Systematics of the Bufo Valliceps Group (Anura: Bufonidae) of Middle America

Abstract

A phylogenetic analysis of morphological characters revealed that the species content of the Bufo valliceps group is limited to eight species (two of them new) occurring between the southern United States and Costa Rica. Several Middle American species usually associated with this group are shown to be closely related, but outside of the Bufo valliceps group. The monotypic genus Crepidophryne is placed in the synonymy of Bufo. The taxon Bufo valliceps macrocristatus is recognized as a species distinct from Bufo valliceps. Seven species in the Bufo valliceps group appear to be allopatric with respect to one another and are restricted to humid primary forest habitat on the lower slopes of the major mountain ranges of southern Mexico, Guatemala, Honduras, and Costa Rica. The species Bufo valliceps is widespread in humid lowland habitats from the southern United States to Costa Rica that are either naturally more open (e.g., savanna) or disturbed secondary growth. There are great differences in size, shape, skin texture, and color pattern between northern and southern populations of this species; however, these differences do not vary along a smooth cline among populations from intermediate areas. Nor is there a discrete break among these continuous variables that separate the northern and southern morphs. Variation in Bufo valliceps is characterized by a high degree of. inter- and intrapopulational variation that cannot be attributed to simple trends associated with latitude, altitude, or climate. Bufo ibarrai, long assumed to be in the Bufo valliceps group but here shown to lie outside of the group, is reviewed and rediagnosed with respect to other similar Central American toads. The taxon Bufo valliceps microtis is placed in the synonymy of Bufo coccifer. Diagnostic accounts for all species in the Bufo valliceps group and a key to the species are provided.