Where do antennomeres go? Why is Platygaster 10-10 in this respect? Not 10-11? Many Hymeoptera males that have one more segment than the females, some, two more. Where do the missing antennomeres ("segments") go.

Well insects only have three segments, the scape, pedicel and flagellum. The flagellum in the wasps is subdivided into several more little segments that are called "antennomeres", since they are not true segments. But why does Platygaster have a female : male ratio of 10:10 in this respect, not 10:11, as I might expect? Although, there are several other groups that also have a similar ratio, this is the one that I study most, and is the basis for the question.

Metanopedias brunneipes (Ashmead) may provide a clue. Although there are ten antennomeres in the male antenna, it appears at first glance through the microscope that there are only 9. But after I cleared an antenna (KOH), and mounted it on a slide in CMC-10, with a little stain (CMC is carboxymethylcellulose, and is a super medium for phase contrast examination), the fourth antennomere was clearly seen to have been flattened, laid to the side of the fifth, and partially fused with the fifth. In fact, it appears that both the fourth and fifth anetennomere share only one articulation, with the third. Four is fused distally with five. And it is situated laterally on five. It gives the appearance, when examined with a dissecting microscope, of being a 9 segmented antenna.

My question is, could this be the mechanism that provides 10 antennomeres in male Platygastrinae? If so, it is most obvious in the contorticornis group (which to me is a genus waiting to be defined), because these species have very large "plate organs" associated with the side of the so-called fourth antennomere - A-IV, the male "sex segment"., as we call it. Does the large plate organ represent a reduced, laterally oriented and fused 4^th antennomere, as I suspect? It is certainly not a typical tyloid, in the usual sense, and perhaps, not in any sense. Where do "tyloids" come from?

I provide here two simple pictures, one drawn from the cleared antenna of Metanopedias brunneipes mounted on a slide (Fratelli 55x oil objective, 6x ocular, camera lucida on my special "Platyscope" a modified Graf Apsco/ Leitz with internal 1.25 auxilliary lense, with extended tube length), and an SEM photo of antennomeres II-IV or V from Platygaster obscuripennis Ashmead. The photo was cleaned up from the original using Adobe Photoshop.

Though simplistic, the idea could be sound. Then, the various groups of species lumped into Platygaster (actually constituting several different genera yet to be described or characterized) actually show several different lines of reduction and modification from this simple lateral migration and fusion. Numerous photos and drawings are available to amplify the concept, but at least for now, I would like to consider this through the contorticornis group, which includes species with the large plate organ like that of P. obscuripennis.