A PHYLOGENY OF PRIMITIVE FROGS (ARCHAEOBATRACHIANS) (CLADISTICS, TAXONOMY, MORPHOLOGY, SYSTEMATICS, EVOLUTION)

Phylogenetic relationships among 40 taxa of archaeobatrachians and two species of neobatrachians were analyzed using the methods of phylogenetic systematics. Data were derived primarily from studies of osteology and myology; 227 derived character-states were defined. Ascaphus truei is the sister-group to all other frogs; at the next level, Leiopelma is the sister-group to all frogs. These taxa were used as outgroups to determine evolutionary direction of the characters. The most parsimonious cladogram produced from these data has a length of 355 steps and a consistency index of 0.64.; The families Leiopelmatidae and Discoglossidae as previously recognized are paraphyletic. Within the latter group, Bombina is the sister-group to Barbourula, and Alytes is the sister-group to Discoglossus. The superfamily Pelobatoidea is the sister-group to the Pipoidea, rather than to the Neobatrachia, as generally believed; rather, the Neobatrachia is the sister-group to the pelobatoids + pipoids. Within the Pelobatoids, relationships among the three major lineages are poorly defined, but each group (megophryines, pelodytids, and pelobatines) is monophyletic. Within the pipoids, Rhinophrynus is the sister-group to the fossil family Palaeobatrachidae + Pipidae. The genus Xenopus is paraphyletic; Hymenochirus is the sister-group to Pipa.; Taxonomic changes include the recognition of the Ascaphidae and Leiopelmatidae for Ascaphus and Leiopelma, respectively; Bombinatoridae for Bombina and Barbourula; and Discoglossidae for only Alytes and Discoglossus. The Megophryinae are raised to full familial rank. Silurana is resurrected for some species of Xenopus. Six new infraorders are named for the following groups: Ascaphidae, Leiopelmatidae, Bombinatoridae, Discoglossidae, Neobatrachia, and Pipoidea + Pelobatoidea. A phylogenetic classification of frogs to the family level is presented.