This is a small species; adult standard length averages 19.8 mm in 10 males (range 18.2-21.7) and 20.6 mm in 10 females (range 18.1-22.0). The head is moderately wide; SL averages 7.2 times head width in males (range 6.2-8.7) and 7.6 times head width in females (range 7.0-8.3). Snouts are rounded to bluntly pointed. Nostrils are relatively large and elongate; the mean ratio of major axis to minor axis is 1.4 in males (range 1.2-1.6) and 1.5 in females (range 1.2-1.8). The eyes are somewhat protuberant and extend beyond the margin of the jaw in dorsal view, especially in males. A suborbital groove intersects the lip on each side of the head. The single cleared-and-stained specimen, a male, has two premaxillary teeth, six vomerine teeth, and no maxillary teeth. Limbs are relatively long; limb interval averages 3.5 mm in males (range 2.5-4) and 4.6 mm in females (range 4-5). Feet are relatively well developed. The middle two fingers and the middle three toes are much longer than the outer digits. Adjacent digits are free from one another only at their tips, which are rounded except in some smaller individuals in which they are slightly pointed. There are poorly developed subterminal pads on some of the larger specimens. The tail is relatively short and only rarely exceeds standard length; mean SL divided by tail length equals 1.23 in males (range 1.01-1.69) and 1.16 in females (range 0.99-1.32). The tail is round (in cross section) in smaller specimens, and quadrangular to somewhat laterally compressed in larger specimens. Coloration in life, based on field notes by J. Hanken for MVZ 182624-32: Most specimens have a greenish dorsal stripe (Hanken and Wake 1998).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Mexico
Thorius dubitus is known only from the vicinity of the type locality near Puerto del Aire, which is ca. 3 km W of the village of Acultzingo, Veracruz, Mexico, very close to the Puebla border. Recorded elevations range from 2380 to 2475 m. The predominant vegetation type is pine-oak cloud forest, which is characteristic of these and other localities that lie along the southeastern edge of the Mexican plateau. Thorius dubitus is an exclusively terrestrial species. Salamanders are found under wood chips, under and inside logs, under the bark of logs, and under rocks.
Thorius dubitus is sympatric with at least two congeners in the vicinity of Puerto del Aire: T. troglodytes, another exclusively terrestrial species; and T. magnipes, which is found both on the ground and in arboreal microhabitats. A third sympatric species may also be present, as a single specimen of T. spilogaster (KU 106818) is recorded from this locality. We have, however, examined hundreds of specimens of Thorius from this locality and others nearby and failed to identify other specimens of T. spilogaster; locality data for this specimen may be in error (Hanken and Wake 1998).
Hanken, J. and Wake, D. B. (1998). ''Biology of the tiny animals: Systematics of the minute salamanders (Thorius: Plethodontidae) from Veracruz and Puebla, Mexico, with descriptions of five new species.'' Copeia, 1998(2), 312-345.
Written by David B. Wake (wakelab AT uclink4.berkeley.edu), Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720
First submitted 2000-11-08
Edited by M. J. Mahoney (2002-02-17)
Species Account Citation: AmphibiaWeb 2002 Thorius dubitus <http://amphibiaweb.org/species/4205> University of California, Berkeley, CA, USA. Accessed Jul 1, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 1 Jul 2020.
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