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Observed and subsequently sweep netted 15th July in my garden located in coastal farmland at 63 degrees N 32 m asl. I suspect it to be a male, and a magnicornis rather than fera. Both species are occurring in Norway, the latter being more common/widespread, but the records are probably somewhat ambiguous.

Any help appreciated as always!

Cheers Jørn

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Dorsal

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Head

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Tip of abdomen

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I think I see median marginals on tergite 2.

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Thanks John, I am so inexperienced in the clinal terms of Diptera, so I do not understand in which way your comment directs. Please elaborate.

I find the specimen to match the abdomen, claw and oe features for magnicornis in key of Tschorsnig & Herting, 1994 - translated by Rayner & Raper (2001), but I am unsure if the frons are broad enough for it, or if the frons points to fera. An experienced eye might tell?

Citation, from page 50:
Frons in males 0.68 - 1.08x, in females 0.94 - 1.28x as wide as one eye. Fore tarsus yellow, seldom brown.
The black longitudinal abdominal stripe ends almost always in a tip on tergite 5. Males: anterior claws almost
as long as the last 2 tarsal segments combined (fig. 146); frons as a rule without oe, seldom 1 oe present
.................................................................................................................................. fera L.

− Frons in males 1.10 - 1.39x, in females 1.27 - 1.55x as wide as one eye. Fore tarsus brown or black. Males:
anterior claws clearly shorter than the last 2 tarsal segments combined; frons with 1 or 2 oe ....................7

7. The black longitudinal abdominal stripe widens towards the end on tergite 5, seldom ending in a point. Males:
anterior claws longer than the last tarsal segment. Females: 4th segment of the fore tarsus clearly wider than
long..................................................................................................................magnicornis Zett.

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It is a female, the claws are much too short for a male.
Females are very difficult.
But in this case, the metatarsi are red, so I have little doubt it is fera.
The shape of the abdominal vitta is highly unreliable.

Theo

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Thanks, Theo! [Edit] I wrongly looked at the foreleg claws, not the hind leg (anterior) claws... I also understand that that all tarsomeres needs to be dark, and have probably greatly misunderstood the oe - outer orbital bristles problematics. Anyway - I will not give up!

Cheers Jørn

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You should look at the fore claws, indeed, although you can use any in this case. But in males it is much longer.
Since all females have 2 pairs of proclinate orbitlas, the feature is only relevant for males. The vertex is broad for a male, but narrow for a female ....

so sexing right is crucial here

Theo