A phylogenetic analysis of Pleurodema (Anura: Leptodactylidae: Leiuperinae) based on mitochondrial and nuclear gene sequences with comments on the evolution of anuran foam nests

FAIVOVICH, J.; FERRARO, D. P.; BASSO, N.G.; HADDAD, C. F. B.; TREFAUT RODRIGUES, M.; WHEELER, W.C.; LAVILLA, E.O.

CLADISTICS (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 vol. 28 p. 460 - 482

0748-3007

Species of the genus Pleurodema are relatively small, plump frogs that mostly occur in strong-seasonal and dry environments. Thegenus currently comprises 14 species distributed from Panama to southern Patagonia. Here we present a phylogenetic analysis ofPleurodema, including all described species and several outgroups. Our goals include testing its monophyly and the monophyly ofthe species groups that were historically proposed, and studying the evolution of some character systems, particularly macroglandsand egg-clutch structure; this last point also provided the chance for a discussion of foam nest evolution in anurans. Our datasetincludes portions of the mitochondrial genes cytochrome b, 12S, 16S, and the intervening tRNAVal; the nuclear gene sequencesinclude portions of rhodopsin exon 1 and seven in absentia homolog I. Our results support a clade composed of Pleurodema andincluding the monotypic Somuncuria Lynch, 1978 nested within it. The latter genus is therefore considered a junior synonym ofPleurodema and its sole species is added to this genus. Furthermore, our results indicate the non-monophyly of several speciesgroups proposed previously. We recognize four clades in Pleurodema: the P. bibroni clade (P. bibroni, P. cordobae and P. kriegi), theP. thaul clade (P. bufoninum, P. marmoratum, P. somuncurensis and P. thaul), the P. brachyops clade (P. alium, P. borellii,P. brachyops, P. cinereum, P. diplolister and P. tucumanum) and the P. nebulosum clade (P. guayapae and P. nebulosum). Ourresults further indicate the need for a taxonomic reassessment of P. borellii and P. cinereum (as did previous studies), P. guayapaeand P. nebulosum, and the three species in the P. bibroni clade. Pleurodema shows a striking pattern of variation in presence ⁄ absenceof lumbar glands. Our results indicate multiple losses or independent gains of this character associated with defensive displays. Thereproductive modes of Pleurodema include four different egg-clutch structures. The optimization of these indicates that there are atleast two independent transformations from the plesiomorphic mode of foam nests to egg-clutch structures involving gelatinousmasses of different sorts (ovoid plates, masses, or strings). We hypothesize that these independent transformations could involvechanges at the behavioural (the loss of foam beating behaviour by the parent) and ⁄ or structural level (transformations involving thepars convoluta dilata, the section of the oviduct where the foam-making substance is secreted). Finally, our study of foam nestevolution in Pleurodema is extended to the other groups of anurans where foam-nesting occurs, on the basis of available data andrecent phylogenetic hypotheses. In the different hyloid groups where it occurs, foam-nesting evolved from clutches laid in water.However, in all ranoids in which foam-nesting occurs, it evolved from terrestrial clutches, with eggs laid hanging in vegetation, or, ifthe clutches are laid on a restricted volume of water, involving endotrophic development.