Male Meigenia are dark while the females are usually light grey like this one.
There 3 Meigenia sp on the UK list: dorsalis, mutabilis and majuscula. The commonest is mutabilis while dorsalis is also fairly common and majuscula is rare. It is only possible to distinguish dorsalis from mutabilis by the examination of the male genitalia. The females of these species are indistinguishable.
Photos taken in Whiteknights Park, Reading, UK on 2013-06-23.