Morphological and molecular characterization of a new species of Fredius (Decapoda, Pseudothelphusidae) from Rondônia, southern Amazonia, Brazil

Abstract

A new species of freshwater crab of the genus Fredius Pretzmann, 1967, from the state of Rondonia, Brazil, is described, illustrated, and characterized in terms of an mtDNA sequence (16S rRNA). Fredius buritizatilis sp. nov. is distinguished from its congeners by the following characters of the male first gonopod: a mesial lobe comprising a long, narrow, spear-like projection that is recurved upward; a cephalic lobe with a distinctly inflated proximal portion with a large patch of strong, corneous spines along its mesial and caudal surfaces; and an auxiliary lobe on the caudal surface that is inflated and shorter than cephalic lobe. The mt16S rRNA sequence of Fredius buritizatilis sp. nov. establishes its systematic position in relation to other species of Fredius included in the analysis. The occurrence of several species of Pseudothelphusidae in the state of Rondonia, Brazil, as well as the relationships of Fredius buritizatilis sp. nov. to other species of the genus, suggests that the affinities of some Brazilian pseudothelphusids are not as close as their geographical proximity might suggest.