Monacoa

Monacoa is a genus of fish in the family Opisthoproctidae^[1] found in Atlantic and Pacific Oceans. They are also known as long-nosed mirrorbellies^[2] or mirrorbelly spookfish, in reference to the bioluminescent organ in their intestines.^{[3][unreliable source?]} The largest species, Monacoa grimaldii, can grow to 8 cm (3.1 in) standard length.^[4]

Monacoa
Monacoa grimaldii
The "sole" is useful in identifying the different Monacoa species
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Argentiniformes
Family:	Opisthoproctidae
Genus:	Monacoa Whitley, 1943
Type species
Opisthoproctus grimaldii Zugmayer, 1911

Species

Until 2016, Monacoa was thought to be a synonym of Opisthoproctus, but in 2016 the name was resurrected and it was determined that there are 3 distinct species in the genus. Monacoa griseus and Monacoa niger are distinguished from M. grimaldii due to differences in the pigmentation of their "soles". An examination of their complete mitochondrial genomes further proves the species are distinct.^[2]

There are currently 3 recognized species in this genus:^[4]

• Monacoa grimaldii (Zugmayer, 1911) (mirrorbelly) [B]
• Monacoa griseus J. Y. Poulsen, Sado, C. Hahn, Byrkjedal, Moku & Miya, 2016 (grey mirrorbelly)^[2] [C & D]
• Monacoa niger J. Y. Poulsen, Sado, C. Hahn, Byrkjedal, Moku & Miya, 2016 (black mirrorbelly)^[2] [A]