Molecular operational taxonomic units reveal restricted geographic ranges and regional endemism in the Indo‐Pacific octocoral family Xeniidae

Aim: To quantify taxon diversity, biogeographic distributions and patterns of community assembly in xeniid octocorals using molecular operational taxonomic units (MOTUs). Location Red Sea, Indian and western Pacific Oceans. Taxon Xeniidae, a family of reef-dwelling octocorals (Anthozoa, Octocorallia). Methods Xeniids collected at 13 locations were sequenced at three barcode loci, and assigned to molecular operational taxonomic units (MOTUs) defined by minimum genetic distance thresholds. Taxon richness (no. of MOTUs) and endemicity (percent of MOTUs found at a single location) were quantified. Patterns of β-diversity (species turnover) and phylogenetic β-diversity (lineage turnover) among geographical regions were visualized using hierarchical clustering, NMDS plots, and distance-decay relationships. Community assembly was investigated by comparing the mean pairwise distance (MPD) and mean nearest taxon distance (MNTD) separating species in each assemblage to values generated for null c...