Diptera.info

Posted by Will van Niekerk on 10-05-2013 18:43

Very similar to one that John Smit suggested might be Acrosticta apicalis, on this thread:

http://www.dipter...d_id=44452

This one about five metres from the same spot and broadly similar (but without the appearance of a particularly elongate abdomen)... so possibly the same.

Location: Chongwe District, Lusaka, Zambia.
Habitat: Sandy, disturbed ground. Quite a cluster on what were probably guinea-fowl droppings.
Date: 04 March 2013.
Size: Small... 6mm or thereabouts.

UPDATE - title updated from 'Ulidiidae - Euxesta/Acrosticta?', as family corrected by Nosferatumyia

Edited by Will van Niekerk on 10-05-2013 20:16

Posted by Nosferatumyia on 10-05-2013 19:21

It looks to be a platystomatid around Elassogaster, indeed, see: http://www.diptera.info/forum/attachments/back_2.jpg -- the cell bcu is entirely blunt, and also long postocular seta can be seen if to lighten some pictures of January 2012, where the same fly was depicted (I have omitted it on my way to Astralia).

It is DEFINITELY NOT Acrosticta.

Posted by Will van Niekerk on 10-05-2013 20:15

... So back in January 2012, I got the genus close but the family wrong in my original guess?
Should I be proud or ashamed?

Thanks, I'll update titles of both threads to reflect family shift/possible genus.

Are there any (External) details that could help confirm genus? They were jumpy little things, so I didn't get all-inclusive images, but there are certainly a few more.

Posted by Nosferatumyia on 10-05-2013 21:32

I do not consider this in emotional or ethical aspects. It is rather difficult to ID the family in this case, anyway, even for John Snit who certainly had some experience with these families.

Otherwise -- sorry, I do not ID Afrotropical Platystomatidae: the most comprehensive keys are those by Hendel (1914).

Posted by Will van Niekerk on 27-02-2016 19:06

(Not pestering, just leaving notes for my later convenience when i get one under a lens).

Using Hendel's 1914 Key, I think this should (!) be either Plagiostenopterina or Elassogaster. The distinction between the two hinges on 'Kleine Querader schief gestellt' vs 'Kleine Querader senkrecht gestellt', respectively.

Working on the assumption that I'm translating correctly, I cannot see anything in the way of cross-veins to distinguish this from (Australian) Plagiostenopterina in the gallery. So I'm leaning towards that, until I get clearer images and hopefully a few specimens when this years batch appear.

Posted by John Carr on 27-02-2016 20:59

You should read McAlpine's review of Australian Platystomatidae, but you may find that nobody alive knows for sure what the difference is. "The type species, E. metallica Bigot, is unknown to me (as it was to Hendel), but Hendel and all subsequent authors have interpreted Elassogaster, possibly correctly, as the generic concept that includes the well known E. linearis (Walker) (syn. Dacus sepsoides Walker) and some closely related African and Oriental species."

McAlpine, D. K. 2001. Review of the Australian genera of signal flies (Diptera: Platystomatidae). Records of the Australian Museum 54:113-199

Posted by Will van Niekerk on 27-02-2016 23:03

#10

Papers on flies get surprisingly dramatic from time to time. Thank you for directing me to McAlpine - for informative and entertainment value.

From a preliminary glance at the key therein. those two, McAlpine's Australian Elassogaster and Plagiostenopterina should be distinct by Elassogaster's bald face (and centre of scutellum), and Plagiostenopterina's dark longitudinal streak in the wing, at least within the key. If we were in Australia, I'd be leaning quite firmly towards Elassogaster.