Thread subject: Diptera.info :: Stevenia umbratica or atramentaria ?
Posted by pjoris on 13-11-2011 16:10
#1
I presume this is a Stevenia - but which one ?
- following Cerretti: R4+5 setose about halway to r-m: umbratica
- following Zeegers: T2 and T3 with discals as well as marginals: atramentaria
- not sure what to say of the hairs on the arista
From indoors in Belgium (Leuven, 12/3/2002).
Joris
Edited by pjoris on 13-11-2011 16:20
Posted by pjoris on 14-11-2011 09:34
#2
In the meantime I am quite convinced this is umbratica - with the bristles on T2 and T3 not what they call "discals" (as they are not in front of the marginals, as explained in Van Emden) - and due to the lack of dusting on the abdomen. Again, confirmation still wellcome. Joris
Edited by pjoris on 14-11-2011 09:35
Posted by Zeegers on 15-11-2011 08:50
#3
It is indeed umbratica (which has become common rapidly over the last 10 years, esp. indoors !).
I don't see any discal seta, unless you are referring to some small lateroldiscals, but laterodiscals never qualify as discals !
Theo
Posted by pjoris on 15-11-2011 12:04
#4
Zeegers wrote:
I don't see any discal seta, unless you are referring to some small lateroldiscals, but laterodiscals never qualify as discals !
Yes, indeed I was mixing laterodiscals with the true "discals". I realize also the setae on R4+5 are not a difference between atramentaria and umbratica (but between umbratica and other species). So I guess the only good differences are the discals on T3 and T4 (counting the first visible T as T1+2) and the hairs on the arista, or is dusting on the abdomen also useable. Thanks, Joris
Edited by pjoris on 15-11-2011 12:20
Posted by Zeegers on 16-11-2011 19:34
#5
The prime feature is the lack of greyish dusting on syntergite 1&2 and tergite 5 in umbratica (present on T 3 and 4).
The best way to judge dusting is always obliquely from behind.
Theo