Centrolenidae, Taylor, 1951

Guayasamin, Juan M., Castroviejo-Fisher, Santiago, Trueb, Linda, Ayarzagüena, José, Rada, Marco & Vilà, Carles, 2009, Figure 6 In A New Species Of Noblella (Amphibia: Strabomantidae) From The Western Slopes Of The Andes Of Ecuador, Zootaxa 2100, pp. 1-97 : 7-9

Centrolenidae , its monophyly and relationships with other anurans

Jiménez de la Espada (1872) described the first genus and species of Glassfrog, Centrolene geckoideum , and placed it the family Polypedatidae (now a synonym of Rhacophoridae ). It was not until the work of Taylor (1951) that the family Centrolenidae was proposed and defined mainly by the fusion of the tibiale (astragalus) and fibulare (calcaneum). Since then, the monophyly of Centrolenidae (sensu Taylor 1951) has not been questioned. Characters shared by all Glassfrogs include a dilated medial process on Metacarpal III ( Hayes & Starrett 1980), T- shaped terminal phalanges ( Taylor 1951), intercalary element between distal and penultimate phalanges ( Taylor 1951), complete or partial fusion of tibiale and fibulare ( Taylor 1951; Sanchiz & De la Riva 1993), eggs deposited out of water ( Ruiz-Carranza & Lynch 1991a), and ventral parietal peritoneum partially or completely transparent ( Fig. 1 ). Additional derived characters may include myological ( Burton 1998, 2004; da Silva 1998; Señaris & Ayarzagüena 2005), osteological ( Guayasamin & Trueb 2007), chromatic ( Schwalm & McNulty 1980), and larval traits ( Haas 2003); however, their relevance remains to be tested at a general scale.

Molecular phylogenies have supported the view of centrolenids as a natural group. Several independent studies based on different datasets and methods have shown high levels of congruence at retrieving a monophyletic Centrolenidae (e.g., Darst & Cannatella 2004; Faivovich et al. 2005; Wiens et al. 2005; Frost et al. 2006; Grant et al. 2006; Guayasamin et al. 2008a). The relationship of Glassfrogs with other anurans, however, has remained controversial. After Jiménez de la Espada (1872) considered that Centrolene geckoideum was related to Rhacophorus , and Taylor (1951) suggested a close affinity with Heleophryninae, most researchers associated centrolenids with Hylidae and Pseudidae based on the presence of intercalary elements (Lynch 1973; Ford & Cannatella 1993; Rueda-Almonacid 1994; Duellman & Trueb 1994). Using larval morphology, Haas (2003) suggested Centrolenidae as sister group of Neobatrachia except Limnodynastes . In a molecular study, Darst and Cannatella (2004) explicitly rejected a Centrolenidae + Hylidae + Pseudidae clade, and presented evidence supporting a Centrolenidae + Leptodactylidae clade (see also Roelants et al. 2007). Contrary to the latter hypothesis, Biju and Bossuyt (2003) and Heinicke et al. (2007) suggested Centrolenidae to be the sister taxon of Bufonidae + Dendrobatidae , although with low support.

Several studies have inferred a close affinity between Centrolenidae and Allophryne ruthveni , a hypothesis first suggested by Noble (1931). Morphological ( Duellman 2001; Burton 2004; Wiens et al. 2005) and molecular ( Austin et al. 2002; Faivovich et al. 2005; Wiens et al. 2005; Frost et al. 2006; Grant et al. 2006; Guayasamin et al. 2008a) studies have corroborated Allophrynidae as the sister taxon of Centrolenidae . This probably led Frost et al. (2006) to propose that the family Centrolenidae should contain the subfamilies Allophryninae and Centroleninae . This classification was followed in some works (e.g., Cisneros-Heredia & McDiarmid 2006 a, 2007; Castroviejo-Fisher et al. 2007b), but Guayasamin and Trueb (2007) stated that the proposal led to unnecessary taxonomic instability, an argument that we expand herein (Results and Discussion).

Phylogenetic studies that include in their sampling Allophryne and Centrolenidae show total congruence in placing Allophryne as the sister taxon of Glassfrogs ( Austin et al. 2002; Faivovich et al. 2005; Wiens et al. 2005; Frost et al. 2006; Grant et al. 2006; Guayasamin et al. 2008a), but moderate congruence about the placement of this clade with respect to other anurans ( Frost et al. 2006; Grant et al. 2006; Guayasamin et al. 2008a). Given that each study has intrinsic limitations (e.g., criteria for phylogenetic inference, taxon and gene sampling), it is difficult to evaluate the significance of the different results. Nonetheless, we have enough information to conclude that the close evolutionary relationship between Allophryne ruthveni and Centrolenidae is real, whereas the relationship of this clade with other frogs remains uncertain ( Fig. 4 ).

Figures

FIGURE 1. Synapomorphies of Centrolenidae. (A) Partial (Nymphargus posadae, QCAZ 25090) and complete ventral transparency (Hyalinobatrachium aureoguttatum, QCAZ 32070). (B) Partial (N. wileyi, QCAZ 26029) and complete fusion between tibiale and fibulare (H. munozorum, KU 155497). (C) Medial process on Metacarpal III and intercalary element (Teratohyla spinosa, KU 32935). The presence of T or Y-shaped terminal phalanges is a synapomorphy of Allocentroleniae (Allophrynidae + Centrolenidae). Photos in (A) by M. Bustamante.

FIGURE 4. Schematic trees summarizing relationships between Centrolenidae and other anurans (Guayasamin et al., 2008a). Note that the Allophryne + Centrolenidae clade is recovered consistently. Circles indicate significant support values for clades recovered by Bayesian (BA, posterior probability ≥ 0.95), maximum likelihood (ML, bootstrap ≥ 70%), and maximum parsimony (MP, bootstrap ≥ 70%) analyses.