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habitus illustration: female of Torymidae

Female of Torymidae

Torymids have a wide host range with both plant and insect eating species. As in some eurytomids, torymids associated with gall-forming insects devour just about anything in the gall, including other parasites, inquilines, and plant tissue. Thus some entomophagous species appear to be fairly omnivorous, and the adult female is the factor which determines the host range of her progeny. Torymidae is currently divided into 2 subfamilies (Grissell 1995): Megastigminae and Toryminae. Two other families, Agaonidae and Ormyridae, have been placed in or out of the Torymidae on various occasions. The phylogenetic position of some of the subfamilies of Agaonidae is still in doubt, and it is possible that some may belong to Torymidae (Grissell 1995). In the Nearctic, Sycophaginae (often called Idarninae) was once placed in Torymidae (Grissell 1979) but more recently was transferred to Agaonidae (Boucek 1988). There is still some debate on whether this placement is correct. The ormyrids have often been placed as torymids because of their enlarged hindcoxa and reduced stigmal vein, but they have also been placed as pteromalids based upon the absence of an exserted ovipositor and the presence of "otherwise pteromaline-like" characters (Riek 1970). Because we cannot currently contribute any concrete alternatives, it is easier to recognize the agaonids and ormyrids as separate families until a broader overview of the Chalcidoidea is available. The Nearctic torymids were most recently treated by Grissell (in Gibson, et al. 1997) and are classified as follows:

Megastigminae: 1 genus, 25 species. The genus was revised by Milliron (1949) who included a key to the world genera.

Toryminae: 18 genera, 147 species. Burks (1969a) gave a key to the 3 Nearctic species of Physothorax which was updated by Boucek (1993). Grissell (1976) arranged the 99 Nearctic species of Torymus into 5 species groups, gave keys to these groups, and revised the 61 western Nearctic species. The genus Monondontomerus (13 species) was revised by Gahan (1941). The Nearctic species of Podagrionini were revised by Grissell and Goodpasture (1981).
STATISTICS: Number of world species: about 900 (200 Nearctic); number of world genera: 65 (21 Nearctic).

BIOLOGY: Megastigmine torymids, in the New World, are entirely phytophagous, mostly within rosaceous and coniferous seeds. The major plant genera known to host these wasps are Abies, Cedrus, Chamaecyparis, Ilex, Juniperus, Larix, Picea, Pseudotsuga, Tsuga, Amelanchier, Rosa, and Pistacia (an introduced species) (Milliron 1949, Grissell 1989). In the Old World, a few entomophagous species are known which attack Cynipidae as well as a few other gall or seed-feeding Hymenoptera and Diptera (these records, however, are not numerous nor particularly well documented).

Torymines are diverse biologically but most are ectoparasitic upon larvae in galls or enclosed in plant tissue such as stems or seedpods. The most common families of gall-forming hosts are Cecidomyiidae and Cynipidae but Tephritidae and Psyllidae are also attacked. The larvae of many other families of Hymenoptera and Diptera serve as hosts, as do a few families of Coleoptera and Lepidoptera. A large number of species (all Podagrionini) attack mantid eggs. Several species have been reared from eggs of Lepidoptera, Heteroptera, Homoptera, and Coleoptera. A few phytophagous species are known from Malus, Crataegus, Ilex, and Acer seeds.

DISTINGUISHING CHARACTERS: Female torymids are fairly easily distinguished by the exserted ovipositor sheaths which project clearly from the metasoma. (In some specimens of other families the ovipositor, itself, may slip out of the metasoma as a hairlike, bare spine, but in torymids the coverings of the ovipositor (i.e., sheaths) are permanently exserted and cannot be retracted.) The family Agaonidae is also characterized by the exserted ovipositor sheaths but is separated from Torymidae by the forward-projecting head and the mandibles modified with an elongate, rasplike appendage. Unfortunately at least a few species in almost all other families of chalcidoids have exserted ovipositor sheaths, so that care must be taken when using this character alone. Another character we find useful is that torymids almost always have the stigmal vein essentially sessile (shortened) while similar appearing (i.e., with exserted ovipositor) pteromalids and eupelmids have an elongate stigmal vein. A character that also works well in female torymids, but is not always readily visible, is that the cerci of the last tergum are exserted, being longer than wide, and a small flap (epipygium) is present at the posterior margin of the tergum. Other chalcidoid females have the cerci more or less "bumplike." In the few pteromalids with exserted cerci, there is no epipygium and the ovipositor is not exserted. The aberrant tribe Podagrionini may be characterized by its "torymid" characters, plus the enlarged hindfemora as in the Chalcididae. Male torymids are generally less easily separated than females (because they lack the obvious ovipositor), but the relatively short stigmal vein and exserted cerci are often enough to distinguish these from specimens of other families.

COLLECTING: Torymids are often swept from shrubbery or trees, especially if galls are present. In general, there may not be much torymid diversity on a single plant species, but often within a collecting area one can find a diversity by collecting off different plant species. Small-flowered composites and umbellifers are good for sweeping. Rearing almost any type of gall will usually yield a few (or many) torymids.

DISTRIBUTION: Megastigmines are predominantly of northern distribution. Torymines are found throughout the world in small numbers, except for the speciose genus Torymus, which is essentially Holarctic in distribution.

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