Description
This salamander measures from 39.1-53.3mm SVL in adult males and 44.5-53.0mm SVL in adult females. Bradytriton silus has a robust, cylindrical body with a short, stocky tail (mean SL/tail length of 1.4). The head is broad and rounded, with a short, broad snout, and there is no clearly defined neck. Nostrils are small. The adetoglossal tongue has a distinct small pad. Eyes are moderately sized and in dorsal view protrude slightly beyond the jaw margin. Adult males have 3-8 premaxillary teeth, while females have 6-10. The row of maxillary teeth extends to a point nearly posterior to the eye. A single, curved row of vomerine teeth is present. Posterior vomerine teeth are present in two bilateral patches. A well developed gular fold and large sublingual fold are also present. Limbs are short and thin, with small syndactylous hands and feet that lack subdigital pads. Digits are mostly cartilaginous, including most of the terminal phalanges, with only the proximal phalanx of the longest finger and toe consistently well-ossified. Distinct post-iliac glands are present. The short tail has a marked basal constriction. The tail is also strongly tapered and laterally compressed, with a prominent dorsal glandular ridge running along its length.

Females have shorter snouts and poorly developed labial protuberances, while males have prominent, wide labial protuberances and large, hooked premaxillary teeth extending through or under the lip. Males also have mental glands but they are not visible externally.

The dorsal coloration is reddish brown, extending halfway down the lateral surfaces. The head is nearly black, having black cheeks flecked with white. The lower flanks and the sides of the tail are also black with white speckling. Legs are brown proximally, shading into black with white flecks distally. The feet are black with white speckling. Eyes are chestnut brown.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Guatemala, Mexico

View distribution map in BerkeleyMapper.

Endemic to extreme northwestern Guatemala, on the eastern slopes of the Sierra de los Cuchumatanes. The type locality is near Chiblac, at 1,310m asl, with a second locality recently discovered at Finca Ixcansán at 1,640 m asl, about 50km NW of the original locality. This species inhabits humid cloud forest receiving 5 to 6 meters of annual rainfall.

Life History, Abundance, Activity, and Special Behaviors
Bradytriton silus is a focus species for Conservation International, which has chosen ten critically endangered Guatemalan amphibians for special research efforts. This species was rediscovered by a joint University of California at Berkeley Museum of Vertebrate Zoology and Universidad de San Carlos de Guatemala expedition, in January 2009, 33 years after last being collected in 1976. Eight specimens were collected in January 2009. Six were found under or inside logs, one was walking in the forest at night, and one was collected from a pitfall trap (Papenfuss pers. comm.). This species presumably has direct development.

Trends and Threats
The habitat at the type locality (Chiblac) is under severe pressure from increasing human use (IUCN 2008). The habitat at the second locality (near Finca Ixcansán) is relatively undisturbed but there has been selective logging of hardwood trees. Areas surrounding the second locality have been nearly completely logged in the past, and are now a combination of grassland, cow pasture, cornfields, and secondary forest (Papenfuss pers. comm.).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization
Habitat fragmentation

Comments
This species is the sole member of its genus. The generic name Bradytriton refers to the slow and lethargic movement of this salamander. The specific name silus is Latin for pug-nosed, referring to the short, broad, wide snout.

References

IUCN (2008). 2008 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 7 February 2009.

Wake, D. B., and Elias, P. (1983). ''New genera and a new species of Central American salamanders, with a review of the tropical genera (Amphibia, Caudata, Plethodontidae).'' Contributions of the Natural History Museum of Los Angeles County, 345, 1-19.

Species Account Citation: AmphibiaWeb 2009 Bradytriton silus <https://amphibiaweb.org/species/4025> University of California, Berkeley, CA, USA. Accessed Nov 25, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 25 Nov 2024.

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