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Hello, I have some strange specimens of the Winthemia. I need your advice how to separate the variegata-group from the quadripustulata-group. The following specimen have a lot of black bristles behind the post-ocular hairs, so it seams, that it should be in the variegata-group, but other characters show different. Sorry that in my photos black bristles are not visible.

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Middle black stripes on the thorax

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Abdomen with equivalent hairs, without D-discal bristles

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Erikas, I hardly dare to ask, but

Are you sure it is Winthimia ?

I don't see any hairs on the eye.

Is that a trick of the light / background ?


Theo

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Theo,
yes, it is the trick of the light, you can hardly see a few hairs on the left eye. I identified them as quadripustulata first, but then I noticed, that vertex of these specimens is wider, and parafacial golden in contrast with others.

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OK

The vertex is too wide indeed for male quadri.

I will have a look at it, but not tonight.



Theo

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the black hairs behind occipital row are often difficult to see in variegata, so if you see them, I have no doubt they are there.

Other points:

quadripustula is not reddish at side of tergites, variegata is.

The calypter is purely white in quadripustulata and distinctly yellow in variegata.

Last point is not visible in your pictures.

The vertex is very broad. Is this a male ??


Theo

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In variegata, both in male and female sex, the hairs on tergites are long and erect,

It does not correspond to your last picture.


Theo

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The calypter is purely white and it is the male.

Thanks for your experiance, Theo.

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Specimens like this are dominant in Lithuania, but we have the usual quadripustulata as well. What about the Netherlands?

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if it is a male, it is very aberrant, since the vertex is much much broader than in my males Winthemia, whether quadripustulata or variegata. If you have one only like this, it might be some weird intersex. If you have more.... that is unlikely.

Male quadripustulata should have more dense hairs on ventral side of tergite 4 and 5, see key in Tschorsnig & Herting


Theo

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They indeed have more dense hairs on ventral side of tergite 4 and 5, the male postabdomen is well developed. I could dissect my specimens, but Tschorsnig does not provide figures of the Winthemia genitalia...