Molecular and morphological support for a new species of the <i>Paguristes tortugae</i> Schmitt, 1933 complex (Decapoda: Anomura: Diogenidae) from Brazil

Abstract A phylogenetic analysis (12S rRNA and 16S rRNA) revealed that individuals previously identified as Paguristes tortugae cluster into several western Atlantic lineages, one containing a definable group from Brazil and others largely comprised of specimens from Central and North America. Our molecular-based phylogeny, the first to include sequence data for the holotype of P. tortugae, revealed the compared Brazilian population to represent a new species, here described as Paguristes brazuca sp. nov. It is one of four presently described species in which the eyestalk in life is known to bear a distinctive band of dark brown or maroon, variably bracketed distally and proximally by irregular bands of white. While definitive morphological characters to support the molecular distinction are presently lacking, subtle differences in the dark peduncular band appear to separate the new species from P. tortugae. We also provided an identification key for species commonly considered to comprise the Paguristes tortugae complex.