press, San Diego, California, USA.

Wake, D. B. (2003). ''Costa Rican worm salamander, Oedipina uniformis.'' Grzimek's Animal Life Encyclopedia, Volume 6, Amphibians. 2nd edition. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.

Species Account Citation: AmphibiaWeb 2009 Oedipina uniformis: Common Worm Salamander <https://amphibiaweb.org/species/4117> University of California, Berkeley, CA, USA. Accessed May 14, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 14 May 2025.

AmphibiaWeb's policy on data use.