Diptera.info :: Identification queries :: Diptera (adults)
 Stevenia umbratica or atramentaria ?
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| pjoris |
Posted on 13-11-2011 16:10
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Member Location: Posts: 98 Joined: 07.04.09 |
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 |
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| pjoris |
Posted on 14-11-2011 09:34
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Member Location: Posts: 98 Joined: 07.04.09 |
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 |
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| Zeegers |
Posted on 15-11-2011 08:50
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Member Location: Soest, NL Posts: 19133 Joined: 21.07.04 |
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 |
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| pjoris |
Posted on 15-11-2011 12:04
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Member Location: Posts: 98 Joined: 07.04.09 |
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 |
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| Zeegers |
Posted on 16-11-2011 19:34
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Member Location: Soest, NL Posts: 19133 Joined: 21.07.04 |
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 |
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