Description

Diagnosis: Distinguished from most other Central American Talamancan salamanders by its large size (87.7 mm SL) and uniformly dark ground color. Can be distinguished from all other large black species of Bolitoglossa by having smaller and fewer maxillary and vomerine teeth, as well as the following: B. robusta has a cream-colored ring at the tail base; B. nigrescens is more robust, with shorter limbs; B. magnifica is less robust; B. anthracina has more slender limbs with longer and more slender digits; B. copia has more foot webbing and has white pigment on the throat and jaw region (Hanken et al. 2005).

Description: The description is based on the adult female holotype, the only specimen collected for this species. The holotype measures 87.7 mm in SVL, and 75.6 mm in TL. The head is short and relatively wide (head length to width ratio 1.52). The snout is broad and truncated. Nostrils are small. Nasolabial protuberances are moderately developed. Eyes are moderat in size, and do not protrude past the jaw margins in dorsal view. A distinctly visible pair of glandular openings is found on the roof of the mouth between the choanae. The holotype has few and very small teeth; premaxillary and maxillary teeth hardly protrude through the gums. The limbs are short and robust. Limb interval is 2.5. Hands and feet are large, with digits bluntly pointed digital tips. Webbing is well developed, leaving only the distalmost 1 1/2 phalanges of longest digits free. The fingers in order of decreasing length are 3>4>2>1, and the toes are 3>4>2>5>1. Subterminal pads are present on all digits. The tail is relatively short compared to SL (SL:TL = 1.16). The postiliac gland is large and pale (Hanken et al. 2005).

In preservative, the dorsum and venter are uniformly dark gray to black. Some irregular white patches are present on the snout, around the nostrils, and in front of the eyes. The subocular groove is unpigmented. Obscure white markings are found on eyelids and in the temporal region. The area on the trunk near limb insertions and the gular fold are paler. Wrist, ankle and knuckles are also paler on the dorsal side. Palms and soles are unpigmented. Tiny cream-yellow glands cover the dorsum, which were secreting mucus at the time of collection; the yellow mucus also covers the dorsal surface of the tail (Hanken et al. 2005).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Costa Rica

View distribution map in BerkeleyMapper.

The holotype was collected from Quebrada Valverde in the Parque Nacional Tapantí, Cartago Province, Costa Rica, in tropical premontane rainforest, at 1555 m asl (Hanken et al. 2005).

Life History, Abundance, Activity, and Special Behaviors
The female holotype was collected as she was laying a clutch of 31 eggs. The eggs of this species are approximately 7 mm in diameter. Eggs were preserved with the specimen but were not allowed to develop; this species is presumed to breed by direct development. B. obscura is sympatric with two other species of moss mat-inhabiting plethodontids, both diminutive: Bolitoglossa diminuta and Nototriton picadoi (Hanken et al. 2005).

Trends and Threats
Known only from the holotype, collected in 1969 (Stuart et al. 2008). Occurs within at least one protected area, the Parque Nacional Tapantí (Hanken et al. 1985).

Comments

First described by Hanken et al. (1985). The specific name derives from the Latin obscura, meaning dusky or unclear, and referring to the coloration as well as to the initial confusion of this species with other large black Bolitoglossa species.

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

References

Hanken, J. Wake, D. B., and Savage, J. M. (2005). ''A solution to the large black salamander problem (genus Bolitoglossa) in Costa Rica and Panamá.'' Copeia, 2005(2), 227-245.

Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.

Species Account Citation: AmphibiaWeb 2011 Bolitoglossa obscura: Tapantí Giant Salamander <https://amphibiaweb.org/species/6432> University of California, Berkeley, CA, USA. Accessed Jan 29, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 29 Jan 2025.

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