Melanostoma dubium (Zetterstedt, 1837)Nomenclature
There is much confusion about this species. Stubbs & Falk (1983) described 'form A', intermediate between M. dubium and M. mellinum, and the work of MacGowan et al. (1997) showed that these form an altitudinal cline and question whether M. dubium is really a separate species. Recent DNA analysis suggests that the interpretation of MacGowan et al. (1997) may be correct, but also did not support the separation of M. mellinum and M. scalare! A species that remains on the checklist until voucher material is checked.Biology
The larva is unknown, but assumed to be a general predator amongst leaf litter like others of this genus. Adults are found at higher altitudes on moorland, especially along stream sides and around wet flushes.Distribution
Recorded from the main upland areas of Scotland and northern England from around 250m upwards. Perhaps most often found above 500m (although there is little hoverfly recording at this altitude). Although there are old records from the Pennines, Cumbria and Exmoor, there are very few recent English records and only from the higher peaks of the Cumbria.Status
Lower Risk (Nationally scarce) - Ball & Morris, 2010. Notable - Falk, 1991.