Hybridization events are not uncommon in marine environments where physical barriers are attenuated. Studies of coral reef taxa have suggested that hybridization predominantly occurs between parapatric species distributed along biogeographic suture zones. By contrast, little is known about the extent of sympatric hybridization on coral reefs, despite the large amount of biogeographic overlap shared by many coral reef species. Here, we investigate if the propensity for hybridization along suture zones represents a general phenomenon among coral reef fishes, by focusing on the marine angelfishes (family Pomacanthidae). Although hybridization has been reported for this family, it has not been thoroughly surveyed, with more recent hybridization studies focusing instead on closely related species from a population genetics perspective. We provide a comprehensive survey of hybridization among the Pomacanthidae, characterize the upper limits of genetic divergences between hybridizing species and investigate the occurrence of sympatric hybridization within this group. We report the occurrence of hybridization involving 42 species (48% of the family) from all but one genus of the Pomacanthidae. Our results indicate that the marine angelfishes are among the groups of coral reef fishes with the highest incidences of hybridization, not only between sympatric species, but also between deeply divergent lineages.

The fairy wrasses (genus Cirrhilabrus) are among the most successful of the extant wrasse lineages (Teleostei: Labridae), with their 61 species accounting for nearly 10% of the family. Although species complexes within the genus have been diagnosed on the basis of coloration patterns and synapomorphies, attempts to resolve evolutionary relationships among these groups using molecular and morphological data have largely been unsuccessful. Here we use a phylogenomic approach with a data set comprising 991 ultraconserved elements (UCEs) and mitochondrial COI to uncover the evolutionary history and patterns of temporal and spatial diversification of the fairy wrasses. Our analyses of phylogenetic signal suggest that most gene-tree incongruence is caused by estimation error, leading to poor resolution in a summary-coalescent analysis of the data. In contrast, analyses of concatenated sequences are able to resolve the major relationships of Cirrhilabrus. We determine the placements of species that were previously regarded as incertae sedis and find evidence for the nesting of Conniella, an unusual, monotypic genus, within Cirrhilabrus. Our relaxed-clock dating analysis indicates that the major divergences within the genus occurred around the Miocene-Pliocene boundary, followed by extensive cladogenesis of species complexes in the Pliocene-Pleistocene. Biogeographic reconstruction suggests that the fairy wrasses emerged within the Coral Triangle, with episodic fluctuations of sea levels during glacial cycles coinciding with shallow divergence events but providing few opportunities for more widespread dispersal. Our study demonstrates both the resolving power and limitations of UCEs across shallow timescales where there is substantial estimation error in individual gene trees.

Plectranthias takasei is described from two specimens collected in Izu Oceanic Park, Sagami Bay, Honshu, Japan. It is distinguished from congeners in having the following combination of characters: dorsal rays X,15; no fleshy flaps on dorsal-fin spines; pectoral rays 13, all unbranched; branched caudal-fin rays 8 + 7; lateral line scales 28 (including intermittent and terminal pitted scales); circumpeduncular scales 12; fourth dorsal-fin spine longest; and preopercle without antrorse spines or serrations ventrally, with 2-3 weak serrations or crenulations posteriorly.