Pteromalus isarchus Walker, 1839

Gómez, Jose F. & Nieves-Aldrey, Jose Luis, 2012, Notes on the larval morphology of Pteromalidae (Hymenoptera: Chalcidoidea) species parasitoids of gall wasps (Hymenoptera: Cynipidae) in Europe, Zootaxa 3189, pp. 39-55 : 52

Pteromalus isarchus Walker, 1839

Measurements. Body length: 1.7–2 (1.8) mm, maximum width: 0.8–1 (0.9) mm (n=4) ex gall Xestophanes potentillae (Retzius) .

Description. body more or less fusiform, tapering slightly anteriorly and gradually posteriorly, widest at middle ( Fig. 4 F).

Head (anterior view) ( Fig. 6 F). Almost hexagonal; antennal area not bulging and relatively conspicuous.

Mouth parts ( Fig. 7 F). Ventral margin of the clypeus curved; labrum more or less trapezoid almost 3.3× wider than long.

Biology. The species P. isarchus is an oligophagous parasitoid of Xestophanes (Cynipidae) galls on Potentilla spp . ( Fig. 9 C). It is mainly a primary ectoparasitoid of cynipid larvae and in the Palaearctic has been recorded from two different species of Xestophanes (Askew et al. 2006) , although in the Iberian Peninsula it is more commonly found within the parasitoid community of X. potentillae ( Garrido-Torres & Nieves-Aldrey 1990, Gómez et al. 2006).

Material examined. ex gall X. potentillae on Potentilla reptans (Rosaceae) , Spain, Asturias: Ajuyán-Oviedo (07/09/2005) L. Parra leg. (n=3); Tarragona: Colldejou (14/08/2003) J. L. Nieves leg. (n=1).

Figures

FIGURE 4. Ventral view of terminal instar pteromalid larvae (A = agamic generation; S = sexual generation for host). A. Arthrolytus glandium ex Callirhytis rufescens (A). B. Cecidostiba fungosa ex Andricus quercusradicis (S). C. Cecidostiba geganius ex Andricus quercusradicis (A). – D. Pteromalus bedeguaris ex Diplolepis rosae. E. Pteromalus hieracii ex Aulacidea follioti. F. Pteromalus isarchus ex Xestophanes potentillae. G. Rivasia fumariae ex Neaylax versicolor. H. Stinoplus lapsanae ex Timaspis lapsanae.

FIGURE 6. Anterior view of the head of terminal instar pteromalid larvae (A = agamic generation; S = sexual generation for host). A. Arthrolytus glandium ex Callirhytis rufescens (A). B. Cecidostiba fungosa ex Andricus quercusradicis (S). C. Cecidostiba geganius ex Andricus quercusradicis (A). D. Pteromalus bedeguaris ex Diplolepis rosae. E. Pteromalus hieracii ex Aulacidea follioti. F. Pteromalus isarchus ex Xestophanes potentillae. G. Rivasia fumariae ex Neaylax versicolor. H. Stinoplus lapsanae ex Timaspis lapsanae.

FIGURE 7. Anterior view of mouthparts of terminal instar pteromalid larvae (A = agamic generation; S = sexual generation for host). A. Arthrolytus glandium ex Callirhytis rufescens (A). B. Cecidostiba fungosa ex Andricus quercusradicis (S). C. Cecidostiba geganius ex Andricus quercusradicis (A). D. Pteromalus bedeguaris ex Diplolepis rosae. E. Pteromalus hieracii ex Aulacidea follioti. F. Pteromalus isarchus ex Xestophanes potentillae. G. Rivasia fumariae ex Neaylax versicolor. H. Stinoplus lapsanae ex Timaspis lapsanae.

FIGURE 9. A. Larval cell of of Callirhytis rufescens (Agamic generation) with terminal-instar larvae of Arthrolytus glandium. B. Galls of Aulacidea hieracii on Hieracium spp. C. Galls of Xestophanes potentillae on runners of Potentilla reptans. D. Old galls of Callirhytis glandium (Agamic generation). E. Lateral habitus of Cecidostiba fungosa, adult female. F. Galls of Andricus quercusradicis (Agamic generation) on Quercus pyrenaica. G. Cross-section of unilocular gall of Neaylax versicolor showing fully-grown larva of Rivasia fumariae. H. Fresh galls of Diplolepis rosae on Rosa spp. shrub. I. Lateral habitus of Pteromalus bedeguaris, adult female. J. Galls of Timaspis lapsanae on Lapsana communis. K. Terminal instar larva of Stinoplus lapsanae ex gall of Timaspis lapsanae.