Evolution in the genus Rhinella: a total evidence phylogenetic analysis of neotropical true toads (Anura: Bufonidae).

PEREYRA MARTÍN OSCAR; BLOTTO, BORIS; BALDO, DIEGO; J.C. CHAPARRO; RON SANTIAGO; ELIAS-COSTA, AGUSTÍN; IGLESIAS, PATRICIA; P. VENEGAS; THOMÉ, TEREZA; J.J. OSPINA-SARRIA; N. MACIEL; M. RADA; KOLENC, FRANCISCO; BORTEIRO, CLAUDIO; M. RIVERA-CORREA; F. ROJAS-RUNJAIC; J. MORAVEC; I. DE LA RIVA; W.C. WHEELER; S. CASTROVIEJO; T. GRANT; C.F.B. HADDAD; J. FAIVOVICH

BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY

AMER MUSEUM NATURAL HISTORY

Lugar: New York; Año: 2021 vol. 447 p. 1 - 156

0003-0090

ABSTRACTTrue toads of the genus Rhinella are among the most common and diverse group of neotropical anurans. These anurans are widely distributed throughout South America, inhabiting a great diversity of environments and ecoregions. The genus was defined based on molecular characters and lacks a proper diagnosis. Some phenetic species group also were traditionally recognized within Rhinella. Nevertheless, the monophyly of some of them was rejected in previous phylogenetic analyses, and many species remain unassigned to any of them due the poor definition of these groups. In addition, the identity and taxonomy of several species are problematic, and hinder the specific recognition and description of some putative undescribed taxa. In this work, we first perform phylogenetic analyses of separate mitochondrial and nuclear datasets to test the occurrence of hybridization and/or genetic introgression in the group. The comparative analysis of both datasets revealed unidirectional mitochondrial introgressions of (a) an unknown parental species into R. horribilis (?ghost introgression?), and (b) R. dorbignyi into R. bernardoi. According to these results, the mitochondrial and nuclear datasets of these species were considered separately in subsequent analyses. Subsequently, we performed total evidence analyses of Rhinella. These analyses included the revised molecular (four mitochondrial and five nuclear genes) and a phenotypic (86 characters) datasets for 83 nominal species of Rhinella (plus several undescribed and problematic species) from multiple localities and several outgroups. In the total evidence analyses, Rhinella was recovered as non-monophyletic due to the position of R. ceratophrys that is the sister taxon of Rhaebo nasicus with strong support. Among outgroups, the strongly supported Anaxyrus + Incilius is the sister clade of all the other species of Rhinella. The genus Rhinella (excluding R. ceratophrys) is monophyletic, well supported, and composed of two major clades. One of these is moderately supported and composed of the species of the former R. spinulosa group (including R. gallardoi), those of the monophyletic R. granulosa, R. crucifer, and R. marina groups, and a clade composed of the mitochondrial sequences of R. horribilis. The other major clade is strongly supported and composed of all the species from the non-monophyletic R. veraguensis and R. margaritifera groups, the former R. acrolopha group, and R. sternosignata. According to these results, we defined eight species groups of Rhinella that are mostly diagnosed by phenotypic synapomorphies in addition to a combination of morphological character states. Rhinella sternosignata is the only species that remains unassigned to any group. We also evaluate the taxonomic status of several taxa according to the total evidence analyses: (a) nine species are synonymized, (b) three subspecies are considered valid species, and (c) 15 lineages are considered to represent putative undescribed species.Finally, we also discuss some relevant points on the knowledge of Rhinella: (a) the frequent occurrence of hybridization, deep mitochondrial divergence, and ?ghost introgression?; (b) the fragmented phenotypic evidence known for Rhinella, including putative character systems that could be used for future phylogenetic analyses of the group; and (c) the known fossil record of Rhinella and its validity as calibration points in divergence dating analyses.