Yssichromis sp. nov. "argens" is an undescribed species of ray-finned fish in the family Cichlidae that was endemic to Lake Victoria

Lake Victoria

Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake....

, but now is extinct in the wild

Extinct in the Wild

Extinct in the Wild is a conservation status assigned to species or lower taxa, the only known living members of which are being kept in captivity or as a naturalized population outside its historic range.-Examples:...

 and survives only in private and public aquariums, some of which take part in a Species Survival Plan of the Association of Zoos and Aquariums

Association of Zoos and Aquariums

The Association of Zoos and Aquariums was founded in 1924 and is a nonprofit organization dedicated to the advancement of zoos and public aquariums in the areas of conservation, education, science, and recreation.The AZA headquarters is located in Silver...

 ("sp. nov." is a Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 abbreviation for "species novae", used to highlight that a species has not been officially described

Binomial nomenclature

Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...

 yet, and the name therefore is not scientifically valid).

The type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 of its alleged genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Yssichromis, Y. fusiformis, is nowadays usually included in Haplochromis

Haplochromis

Haplochromis is a ray-finned fish genus in the family Cichlidae. It has been used as the default "wastebin taxon" for Pseudocrenilabrinae cichlids of the East African Rift, and as such became the "largest" fish "genus"...

again. The delimitation of Haplochromis remains not very well resolved, and while the present species may belong there, it may just as well belong to some other genus of the Haplochromini.