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 Chrysotoxum elegans?
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| bubu |
Posted on 01-07-2020 06:54
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Member Location: Posts: 20 Joined: 03.08.19 |
This is the same chrysotoxum I posted yesterday. Ok., the identification of this syrphidae seems to be difficult, therefore I post two other pictures: picture 2: Edited by bubu on 01-07-2020 06:57 |
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| bubu |
Posted on 01-07-2020 06:55
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Member Location: Posts: 20 Joined: 03.08.19 |
picture 3: |
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| Sundew |
Posted on 03-07-2020 22:02
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 Member Location: Posts: 3890 Joined: 28.07.07 |
Chrysotoxum is difficult for sure, especially if the pictures do not show the necessary characters... Each key, e.g. this https://books.goo...&hl=de, starts with the length relations of the three antennal segments (3 longer or as long as 1+2, or 3 shorter than 1+2). I think we have the first case here, so Ch. elegans is out. Then, we have to estimate the length of hairs on tergites 3 and 4. I cannot see them. However, "hairs very short, tergites seemingly bare" would lead us to Ch. intermedium, which looks clearly different. So we have to assume that there are "long hairs". That leads to three species: cautum, arcuatum, fasciolatum. Now again the antenna segments are important: in cautum, 3 is as long as 1+2 and 1 is shorter than 2. (Besides, the cautum female has a longitudinal membraneous strip on tergite 6 - but there is no picture of the abdomen tip.) It seems that segment 3 is longer than 1+2, so the candidates are arcuatum or fasciolatum. Size would tell them apart, but you didn't mention it. Then, the key says that fasciolatum has a dark spot in the top wing half, which your fly has, too. However, the yellow stripes look very straight in this species (https://www.galer...asciolatum), and the abdomen is more elongate. Shape and abdominal pattern of your fly would match better with arcuatum, but, as you see, there is much uncertainty! Regards, Sundew P.S. Never forget to tell the locality! "Living room" is not enough, country is better  . |
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| bubu |
Posted on 04-07-2020 07:36
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Member Location: Posts: 20 Joined: 03.08.19 |
Good morning Sundew, first thank you for giving such detailed explanations! Sure, living room is not very helpful , I've forgotten to say that I live in Germany, in the south of Rheinland-Pfalz.And sorry, that I can not show the necessary details (have to buy a new camera ;-)), but the tip of the abdomen of this chrysotoxum you can see at the first picture of it, I posted the 30.06.2020. Please have a look on it. The length of this syrphidae was about 12-15 mm. I hope this added informations will help to give my chrysotoxum a name... Have a sunny sunday and kind regards, bubu |
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| Sundew |
Posted on 04-07-2020 16:05
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Member Location: Posts: 3890 Joined: 28.07.07 |
Hi, So you are not far away from me, I'm living west of Stuttgart at the moment. Sorry, your other picture does not show the abdomen tip; I add a picture where the peculiar cautum tergite is marked by an arrow. However, a clear picture of the antenna is absolutely necessary for identification. If you remember the size correctly, arcuatum would be less possible than cautum and fasciolatum. Nevertheless I do not believe in cautum for the reasons already mentioned; my cautum specimens also had no dark wing parts. C. fasciolatum somehow looks different (https://www.dipte...d_id=63936)... I would call the pictures "Chrysotoxum cf. arcuatum" at best. BTW, there are lots of misidentified pictures in the internet, some don't even show the right genus. Well, unambiguous identifications from pictures are impossible in many, many cases - we must accept that. Console yourself with the fact that most people don't even know that your specimen is a hoverfly and not a wasp, let alone a Chrysotoxum. Best wishes, Sundew |
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but don't see the image in the post.