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Very small fly on the window, 24/11/2020 (Spain: Girona: Catalonia: Beuda).

Identification following Marshall & Richards in McAlpine et al 1987 Manual of Nearctic Diptera to Leptocera, but then stopped as arriving to a cul-de-sac (as there are some genera missing in that key, present in Spain, Carles-Tolrà, 2002).

Wing apparently functional;
halter with knob
Cell cup open to wing margin, CuA2 absent, and cell bm confluent with cell dm;
CuA1 never reaching wing margin, except as a weak fold.
LIMOSININAE

Disc of scutellum bare.
Margin of scutellum always bare between apical bristles
Mid tibia with a long preapical ventral bristle

Mid tibia with an apicoventral bristle
Scutellum with six marginal bristles (so it's not Peremis fenestralis)
Leptocera Olivier (four subgenera).

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Mid tibia with a long preapical ventral bristle and with an apicoventral bristle
Scutellum with six marginal bristles

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Hi Rafael,
You have missed the small setae on either side of the scutellum just behind the thorax (they can be hard to see) Leptocera nigra seems most likely, to confirm if it is nigra there will be along postero-apical bristle that extends downwards over and close to the metatarsus and acrosticials will all be short

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Thanks for your answer :P



1. There are 8 lateral marginal setae on scutellum

2. I have been looking the mid leg of L. nigra to compare, here: http://www.spessa...leg3a.html and it looks similar.

On my fly mid basitarsi there is:
- one apical ventral setae
- one apical posterior setae
(any of them extends downwards over and close to the basitarsus)
(when you say "metatarsi" do you refer to hind tarsi?: there are only a row of hairs there)

3. There are several rows of setae on mesoscutum (more than the usual for calyptrata) and it’s hard to say which rows are achrosticals, there could be some long setae in there ... or not

4) Do you know which sex it is?

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On the mid tibia, postero apical, extends directly downwards, it's very close to the basitarsis and can be hard to see even though long and strong. If the acrosticials aren't distinctly longer and stronger than other setae then should be nigra. Looks like a male from the shape.

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Hi David (?), is it possible the quetotaxy of the mid leg of the male of this species is different from the one of the female ?

In the link shown before there is a mid leg of the supposed male; but there are pics of other specimens, a different one from a supposed female: http://www.spessa...leg2a.html

Anyway, the apical tibial setae next to basitarsus could be hidden in my pictures...

In this other picture it seems there are no long setae on achrostical postion, so we can say this is Leptocera nigra:

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Finally I understood that Leptocera nigra thorax has hairs (that look like small setae), small achrosticals and big dorsocentrals. "Acrosticales indistinctes de la pilosité du fond."(Séguy)

L. fontinalis and L. oldenbergi have hairs, big achrosticals and big dorsocentrals (Acrosticales distinctes de la pilosité du fond.)

I found my specimen different from this one Leptocera nigra:
http://www.microp...0nigra.htm but now I understood this one has the dorsocentrals fallen.

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There is no elongate posteroapical seta on the mid tibia, ruling out Leptocera nigra. This is either Leptocera caenosa or Leptocera fontinalis (based on the key to European Leptocera in Rohacek (1982)), I'd be inclined to say L. caenosa since the arista appears to be fairly long-haired but the palps or terminalia aren't visible to confirm.

Gregory Kuwahara at https://www.inaturalist.org/observations/65528643