本属は2種を含む。もう1種のM. danae Regan et Trewavasは東部太平洋に分布し,眼後発光器の径が眼径の25%以下であることを特徴とする。(藤井)
Distinctive characters:
(Family):Dorsal fin located far posteriorly, opposite to anal fin just before caudal fin. Skin without scales or scale-like patterns. Hyoids and lower jaw symphysis connected only by a single muscular cord; no floor of mouth. Gill teeth much reduced or completely absent. (Genus):Pectoral fin present. Suborbital luminous organ large. Pelvic insertion nearer to caudal fin base than to tip of snout. No barbel on chin. No serial photophores. (Species):Diameter of postorbital luminous organ more than 25% of that of eye.
Distribution:
Tropical to subtropical waters of three major oceans. Type locality-42°N, 50°W.
Remarks:
The genus includes 2 species. Another species, M. danae Regan et Trewavas, is known from the eastern Pacific, and characterized by having small postorbital luminous organ (its diameter less than 25% of eye diameter). (Fujii)