DIPTERA > BRACHYCERA | Higher Diptera

MUSCOMORPHA > SCHIZOPHORA > Calyptratae > Muscoidea > Muscidae (293 species)

(subfamily: Mydaeinae)

Mydaeinae (23)

Unlike the Muscinae, which includes a similar number of species in ten genera and two tribes, this subfamily comprises just five genera: Graphomya (2), Gymnodia (1), Hebecnema (5), Mydaea (13), Myospila (2).

Graphomya

The genus may include two species Graphomya maculata and Graphomya minor, but when you look at the distribution data it becomes clear that the latter is seldom recorded. In fact, there has only ever been one unconfirmed record of Graphomya minor locally from either Dorset (VC9) or South Hampshire (VC11) according to the NBN Atlas whereas, on the other hand, Graphomya maculata is a widespread, frequently seen species. It is a robust muscid with distinctive thoracic markings and a strongly patterned abdomen; both features varying between the sexes, most notably being the colour of the abdomen, which is grey/black in the female, but orangey-brown in the male as can be seen in the following photos.

Hebecnema

Five rather similar, dark-coloured flies that can be a little tricky to reliably identify from photos. I've only photographed a couple of individuals, both males and, from what I can tell, both are Hebecnema vespertina.

It is a relatively small species distinguished from a combination of characters including having bare eyes, entirely dark legs and yellow haltere knobs (the other four species may have hairy eyes, orange legs and dark-coloured haltere knobs). Females can prove to difficult to separate from Hebecnema umbratica, but the males have a couple of additional features of infuscated wings and eyes that almost meet at the top.   

Although the biggest challenge for me is actually determining that an individual is a Hebecnema, it's worth noting that, despite the low number of local records, any one of these five species could be encountered. Possibly not Hebecnema fumosa as it is rather scarce, but certainly with any of the others. Hebecnema vespertina and H.umbractica are the most frequently recorded. The male of the latter has hairy eyes and, as such, could only be confused with Hebecnema fumosa which, despite being scarce, is a larger, longer winged fly. The other two species are Hebecnema nigra and H.nigricolor, the former being the only member of the genus with dark haltere knobs, and the latter the only species with orange legs.  

Mydaea

A relatively large genus with thirteen species, but when you start looking at the distribution data and local records, there are probably only eight that are likely to be encountered. Locally there have only been ten confirmed records across both Dorset (VC9) and South Hampshire (VC11) combined, which is obviously of no use when trying to get a feel for the species that could be found. Nationally, the two most frequently recorded species by far are Mydaea corni and Mydaea urbana.

Mydaea corni - a fairly large, robust species with a densely dusted and striped thorax, and entirely reddish-orange scutellum, wing bases and legs.

Mydaea humeralis - broadly grouped with Mydaea corni and a couple of other species that have similar appearance, but separable by having a scutellum that has a variable amount of darkening at the base. The males can be distinguished by the darkened bases of the front tibia, and the females by their orange humeri. The species is also a tad smaller and typically darker than the far more common species Mydaea corni. However, females particularly are very difficult to separate from Mydaea setifemur without close examination of leg bristles and, although that species has never been officially recorded from my area, it can't be ruled out, so although Mydaea humeralis is definitely the most likely species for the individual featured below, it is not certain.

Mydaea urbana - one of five Mydaea species with a dark ground-coloured pronotum and yellow/orange femora and tibia; slightly larger and more strongly dusted than the very similar Mydaea orthonevra, but not reliably separable without close inspection of various bristles, which cannot realistically be done from photos.

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