Proceratophrys boiei

Dias, Pedro Henrique Dos Santos, Carvalho-E-Silva, Ana Maria Paulino Telles De & Carvalho-E-Silva, Sergio Potsch De, 2013, Larval chondrocranium morphology of five species of Proceratophrys Miranda-Ribeiro (Amphibia; Anura; Odontophrynidae), Zootaxa 3683 (4), pp. 427-438 : 434-435

The Proceratophrys boiei taxonomy

Proceratophrys boiei is de most widely distributed species in the genus, occurring from southeastern Minas Gerais and Espírito Santo to southeastern Santa Catarina ( Frost, 2013). Prado & Pombal (2008) revised the taxonomy of this species, and did not find morphometric differences among the samples from different localities along the species distributions. However, they mentioned a tendency of decreasing of the curvature of frontoparietals crests and an increase in the prominence of the posterior portion of the same feature in specimens of Santa Catarina and Paraná states.

Prado & Pombal (2008) also noted a marked depth on the head in specimens of Rio de Janeiro. They opted not to give specific status to those populations because they found great variation in those characters along the distribution of Proceratophrys boiei .

More recently, Amaro et al. (2012) investigated the demographic history of Proceratophrys boiei using three molecular markers (RAG-1; Cytb; 16S) and chromosomal data. They found two well supported clade, which they called South clade, including specimens from the southeastern São Paulo and Santa Catarina, and North clade, including specimens from northeastern São Paulo, Rio de Janeiro, Minas Gerais and Espírito Santo.

They also found a strongly supported division of the North clade in two; the North clade 1 for the specimens from Espírito Santo and Minas Gerais, and the North clade 2 for Rio de Janeiro and São Paulo. They emphasized the need of examination of additional morphological and acoustic characters to reveal phenotypic congruence with their results (Amaro et al., 2012).

We found a significant morphological variation in the chondrocranium of the three populations of Proceratophrys boiei studied. The population of Rio de Janeiro state, represented by tadpoles collected in Teresópolis municipality, is more similar to the other species of Proceratophrys that possess palpebral appendage ( P. appendiculata , P. laticeps and P tupinamba ).

Specimens from Minas Gerais presented elongations of the taenia tecti marginales and of the tectum synoticum, originating the taenia tecti medialis and transversales. It has been shown that this might occur along the development of the chondrocranium ( Candioti et al. 2005) but it does not seem to be the case. Specimens of the same developmental stages of others populations and ontogenetic series of others species did not show such variations, leading us to conclude that it is a particularity of the specimens from Minas Gerais.

The morphology of the suprarostral cartilage also corroborates this hypothesis. The cartilaginous connection of the distal portion of the alae with the corpora was only observed in this population.

The population of Paraná state also presented unique morphology. The hipobranchial planum is reduced and ends in a rounded projection. The ceratobranchial IV is clearly more developed and the pars reuniens is expanded in midline. Our data is congruent with the pattern recovered by Amaro et al. (2012), with morphotypes representing the three clades found by them.

The genus Proceratophrys has been shown more diverse than previously thought—eleven new species were described in the last five years ( Prado & Pombal 2008; Cruz & Napoli 2010; Ávila et al. 2011; Martins & Giaretta 2011; Napoli et al. 2011; Cruz et al. 2012; Teixeira et al. 2012; Dias et al. 2013). Moreover, the geographical distributions of the species are highly vicariant ( Izecksohn et al. 1998) with few areas of sympatry among then, and it is expected that more than one taxon exist within Proceratophrys boiei .

In recent years taxonomists have employed an integrative approach in species descriptions, and distinct lines of evidences may be evoked to propose hypothesis of new species ( Padial et al. 2009, 2010; Padial & De la Riva 2010; Rosa et al. 2012). Our findings on chondrocranium morphology plus the molecular and chromosomal evidences provided by Amaro et al. (2012) lead us to propose that the populations of Minas Gerais and Paraná states might represent new evolutionary lineages and should be treated as unconfirmed candidate specie (UCS) (Vieties et al. 2009) until we finish further analyses.