Synosis caesiellae, 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 : 2403-2405

Synosis caesiellae sp. n.

Female

Body length 3.8–4.8 mm. Fore wing length 3.3–4.2 mm. Flagellum with a lower number of segments than other British Synosis species , 26–28 in females. Ocelli smaller than in S. fieldi , ocellar–ocular distance ca 0.8 times the maximum length of a lateral ocellus ( Figure 19 ). Propodeum with either a clear if short transverse carina separating the area superomedia from the area basalis ( Figure 20 ) or this carina so shortened that the two areas converge in a more or less quadrate raised vestige of the carina ( Figure 21 , cf. the condition in S. meridionalis Tolkanitz ). Area basalis longer than in S. parenthesellae , carinae meeting at a narrower angle ( Figures 20–22 ). Usually lacking the anterior transverse carina of the propodeum, never with a groove running across. Two specimens (Oxfordshire, May and Port Appin, September) with distinct transverse carinae demarking the anterior side of the area superomedia ( Figure 20 ) but the area superomedia always appears to be rather pointed, with a less conspicuous lateral angulation than in S. parenthesellae . Face with yellow malar space, with edge rather ill-defined. Hind coxae of British specimens range in coloration from entirely pale reddish to mid-brown, sometimes with darker patches dorsally and ventrally; one Swedish specimen with the basal three-quarters dark and the apical quarter abruptly paler, as in S. fieldi and some S. parenthesellae .

Male

Body length 4.0– 4.3 mm. Fore wing length 3.1–3.2 mm. Flagellum with 27 or 28 flagellar segments. Yellow of the face not extending beyond the anterior tentorial pits. Propodeum usually with lateral vestiges of anterior transverse carinae ( Figure 22 ).

Comments

Differs from S. meridionalis in the broader area of contact of the areas superomedia and basalis (sometimes represented by a transverse carina in S. caesiellae ); the lower number of flagellar segments (30 in the holotype female of S. meridionalis ); and the lack of a sharp division between the yellow of the face and dark brown of the gena.

Material examined

Holotype: ♀, ‘‘Burghfield Common, Reading, Berks. [ England, UK], ex Swammerdamia caesiella , Betula , 9/10.1978, em. 29.5.1979 (M.R. Shaw)’’ (NMS). Paratypes: England: 2 „„, same details as above except em. 20 May 1979 and 24 May 1979 (NMS); 1♀, Havant Thicket, Hants., ex Swammerdamia caesiella on Betula 18 October 1980, em. March 1981 (J. R. Langmaid) (NMS); 1♀, Abbots Moss, Cheshire SJ 5868, Malaise trap 2, Quercus / Betula /Pinus, 27 June to 23 July 1986 (R. R. Askew) NMSZ 1988.002 (NMS); 1♀, Abbots Moss, Cheshire, ex Swammerdamia caesiella on Betula 18 October 1976, em. 24 May 1977 (M. R. Shaw) (NMS); 1♀, Nettlebed, Oxon., ex Swammerdamia caesiella on Betula , 21 October 1995, em 1996 (I. Sims) (NMS); 1♀, Savernake Forest, Wilts., SU 229656, Malaise trap, 31 May to 13 June 1990, NMSZ 1993.033 (K. Porter) (NMS); 1♀, same details as above except 20 September to 11 October 1993 (NMS). Scotland: 1♀, Port Appin, Argyll, 5 September 1954, on Vaccinium (E. C. Pelham-Clinton) (NMS) ; 1♀, 1 „, Berrie Dale, Hoy, Orkney, ex micro (? Teleiodes proximella ) on Betula , September 1984, em. May 1985 (R. I. Lorimer) (NMS). Sweden: 1♀, Skäralid, 3 July 1938 (D. M. S. and J. F. Perkins) B.M. 1938.414 (BMNH).

Biology

Six specimens were reared from Swammerdamia caesiella (Hübner) ( Lepidoptera : Yponomeutidae ) on Betula , collected in four locations in October, emerging from March to May the following year. Two further specimens are labelled as reared from? Carpatolechia [5 Teleiodes ] proximella (Hübner) on Betula collected in September and emerging in May. The uncertainty in host identification raises the possibility these may also really be from S. caesiella . Non-reared specimens have been collected in May/June, July, August, and September/October. The wide geographical and temporal spread of specimens reflects the distribution of the host species, S. caesiella , which is widespread and bivoltine.

Etymology

This species is named after the yponomeutid species from which it has been reared.

Figures

Figures 19–22. Synosis caesiellae. (19) ♀, Port Appin, dorsal view of head showing ocelli. (20) ♀, Port Appin, propodeum. (21) ♀, Berrie Dale, ex?Carpatolechia, propodeum. (22) „, Burghfield, ex Swammerdamia, propodeum.