Empria tridens (KONOW, 1896)

Liston, A. D., Knight, G. T., Heibo, E., Bland, K. P., Barstad, Trond Elling, Blank, S. M., Boeve, J. - L., Fiedler, K., Grearson, K. J., Halstead, A., Jacobs, H. - J., Jansen, E., Lonnve, O., Prous, M., Robinson, J. & Taeger, A., 2012, On Scottish sawflies, with results of the 14 International Sawfly Workshop, in the southern Highlands, 2010 (Hymenoptera, Symphyta), Beiträge Zur Entomologie = Contributions to Entomology 62, pp. 1-68 : 37

Empria tridens (KONOW, 1896)

Baddoch, 1 ♀, 04.vi.2010, leg. Blank, Liston & Taeger, det. M. Prous.

The Kindrogan individual (SDEI-GISHym14894), with peculiar morphology of the head (Fig. 7; strongly inflated towards the rear, with small eyes), was mentioned by Prous et al. (2011). Other characters, including the morphology of the saw (http://www.morphbank.net/?id=588539), are not distinguishable from E. tridens (Konow, 1896) . According to molecular data, the specimen is not remarkable (see Prous et al. (2011, particularly Fig. 18). Mitochondrial DNA of the specimen is very similar to a group of sequences comprising mainly E. tridens and E. basalis (see Fig. 20 in Prous et al., 2011).

This individual is at present most conveniently considered to be a developmental [teratological] abnormality. However, a female E. tridens with a head very similar to the Kindrogan specimen has also been collected by Knight in Cumbria. The existence of two such specimens indicates a need to try to exclude other possible causes of the abnormality. Alternative causes are for example pathological (e.g. infection of the pharyngeal glands by a nematode). The habit of mature larvae of Empria species (and many other Allantinae ) of boring into substrates such as rotten wood, rich in nematode species that are known to infect the postpharyngeal glands of ants ( Wheeler 1928), might expose them (or the prepupal and pupal stages) to such infection (by anology with infection of ants, perhaps in the salivary glands of sawflies?). So it may be worth noting that pupation of Empria species is in a cell in the substrate, lacking any clearly identifiable cocoon and thereby increasing the vulnerability of prepupae and / or pupae to nematode infection.