Comparative morphology of pond, stream and phytotelm-dwelling tadpoles of the South American Redbelly Toads (Anura: Bufonidae: Melanophryniscus)

We present a comprehensive review of larval morphology in the Neotropical toad genus Melanophryniscus. The taxa studied included 23 species with representatives of recognized phenetic groups and different larval ecomorphological guilds: pond, stream, and phytotelm-dwelling tadpoles. Their external morphology variation is congruent with current phenetic arrangement based on adult features, but also reflects the habitat where larvae develop. Lotic tadpoles (i.e. M.tumifrons group and M.krauczuki) in general exhibit a more depressed body, a longer tail with lower fins, and larger oral discs than lentic forms (i.e. M.stelzneri group, M.moreirae, M.sanmartini, and M.langonei). Despite their peculiar, confined microhabitat, phytotelm larvae do not diverge markedly from non-arboreal species. The distinctive features of all species are the presence of a pineal end organ and the placement of the intestinal reversal point at the left of the abdomen in typical larval stages. The buccal cavity and musculoskeletal anatomy are quite conserved between species, yet some characteristics differ from those of other bufonids. The presence of one pair of subhyoid muscles is apparently an exclusive trait of Melanophryniscus among Bufonidae.Fil: Baldo, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Vera Candioti, María Florencia. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Haad, María Belén. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kolenc, Francisco. Museo Nacional de Historia Natural; UruguayFil: Borteiro, Claudio. Museo Nacional de Historia Natural; UruguayFil: Pereyra, Martín Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Zank, Caroline. No especifíca;Fil: Colombo, Patrick. Universidade Federal do Rio Grande do Norte; BrasilFil: Bornschein, Marcos R.. Universidade Federal do Paraná; BrasilFil: Netto Sisa, Flavia. Instituto de Investigación Biológica del Paraguay; ParaguayFil: Brusquetti, Francisco. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Conte, Carlos E.. Universidade Federal do Paraná; BrasilFil: Nogueira Costa, Paulo. Universidade Federal do Rio de Janeiro; BrasilFil: Almeida Santos, Patricia. Universidade Federal do Rio de Janeiro; BrasilFil: Pie, Marcio R.. Universidade Federal do Paraná; Brasi