Thread subject: :: Melanostoma

Posted by Juergen Peters on 14-05-2005 21:38


I don't want to flood the forum with too many contributions a day, so only this last one today...

I still have difficulties to distinguish the two main Melanostoma species here in Ostwestfalen/Germany, M. mellinum and M. scalare, which are both numerously on the wing currently. The keys only give attributes which can't be seen on a lower res photograph, but is it generally correct that the yellow markings on the male abdomen of M. scalare are broader than on M. mellinum?

So, is this a male M. mellinum?

And this a male M. scalare?

And what about this female?

Last not but least another syrphid. I think this is Dasysyrphus albostriatus (?).

Thanks again!

Posted by Gerard Pennards on 15-05-2005 22:18

Hello Juergen,
Well, your first picture is not a male Melanostoma, but a male Platycheirus! Something like P. scutatus or P. splendidus, but not to distinguish from this photo!
Second photo is indeed a male Melanostoma, in this case M. mellinum! Males of mellinum have a relatively short abdomen, which does NOT extend beyond the wings!
Third picture is a female of Melanostoma, in this case I think it is mellinum! You can just see that the frons (above the antenna) is shining!
So, to explain difference between scalare and mellinum:
Males from mellinum have relatively short straight abdomens, not extending beyond the wings. Males of scalare have an elongated almost lineair abdomen which is extends beyond the wings.
Female mellinum have a shiny face and frons, and a bare arista on the antenna (which is totally useless in a picture! ):D
Female scalare have a dusted face and abdomen, and their arista is short haired.
In older works it is usually also the shape of the spots on the abdomen which is used, but this is often quite difficult to see!
And yes, your last picture is indeed afemale of dasysyrphus albostriatus!

Posted by Juergen Peters on 16-05-2005 22:45

Hello, Gerard!

Thank you very much for your explanations!

Gerard Pennards wrote:
Well, your first picture is not a male Melanostoma, but a male Platycheirus!

Oh! That shows again my lacking experience...