''Eoprephasma'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of

stick insect The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks. They are also occasionally referred to as ...

in the susumaniid subfamily

Susumaniinae Susumanioidea is an extinct superfamily of Phasmatodea, known from the Middle Jurassic to Eocene. They lie outside the modern crown group of Phasmatodea. Members of the group typically possess large, fully developed wings. Taxonomy According to ...

known from a group of Eocene fossils found in

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. When first described there was a single named species, ''Eoprephasma hichensi''.

History and classification

When described, ''Eoprephasma'' was known from two isolated wings which are compression-impression fossils preserved in a layer of soft sedimentary rock. Along with other well preserved insect fossils, the ''Eoprephasma'' specimens were collected from layers of Ypresian age '' Lagerstätte'' lake sediments Washington, USA, and an additional three partial Susumanioidea fossils were recovered from British Columbia, Canada. The partial Susumanioidea specimens were found in the Tranquille Formation belonging to the Kamloops group that outcrops at the McAbee Fossil Beds near Cache Creek, BC. The two ''E. hichensi'' wing were recovered from the Tom Thumb Tuff member of the

Klondike Mountain Formation The Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation, named for the type location designated in 1962, Klondike Mountain north of Republic, Wash ...

Republic, Washington Republic is a city in Ferry County, Washington, United States. The population was 1,073 at the 2010 census, a 12.5% increase over the 2000 census. It is the county seat of Ferry County. It was the largest mining camp in the Republic Mining Distr ...

which is designated the type locality for the species, with the holotype recovered from the "Boot hill" site #B4131, and the paratype from the "Corner lot" site #A0307. At the time of description, the species type series consisted of the holotype specimen, SR 12-004-007 and paratype specimen SR 93-10-02 were preserved in the Stonerose Interpretive Center fossil collections. The three Susumanioidea fossils, part/counterpart F-846 and F-951 plus F-1392 and F-1393 are deposited in the Thompson Rivers University. The counterpart specimen F-1099 is also in the Thompson Rivers University collections, while the part side, PB-3825 is at the Burke Museum of Natural History and Culture. All the insects were first studied by Canadian entomologist S Bruce Archibald and German entomologist Sven Bradler, with their 2015

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

of the new genus and species being published in the journal ''Canadian Entomology''. Archibald and Bradler noted the genus name to be a combination of "eo", from Eocene, "pre" and "''

Phasma ''Phasma'' is an Australasian genus of stick insects in the family Phasmatidae, subfamily Phasmatinae and tribe Phasmatini. Species The Catalogue of Life The Catalogue of Life is an online database that provides an index of known species o ...

''", referencing the status of the genus as a stem group phasmatodean. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''hichensi'' is in honor of Keir Hichens, who first found the specimen in 2012 and donated it to the Stonerose Interpretive Center. The fossils were described by Archibald and Bradler as the youngest members of the Phasmatodea stem group lineage Susumanioidea. Prior to the 2015 paper, the oldest Susumanioidea were Chinese fossils dating to the Jurassic, while the youngest member of the superfamily dated to the Paleocene Paskapoo Formation in Alberta, Canada. Due to the incomplete nature of the McAbee fossils, it was not possible for Archibald and Bradler to distinguish them from the Canadian fossils, which are also incomplete. Phylogenetic analysis of Susumanioidea published by Yang ''et al'' (2021) resulted in placement of ''Eoprephasma'' as the sister group to ''

Renphasma ''Renphasma'' is an extinct genus of stick insect which existed in what is now China during the early Cretaceous period. It was named by André Nel and Emmanuel Delfosse in 2011, and the type species is ''Renphasma sinica,'' found in the early Apt ...

'' deep within the

Susumaniidae Susumanioidea is an extinct superfamily of Phasmatodea, known from the Middle Jurassic to Eocene. They lie outside the modern crown group of Phasmatodea. Members of the group typically possess large, fully developed wings. Taxonomy According to ...

subfamily

Description

The ''Eoprephasma hichensi'' specimens are both well preserved, though partial, forewings. The overall length of the holotype forewing is long and has an estimated width of . The paratype is notably smaller, being approximately and only about wide. Both wings have a dark coloration, light veins of varying width, and numerous cross-veins. The wings are distinguished from other Susumanioidea members by both the CuA, apical cubitus vein, and the CuPα, posterior cubitus alpha vein, being forked.

References

{{Taxonbar, from=Q19636545 Ypresian insects Fossils of the United States Fossils of British Columbia Prehistoric insects of North America Phasmatodea genera Insects described in 2015 Fossil taxa described in 2015 Paleontology in Washington (state)