Arboreal Thorius

This is a very small species of Thorius. Average length in four adult males was 17.0 mm (range 16.1-18.4mm). In seven females the mean length was 17.2 mm (range 15.2-20.0). The salamander have a very slender body and a relatively wide head with a bluntly pointed snout. The mean ratio of SL to head width is 6.7 in both males and females (range 6.1-7.3). The nostril is round or slightly oval; the mean ratio of major to minor axis is 1.3 (range 1.0-1.7). The eyes are moderately large and protrudant. There is a suborbital groove intersecting the lip on both sides. Individuals of the species have very few teeth. Some have one premaxilliary tooth. Mean number of vomerine teeth is 6 (range 5-7) in males and 4.5 (range 4-5) in females. Limbs are long; limb intervals were 4 in one male and average of 3.4 in females (range 2-4.5). Hands and feet are narrow. The tail is relatively long and tapers from midpoint to tip.The species has a reddish dorsal stripe. Some individuals may have an ornate pattern, others a normal stripe. Legs and venter may be lighter in color. Also, there may be whitish spots on the tip of the snout and below the eye (Hanken and Wake 1994).

Country range is Mexico. The range is known from type locality and other nearby cloud forest localities along Hwy 175 on the Atlantic draingage of the Sierra de Juarez. The lowest recorded elevation is 2170 m.The species is sympatric with T. aureus at upper elevations (Hanken and Wake 1994).The species may be common in warm areas under the bark of rotting logs (Feder 1982).

Thorius arboreus, commonly known as the arboreal minute salamander, is a species of salamander in the family Plethodontidae. It is endemic to Sierra de Juarez, Oaxaca, Mexico. The specific name arboreus, derives from the Latin word arbor, meaning tree, referring to the arboreal habitat of this species.