Stethoncus Townes

Broad, Gavin R. & Shaw, Mark R., 2005, The species of four genera of Metopiinae (Hymenoptera: Ichneumonidae) in Britain, with new host records and descriptions of four new species, Journal of Natural History 39 (26), pp. 2389-2407 : 2393-2394

Genus Stethoncus Townes

Diagnosis

Stethoncus is a small genus with only four previously described species. The genus has a wide distribution, being found in Southern India ( S. indicator Aubert ( Aubert 1965)), the Palaearctic ( S. sulcator Aubert ( Aubert 1965; Kusigemati 1971)), arctic North America ( S. arcticus Townes ( Townes HK and Townes M 1959)) and Costa Rica ( S. auberti Gauld and Sithole ( Gauld and Sithole 2002)). The genus is easily identified, as the upper part of the face ends in a transverse ridge before the antennal sockets ( Figures 8 , 10 ) and the upper margin of the pronotum is very wide and swollen ( Figures 9 , 11 ). We have found one species in Britain which represents a new species that we describe below. Stethoncus sulcator , the only other species known in Europe, is re-described below for comparison.

Comments

Gauld and Sithole (2002) hypothesize that Stethoncus may be derived from within Hypsicera Latreille. The two genera share the apomorphy of the fore wing vein M + Cu having a shallow ‘‘bump’’ (dorsal inflection) at about two-thirds of its length (although hardly apparent in some species of Hypsicera ) and the transverse ridge of the upper face can clearly be derived from the form found in Hypsicera , which has an inter-antennal projection. However, in the absence of a formal cladistic analysis we prefer to retain Stethoncus as a separate genus.

Figures

Figure 8. Stethoncus monopicida ♀, head, anterior view.

Figure 9. Stethoncus monopicida ♀, mesoscutum, dorsal view.

Figure 10. Stethoncus sulcator ♀, head, anterior view.

Figure 11. Stethoncus sulcator ♀, mesoscutum, dorsal view.