An illustrated catalogue of type specimens of the bathyal brittlestar genera Ophiomusium Lyman and Ophiosphalma H. L. Clark (Echinodermata: Ophiuroidea).

Type specimens of 61 species of the bathyal ophiuriod genera Ophiomusiu m Lyman and Ophiosphalma H.L. Clark are illustrated and their main features outlined, to form a partial catalogue for current and future workers. Thirty-nine species of Ophiomusium and 22 of Ophiosphalma are recognised, based largely on the number of exposed tentacle pores on the basal ventral arm plates. Most of the Ophiosphalm a listed here are new combinations from their original genus, Ophiomusium . Ophiomusium sculptum Verrill is a junior subjective synonym of O. acuferum Lyman, and Ophiosphalma fimbriatum (Koehler) is a junior subjective synonym of O. glabrum (Lutken & Mortensen). The subspecies Ophiomusium fimbriatum atlanticum Hertz and Ophiomusium facunda muta Hertz are elevated to full species.  Because of their bathyal habitat (<4000 m), representatives of these genera are relatively rare in collections, and it will require fresh material of a range of sizes, for morphological comparison and for DNA analysis, to reliably confirm their taxonomic validity and clarify their relationships.