Lepidarchidae is a small

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

in the order

Characiformes Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A.: "Relationsh ...

. It contains only two threatened,

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genera native to western Africa. The following genera are in this family: * ''

Arnoldichthys ''Arnoldichthys'' is monospecific genus of freshwater ray-finned fish belonging to the family Lepidarchidae, the African tetras. The only species in the genus is ''Arnoldichthys spilopterus'', the Niger tetra. This taxon is endemic to Nigeria. D ...

Myers Myers as a surname has several possible origins, e.g. Old French ("physician"), Old English ("mayor"), and Old Norse ("marsh"). People * Abram F. Myers (1889–after 1960), chair of the Federal Trade Commission and later general counsel and b ...

, 1926 * ''

Lepidarchus The Adonis tetra (''Lepidarchus adonis'') also known as the jellybean tetra, is a very small African fish of the family Lepidarchidae. It is the monotypic, only member of its genus, and one of two members of its family. Range ''Lepidarchus adon ...

'' Roberts, 1966 Both of these genera were previously placed in

Alestidae African tetras (family (biology), family Alestidae, formerly spelled Alestiidae) are a group of Characiformes, characiform fish found exclusively in Africa. This family contains about 18 genera and 119 species. Among the best known members are th ...

, but moved to their own family in 2024 when this placement was found to be

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

, as these two genera are more closely related to the

Hepsetidae ''Hepsetus'' is a genus of freshwater ray-finned fishes belonging to the monotypic family Hepsetidae, the African pikes or African pike characins, in the order Characiformes. It was long believed that only a single widespread species existed, ''H ...

than to alestids. Molecular phylogenetic estimates suggest that this family has an ancient divergence dating to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

(

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

, about 84–77.5 mya). The divergence of these two families appears to have been driven by the

Trans-Saharan Seaway The Trans-Saharan seaway was a sea in the present-day Sahara in the Late Cretaceous period to the Early Eocene In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eoce ...

, which served as a marine barrier between western and eastern Africa at the time.

References

{{Taxonbar, from=Q130973050 Characiformes families Characiformes