Geographical and Ecological Notes on Cisandine to Platine Frogs

From the point of view of the frog fauna, the great Eastern or Cisandine to Platine Subregion of South America, west of the Andes and north of Bahia Blanca, can be divided into 4 provinces. They correspond roughly to the 4 divisions proposed by Humboldt and by Martius (1840-1849): Hylaea (Naiiades), Continental Province (Oreades and Hamadryades), Platine-Cisplatine Province (Napeae) and Atlantic Province (Dryades). The Northern Hylaea and its known frogs are rather homogenous. The Continental Province can be subdivided into a Chaquean, a Northeastern and a Planaltine Subprovince. The Cisplatine-Platine Province whose southern limits are vague may be divided into Oriental and Mesopotamic Subprovinces. The Atlantic Province stretches along the southeastern and eastern coast. It comprises 4 life-zones: maritime scrub (Restinga), coastal lowlands (Baixada), montane rain-forest and alpine meadows (Hochstaudenwiesen). A fifth disjointed province might be formed by grouping together the different continental orographic systems, such as the Maritime Escarpment of Brazil and the inland parallel sierras, the mountains that separate the Brazilian shield from that of the Guianas, the ranges between Brazil and Venezuela and even the Andes. The Cisandine to Platine frog fauna is only partly generalized. It presents osteological specializations that seem like a reversal of evolution; it also shows caenogenetic innovations that give the impression of frustrated attempts to attain the direct development of the higher classes of vertebrates.