DOI: 10.3897/asp.83.e153079

Authors: Edvanda A. Souza-Carvalho, Célio Magalhães, Fabrício L. Carvalho, Fernando L. Mantelatto

Abstract: Abstract The generic system of the Neotropical crabs of the subfamily Trichodactylinae H. Milne Edwards, 1853 has remained quite stable over the last 30 years, but the recognition or not of the genus Mikrotrichodactylus Pretzmann, 1968 has been a matter of debate: erected as a subgenus, it was treated with generic status in Rodríguez’ classificatory system but some subsequent works considered it a junior synonym of Trichodactylus Latreille, 1828. Based on this scenario, an integrative analysis based on molecular (using two mitochondrial, 16S rRNA and COI, and one nuclear, Histone 3, genes) and morphological (using diagnostic characters traditionally used on the identification of the family) data was performed in order to clarify the phylogenetic position of the genera within Trichodactylinae. The inferred phylogeny recovered three great lineages within Trichodactylinae with high support values in both Bayesian Inference and Maximum Likelihood phylogenetic analyses, corroborated the non-monophyletic status of Trichodactylus, and confirmed the full generic status of Mikrotrichodactylus. A taxonomic rearrangement of Trichodactylinae is proposed but the positioning of “Trichodactylus” quinquedentatus Rathbun, 1893 remains doubtful and was treated herein as a taxon inquirendum et incertae sedis. This taxon seems to be closer related to Rodriguezia Bott, 1969, and Avotrichodactylus Pretzmann, 1968; however, more data are needed before additional taxonomic adjustments concerning its positioning within the subfamily is proposed. In the current proposal, Trichodactylus is composed by four species, Mikrotrichodactylus by six species, Avotrichodactylus and Rodriguezia by three each, in addition to “Trichodactylus” quinquedentatus.

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DOI: 10.3897/asp.82.e115268

Authors: Nielson Felix Caetano França, Célio Magalhães, Fernando Luis Mantelatto

Abstract: The taxonomic status of the freshwater crab Dilocarcinus septemdentatus (Herbst, 1783) is still not well established. Currently, the main issue involves synonymization with D. spinifer H. Milne Edwards, 1853, based on a variation of the angulation of the gonopod apex. These species are distributed along rivers and lakes in northern South America, with disjunct occurrences in central-west Brazil and Argentina. Due to these inconsistencies, an integrative approach was performed to elucidate these questions, with morphological (including NanoCT-Scan) and molecular analysis (Maximum Likelihood Trees, Bayesian Inference, Genetics Distance Matrix, and Haplotype Network), based on mitochondrial markers COI and 16S rRNA. Both analysis revealed and supported the existence of a species complex under the name of D. septemdentatus. Based on the results obtained, we propose the revalidation of D. spinifer, the description of a new species, and the redescription of D. septemdentatus s. str., with a neotype designation for this species. The hypothesis that this species complex originated in the Pebas System, an extensive mega wetland system that existed along the lowlands of Western Amazonia from late Oligocene to late Miocene (c. 23–11 mya) is discussed.

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