Description of a new moray eel (Anguilliformes: Muraenidae) from the Philippines, with a preliminary assessment of genetic and morphological variations of the Uropterygius concolor species complex.

Uropterygius concolor Rüppell, the type species of the genus Uropterygius, is a small, uniformly brown moray considered to be widely distributed in the Indo-Pacific region. However, a recent study indicated that the real U. concolor is currently known only from the type locality in the Red Sea, and species recorded outside that of the Red Sea may represent a species complex that comprises several species. In this study, we assess the genetic and morphological variations of this species complex based on available data. Analyses of cytochrome c oxidase subunit I sequences revealed at least six distinct genetic lineages recognized under "U. concolor". After carefully comparing the morphologies, one of the lineages is described herein as a new species, Uropterygius mactanensis sp. nov., based on 21 specimens collected from Mactan Island, Cebu, Philippines. Another distinct lineage is considered to be a possible undescribed species based on diagnostic morphological characters. Although the taxonomic status of junior synonyms of U. concolor and some lineages still remain unresolved, this study provides informative morphological characters (i.e., tail length, trunk length, vertebrae number, and arrangement of teeth) that can be used in future studies on this species complex.