Stethoncus monopicida, Broad & Shaw, 2005

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 : 2396-2397

Stethoncus monopicida sp. n.

Stethoncus sulcator Aubert ; Gauld and Sithole 2002, p 222, misidentification.

Female

Body length 4.4–5.4 mm. Fore wing length 3.2–3.8 mm. Antenna with 21–25 flagellar segments, shortened and somewhat laterally compressed, F1 averages 0.89 times as long as wide in lateral view, 1.67 times in anterior view; F2 (this and following measurements in lateral view) 0.70; middle flagellomeres 0.75; penultimate flagellomere 0.83. Scape with stout setae ventrally ( Figure 8 ). Mesoscutum approximately 1.25 times as wide as long (width measured at the tegulae and the length from the mid-point of the tegula line to the anterior edge) ( Figure 9 ). Mesosoma and head uniformly, regularly punctate, with rather long setae over much of the dorsum of the body. Propodeum with broadly confluent areas superomedia and basalis, the lateromedian longitudinal carinae straight except for a slight inflection at the point where the areas superomedia and basalis meet and, often, basally. The dorsal longitudinal carinae of the first metasomal tergite end at about the mid-point of the tergite. Black, but with mouthparts, upper edge of face before the antennal shelf, antennae, tegulae and legs (except hind coxae) yellowish brown. Metasoma slightly paler than mesosoma. Pterostigma mid-brown.

Male

Body length 4.8–4.9 mm. Fore wing length 3.5 mm. Similar to female but with antennal flagellum slenderer, not laterally compressed, with 21–27 flagellar segments, F1 averages 1.74 times as long as wide; F2 1.3; middle flagellomeres 1.55; penultimate flagellomere 1.50. The dorsal longitudinal carinae of the first metasomal tergite end at about threequarters to four-fifths of the length of the tergite.

Comments

This species is separable from S. sulcator Aubert by having the pronotum postero-dorsally with more curved sides (compare Figures 9 and 11 ); the mesoscutum wider (compare Figures 9 and 11 ); the longer first segment of the female flagellum (compare Figures 8 and 10 ); and the straighter lateromedian longitudinal carinae of the area superomedia. Stethoncus arcticus Townes (one paratype male examined, Mt McKinley, 2 ° 009, 15 August 1954 (D. Townes), in AEI) has an even slenderer mesoscutum than sulcator and also a slenderer first tergite.

Material examined

Holotype: ♀, ‘‘Scotland [ UK], DN, Rhossdu [sic] estate, A.F.G. Dixon B.M. 1961.101 Host: Monophis [sic] rusticella Hb. Em. Ex Barn Owl pellet Rossdhu June 1959 ’’ ( BMNH) . Paratypes: Scotland: 1 „, same data as holotype ( BMNH) . England: 1♀, Silwood Park , Ascot, Berks., 51 ° 249N, 0 ° 389W, Malaise trap in wet woodland, 30 August to 6 September 1999 (G. R. Broad) ( BMNH) ; 1♀, Chippenham Fen , Cambs., TL 650693, Malaise trap: carr at reedbed edge, 16–24 June 1983 (J. Field) ( NMS) ; 1 „ and 1♀, as above but 9–22 July 1983 ( NMS); 1 „, as above but 8–21 August 1983 ( NMS) ; 3♀♀, as above but 15–27 August 1983 ( NMS) ; 1♀, Wychwood Forest , Oxon., SP 345170, Malaise trap, 17 July to 14 August 1990 (K. Porter) ( NMS) ; 1♀ Monks Wood , Hunts., TL 199797, Rothamsted light trap, 15 June 2004 (N. Greatorex-Davies) ( BMNH) .

Biology

The holotype female and a paratype male were reared from Monopis laevigella ([Denis and Schiffermüller]) (5 rusticella (Hübner)) ( Lepidoptera : Tineidae ) in Barn Owl ( Tyto alba (Scopoli)) pellets; the host pupae are preserved with the specimens. The pellets were collected at the bottom of a chimney below a Barn Owl roost and these were the only parasitoids reared (A. F. G. Dixon, personal communication to M. G. Fitton). These are the specimens referred to as S. sulcator by Gauld and Sithole (2002).

Etymology

This species’ name is derived from the tineid genus, Monopis , from which it has been reared.

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.