Diversity and Molecular Phylogeny of Pagurid Hermit Crabs (Anomura: Paguridae: <i>Pagurus</i>)

Species of the genus Pagurus have diversified into a wide variety of marine habitats across the world. Despite their worldwide abundance, the genus diversity and biogeographical relationship are relatively less understood at species-level. We evaluated the phylogenetic relationship and genetic diversity among the Pagurus species based on publicly available mitochondrial and nuclear markers. While independent analyses of different markers allowed for larger coverage of taxa and produced largely consistent results, the concatenation of 16S and COI partial sequences led to higher confidence in the phylogenetic relationships. Our analyses established several monophyletic species clusters, substantially corresponding to the previously established morphology-based species groups. The comprehensive species inclusion in the molecular phylogeny resolved the taxonomic position of a number of recently described species that had not been assigned to any morpho-group. In mitochondrial markers-based phylogenies, the “Provenzanoi” group was identified as the basal lineage of Pagurus. The divergence time estimation of the major groups of Pagurus revealed that the Pacific species originated and diversified from the Atlantic lineages around 25–51 MYA. The molecular results suggested a higher inter-regional species diversity and complex phylogenetic relationships within the diverse and heterogeneous members of the genus Pagurus. The study presents a comprehensive snapshot of the diversity of pagurid hermit crabs across multiple geographic regions