gracilis, Melanonus Günther [A.] 1878:19 [3] [Annals and Magazine of Natural History (Series 5) v. 2 (nos 7/8/9)(art. 2/22/28); ref. 2010] Antarctic Ocean, 62°26'S, 95°44'W, Challenger station 152, depth 1975 fathoms. Holotype (unique): BMNH 1887.12.7.22. On page 3 of separate. See also Günther 1887:84, Pl. 14 (fig. B) [ref. 2013]. Henriques et al. 2001:43 [ref. 25317] suggest that there may be only one species in the family. •Valid as Melanonus gracilis Günther 1878 -- (Cohen 1986:329 [ref. 5646], Paxton et al. 1989:304 [ref. 12442], Pequeño 1989:45 [ref. 14125], Paulin et al. 1989:120 [ref. 24556], Cohen 1990:540 [ref. 15766], Chiu & Markle 1990:188 [ref. 21686], Cohen in Cohen et al. 1990:318 [ref. 18936], Miller 1993:561 [ref. 21297], Gomon et al. 1994:337 [ref. 22532], Trunov 1999:463 [ref. 24579], Henriques et al. 2001:43 [ref. 25317], Duhamel et al. 2005:274 [ref. 32059], Paxton et al. 2006:618 [ref. 28995], Gomon 2008:349 [ref. 30616], Struthers 2015:868 [ref. 34261], Iwamoto & Cohen 2016:2006 [ref. 34586], Sutton et al. 2020:230 [ref. 37832]). Current status: Valid as Melanonus gracilis Günther 1878. Melanonidae. Distribution: Southern circumglobal. Habitat: marine.