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Can someone help me to clarify if this is Xylota florum or meigeniana? West coast of Sweden, it is a female with a body length of 12 mm, or slightly more. As I understand it, the size and the long hairs on the hind femura indicates florum, but the entirely dark hind tarsi indicates meigeniana.

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2nd picture.

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Hind leg.

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Last pic.

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I cannot see all the characters needed, but from these photos it appears a X. florum (hind femur is quite diagnostic)

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Thanks! What other details would you like to see? I still have the fly.

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Thanks krafttho, but no need :)

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The wings are distinctly darkened, so my gut feeling is meigeniana.


Theo

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I'm still thinking it's florum :). Hind femur hairs are so long (near 1/2 of hind femur width) with not equal height with each others, especially those at 1/ 4 and 3/5 of its length, and hairy area length is too long for being compatible to meigeniana

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The first pic shows the correct sight on the hind femur: we need to assess the anterodorsal hairs. Little as this may be: it looks different than the closeup of the leg.
So, are we very sure the closeup is from the right leg (hind) and angle (anterodorsal ) ?

And what about the dust pattern on the face ? Very useful feature !

@Valerio: this is clearly less than 80 % coverage, so no total fit to florum either.

Theo

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Ok, but what about hair height? It appears as non identical.

Sorry krafttho, can you please pin the specimen and get some oriented shots of its hind femur?

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I don't want to jump to conclusion. For me, it is at the moment inconclusive, there is no need to pin a name on it, nobody will die if we proposed the final call.
If we are looking at the posterodorsal hairs, unequal lenght means nothing.
And let's use all characters available: I love to see the dust pattern on the frons.

Theo

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Thanks for an interesting discussion, I did not know that this pair of species were so difficult. The detailed picture of the leg above is definitely the right hind leg. Here is another picture of the right hind leg from a slightly different angle.

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Here is a picture of the left hind leg.

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Head.

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And one more picture of the head, hopefully showing the details you asked for.

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Still a tough call. The dust pattern settles the matter at either florum or meigeniana, it supports meigeniana.

Did you flash the first picture of all ?
If not, in that case the mesopleuron / anepisternum is clearly shining, which would definitely settle it as meigeniana.
If you did flash, we might be tricked, though....

The hairing of femur 3 is still very confusing, it does not fit meigeniana neither florum for the reasons both mentioned previously.

Sorry not to be of more help.

If you have the specimen, check for the shinyness of the mesopleuron !


Theo

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Thanks once again! At least I was right when I found mixed characters for the two species. All the pictures above have been taken using a flash, so I just took some new photos in neutral daylight. The mesopleuron does not look very shiny to me, but I do not have any experience so I would be happy to hear what you say. I have also read that the hind tarsi should have the three inner segments yellow in female florum, whereas they should be black in meigeniana - any comments on that character? On my fly the hind tarsi are completely black.

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Other side. Difficult to get sharp pictures without a flash due to long exposure times.

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In your last photos, wings appear really darkened toward tip. I think this is a substantial thing confirming Theo idea about meigeniana; never seen or read about a florum with that pattern (even if it isn't used in keys vs florum). All the others characters, to me, appear more questionable/speculative than this.

I think we can conclude is meigeniana ...after long time :D

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OK, many thanks to both of you for your help, I really appreciate it! Best regards, Thomas