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Luc Bettinelli : France : Arc-et-Senans : 25610 : 15/11/2024
Altitude : 236 m - Taille : 8 mm ?????
Réf. : 352347


Luc Bettinelli : France : Arc-et-Senans : 25610 : 15/11/2024
Altitude : 236 m - Taille : 8 mm ?????
Réf. : 352348

Hello, the question has already been asked, without me finding a very clear answer (I may have searched insufficiently): does the shaded spot on r-m* at least allow us to direct towards the supposed commune Trichocera regelationis? Can we name this specimen?

Thank you.

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According to the key by Peeters & Oosterbroek https://ccw.natur..._2014b.pdf, T. regelationis is characterized by an infuscated crossvein r-m, but the abdominal segments must not be banded (= yellow anteriorly, dark posteriorly). In the latter case it would be T. annulata. Unfortunately, we can neither see the abdomen nor the female cercus, the shape of which is also important for identification. So I would go with T. cf. regelationis.
Regards, Sundew

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Luc Bettinelli : France : Arc-et-Senans : 25610 : 15/11/2024
Altitude : 236 m - Taille : 8 mm ?????
Réf. : 352385


Thank you very much for the answer and for this link for the key, more concise and more affordable than the one I found (which is very good by the way). I don't have a good photo of the abdomen but just with this side view, I feel like we can rule out annulata. What do you think?

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I know the comprehensive paper by Krzemińska. It covers all 59 European species whereas Peeters & Oosterbroek deal only with the 9 species occurring in the Be-Ne-Lux countries. I learn from Krzemińska that in France there are also 9 species, but three of them (forcipula, lutea, dahlae) are missing in Peeters & Oosterbroek. On the other hand, Krzemińska mentions three more species with infuscated r-m (gigantea, muelleri, hiemalis) that, however, seem not to occur in France. So the three French species missing in Peeters & Oosterbroek would not show this feature. Krzemińska does not emphasize infuscated wing veins in T. annulata, but mentions that they may occur in some specimens. So annulata is still not off the table. I tried to brighten your last photo with photoshop but cannot estimate the colouring of the abdomen. As shown in https://diptera.i..._id=108782, the banding can be rather inconspicuous. And here my wits end. I am not an expert of Nematocera, and they say that in nearly all cases a safe ID is only based on genital characters and ID-ing from a photo is very bold... Compare also the discussion in https://diptera.i..._id=108781 where ambiguities could not be resolved. I missed the thread https://diptera.i..._id=111678 that shows a good annulata in my opinion, the quality of the pictures is nice. But, as already written above, in your case I do not dare to go further than "cf. regelationis".
Regards, Sundew

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Thank you a lot for this very reasoned and interesting response!
I commend your prudence, although the first link to show the possible discretion of the distinctive color of the annulata's abdomen would have rather reassured me in my choice to rule it out (in my opinion, it still remains clearly visible in the other photo).