This is a genus of kelp fly in the family Coelopidae. , it is monotypic, consisting of its type species This canus. This and T. canus were respectively circumscribed and described in 1991 by the Australian entomologist David K. McAlpine. It is endemic to southern Australia.
Taxonomic history
David K. McAlpine of the Australian Museum circumscribed and named the genus This in a 1991 overview of Australian Coelopidae, which was published in the journal Systematic Entomology. In the same paper McAlpine named and described its type species T. canus, the only species included in the genus. McAlpine and Geoff Holloway collected the male T. canus holotype in 1971; it was deposited in the collections of the Australian Museum. Approximately 450 specimens of T. canus were designated as paratypes; collections holding paratypes include: the Australian Museum, the South Australian Museum, the Natural History Museum, London, the Muséum national d'Histoire naturelle, Paris, and the National Museum of Natural History, Washington.
McAlpine placed This in a new tribe, Coelopellini; he initially included three genera in this tribe: his new genera This and Rhis, as well as Coelopella, which John Russell Malloch circumscribed in 1933. McAlpine concurrently created the tribe Ammini, consisting of the genera Amma, Icaridion, and Beaopterus.
Rudolf Meier and Brian Wiegmann conducted a phylogenetic study of twenty two species of Coelopidae based on genetic sequencing of EF-1α and 16S rDNA as well as morphological characteristics. Meier and Wiegmann argued that neither Coelopellini nor Ammini as McAlpine had circumscribed them were monophyletic, but that together they formed a clade. , the Tree of Life Web Project follows Meier and Wiegmann's phylogeny. In 2011, Smithsonian Institution entomologist and McAlpine combined Ammini with Coelopellini, resulting in an expanded, monophyletic tribe Coelopellini.
The generic name This comes from the Ancient Greek word (thís), which means "sea shore", particularly in Homeric Greek. Some have found it humorous that This is a homograph of the English proximal demonstrative this. American entomologist Arnold S. Menke included This in a 1993 list of taxon names which he deemed to be either "funny" or "curious"; the list was printed in a biological humor magazine published by the American entomologist Neal L. Evenhuis. Menke also reported that McAlpine had a poster on his office door which illustrated a This specimen and was captioned "Look at This!". The specific name for its type species is a Latin adjective, , with meanings including "white", "grey-haired", and "foam-capped".
Description
Genus
In McAlpine's 1991 as well as Mathis and McAlpine's 2011 keys to Coelopidae genera, This and Rhis formed a couplet. Some of the characteristics distinguishing This from Rhis include: moderately long vibrissal setae at a prominent angle, the presence of two humeral, postpronotum bristles, and a deeply bilobed surstylus on males.
Other generic features include a face whose profile is concave and which lacks a medial carina, short setulae on its cheeks. Its arista is shorter than the diameter of its eye, and the segment 6 is covered in short hairs.
Species
Both sexes of T. canus have a similar morphology. It has a pale grey head, a pale orange-brown cheek, orange-brown antennae, and a brown arista. Its thorax is light gray and is covered in black hairs. The legs are yellow or yellowish-brown. Both the tegulae and veins on its pale wings are yellow. The head is slightly narrower than the thorax, and the legs are stout.
McAlpine provided similar measurements for both males and females, although Jennifer Blyth argued T. canus exhibited sexual dimorphism due to the males' wing size being on average 71.6% than that of the females in her study.
Distribution
The genus This is endemic to Australia, and T. canus is one of the most common species of Coelopidae in Australia. T. canus is found along the southern coast of Australia, and had been found in the Australian Capital Territory, New South Wales, Queensland, South Australia, Tasmania, Victoria, and Western Australia. Its range also includes Clarke Island, off the coast of Tasmania. Its type locality is Dee Why, a suburb of Sydney. It has been documented as far north as Noosa, Queensland on the east coast and Geraldton, Western Australian on the west coast. It can also be found as far inland as Canberra.
