Thread subject: Diptera.info :: Scatella ID
Posted by Carnifex on 10-05-2026 20:56
#1
lacustris or
stagnalis?
In Steyr (Upper Austria), late April
Posted by Tony Irwin on 11-05-2026 10:12
#2
This is
lacustris.
Scatella stagnalis is a brown species, and has a rounded white distal wingspot. Your specimen is greyer, and the distal wingspot is constricted in the middle.
Posted by Carnifex on 11-05-2026 12:54
#3
It looked rather brown to me, thus I was unsure.
Also, the dumbbell shape of the distal white spot I found not convincing, as I was imagining it could also be a combination of both wings, the underlying spot from the other wing shining through.
Lastly, I am confused - according to GBIF,
lacustris is a synonym of
stagnalis - not of
tenuicosta, as I was assuming.
Posted by Tony Irwin on 11-05-2026 18:12
#4
The back lighting does make the fly look rather brown, but it is grey enough to be
lacustris. The shape of the wingspot is large and oval in
stagnalis, unlikely to form a dumbell shape when the wings are overlapped.
The listing of
lacustris as a synonym of
stagnalis is wrong. If you read the abstract of the quoted paper (Zatwarnicki and Irwin 2018), it clearly states that
tenuicosta is a synonym of
lacustris. I don't know why the confusion has arisen, but thanks for pointing it out.
Posted by Carnifex on 12-05-2026 07:08
#5
Thanks, so the GBIF entry would need to be flagged.
Also, on Systema Dipterorum,
S. lacustris is not listed as valid, in contrast to
tenuicosta
.
Edited by Carnifex on 12-05-2026 07:09