Chasmistes cujus Cope, 1883

Open encyclopedia reference

The cui-ui (Chasmistes cujus) is a large sucker fish endemic to Pyramid Lake and, prior to its desiccation in the 20th century, Winnemucca Lake in northwestern Nevada. It feeds primarily on zooplankton and possibly on nanoplankton (such as algae and diatoms). The maximum size of male cui-ui is approximately 53 cm (21 in) and 1.6 kg (3.5 lb), while females reach approximately 64 cm (25 in) and 2.7 kg (6.0 lb). A cui-ui typically lives for 40 years but does not reach sexual maturity until at least age eight. The cui-ui is an endangered species, and one of the few surviving members of its genus. The cui-ui population is generally improving in numbers, having attained an estimated population exceeding one million in 1993, thanks to the efforts of the U.S. Environmental Protection Agency in analysis of the Truckee River spawning grounds and of the Nevada Department of Environmental Protection and EPA in following up on protection measures.

Wikipedia contributors, Cui-ui; see linked history · CC BY-SA 4.0 . Plain-text lead excerpt, at most 180 words; no infobox or later sections Retrieved 2026-10-05T19:17:41.263062+00:00. This reference remains separate from the taxonomic record.

Identity & source status

Scientific name

Chasmistes cujus Cope, 1883

Name authority

Cope, 1883

Rank

species

Accepted status

accepted

Kingdom

Animalia

Phylum

Chordata

Class

Teleostei

Order

Cypriniformes

Family

Catostomidae

Genus

Chasmistes

Extinction status

Not supplied by this source

Source habitat flags: Marine: no · Freshwater: yes · Terrestrial: no. These do not form a complete habitat description.

Classification family tree

Nested taxonomic groups from the source. This is not a direct-ancestor chain, a dated evolutionary tree or a phylogenetic reconstruction.

1. domainEukaryota (Chatton, 1925) Whittaker & Margulis, 1978
2. kingdomAnimalia
3. phylumChordata
4. subphylumVertebrata
5. infraphylumGnathostomata
6. parvphylumOsteichthyes
7. gigaclassActinopterygii
8. superclassActinopteri
9. classTeleostei
10. orderCypriniformes
11. familyCatostomidae Agassiz, 1850
12. subfamilyCatostominae Agassiz, 1850
13. tribeCatostomini Agassiz, 1850
14. genusChasmistes Jordan, 1878
15. speciesChasmistes cujus Cope, 1883

Close classified relatives

These entries share the source’s genus, Chasmistes. They are not necessarily the closest relatives established by molecular evidence.

Browse 60 records assigned to Catostomidae.

Source literature & publication evidence

References attached to this source record, including nomenclatural citations where supplied. This is a selected bibliography; abbreviated citations remain in the source’s form.

1. Cope, E. D. (1883). On the fishes of the Recent and Pliocene lakes of the western part of the Great Basin, and of the Idaho Pliocene lake. Proceedings of the Academy of Natural Sciences of Philadelphia, v. 35: 134–166, 1 map. Source fields: Taxon.tsv dwc:namePublishedIn, Taxon.tsv dcterms:references

Origins, evidence & remaining research

Name authority and publication references document nomenclature where the source supplies it. They do not establish evolutionary origins or the earliest fossil occurrence.

Specimen-level evidence, morphology, ecological research, phylogenetic studies, a comprehensive bibliography and a located literary passage have not yet been compiled for this record. A suitable sourced image remains to be added.

Dataset citation & attribution

This exact taxon in ChecklistBank · Catalogue of Life 2026-09-11

Catalogue of Life 2026-09-11; dataset 316321; doi:10.48580/dgz5n. https://creativecommons.org/licenses/by/4.0/ . Retrieved 5 October 2026.

Stable key: col:TQ6Z. Classification follows source parent identifiers. English common names may vary by region.