Mexican rivulus

The Mexican rivulus (Millerichthys robustus) is a species of killifish from the family Rivulidae which is endemic to Mexico where it is found in the Papaloapan and Coatzacoalcos River basins. This annual killifish grows to a total length of 4 cm (1.6 in). It is the only known species in its genus, but its exact taxonomic position remains uncertain, as it has not been included in any phylogenetic study.^[2][3] This species was described by Robert Rush Miller and Carl Leavitt Hubbs as Rivulus robustus in 1974,^[4] it was reclassified in the monotypic genus Millerichthys in 1995, the generic name honouring Robert Rush Miller.^[5]

Mexican rivulus
Conservation status
Endangered  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cyprinodontiformes
Family:	Rivulidae
Genus:	Millerichthys W. J. E. M. Costa, 1995
Species:	M. robustus
Binomial name
Millerichthys robustus (R. R. Miller & C. L. Hubbs, 1974)
Synonyms
Rivulus robustus Miller & Hubbs, 1974