Glass frog

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Glass Frogs
Hyalinobatrachium ruedai
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Suborder: Neobatrachia
Family: Centrolenidae
Taylor, 1951
Distribution of Centrolenidae (in black)
Distribution of Centrolenidae (in black)
Genera

Centrolene
 Cochranella
 Hyalinobatrachium
 Nymphargus

Glass frog (or Glassfrogs) is the common/popular name for the frogs of the amphibian family Centrolenidae (order Anura). While the general background coloration of most glassfrogs is primarily lime green; the ventral skin of some members of this family is transparent (species of the genus Hyalinobatrachium). The internal viscera, including the heart, liver, and digestive tract can be seen due to the translucency of the ventral skin. This particular characteristic is the origin of their common name (Glass Frogs or Glassfrogs).

Contents

[edit] Historical Account of Taxonomy

The first described species of Centrolenidae was the "giant" Centrolene geckoideum, named by the notable scientist 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 treefrogs in the genera Hylella or Hyla.

The family Centrolenidae was proposed by Edward H. Taylor in 1951. Between the 50s and 70s, most species of Glassfrogs 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 where know to occur in South America. In 1973, John D. Lynch and William E. Duellman, published a large revision of the Glassfrogs 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 taxonomical classification of the Glassfrogs was problematic during those years. Although four genera had been described for Centrolenidae (Centrolene, Centrolenella, Cochranella, Teratohyla), the taxonomical arrangements were always incomplete, and not valid for all species. In 1991, after a major revision of the species and taxonomic characters, the herpetologists Pedro Ruiz-Carranza and John D. Lynch published a new proposal for a taxonomic classification of the Centrolenidae based on cladistic principles and defining monophyletic groups [1]. That paper was the first of a series of contributions dealing with the Glassfrogs from Colombia that lead them to described almost 50 species of Glassfrogs. 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[1]. 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[1]. Since the publication of the extensive revision of the Colombian Glassfrogs, several other publications have dealt with the Glassfrogs from Venezuela, Costa Rica, and Ecuador.

Recent molecular studies [2] have found that the three genera of Glassfrogs are non-monophyletic units, although taxon sampling was limited. The genus Centrolene is paraphyletic towards the genus Cochranella, and some species of Hyalinobatrachium were apparently more related to Cochranella. Furthermore, they included the genus Allophryne in the family Centrolenidae, dividing the family into two subfamilies: (1) the subfamily Allophryninae for the genus Allophryne, and (2) the subfamily Centroleninae for the genera Centrolene, Cochranella, and Hyalinobatrachium. A reanalysis of morphological traits suggested a polyphyletic Centrolene and Cochranella, and supported the monophyly of the Hyalinobatrachium fleischmanni group [3] Other studies have addressed the same problem; e.g., in 2006 a scientific paper describing a new species of Centrolene from Ecuador [4] removed the species "pulveratum" and "antisthenesi" from Hyalinobatrachium and placed them inside the genus Cochranella as Cochranella pulverata and Cochranella antisthenesi. Although these changes kept Cochranella paraphyletic, they "clean" Hyalinobatrachium in order to define a monophyletic group. A recent review of the family [5] has recognized a new genus, Nymphargus, for the species with basal webbing among outer fingers (part of the previous ocellata species group). In that review, all species-groups were found to be non-monophyletic, and it was suggested that they should not be used anymore until a phylogenetic hypothesis for the entire family is available.

[edit] Taxonomic classification

The family Centrolenidae is a clade of anurans. Previously, the family Centrolenidae was considered closely related to the family Hylidae (tree frog); however, recent phylogenetic studies[2] have placed the Centrolenidae (and its sister taxon the family Allophrynidae) closer to the family Leptodactylidae.

The monophyly of Centrolenidae (excluding Allophryne) is supported by morphological and behavioral characters including[2] [4]: (1) presence of a dilated process on the medial side of the third metacarpal (an apparently unique synapomorphy); (2) ventral origin of the musculus flexor teres digiti III relative to the musculus transversi metacarpi I; (3) terminal phalanges T-shaped; (4) exotroph, lotic, burrower/fossorial tadpoles with a vermiform body and dorsal C-shaped eyes, that live buried within leaf packs in still or flowing water systems; (5) eggs clutches deposited outside of water on vegetation or rocks above still or flowing water systems. Several molecular synapomorphies also support the monophyly of the clade [2].

