Synonyms and other taxonomic changes
Formerly, tribe Polysphinctini, which Townes & Townes (1960) regarded as a "specialized offshoot" of Ephialtini (Pimplini of Townes). This was tantamount to saying that Ephialtini are paraphyletic, which Gauld & Dubois (2005) confirmed by cladistic analysis, resulting in their relegation of the group to genus group status.
18 genera worldwide; 35 spp. in 11 genera north of Mexico(1)(2)
The taxa of the Polysphincta genus group (Pgg) are parasitoids of free living spiders, but those of the genus Schizopyga apparently sting the spider to death before laying an egg upon it. Schizopyga is only marginally different in this habit from Zaglyptus, which, however, lacks important characters of the Pgg (e.g. different type of ovipositor) that exclude it from the Pgg. Zaglyptus invades nests of spiders that stay with their eggs and stings the spider to death and then oviposits multiple times on the eggs of the spider. The Zaglyptus larvae consume the eggs and usually also the body of the mother spider, and sometimes Zaglyptus females also oviposit on the body of the mother spider. The species of the ephialtine genus Tromatobia are parasitoids of spider egg sacs, and species of Clistopyga, which are more similar in many respects to the genera of the Pgg, are thought to parasitize eggs sacs of spiders that are deposited in crevices. Species of another ephialtine genus, Iseropus, are gregarious parasitoids of lepidopterous larvae in silken cocoons or cases. Therefore, it is not difficult to conceive ways in which the taxa in the Pgg may have evolved.
Townes, H. K. and M. C. Townes, 1960. Ichneumon-flies of America North of Mexico: 2. Subfamilies Ephialtinae, Xoridinae, Acaenitinae. United States National Museum Bulletin 216, part 2, vii + 676 p.
Gauld, Ian and Jaques Dubois, 2005. Phylogeny of the Polysphincta group of genera (Hymenoptera: Ichneumonidae: Pimplinae): a taxonomic revision of spider ectoparasitoids. Systematic Entomology 31(3): 529-564.