Systematic Status of a South American Frog, Allophryne ruthveni Gaige

The authors reassess the systematic status of a diminutive South American frog by examining six specimens, including a newly reported male, using standard measurements, cleared-and-stained skeletal preparations, and x-rays. They present an expanded genus diagnosis and a detailed species description covering external morphology, osteology, coloration, and intraspecific variation, list specimen localities, and compare earlier family placements and opinions. Illustrations, measurements, and anatomical observations are used to clarify diagnostic characters and to evaluate the frog's taxonomic affinities.