Chalcidoidea, Latreille, 1817

Burks, Roger A., Krogmann, Lars & Heraty, John M., 2018, Simultaneous Discovery and Taxonomic Placement of New Extant and Fossil Genera of Herbertiinae (Hymenoptera: Chalcidoidea: Pteromalidae), Insect Systematics and Diversity (AIFB) 2 (5), No. 1, pp. 1-8 : 7

Chalcidoidea

Because Pteromalidae is currently an assemblage of taxa that may belong to a variety of family-level lineages, it is imperative to compare Exolabrum and Versolabrum with other subfamilies to ensure that they are properly placed. Because of the high amount of homoplasy and subjectivity in interpretation of the important features of many groups similar to Herbertiinae , placement of the two new genera is not straightforward. Preliminary molecular data (Heraty et al., unpublished data) provided no clear answer on the family placement of Exolabrum , although more gene regions indicated it as the sister group of Herbertia than of any other taxon.

Some other subfamilies of Pteromalidae are arguably similar to Exolabrum and Versolabrum , but are eliminated from consideration based on one or more features. Cleonyminae is very similar to Exolabrum , especially, based on a simple list of features ( Table 1), but was eliminated from consideration because of a lack of shared features with any of its tribes as defined by Gibson (2003). Because of the unambiguously complete notauli of Exolabrum ( Fig. 9 ), it is not similar to Cleonymini. It differs from Boucekiini in having a syntergum instead of a separated Mt 9. In Chalcedectini, the metatibial spurs are either absent or, if present, arise from a projection. Ooderini and Heydeniini differ from Exolabrum in a large number of peculiar features. This leaves Lyciscini as one of the groups most similar to Exolabrum , but Lyciscini almost invariably have a smooth median strip on the pronotum dorsally, which is absent from Exolabrum and Versolabrum ( Figs 9 and 14 ). Gibson (2003) discussed the subjectivity inherent in evaluating the divergent eyes of Cleonyminae and similar taxa, which renders that feature less diagnostic when there is doubt. The elimination of Lyciscini from consideration was confirmed by examination of the subforaminal bridge of Exolabrum ( Fig. 7 ), which had the sunken, separated bridge, and postgenal lamella similar to the state found in Herbertia ( Mitroiu 2008: fig. 29). In contrast, Lyciscini and other Cleonyminae possess a medially united postgenal bridge and no postgenal lamella ( Mitroiu 2008, Burks and Heraty 2015).

Asaphinae and Eunotinae were also strongly considered as the best placement for these genera, but these subfamilies apparently always have a flat subformaminal bridge instead of a sunken one ( Mitroiu 2008, Burks and Heraty 2015). Erotolepsiinae is also superficially similar to Exolabrum and Versolabrum , but is probably best defined by the presence of longitudinal dorsal carinae on Gt 1 (Bouček 1988), which are absent from the new genera.

Other chalcidoid families and subfamilies differ from Exolabrum and Versolabrum in many ways, although taxa with a noncollapsing gaster, such as Ormyridae and Leucospidae , were also considered for taxonomic placement. A noncollapsing gaster is defined as one where the gaster is strongly sclerotized and is mostly or entirely inflexible, but consisting of the usual number of terga. Ormyridae , especially, differs in having a reduced, flexible labrum ( Darling 1988). It should be noted that a noncollapsing gaster also occurs sporadically in other Chalcidoidea , including Heimbrinae (Eurytomidae) and Fusiterga Bouček in Coelocybinae ( Pteromalidae ), and thus can be considered homoplastic at the family level.

Given the homoplastic distribution of most of the characters consulted, we ultimately relied upon those that seemed the most consistent and informative: the labrum, the posterior surface of the head, and the possession of an oblique basitarsal comb ( Fig. 4 : BTC) that crosses the basitarsal notch. Most other Pteromalidae have a longitudinal basitarsal comb occurring along the edge of the basitarsal notch. These features led to placement in Herbertiinae , which was consistent with head shape and position (broad, directed ventrally) and mesoscutal and mesoscutellar shape, even if the new genera do not share characteristics of setation with Herbertia . This leads us to speculate that the apparently unique mesosomal setal features of Herbertia represent apomorphies of the genus, but not of the subfamily. Instead, Herbertiinae seems best defined by the following combination of features: labrum exposed and setose on external surface (not only along the margin), clypeus strongly transverse, subforaminal bridge separated and sunken, protibia with oblique basitarsal comb.

Figures

Figs 5–10. Exolabrum vannoorti n. gen., n. sp. Figs 5–6, female holotype. 5. Habitus, with close-up of prepectus on top right. 6. Head, anterior. Fig. 7, male paratype. Head, posterior, occ = occipital carina, pgl = postgenal lamella, sfb = subforaminal bridge. Figs 8–10, female holotype. 8. Antenna. 9. Head and mesosoma, dorsal. 10. Metanotum and propodeum.

Figs 13–16. Versolabrum coriaceum n. gen., n. sp. 13. Head, oblique anterior view, of female paratype. 14. Mesosoma, dorsal view, of female holotype. 15. Mesosoma, ventrolateral view of female paratype. 16. Fore wing venation of female holotype.

Figs 1–4. Herbertia sp. female, 1. Head. 2. Mesosoma (pronotum removed), dorsal view. 3. Mesosoma, lateral view, bls = burr-like seta. 4. Fore tarsus, btc = basitarsal comb.