Thread subject: Diptera.info :: Brachypterous Ephydridae

Posted by Paul Beuk on 21-12-2007 09:10
#1

Can someone give me a quick pointer to what brachypterous (or in this case polymorphic) species of Ephydridae we have in Northwestern Europe. I go a small sample of smallish Ephydridae from a pitfall which superficially look conspecific, but one specimen is brachypterous. I only have a very outdated key to dive into, so if someone has a lead for me to ease my struggle...

Posted by David Gibbs on 21-12-2007 10:47
#2

try Philygria (including Nostima)

semialata (Collin, 1913)
mocsaryi
nubeculosa
stenoptera

Posted by Tony Irwin on 21-12-2007 11:25
#3

None of the species David suggests has a macropterous form, as far as I know, although there are similar, related species that are macropterous (but they are not usually collected in pitfalls! :(). The only genus of which I am aware that has both macropterous and brachypterous forms in the same species is Limnellia - they are recognised by the spots on the wings. Both suturi and quadrata have been found as brachypterous forms (the subject of a paper which awaits completion - Oh, for a few more free days!! :@)

Posted by Paul Beuk on 21-12-2007 14:09
#4

Despite what you mention, Tony, it appears they are Philygria. I will check Hollmann-Schirrmacher's monography on Ilytheinae, that gives special reference to Philygria.

Posted by Tony Irwin on 21-12-2007 16:54
#5

Interesting ... I wonder if these are Philygria (=Nostima) picta - in this species both sexes have reduced wings, but the reduction is more extreme in the female (- sexual dimorphism rather than polymorphism). Among the Philygria that David suggests, semialata was originally placed in Nostima, distingished by plumose arista and two, rather than three, dorsocentral pairs (including pre-scutellars). It is a species that is most often recorded by pitfall trapping, in Britain associated with grassy heaths.
If you have found a different Philygria with fully macropterous and brachypterous forms, then that is certainly remarkable! In any case a good find! B)

Posted by Paul Beuk on 21-12-2007 19:56
#6

The specimens indeed have two pairs of dorsocentral setae and the arista has rather longish hairs dorsally. As far as I could tell (the specimens are at work and I am at home now for almost two weeks) the brachypterous specimen was a male and there were males among the other specimens as well. The fully winged specimens do not have really large wings, true, the tips just extend over the tip of the abdomen. I have not yet checked Hollman-Schirrmacher.

Posted by Paul Beuk on 22-12-2007 20:38
#7

Hollmann-Schirrmacher does not make me very happy. There is no key to all Philygruia species but only to those with a single row of acrostichals (my specimens have none). Furthermore, there are a number of species with 'reduced wings', which I think are similar to the 'macropterous' specimens I have (wing tip then probably at level of abdominal tip). But my brachypterous specimen is truely brachypterous, so wing even further shortened and narrowed, so that the wing venation is also reduced: the major veins are the radial veins and vein M1+2 (the costa extending to that vein), but no veins posterior of that because there practically is not any wing left there. Non of the species mentioned by Hollmann-Schirrmacher seems to want to accomodate that specimen of mine.
But there is one 'maybe': One way or the other, semialata is not mentioned by Hollmann-Schirrmacher... Due to some unclear references in the book I cannot be entirely certain why the species is not mentioned. Of the former genus Nostima only picta and flavitarsis are mentioned and according to him it should be substantiated elsewhere in the book why other species (he does not even mentioned which ones) are not discussed. Possibly semialata is one of them. Oddly enough, he mentions that THE species of Philygria are discussed in chapter 4.5. Well, not all of them it turns out.

Posted by Tony Irwin on 22-12-2007 22:01
#8

I think Hollmann-Schirrmacher only set out to monograph Philygria s.s.
In the process, his cladistic analysis suggested that Nostima should be included within Philygria, but he didn't deal with all the Nostima species (probably not having access to semialata among others).
From your description of the venation, they certainly sound like semialata. Collin figured the wings in his paper in The Entomologist - unfortunately don't have a copy here which I can scan for you. Let me know if you'd like a copy after Christmas!

Posted by Paul Beuk on 22-12-2007 23:00
#9

Do you need to ask? Yes, please!

Posted by Paul Beuk on 27-12-2007 21:25
#10

Today I received Tony's reprint in pdf format. Preliminary: The one true brachypterous specimen I have has the wign as illustrated for the semialata female (but in my recollection it was a male). However, all other specimens have significantly larger wings than was illustrated for the semialata male. So even if I am screwing up the sexes (plz, no comment required ;)) I think that the 'macropterous' specimens might be something very interesting. So,...
Anyone have material of semialata I can study? :D

Posted by Tony Irwin on 27-12-2007 23:03
#11

I know I have some in alcohol somewhere (presumably yours are the same) - I may be able to sort them out next week .... (unless someone has some more accessible!)

Posted by Paul Beuk on 04-01-2008 09:33
#12

Well, the brachypterous specimen is P. semialata, a female. Not previously recorded from the Netherlands.
The 'macropterous' specimens actually have much bigger wings than I remembered. That is probably due to the fact that the same sample also had some brachypterous Chloropidae of the same size and coloration (in alcohol all those lovely dust patterns on the Ephydridae are invisible). These 'macropterous' Philygria were indeed Philygria and, oddly enough, they were P. picta, precisely the other species with two pairs of dorsocentral setae and no acrostichals. Any thoughts on what the chances would be that both occur together?

Posted by Tony Irwin on 04-01-2008 15:16
#13

Despite its widespread disribution (from Canada to Guatemala in the Nearctic and from the Azores to Japan in the Palaearctic), not much is known about the ecology of Nostima picta . It probably has a fairly wide habitat range, so it is quite possible that both species will occur together.