J. HVM. RES. Vol. 10(1), 2001, pp. 29-54 The Australian Species of Pachynenron Walker (Hymenoptera: Chalcidoidea: Pteromalidae) Gary. A. P. Gibson Systematic Entomology Section, Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6 (E-mail:
[email protected]) Abstract. — Four species of Pachyneuron Walker are recognized from Australia: P. aphidis (Bouche 1834), P. emersoni Girault (1916), P. nelsoni Girault (1928) and P. rieki Gibson, n. sp. A lectotype is designated for P. emersoni. Pachyneuron kingsleyi Girault (1916) is formally synonymized with P. emersoni (new synonymy). Males and females of the four species are differentiated by key features, illustrated, and compared with morphologically similar species present in other regions. Pachyneuron emersoni and P. rieki are restricted to Australia, P. aphidis and P. nelsoni are more widely distributed. World distribution is summarized for P. aphidis and P. nelsoni and Australian distribution and host records are compiled for all the species. Pachyneuron Walker consists of about 50 recognized world species with the follow-ing distribution as listed by Noyes (1998): Afrotropical (4), Australasian (5), Oriental (8), Neotropical (11), Nearctic (12) and Pa-learctic (28). Szelenyi (1942) gave a key to the Palearctic species, Graham (1969) to the European species and Kamijo and Takada (1973) to the Japanese species, but in other areas the species are unrevised and some distributional records listed in Noyes (1998) are questionable. Most spe-cies are hyperparasites of Aphididae or of other plant sucking Hemiptera (Coccoi-dea, Psylloidea) through their Braconidae (Ichneumonoidea) or Aphelinidae and En-cyrtidae (Chalcidoidea) primary parasit-oids, or are primary parasitoids or hyper-parasitoids of the predators of these plant pests (Diptera: Syrphidae, Chamaemyi-idae; Coleoptera: Coccinellidae; Neurop-tera: Chrysopidae). Some species are also recorded as pupal parasitoids of mining or gall forming Diptera (Agromyzidae, Chlo-ropidae, Cecidomyiidae) or as egg para-sitoids of several families of Lepidoptera (apparently as hyperparasitoids), and there are rare records from other families of Diptera, Hymenoptera and Coleoptera (Noyes 1998). Boucek (1988) listed four species of Pa-chyneuron from Australia, but suggested that P. ki)igsleyi Girault was probably only a form of P. emersoni Girault and estimat-ed that there were probably five valid spe-cies. Based on the very few localities listed by Boucek (1988) for the species and the absence of other than the original publi-cations of Girault on Australian Pachyneu-ron, the genus might be thought to be rel-atively rare and unimportant. However, three of the four recognized species are common and two are widely distributed throughout Australia (Figs. 49-51). I ex-amined over 2,000 specimens for this study and the species undoubtedly are major factors in the population dynamics of Australian aphids and their syrphid predators. The purpose of this study is to differentiate the Australian species and to tabulate the known hosts and distribution of the species in Australia. MATERIALS AND METHODS Literature citations for W.H. Ashmead and A. A. Girault incorporate the paper numbers, between brackets following the
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