American Entomological Institute

A new species, Collyria catoptron, is described from Gansu Province, China. It is an egg-larval koinobiont parasitoid reared from Cephus fumipennis, a grass-mining sawfly that attacks wheat. Collyria catoptron is currently being evaluated as a possible biological control agent for Cephus cinctus in North America.

Various bacterial species in the genus Pasteuria have great potential as biocontrol agents against plant-parasitic nematodes, although study of this important genus is hampered by the current inability to cultivate Pasteuria species outside their host. To aid in the study of this genus, an extensive 16S rRNA gene sequence phylogeny was constructed and this information was used to develop cultivation-independent methods for detection of Pasteuria in soils and nematodes. Thirty new clones of Pasteuria 16S rRNA genes were obtained directly from nematodes and soil samples. These were sequenced and used to construct an extensive phylogeny of this genus. These sequences were divided into two deeply branching clades within the low-G + C, Gram-positive division; some sequences appear to represent novel species within the genus Pasteuria. In addition, a surprising degree of 16S rRNA gene sequence diversity was observed within what had previously been designated a single strain of Pasteuria penetrans (P-20). PCR primers specific to Pasteuria 16S rRNA for detection of Pasteuria in soils were also designed and evaluated. Detection limits for soil DNA were 100-10,000 Pasteuria endospores (g soil)(-1).

The phylogenetic relationships of the suprageneric groups of the ichneumonid subfamily Pimplinae (Hymenoptera) are re-assessed using 166 morphological and biological characters for 162 species, representing all of the available described genera and subgenera. The cladistic analysis was repeated using abstracted genera, re-codedfrom the ­initial set of species, as terminal taxa. The topology of the resulting cladograms was similar. In the first (primary) analysis several genera (including Neotheronia, Itoplectis, Dolichomitus, Dreisbachia, Polysphincta, Oxyrrhexis and Zonopimpla) were not retrieved as monophyletic groups; however, all except the last were found to be monophyletic in the second analysis. These results suggest that using abstracted taxa may force a ‘false monophyly’ on the preselected groups. Thus we reject the use of such abstractions, preferring instead to use exemplar speciesthat together show much of the variation that occurs within a hypothesizedgenus. Within the Pimplinae three major groupings were recognized, the Delomeristini (including the Perithoini syn. nov.), the Pimplini and the Ephialtini. Within the Pimplini, two generic groups were recovered, the Xanthopimpla and Pimpla genus-groups, but a third postulated group, the Theronia genus-group, was found to be paraphyletic. Within the Ephialtini five groups wererecognized, the Pseudopimpla, Alophosternum, Camptotypus, Ephialtes and Sericopimpla genus-groups. The spider parasitizing complex of genera (the Polysphincta genus-complex) was found to nest within the Sericopimpla genus-group confirmingthe placement of Polysphinctini as a synonym of Ephialtini. Problems with the status of some existing genera are highlighted, but formal nomenclatural changes are not proposed. The ancestral Pimplinae are hypothesized to have been solitary ectoparasitic idiobiontson weakly concealed immature Hymenoptera. The major radiations within the Pimplinae are shown as: (1) a progressive exploitation of cocooned, then weakly cocooned, lepidopterous pupae in the Pimplini leading to idiobiont endoparasitism; (2) increasing specialization to attack hosts deeply concealed in wood in the Ephialtes genus-group, and (3) specialization on a variety of cocooned hosts, including spider egg sacs, leading to koinobiont ectoparasitism of spiders. A brief synopsis of the distribution of the group is given, and some biogeographical inferences drawn. The group is presumed to have originated and radiated on Laurasia; no evidence for trans-Antarctic relationships can be found.

The monophyly of the ichneumonid clade Pimpliformes is established and the phylogenetic relationships of the eight component subfamilies are resolved. The clade (Acaenitinae + (Diacritinae + (Cylloceriinae + (Diplazontinae + Orthocentrinae)))) is the sister‐lineage to the clade (Pimplinae + (Rhyssinae + Poemeniinae)). The Nearctic genus Cressonia Dasch is transferred to the Diacritinae from the Orthocentrinae. Tribes are not recognized in the Acaenitinae as the Coleocentrini ( sensu Townes, 1971) is paraphyletic with respect to the Acaenitini. The Cylloceriinae is recognized as comprising three genera, Cylloceria Schiødte, Allomacrus Förster and Sweaterella gen.n. The Orthocentrinae, including the Helictinae of authors, is shown to be monophyletic, but the latter is clearly shown to be paraphyletic if the Orthocentrus genus‐group is excluded. The Pimplinae comprises four monophyletic tribes: the Delomeristini, consisting of Delomerista Förster and Atractogaster Kriechbaumer; the Perithoini trib.n., which includes only Perithous Holmgren (= Hybomischos Baltazar syn.n.); the Pimplini, which includes the Theronia genus‐group as well as the Pimpla genus‐group; and the Ephialtini, which includes the Polysphinctini syn.n., a monophyletic group that previously rendered the restricted Ephialtini paraphyletic. The tribe Delomeristini is the sister‐group to the clade (Ephialtini + (Perithoini + Pimplini)). The subfamily Poemeniinae is recognized as comprising three tribes: the Pseudorhyssini (trib.n.) which includes the single Holarctic genus Pseudorhyssa Merrill; the Rodrigamini (trib.n.) which includes only the Costa Rican genus Rodrigama Gauld; and the Poemeniini. The tribe Pseudorhyssini is the sister‐group to the clade (Rodrigamini + Poemeniini). The phylogenetic inter‐relationships of the genera of Poemeniini are resolved. A new genus from South Africa, Guptella (gen.n.) is described, and Achorocephalus Kriechbaumer is shown to be a synonym of Eugalta Cameron (syn.n.). The evolution of biological traits within the Pimpliformes is discussed with reference to the elucidated phylogeny, and zoogeographic patterns are outlined.

Abstract Acaenitus dubitator (Panzer) is found to be a koinobiont endoparasitoid of the larva of an endophytic beetle, Cleonis piger (Scopoli) (Curculionidae), in Britain, suggesting a similar mode of development for the ichneumonid subfamily Acaenitinae as a whole. The parasitoid can overwinter in its cocoon in one of two ways. Individuals overwintering as essentially unaltered mature larvae do not become adult the following summer, while those that overwinter as morphologically distinct prepupae are committed to pupate and become adult immediately afterwards. The change from mature larva to prepupa takes place in late summer, soon after the time of cocoon formation, but a proportion of mature larvae lie over in the first year, and perhaps subsequently. This appears to be an adaptation to life in a particularly harsh and uncertain environment. The egg, prepupa, and first, second and final instar larvae are described and figured. Previous interpretations of the cephalic sclerites of final instar acaenitines are revised.