Posted by Paul Beuk on 24-05-2005 06:14
#6
Juergen Peters wrote:
Yes, another Empis I regularly find here, is rather small and fragile: Empis stercorea (but otherwise not to confuse with another species).
I hate to be a pest but unfortunately, there is a very similar species:
E. aemula. The females are almost indistinguishable (you will need to compare them side by side) and the males can be separated by the genital characters. Both have a single median stripe on the mesonotum. And to be honest, there are even several others, like
E. univittata.
At the beginning I found it hard to believe that this should be the same genus as the large and strong E. tesselata.
Actually, the true systematic classification into
Empis and
Rhamphomyia is a mess. The convenient classification is based on the absence or presence of the fork in R4+5 but in evolutionary terms some subgenera of
Empis and
Rhamphomyia are more closely related than they are to subgenera of their own genus. For example: Both the subgenera
Empis (Empis) and
Rhamphomyia (Pararhamphomyia) may not be what you might call single evolutionary units, but their species probably are all closer related to each other than that
Empis (Empis) species are related to
Empis (Xanthempis) (where
E. stercorea belongs).
So current classification is practical (most of the time, anyway) rather than 'biological'. Maybe it will be sorted out some day...