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Machimus/Tolmerus driving me crazy.

Collected 7 specimen of these creatures. All were caught in Broom (Cytisus sp) on dry soil near Souesmes, Sologne, France. They are similar to T. atricapillus but they are larger, all are about 18-19 mm. Abdomen and thorax dusted golden brown, most hair is yellow, bristles on legs all black, 2-4 bristles on margin scutellum. Beard upper side black, lower side red! Hairs on elongation sternite 8 red! and some black. Postocular bristles red! and black. Legs with lots of red/brown. In appearance and behaviour distinctly different from T. atricapillus. As mentioned they are larger, golden brown and prefer to hang in Broom, more then 50 specimen were hanging there in an area of 50x50 meters, temperature about 30 C. On the bare ground Asilus crabroniformis ruled, over 15 specimen. Keys by Seguy and Engel bring no satisfying solution. Is this maybe a special form?

Edit of tuesday september 6.

Compared my male Loire specimina with 10 randomly picked male specimina of T. atricapillus from the local Museum. I checked them basically for i had little time.

All 10 Dutch specimina had black postocular bristles, a black and white (sometimes yellowish) beard (mystax), and black hairs on elongation of 8th sternite. All but 1 were smaller in size. All Loire males had a black and red beard, more red than black postoculair bristles and red hairs on elongation with some sparse black.

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Maybe this helps......space between eyes is half of the size of one eye.

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Hi Reinoud
Size is not shocking to Tolmerus atricapillus.
I find the picture all the criteria of this species, except the reddish color and facial swelling is low prominent, unless the picture is misleading.
But I do not know what else it could be other that T. atricapillus.

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Thanks Cristophe! I have to agree but it keeps on bothering me....Size is very variable, i know. But i have seen hundreds of atricapillus in NL. In my collection average size is about 13 mm and none with red hair or bristles. Average of the red haired (7 specimina) is 17mm. All of these share red hair and bristles and golden brown dusting. I also caught a normal one but not in the broom field. It is against the odds. wish there was an expert who had been there to share the experience because i was convinced i collected an entirely other species than T. atricapillus. But when i used keys of Seguy and Engel i ended up there. On the left Redbeard male and on the right Normal male caught in the forest nearby. Please note difference in colour dusting thorax.

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Following pictures of male and female in their tipical posture and very much alive.

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Female

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It's not for me Tolmerus atricapillus.
Check if it Machimus chrysitis, first the last sternites and hypopygium.

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Thanks again Christophe!

Description fits better but there is still a problem. Scutellum marginal bristels: 2-3 with all specimina and black. Hypopygium has not the tipical shape of M. chrysitis...:S

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Just to keep it up there :| Has anybody got a clue?

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Put them under the microscope again:

Presutural hair: very short, much shorter than average T. atricapillus.

Orbital bristles: Mostly white with T. atricapillus mostly black.

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I still want to know! If someone has an idea or question let me know!

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I do not know if Tolmerus atricapillus calceatus still exists. Although i'm still convinced this is a different species. Mostly because of different behaviour, posture, size and colour. :) Is there a Machimus/Tolmerus expert in the house??????

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I think this problem is solved (almost). Update will follow on this solistic thread.

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This is Tolmerus calceatus (Meigen, 1820) Publication will follow somewhere in the future Rehabilitation of a species supported by DNA analysis.

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Congratulations|t

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Good job Reinoud!

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And here it finally is: https://www.researchgate.net/publication/328642153_Tolmerus_calceatus_Meigen_confirmed_as_a_valid_species_separate_from_Tolmerus_atricapillus_Fallen_Diptera_Asilidae?fbclid=IwAR1hI423wnFma8Lbv-1KQ-b2CsYhhDcNJTfw9gzgSw8iU1-awk1_KeUztU8

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Very good Job! Thanx Reinoud |t