''Pseudosiobla campbelli'' is an extinct

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

sawfly Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...

in the family

Tenthredinidae Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem ...

that is known from early

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

stage lake deposits near the unincorporated community of

Horsefly, British Columbia Horsefly is an unincorporated community on the northwest shore of the Horsefly River, in the Cariboo region of central British Columbia. The location, via BC Highway 97, Likely Rd, and Horsefly Rd, is about northeast of Williams Lake, and by roa ...

History and classification

The species is known from only the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, a single, mostly complete adult female, now deposited in the Geological Survey of Canada collections as specimen number "GSC No. 22689". The

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

specimen is from deposits of the " Horsefly shale" along the

Horsefly River The Horsefly River is a river in the Cariboo district of British Columbia, Canada. Originating near the Wells Gray Provincial Park, it flows into Quesnel Lake, the source of the Quesnel River which in turn is a major tributary of the Fraser River. ...

in the

Cariboo District Cariboo District was a federal electoral district in British Columbia, Canada, that was represented in the House of Commons of Canada from 1871 to 1872. It was created when the province of British Columbia joined Confederation in 1871. Like ot ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. The holotype was first studied by Harington Rice of the Geological Survey of Canada. Rice published his 1968

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 ...

for ''P. campbelli'' in the Geological Survey of Canada professional paper number 67-59. The

specific Specific may refer to: * Specificity (disambiguation) * Specific, a cure or therapy for a specific illness Law * Specific deterrence, focussed on an individual * Specific finding, intermediate verdict used by a jury in determining the fina ...

name ''campbelli'' was coined in honor of R. B. Campbell who collected the holotype specimen in 1959. ''Pseudosiobla campbelli'' is the smallest species of '' Pseudosiobla'' to be described from the fossil record. The single known female possesses a head, thorax and posterior segments of the abdomen which are dark brown to black. The central segments of the abdomen appear to have been pale colored. The wings are hyaline with very dark veins and short, stout hairs across the wing membrane. While the specimen is missing portions of her legs and antennae, her

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

is visible and well preserved. ''P. campbelli'' is distinguished from members of the related genus '' Eriocampa'' in general and '' E. tulameenensis'' found in the related lake deposits in Princeton, B.C. by several features: ''P. campbelli'' is notably larger than members of ''Eriocampa'' and the wing vein patterning is distinct. There are only two other described species of ''Pseudosiobla'' from the fossil record, '' P. megoura'' and '' P. misera''. Both species are described from specimens found in the

Florissant Formation The Florissant Formation is a sedimentary geologic formation outcropping around Florissant, Teller County, Colorado. The formation is noted for the abundant and exceptionally preserved insect and plant fossils that are found in the mudstones and ...

of Colorado which, at 39 million years old, is younger in age then the Horsefly locality, dated to approximately 49 million years old. ''P. campbelli'' can be distinguished from both younger species in that ''P. campbelli'' is the smallest species of the three. ''P. megoura'' also possesses an abdomen which is twice as long as that of ''P. campbelli''. ''P. misera'' has a larger and more elongate abdomen. In his 1908 paper on the

Tenthredinoidea The Tenthredinoidea are the dominant superfamily of sawflies within the Symphyta, containing some 8,400 species worldwide, primarily in the family Tenthredinidae. All known larvae are phytophagous, and a number are considered pests. The included ...

of Florissant, S.A. Rohwer, put the possibility of ''P. megoura'' and ''P. misera'' being the same species.

References

{{Taxonbar, from=Q7255564 † Eocene insects Fossil taxa described in 1968 Fossils of British Columbia Prehistoric insects of North America Horsefly Shales