Dermophis mexicanus

Dermophis mexicanus
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Order:	Gymnophiona
Clade:	Apoda
Family:	Dermophiidae
Genus:	Dermophis
Species:	D. mexicanus
Binomial name
Dermophis mexicanus (A.M.C. Duméril & Bibron, 1841)
Synonyms
Siphonops mexicanus A.M.C. Duméril & Bibron, 1841 Amphisbaena versatilis Gray, 1850 Dermophis mexicanus — W. Peters, 1880 Gymnophis clarki Dunn, 1928 Dermophis eburatus Taylor, 1968 Dermophis septentrionalis Taylor, 1968 Gymnophis mexicanus — Dubois, Ohler & Pyron, 2021

Dermophis mexicanus, also known commonly as the Mexican burrowing caecilian or the Mexican caecilian, and locally as the tapalcua or tepelcua, is a species of limbless amphibian in the family Dermophiidae. The species is native to Mexico and Central America, where it burrows under leaf litter and plant debris.

Description

The adult Mexican burrowing caecilian grows to a length of 30 to 50 cm (12 to 20 in). In general appearance, it resembles a large earthworm. Around a hundred transverse annular folds in the skin give the appearance of segments. The head has a pointed snout, a single row of teeth in the lower jaw, and two vestigial eyes covered with skin, with a pair of protrusible tentacles between the eyes and the nostrils. The body is elongated and there are no limbs. The upper surface is dark grey and the under surface pale grey with darker markings on the annuli.

Distribution and habitat

The Mexican burrowing caecilian is found in Mexico, Guatemala, El Salvador, Honduras, Nicaragua, and possibly Belize, mostly on the Atlantic side, but also in some isolated parts of the Pacific slope. Its natural habitats are subtropical or tropical dry forests, moist lowland forests, moist montane forests, plantations, rural gardens, and heavily degraded former forests. It is fossorial, living in damp, loose soil and under leaf litter, logs, and plant debris, often in banana and coffee plantations. It is found at altitudes of up to 1,200 m (3,900 ft) above sea level.

Biology

The Mexican burrowing caecilian feeds on invertebrates, including earthworms, termites, crickets, slugs, and snails. It emerges onto the ground surface on nights with light rainfall and catches small prey that come within its reach. Larger individuals may eat mice and small lizards. It moves by internal concertina-like movements and by undulating its body from side to side.

This caecilian is viviparous. Males start spermatogenesis at 1 years of age but may not reproduce until year two due to a greater abundance of spermatogenic lobules. Females can start reproducing after 1 year, but most reproduce in their second year. Fertilisation is internal and up to 16 developing larvae subsist on the yolks of their eggs for three months. Then, they develop rasping teeth and feed on maternal glandular secretions, scraping the inside of the oviduct to stimulate their production. When the young emerge, after 11 months of gestation, they are 10 to 15 cm (3.9 to 5.9 in) long. They then shed their larval teeth and rapidly grow a set of adult ones.

Status

The Mexican burrowing caecilian is listed as least concern in the IUCN Red List of Threatened Species. It has several disjunct populations, and in areas where it used to be abundant it now seems to be less common, and the locations in which it is found seem to be fewer in number. It may be persecuted in some locations because it superficially looks like a snake.

Further reading

• Duméril A-M-C, Bibron G (1841). Erpétologie Générale ou Histoire Naturelle Complète des Reptiles, Tome huitième [volume 8]. Paris: Roret. ii + 784 pp. (Siphonops mexicanus, new species, pp. 284–285) (in French).