female Aenigmatias
In a previous post “What is so great about phorids,” I showed photos of 3 strange looking phorid flies. The first of these is a female that has a body form we call limuloid, after the horseshoe crab Limulus. This is a defensive body form that allows the female fly to live within a nest of ants or termites. The rounded body form, with few large setae, makes it difficult for an ant or termite to grab them (at least, that is the theory!). They used to be all categorized in a group called the Aenigmatiinae, but our knowledge of phorid phylogeny is changing as we know more and more about the groups, so the Aenigmatiinae probably won’t be around as a name much longer.
The name bearing genus for this former group is Aenigmatias, a northern hemisphere genus that includes about a dozen species. The females have a classic limuloid shape, whereas the males are much more normal in appearance and carry the females around in copula. These flies are parasitoids of Formica ant pupae, although no modern work has been done on their natural history.
in copula pair of Aenigmatias
All of the rest of these flies live in termite nests. That makes me skeptical, in part, that they form a natural group with Aenigmatias. Here is the Southeast East Asian genus Epicnemis:
female Epicnemis
The Old World tropical genus Psyllomyia is found in both Africa and Southeast Asia:
female Psyllomyia
The Southeast Asian genus Palpiclavina is less limuloid than some of the others, as it has retained wings and large setae:
female Palpiclavina
But the most limuloid of the phorid females are those of the genus Thaumatoxena, whose abdomens are completely fused into a carapace-like shell:
female Thaumatoxena
Note that the large round things on the head are not eyes; they are antennae. The true eyes are extremely small, and on the very side of the head.
Great photos Brian. It is interesting that the female Thaumatoxena has such large setae if indeed their reduction is linked to ants/termites being able to grab them. Or perhaps their setae are thin enough not to be grabbed, like we see with pin cushion millipeds and ants?
Relative to some other phorids, they are reduced, but I know what you mean. Someone needs to study Thaumatoxena natural history,
Of the various structures that I (a myrmecologist-in-training) know of belonging to symphiles and xenobionts I’ve never heard of setae used in this manner, in either myrmecophilous or termitophilous species. I suspect that in general they are too insubstantial and relatively easy to remove from the body wall (compared to, say, a horny outgrowth of the cuticle). Generally with structures used in such a manner I think of things like the pronotal horns of Cremastocheilus or the antennae of certain Paussine carabids. However, I’d be happy to be told otherwise!
Brilliant photos!
How good are the taxonomic characters in Phoridae females?
It depends on the group. Usually, male characters are better, except in parasitoids, where female ovipositors are highly distinctive.