genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
of
killifish
A killifish is any of various oviparous (egg-laying) cyprinodontiform fish (including families Aplocheilidae, Cyprinodontidae, Fundulidae, Profundulidae and Valenciidae). All together, there are 1,270 species of killifish, the biggest famil ...
in the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Rivulidae
The Rivulidae are a family of killifishes in the order Cyprinodontiformes. They are commonly known as rivulids, South American killifish or New World killifish. The latter names are slightly misleading, however, as they are neither restricted to ...
. These annual
killifish
A killifish is any of various oviparous (egg-laying) cyprinodontiform fish (including families Aplocheilidae, Cyprinodontidae, Fundulidae, Profundulidae and Valenciidae). All together, there are 1,270 species of killifish, the biggest famil ...
are
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...
to seasonal pools, swamps and lagoons in the upper Araguaia–
Tocantins
Tocantins () is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers and had an estimated population of 1,496,880 in 2 ...
and middle Xingu river basins in Brazil. Most are from savanna regions, but ''M. gesmonei'' is from the Amazon rainforest.
They are small fish, up to in
total length
Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.
Overall length
* Standard length (SL) is the length of a fish ...
. The males are mottled or spotted orange-red and
turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrated phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone and ornamental stone for thousands of y ...
-blue, and have long, pointed fins. The much duller females have "normal" fins.