Genus Abyssophthalmus Schweitzer & Feldmann, 2009

TYPE SPECIES. — Prosopon spinosum Meyer, 1842, by original designation of Schweitzer & Feldmann (2009).

DIAGNOSIS (by Schweitzer et al. 2018). — Rostrum long, straight sided, extending well beyond augenrests; augenrests deep, directed forward, bounded by intra-, outer-, and subaugenrest spines, sometimes possessing inner-augenrest spine; outer-augenrest spine long, prominent, directed forward or anterolaterally; cervical and branchiocardiac grooves well developed; postcervical groove composed of two discrete segments, nearly continuous, extending laterally and crossing axis to bound anterior margin of cardiac region, postcervical groove may be indistinct and poorly developed; lateral margins parallel sided, position of maximum width variable; subhepatic region well developed, situated below orbit.