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.[1] [2] The specific name arboreus, derives from the Latin word arbor, meaning tree, referring to the arboreal habitat of this species.
With males measuring 16.1mm18.4mm and females 15.2mm20mm in snout–vent length, it is a very small species even among the generally small Thorius.[2] [3] It has a slender habitus. The head is relatively wide; the snout is bluntly pointed. The eyes are relatively large. Maxillary teeth are lacking. The limbs are relatively long. There is a reddish dorsal stripe; some individuals have an ornate pattern where the dorsolateral margins of the stripe are "pinched" over the shoulders.
Its natural habitat is cloud forest. It is an arboreal species typically occurring in the leaf axils of bromeliads. It tolerates some habitat degradation provided that shade remains. Main threats to it are encroachment of agriculture and logging.