Biology of Tiny Animals: Systematics of the Minute Salamanders (Thorius: Plethodontidae) from Veracruz and Puebla, Mexico, with Descriptions of Five New Species

Minute plethodontid salamanders, genus Thorius, are far more diverse taxonomically than has been recognized previously. Populations of these salamanders from the Mexican states of Veracruz and Puebla are assigned to 10 species, five of which are described as new. Combinations of morphological and allozymic characters are used to sort the species and to make initial assessments of relationships. Valid existing names include Thorius pennatulus, T. troglodytes, T. dubitus, and T. schmidti. Thorius narismagnus, from the Sierra de Los Tuxtlas, which previously was considered to be a disjunct subspecies of T. pennatulus, is elevated to species rank. Thorius maxillabrochus is treated as a subjective junior synonym of the sympatric T. schmidti. New taxa include Thorius lunaris, T. magnipes, T. minydemus, T. munificus, and T. spilogaster. All 10 species can be distinguished by morphological characters, but the distinctiveness of the taxa is bolstered by allozymic characters and by extensive sympatry. As many as three, and possibly four, species occur in sympatry, with some evidence of segregation by microhabitat (arboreal vs terrestrial). Adult body sizes span the range known for the genus, from very small in T. pennatulus (maturing at < 16 mm standard length) to large in T. lunaris (adults reaching > 31 mm). Collectively these species display a wide elevational distribution, from less than 1000 m (T. pennatulus, T. narismagnus) to more than 3000 m (T lunaris, T. spilogaster). Discovery of these new species adds to the rich herpetological diversity of east-central Mexico and underscores its importance as a principal center of radiation of tropical plethodontid salamanders.