Minute Thorius

The description of Hanken and Wake (1998) is based primarily on data from two adult males (MVZ 131444, the holotype, and UIMNH 21816) and one female (UIMNH 21818). Complete measurements could not be obtained from the remaining paratypes, which are poorly preserved. Although very small, this species is characterized by a relatively robust habitus; adult standard length averages 18.2 mm in males (range 17.1-19.2) and 21.3 mm in the female. The head is relatively broad; SL averages 6.6 times head width in males (range 6.4-6.8) and is 6.9 times head width in the female. The snout is bluntly pointed in the female and more sharply pointed in males. Nostrils are relatively large and round to slightly oval; the mean ratio of major axis to minor axis equals 1.2 in males (range 1.1-1.2) and 1.3 in the female. Eyes are relatively large and protuberant; their outline extends beyond the margin of the head in dorsal view. A suborbital groove intersects the lip on each side of the head. There are 1-2 premaxillary teeth in males (mean 1.5) and 3 in the female. Vomerine teeth average 5.5 in males (range 5-6); there are 9 in the female. A moderate number of maxillary teeth (19) are present in the female; males have few or no teeth (range 0-3). Limbs are relatively long and slender; limb interval averages 3.5 in males (range 3-4) and is 4.0 in the female. Hands and feet are very small; the hand is so short and narrow as to be barely distinguishable from the distal limb. Toes are distinct; all are free or partly free at their tips. The third finger and toe are sharply pointed and much longer than adjacent digits, which are bluntly pointed. The fourth finger and fifth toe are barely distinguishable externally. Fingers, in order of decreasing length, are 3-2-4-1; toes are 3-2-4-1-5. The tail is relatively short and stout in males; mean SL divided by tail length equals 1.07 (range 1.03-1.10). The tail is missing from the female specimen. Coloration of paratypes appears to resemble that of the holotype (dark with a dorsal stripe and ventral white spotting), although some specimens are faded. The iris is very dark brown to black. The mental gland is relatively large and ovoid. The postiliac gland is barely perceptible (Hanken and Wake 1998). General coloration dark brown with a lighter brown dorsal stripe. Lower flanks dark brown speckled with white. Ventral parts lighter, with a network of white spots (Raffaëlli 2007).The species name, used as an adjective, is a conjunction of two Greek words, minys (small) and demas (body, frame), in reference to the extremely tiny adult body size of these animals, which are small even in comparison to most other Thorius (Hanken and Wake 1998).

The type series of Thorius minydemus is from the vicinity of the village of La Joya, Veracruz, Mexico, ca. 21 km NW of the city of Jalapa and 3 km E of the town of Las Vigas. Recorded elevation for La Joya varies between 2,100 and 2,250 m. Based on field notes of D. B. Wake (23 Oct. 1981): The type locality is at the lower elevational range of mixed pine-oak forest in this region. It is a marginal cloud forest, consisting of oaks and pines growing on poor soil in an area of extensive lava flows. Bromeliads are abundant, especially in the oaks. Two additional specimens are referred to this species, KU 26140 and 26159. Both were collected by W. W. Dalquest from Las Vigas, elev. 8500 ft, 16 Oct. 1948. While Las Vigas is the principal locality for T. munificus, there is no indication from our own field experience that this species and T. minydemus occur in sympatry. The exact collection locality of Dalquest's specimens is unknown (Hanken and Wake 1998).

Presumably reproduces by direct development (Stuart et al. 2008).

This species is rare and is a micro-endemic, with a very restricted and fragmented range (Stuart et al. 2008. It is under significant threat from habitat loss and alteration due to logging, mining, agriculture, livestock grazing, and human settlement (Stuart et al. 2009). It does not occur within any protected areas (Ochoa-Ochoa et al. 2009; Stuart et al. 2008). One locality, Cerro Loma Alta, had been almost completely destroyed as of 2003, due to logging and invasive plants, and no salamanders were found there (Stuart et al. 2008). At another locality, La Joya, only about 15 ha of habitat were still available as of 2004, with the surrounding area severely disturbed by both logging and mining (Stuart et al. 2008). As of November 2009 this species was still present at La Joya (S. M. Rovito, pers. comm.).

Thorius minydemus, commonly known as the La Hoya minute salamander, is a species of salamander in the family Plethodontidae. It is endemic to Mexico and only known from near its type locality near La Joya, Veracruz. Its natural habitats are cloud and pine-oak forests with many bromeliads.

The species is threatened by habitat loss and may already be extinct.