Overlooked for over a century: <i>Ophioderma occultum</i> sp. nov. (Echinodermata), a new species of brittle star from the Eastern Pacific

We describe a new species of ophiodermatid brittle star from the Eastern Pacific: <i>Ophioderma occultum</i> sp. nov. This species has been mistakenly recorded since 1899 as a colour phase of one of its congeners, <i>Ophioderma panamense</i>. However, the integrative use of morphological and molecular data, and comparison with type material of other Eastern Pacific <i>Ophioderma</i>, led to its differentiation as a novel species. <i>Ophioderma occultum</i> sp. nov. is characterised by having radial shields and adoral shields covered with granules, dorsal arm plates divided typically into two pieces, and a particular colour pattern: a dark grey to brown body, and arms with subtle lighter transverse bands and parallel longitudinal white bands over some median and distal segments. Molecular information based on the mitochondrial genes cytochrome oxidase subunit I (COI) and 16S also supported the species’ validity, coinciding with the morphological observations. In particular, the molecular marker 16S had not been used before for species delimitation in this genus and was proven here to be resolutive. In contrast to most species of <i>Ophioderma</i> from the area, <i>Ophioderma occultum</i> sp. nov. shows a restricted distribution to the northern Mexican Pacific (Gulf of California and islas Revillagigedo). This new species is the 10^th <i>Ophioderma</i> described from the Eastern Pacific and the 34^th worldwide. http://www.zoobank.org/urn:lsid:zoobank.org:pub:A5FFAC55-E5BE-42F6-8371-7B745911F157