The Glass Frog

glass-frogGlass frog (or Glassfrogs) is the common name for the frogs of the amphibian family Centrolenidae (order Anura). While the general background coloration of most glass frogs is primarily lime green, the abdominal skin of some members of this family is translucent. The internal viscera, including the heart, liver, and gastrointestinal tract are visible through this translucent skin, hence the common name.

The first described species of Centrolenidae was the “giant” Centrolene geckoideum, named by Marcos Jiménez de la Espada in 1872, based on a specimen collected in northeastern Ecuador. Several species were described in subsequent years by different herpetologists (including G. A. Boulenger, G. K. Noble, and E. H. Taylor) but usually placed together with the tree frogs in the genera Hylella or Hyla.

The family Centrolenidae was proposed by Edward H. Taylor in 1951. Between the 1950s and 1970s, most species of glass frogs were known from Central America, particularly from Costa Rica and Panama, where E. H. Taylor and Jay M. Savage extensively worked, and just a few species were known to occur in South America. In 1973, John D. Lynch and William E. Duellman, published a large revision of the glass frogs from Ecuador showing that the species richness of Centrolenidae was particularly concentrated in the Andes. Later contributions by authors like Juan Rivero, Jay Savage, William Duellman, John D. Lynch, Pedro Ruiz-Carranza and José Ayarzagüena increased the number of described taxa especially from Central America, Venezuela, Colombia, Ecuador, and Peru.

The evolutionary relationships, biogeography, and character evolution of centrolenids were discussed by Guayasamin et al. (2008). Glass frogs originated in South America and dispersed multiple times into Central America. Character evolution seems to be complex, with multiple gains and/or losses of humeral spines, reduced hand webbing, and complete ventral transparency.

The taxonomical classification of the glass frogs has been problematic. In 1991, after a major revision of the species and taxonomic characters, the herpetologists Pedro Ruiz-Carranza and John D. Lynch published a proposal for a taxonomic classification of the Centrolenidae based on cladistic principles and defining monophyletic groups. That paper was the first of a series of contributions dealing with the glass frogs from Colombia that lead them to described almost 50 species of glass frogs. The genus Centrolene was proposed to include the species with a humeral spine in adult males, and the genus Hyalinobatrachium to include the species with a bulbous liver. However, there was an heterogeneous group of species that they left in the genus Cochranella, defined just by lacking a humeral spine and a bulbous liver. Since the publication of the extensive revision of the Colombian glass frogs, several other publications have dealt with the glass frogs from Venezuela, Costa Rica, and Ecuador. Via Glass frog

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