The taxonomic classification of Centrolenidae is still controversial, but currently five genera of Glassfrogs are recognized:


[edit] Subfamily Allophryninae




[edit] Subfamily Centroleninae

Centrolene prosoblepon Centrolene prosoblepon from Ecuador

Cochranella cf. albomaculata Cochranella cf. albomaculata from Costa Rica

Hyalinobatrachium ruedai Hyalinobatrachium ruedai from Ecuador

Nymphargus truebae Nymphargus truebae from Peru


Eleutherodactylus, note the form of the head and the snout, and the position of the eyes.
Eleutherodactylus, note the form of the head and the snout, and the position of the eyes.

[edit] Diagnosis from other anurans

The Glassfrogs occur only in the continent of America (see below Distribution), across the Neotropical region. They can be confused just with the greencolor members of the genus Eleutherodactylus or with Treefrogs of the family Hylidae.

However, hylids or Treefrogs have usually the eyes laterally directed whilst the Glassfrogs have them forward directed. Some species of green Treefrogs (especially juveniles) like Hyloscirtus palmeri and Hypsiboas pellucens have the ventral skin transparent but also have calcars on the heels, a character not present in any species of the family Centrolenidae.

Eleutherodactylus have the eyes laterally directed, the toes without membrane, and the snout is usually subovoid or subacuminate in dorsal view and the head is longer than wider.

[edit] Distribution

Centrolenidae is a diverse clade of anurans distributed in the continent of America, from southern Mexico to Panama, and through the Andes from Venezuela to Bolivia, with some species in the Amazonas and Orinoco River basins, the Guiana Shield region, southeastern Brazil, and northern Argentina.

[edit] Biology and Natural History

Members of the family Centrolenidae are mostly arboreal frogs that live along rivers and streams (during the breeding season), and are particularly diverse in montane cloud forests of South America, although some species occur also in Amazonian and Chocoan rainforest and semi-deciduous forests. The eggs are usually deposited on leaves of tree or shrubs hanging over the running water of mountain streams, creeks, and small rivers, or over stones close to waterfalls. The method of egg-laying on the leaf is species-specific. The males usually call from leaves close to their egg clutches. The eggs are much less vulnerable to predators than those laid within water, however there is a large risk of parasitism caused by a fly laying its larvae into the egg, so some species show parental care. After they hatch, the tadpoles fall into the waters below. The tadpoles are elongate, with powerful tails and low fins, suited for fast flowing water. During the non-breeding season some species live in the canopy.

[edit] References

  1. ^ a b c Ruíz-Carranza, P.M. and J. D. Lynch. 1991. Ranas Centrolenidae de Colombia I: propuesta de una nueva clasificación genérica. Lozania, 57, 1–30.
  2. ^ a b c d Frost D.R., Grant, T., Faivovich, J., Bain, R.H., Haas, A., Haddad, C.F.B., de Sa, R.O., Channing, A., Wilkinson, M., Donnellan, S.C., Raxworthy, C.J., Campbell, J.A., Blotto, B.L., Moler, P., Drewes, R.C., Nussbaum, R.A., Lynch, J.D., Green, D.M. & Wheeler, W.C. (2006) The Amphibian Tree of Life. Bulletin of the American Museum of Natural History, 297, 1–370. (PDF available by clicking here)
  3. ^ Guayasamin, J. M., M. R. Bustamante, D. Almeida-Reinoso, and W. C. Funk. 2006. Glass frogs (Centrolenidae) of Yanayacu Biological Station, Ecuador, with the description of a new species and comments on centrolenid systematics. Zoological Journal of the Linnean Society 147:489–513.
  4. ^ a b Cisneros-Heredia, D.F. & McDiarmid, R.W. (2006). A new species of the genus Centrolene (Amphibia: Anura: Centrolenidae) from Ecuador with comments on the taxonomy and biogeography of Glassfrogs. Zootaxa 1244: 1-32 - Description of Centrolene mariaelenae. (PDF of the abstract available by clicking here)
  5. ^ Cisneros-Heredia, D.F. and R.W. McDiarmid. 2007. Revision of the characters of Centrolenidae (Amphibia: Anura: Athesphatanura), with comments on its taxonomy and the description of new taxa of glassfrogs. Zootaxa 1572: 1-82. PDF Available by clicking here


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[edit] Accounts for Glass frogs in other languages

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Chordata – Amphibia – Families of Anura
White-lipped Tree Frog