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 Xanthogramma to be continued
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| Sundew |
Posted on 22-05-2013 23:10
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 Member Location: Berlin and Baden-Württemberg, Germany Posts: 3917 Joined: 28.07.07 |
Hi, When dealing with Mucha Fero's Xanthogramma thread, I realized that I had a Xanthogramma problem, too, concerning X. dives. Using the forum search, I found a lot of hot discussion whether there is one species X. pedissequum or a species group including X. stackelbergi and X. dives. Meanwhile it seems settled that there are several accepted species. When I checked my photo collection of 4 specimens [all superficially labeled "X. cf. pedissequum"], I found that all animals had infuscated wing tips. Speight & Sommaggio 2010 (http://www.entomo...t_BUCH.pdf) say that there are only three European species showing that character: X. citrofasciatum, X. marginale, and X. dives. The two former can be excluded, as they look rather different. X. dives is said to be essentially a southern European insect. The Fauna Europaea states its absence for Germany, though other sources deny this. It is also not mentioned in the species list of Berlin and Brandenburg, however, this may be based on a broad species concept of X. pedissequum. So I would like to ask the Syrphid experts if it is possible that I have not seen any X. pedissequum s. str. yet but came exclusively across X. dives. BTW, some specimens show a colouration of the abdominal membrane that matches X. dives and X. stackelbergi, respectively. The latter species is said, however, to possess clear wing tips without a sign of infuscation. I am looking forward for opinions and explanations - thanks in advance! Sundew Sundew attached the following image:  [124.8Kb] Edited by Sundew on 22-05-2013 23:13 |
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| Fred Fly |
Posted on 23-05-2013 09:06
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Member Location: Germany Posts: 395 Joined: 19.07.11 |
Hi Sundew, at least specimes 2-4 are belonging definately to Xanthogramma dives. Very easy to see because of infuscation of wing tip and colour of hind leg. I think fist male is dives too. All three species of this group occure in Berlin/Brandenburg region. |
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| Sundew |
Posted on 23-05-2013 11:38
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Member Location: Berlin and Baden-Württemberg, Germany Posts: 3917 Joined: 28.07.07 |
Thank you, dear Piet, that is very interesting! Though Speight & Sommaggio 2010 give a detailed description of X. dives, nothing is said about a differing colour of the hind legs. Do you point to the fact that the tibia is very dark so that the dark ring is not discernible? Well, it seems that X. dives is a common species here, at least as common as X. pedisequum - what a surprise! So the find lists should be complemented, but whose task is this? I really do not know whom to inform... Thanks and best wishes, Sundew |
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| Fred Fly |
Posted on 23-05-2013 17:05
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Member Location: Germany Posts: 395 Joined: 19.07.11 |
Hi Sundew, specimen of the pedissequum-group with hind legs nearly black from distal end of femur to tibia and tarsi dorsally and with no clear dark rings visible on femura3 and tibia 3 are belonging to X. dives (as clear visible in your brilliant photos 2-4). This is a good character for field observations. I assume that the authors of the passed and forthcoming Checklists and Red Data Books on German Syrphidae , e.g. Dieter Doczkal and Axel Ssymank, are well informed about the occurence of the Xanthogramma species in Germany. There are some faunstic records published as well. I now read the paper of Speight & Sommaggio 2010 more carefully now, I did not know it. I wonder why it was necessary to designate a lectotype of Syrphus dives Rondani for a single faunistic record from Switzerland. Unfortunately the authors did not redescribe the taxon respectively the lectotype specimen or give a clear definition of it. The syntype series consists of more than one species but they did not give any comment why and how they have chosen the lectotype and therefore the identity of dives Rondani. Following the ICZN all remaining four syntypes become paralectotypes automatically with designating a lectotype independently to which species they belong. At least in this detail they did not act conform to the ICZN . But the give a first, helpful key to this group. |
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