Amazon deep South: Schubarthelphusa, a new genus to accommodate two freshwater crab species from the State of Rondônia, Brazil (Brachyura, Pseudothelphusidae)

Abstract A new genus of pseudothelphusid crab is proposed to accommodate two species from the state of Rondônia in the southern Amazon region of Brazil. The new taxon was retrieved as a separate lineage from the genus Fredius Pretzmann, 1967, based on an integrative approach using molecular phylogenetic analysis and morphological characters of the male first gonopod, as well as taking into account its geographic distribution. In terms of gonopod morphology, the new genus resembles Fredius but it is characterized by an enlarged and distinctly inflated proximal portion of the cephalic lobe, a well-developed patch of strong, corneous spines along the mesial and abdominal surfaces of the cephalic lobe, and a mesial lobe that is extremely developed on a long, narrow, sinuous or convoluted projection. The new genus has the southernmost distribution of the Pseudothelphusidae within the Amazon Basin.