Hawaiian black coral (Antipatharia) complete mitochondrial genomes have limited phylogenetic signal for taxonomic resolution of species

Most inferences about black coral (Antipatharia) phylogenetics have relied on a handful of molecular markers from PCR-Sanger methods but recently complete mitogenomes are shedding additional light on relationships. We present the most complete survey of shallow-water to mesophotic Hawaiian black corals ('ēkaha kū moana) to date based on complete mitogenome sequences. The phylogenetic relationships inferred from whole-mitochondrial phylogenies recover Myriopathidae as monophyletic with <i>Myriopathes</i> and <i>Tanacetipathes</i> as the outgroups to all other Hawaiian black coral taxa. Combining our data with other published mitochondrial datasets for black corals, we find that morphologically similar <i>Cirrhipathes</i> cf. <i>anguina</i> specimens are divergent and may not be conspecifics. Likewise, the genera <i>Antipathes</i> and <i>Stichopathes</i> (family Antipathidae) include species that are more divergent from one another than they are to other genera in family Aphanipathidae. Overall, data show Myriopathidae is a monophyletic family, but the families Aphanipathidae and Antipathidae are polyphyletic, and the genera <i>Antipathes</i> and <i>Stichopathes</i> live up to their reputation as a "taxonomic dumping ground". These phylogenetic analyses underscore the need for continued research to understand the evolutionary history and phylogenetic relationships for black corals generally and 'ēkaha kū moana specifically.