Islas Revillagigedo Nightsnake

Open encyclopedia reference

Hypsiglena unaocularus, commonly known as the Islas Revillagigedo night snake or Clarión night snake, is a species of small colubrid snake endemic to Clarion Island, initially described from a single specimen collected by William Beebe in 1936. During the next several decades, scientists were unable to detect any trace of the snake in their field studies. After an intensive search in 2013, a team of scientist identified 11 snakes that matched the original description of the species. They conducted a series of DNA tests to confirm that the Islas Revillagigedo nightsnake, formerly viewed as the subspecies Hypsiglena torquata unaocularis, is genetically distinct from related mainland snakes and should be recognized as a full species. While never formally declared extinct, this species remained absent from scientific literature due to two main factors: its home on Clarion is extremely remote and only accessible by military escort, significantly restricting the number of biologists who can access this area, and the snake's secretive, nocturnal behavior and dark coloration make it difficult to detect in the field.

Wikipedia contributors, Hypsiglena unaocularus; see linked history · CC BY-SA 4.0 . Plain-text lead excerpt, at most 180 words; no infobox or later sections Retrieved 2026-10-05T12:13:53.642347+00:00. This reference remains separate from the taxonomic record.

Identity & source status

Scientific name

Hypsiglena unaocularus Tanner, 1946

Name authority

Tanner, 1946

Common name

Islas Revillagigedo Nightsnake

Rank

species

Accepted status

accepted

Kingdom

Animalia

Phylum

Chordata

Class

Reptilia

Order

Squamata

Family

Colubridae

Genus

Hypsiglena

Extinction status

Not supplied by this source

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. megaclassTetrapoda
8. classReptilia Laurenti, 1768
9. orderSquamata Oppel, 1811
10. suborderSerpentes Linnaeus, 1758
11. infraorderAlethinophidia Nopcsa, 1923
12. familyColubridae
13. subfamilyDipsadinae
14. genusHypsiglena
15. speciesHypsiglena unaocularus Tanner, 1946

Close classified relatives

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

Browse 1,632 records assigned to Colubridae.

Documented distribution

Source distribution statements, not a complete range map. A listed locality is not necessarily a place of origin.

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. https://reptile-database.reptarium.cz/species?genus=Hypsiglena&species=unaocularus 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:6MSS4. Classification follows source parent identifiers. English common names may vary by region.