Genera of Leptodactylid Frogs in Mexico

Excerpt

INTRODUCTION

According to the most recent review of the Mexican amphibian fauna (Smith and Taylor, 1948), six genera of leptodactylid frogs occur in México. One other genus, Pleurodema, occurs in Lower Central America. Smith and Taylor recognized one species of Engystomops, 28 of Eleutherodactylus, three of Leptodactylus, eight of Microbatrachylus, 12 of Syrrhophus, and five of Tomodactylus. Subsequent to the publication of their checklist of the Mexican amphibia (1948), numerous taxonomic changes have been proposed. Many species of Eleutherodactylus have been added to the fauna, either through the extension of their recorded ranges into México from Guatemala or by the recognition of species unknown in 1948, whereas some nominal species have been synonymized. Microbatrachylus has been regarded as synonymous with Eleutherodactylus (Lynch, 1965); four species of Microbatrachylus currently are regarded as valid (Duellman, 1961, Lynch, 1965). Syrrhophus was revised in part by Duellman (1958) and Firschein (1954), and a species of Tomodactylus transferred to Syrrhophus by Dixon (1957), who redefined Tomodactylus and added more species to the genus.

Since beginning my studies of the Mexican leptodactylids in 1962, I have become acutely aware of difficulties involved in defining the genera. A revision of Eleutherodactylus and a review of Syrrhophus are nearing completion, but prior to their publication it is desirable to redefine the genera of the Mexican leptodactylids, and in so doing recognize an heretofore unnamed genus. The definitions of Eleutherodactylus and Leptodactylus may need to be altered in the future, since both are widespread in South America and occur in the West Indies. Their definitions as given here are as precise as present knowledge permits. Syrrhophus and Tomodactylus are small assemblages that occur only in southwestern United States, México, and Guatemala.

Taylor (1952) synonymized Engystomops with Eupemphix which, although related, should be regarded as generically distinct (Gallardo, 1965). Perhaps the most conservative classification is that of Myers (1962) who, without published evidence, combined Eleutherodactylus, Syrrhophus, and the South American Lithodytes in a single genus.

The major problem for students working with the Mexican leptodactylids has not been the separation of Engystomops or Leptodactylus from other genera but the separation and definition of the eleutherodactyline frogs currently placed in three genera, Eleutherodactylus, Syrrhophus, and Tomodactylus. As will be shown in this paper, these are more conveniently placed in four genera. Once a fourth genus is recognized, certain phylogenetic problems disappear and a reasonable zoogeographic interpretation is possible for Middle American leptodactylid distribution.

In México and northern Central America approximately 55 species of eleutherodactyline frogs (Eleutherodactylus, Syrrhophus, and Tomodactylus) are known. Four genera can be recognized on the basis of the nature of inguinal glands, morphology of the hands and feet, and certain osteological features.

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