Thread subject: Diptera.info :: Anthomyiidae Id

Posted by tristram on 19-10-2018 23:30
#1

I caught a largish male Anthomyiid in Whiteknights Park, Reading, UK on 2018-08-18.
In Michael Ackland's draft key to British Anthomyiidae it keys out to Delia criniventris but the genitalia do not match.
In particular each cercus has a triangular backward-pointing 'tooth' on its inner edge.
Has anybody got any suggestions?
This is a lateral view:

Edited by tristram on 19-10-2018 23:31

Posted by tristram on 19-10-2018 23:32
#2

An oblique view

Edited by tristram on 19-10-2018 23:33

Posted by tristram on 19-10-2018 23:33
#3

And a posterior view:

Posted by tristram on 20-10-2018 11:54
#4

A bit more info:

The fly does have the expected characteristics of D. criniventris: it is largish (Hylemya vagans size), has distinctly yellowish hind tibiae, and there are long hairs on the lateral edges of tergite 3 which curl down and backwards under the tip of the abdomen.

It is only the backward-pointing triangular 'teeth' on the cerci that stop me from marking it as criniventris and moving on.

In the images in Ackland's draft key I can find no species with long cerci that have such 'teeth'.

Edited by tristram on 20-10-2018 11:59

Posted by tristram on 14-12-2019 22:20
#5

I have identified a second one of these in my collection. This one was take in Whiteknights Park, Reading on 2019-08-18 (exactly one year later). It also keys to Delia criniventris and the cerci each have a backward-pointing 'tooth' in exactly the same place as the first one.

After seeing my pictures of the 2018 specimen, Phil Brighton suggested the teeth might be stuck-together hairs. At the time I wasn't convinced but in the 2019 specimen the teeth show very clear striations consistent with them containing hairs and I am now inclined to accept that explanation.

Edited by tristram on 14-12-2019 22:21

Posted by javanerkelens on 15-12-2019 11:59
#6

It sometimes is indeed very confusing with criniventris.
We have several Delia species with those long hairs on the tergites/sternites (penicilliventris, penicillosa, penicillaris, piliventris and criniventris)
The D. penicillaris descriped in the key from Ackland is in fact the description of D. penicilliventris. (D. penicillaris is only known from Italy, Greek mainland and Switzerland)

- With the tibia partly yellowish = criniventris
- Legs all dark and sternite III widened on posterior margin = penicillosa
- Legs all dark and sternite III not widened on posterior margin = penicilliventris
- Legs all dark and sternite III covered with dense setulae on whole disc = piliventris
D. penicillaris is very similar to D penicilliventris, but can’t give you right now the precise differents between those two species, only it is very unlikely this species occur in the UK.

The tuft of hairs on the surstyli are indeed present, but sometimes they are not visible in front and sometimes they are (in your case..)

I also send you some genital photos of my D. criniventris, …… I hope they will be shown, if not, ..I have to reduse them all in size and this probably will take a while.

Johanna

Posted by javanerkelens on 15-12-2019 12:00
#7

1

Posted by javanerkelens on 15-12-2019 12:01
#8

2

Posted by javanerkelens on 15-12-2019 12:01
#9

3

Posted by javanerkelens on 15-12-2019 12:02
#10

4

Posted by javanerkelens on 15-12-2019 12:02
#11

5