Description
Adults are large for caecilians (up to 600 mm total length for Guatemalan specimens from the Pacific versant) and relatively stout-bodied (Savage and Wake 2001). Dorsal coloration is dark gray, with a pale venter as well as pale jaw and tentacle markings (Wake 2003). Body annuli (94-112 primary folds and 35-88 secondary folds) are numerous. Annuli are also darkly pigmented ventrally, in sharp contrast to the pale venter (Savage and Wake 2001). The tentacle is located roughly halfway between the eye and nostril, with the tentacular foramen present in the anterior margin of the maxillary bone (Savage and Wake 2001). The orbit is not roofed over by squamosal bone (Savage and Wake 2001). Teeth are present in a single row on the lower jaw, since splenial teeth are lacking (Savage and Wake 2001).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: El Salvador, Guatemala, Honduras, Mexico, Nicaragua

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

This species occurs in Mexico, from the lowlands and mountains of Guerrero on the Pacific versant and Veracruz on the Atlantic versant, southward to northern Panama. It is generally fossorial but is also found on the surface in leaf litter. It prefers to make burrows in moist, friable soil but is able to make use of a diversity of soil types (Wake 1980).

Life History, Abundance, Activity, and Special Behaviors
Dermophis mexicanus spends much of its time in burrows in moist, loose soil (Wake 2003). However, it also forages on the surface, often emerging at dusk if there is a light rain (Wake 2003). D. mexicanus is a sit-and-wait predator with a diet composed of soil or leaf-litter invertebrates (e.g., earthworms, termites, orthopteran instars) and perhaps occasional vertebrates (smaller lizards and baby mice, depending on the size of the individual caecilian) (Wake 2003). Feeding mechanics have been studied (e.g., Bemis et al. 1983).

D. mexicanus constructs its own burrow (Wake 2003). Modes of locomotion include internal concertina motion and lateral undulation (Summers and O'Reilly 1997).

Sexual maturity occurs at two to three years of age. How mates are attracted and whether they undergo courtship is not known. As is the case for all caecilians, Dermophis mexicanus has internal fertilization, with the male extruding the rear part of the cloaca into the female's cloaca to transfer sperm. Although males can produce sperm nearly year-round (11 months; Wake 1995), females in a given population show synchronous development of embryos in the oviduct, implying that there is a short and synchronized breeding period but no sperm storage. Embryos are small (2 mm in diameter) and feed on the egg yolk supply for only about three months of gestation before the yolk supply is exhausted. At that point the mother makes a nutritious secretion from internal oviduct glands. Fetal caecilians move around within the oviduct and have specialized dentition with which they scrape the oviduct skin in order to stimulate and ingest the mother's nutritive secretion. The dentition is shed at birth and a quite different adult dentition is rapidly acquired within a few days. Fetuses also have elaborate tri-branchiate gills (Wake 2003).

Pregnancies are 11 months long and this species is viviparous. Females give birth to three to sixteen young when the rainy season begins in May/June. Newborns measure 10-15 cm in length, while the mother herself is only 30-45 cm long (Wake 2003).

Trends and Threats
Although this species remains locally abundant in some localities, its habitat is being altered or destroyed as deforestation occurs. It does seems to adapt well to some kinds of farm use. For instance, this species is abundant on some coffee fincas where the coffee hulls are piled up to decay, resulting in the kind of moist organic soil in which Dermophis (along with its primary food, earthworms) thrives (Wake 2003).

Relation to Humans
It is of value to humans because of its ability to turn soil as it burrows, and because it consumes insects among other prey (Wake 2003).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities

References

Bemis, W. E., Schwenk, K., and Wake, M. H. (1983). ''Morphology and function of the feeding apparatus in Dermophis mexicanus (Amphibia: Gymnophiona).'' Zoological Journal of the Linnean Society, 77, 75-96.

Savage, J. M., and Wake, M. H. (2001). ''Reevaluation of the status of taxa of Central American caecilians (Amphibia: Gymnophiona) with comments on their origin and evolution.'' Copeia, 2001(1), 52-64.

Summers, A. P., and O'Reilly, J. C. (1997). ''A comparative study of locomotion in the caecilians Dermophis mexicanus and Typhlonectes natans (Amphibia: Gymnophiona).'' Zoological Journal of the Linnaean Society, 121, 65-76.

Wake, M. H. (2003). ''Mexican caecilian, Dermophis mexicanus.'' Grzimek's Animal Life Encyclopedia, Volume 6, Amphibians. 2nd edition. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.

Wake, M.H. (1980). "Reproduction, growth, and population structure of the Central American caecilian Dermophis mexicanus (Amphibia: Gymnophiona)." Herpetologica, 36, 244-256.

Wake, M.H. (1995). ''The spermatogenic cycle of Dermophis mexicanus (Amphibia: Gymnophiona).'' Journal of Herpetology, 29, 119-122.

Species Account Citation: AmphibiaWeb 2009 Dermophis mexicanus: Mexican Caecilian <https://amphibiaweb.org/species/1877> University of California, Berkeley, CA, USA. Accessed Nov 22, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Nov 2024.

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