Scathophaga taeniopa
Although this species was included in Collin's (1958)[1] key, Chandler (1988)[2] followed Šifner (1995)[3] in synonymising this species with S. suilla. Subsequently Bernasconi et al. (2001)[4] confirmed its status as a good species.
In the field, this is quite a large and stout, rather yellow species with almost clear wings with only a hint of infuscation about the cross-veins. The femora usually have strong black streaks on the outer surface on at least the front legs and sometimes the middle and event the hind pair as well. The sides of the thorax lack the pale, yellowish patch of S. suilla and the humeri have the same colouring and dusting as the rest of the thorax. Wing length: ♂ 5.7 - 7.4 - 8.6 mm (23); ♀ 6.7 - 7.4 - 7.9 mm (14).
References
- A short synopsis of the British Scatophagidae (Diptera). Transactions of the Society for British Entomology, 13, pp.37-56., 1958.
- Checklist of Insects of the British Isles (New Series) Part 1: Diptera. Handbooks for the Identification of British Insects, 12, pp.1-234., 1998.
- Additions to the catalogue of flies of the Palaearctic region (Diptera, Scatophagidae). European Journal of Entomology, 92, pp.513-515., 1995.
- Phylogeny of the genus Scathophaga (Diptera: Scathophagidae) conferred from mitochondrial DNA sequences. Canadian Journal of Zoology, 79, pp.517-524., 2001.
I have found this to be a reasonably frequent species in Speyside and more northerly areas of Scotland, especially in grassy places along the bottoms of glens at mid-altitudes. Collin (1958)[1] reported that it was "not uncommon in Scotland" and also recorded it from Yorkshire (though he had "no records further south than Nottingham"). Falk's record cards (collated during preparation of Falk 1991[2]) give its distribution as "Widespread but localised in the Highlands of Scotland" and note the records from Yorks and Notts (presumably from Collin, 1958[1]). It seems he was intending to categorise it as "RARE - RDB3", but it was not eventually included in the published report.
There are many records in the literature under this name which are more widespread, including all of England and Wales, but they are difficult to interpret because of the confusion between S. suilla and S. taeniopa. I have taken the view that records should only be accepted if there is a specimen available for re-determination according to the modern concept of this species. For example, Peter Skidmore determined many specimens caught during the Welsh Peatland Invertebrate Survey in late 1980s to early 1990s to belong to S, taeniopa (presumably using the key in Collin 1958[1]) and there should be voucher material lodged at Cardiff Museum. Re-examination of these specimens may well prove that the species is more widespread, but material I have so far checked has all been from central Scotland.
World distribution: Palaearctic: Central belt and south of Western Europe. Kubain and Sayan Mountains of Russia. Northern China; Nearctic: Canada. The Species 2000 catalogue (and therefore GBIF), Fauna Europaea and Nearctic checklist still regard it as a synonym of S. suilla so it is difficult to determine an up-to-date world distribution.