Eurytoma robusta Mayr, 1878

Gómez, José Francisco, Nieves-Aldrey, José Luis, Nieves, María Hernández & Stone, Graham Nicholas, 2011, Comparative morphology and biology of terminalinstar larvae of some Eurytoma (Hymenoptera, Eurytomidae) species parasitoids of gall wasps (Hymenoptera, Cynipidae) in western Europe, Zoosystema 33 (3), pp. 287-323 : 312

Eurytoma robusta Mayr, 1878

MATERIAL EXAMINED. — Ex Isocolus scabiosae form rogenhoferi : Spain. Guadalajara, Pozo de Guadalajara, 3.X.2004, J. L. Nieves leg (n = 1).

DESCRIPTION

n = 1; body length 2 mm; body width 1.2 mm ( Figs 5G ; 7G ); body short and wide; ratio L/W = 1.38; ventral margin of body segments convex; anterodorsal protuberances present from second thoracic segment to the seventh abdominal and not protruding beyond the dorsal margin of body segments ( Fig. 7G ).

Antero-medial setae of the antennal area situated slightly below the antennae; antero-medial setae of vertex relatively high on the upper face, closer to the anterior margin of vertex than to the antennae ( Fig. 9F ); ratios SA/LAA = 0.29 and SA/DAV = 1.18; dorsal-labral setae as long as clypeal setae; ventral margin of clypeus indistinct; labrum with slight divisions limited to apical part of labrum; the five medial lobes are not well differentiated; maxillary palps conspicuous ( Fig. 12A ).

Mandibles with two teeth, exposed in part, with the tip of the first tooth visible ( Fig. 12A ); ratio L/W 1T = 2.08; outer margin of first tooth strongly convex; its tip moderately recurved; apex of the second tooth straight, directed upwards in the same direction as the first tooth, and more or less acute; inner margin of mandible, from the base of second tooth, more or less straight and not interrupted ( Fig. 13G ).

BIOLOGY

This species has been recorded as a common ectoparasitoid of some galling tephritid fly species in heads of Centaurea and stems of Cirsium (Asteraceae) . It is not clear whether it is a parasitoid of the cynipid gall species Isocolus scabiosae (Giraud, 1859) form rogenhoferi Wachtl, 1880 as well, which occupies similar habitats. We have reared this species from heads of Centaurea scabiosa L. ( Fig. 14J ) containing both cynipid and tephritid galls. Varley (1937) describes E. robusta as being partially phytophagous after consuming the host larva. Johannesen & Seitz (2003) also studied larval distributions of Eurytoma robusta in galls of the tephritid gall fly Urophora cardui Linnaeus, 1758 .

REMARKS

Eurytoma robusta is one of the few eurytomid species associated with cynipid communities whose larva has already been thoroughly described, by Varley (1937). Our diagnosis provides additional data.

Figures

FIG. 5.— Ventral views ofterminal-instar eurytomidlarvae:A, Eurytomaaspila (Walker,1836) ex Phanacis caulicola; B, E.brunniventris Ratzeburg, 1852 ex Cynips quercus (A); C, E. cynipsea Boheman, 1836 ex Phanacis hypochoeridis; D, E. infracta Mayr, 1904; E, E. mayri Ashmead, 1887; F, E. pediaspisi Pujade i Villar,1994; G, E. robusta Mayr, 1878; H, E. rosae Nees, 1834 ex Diplolepis rosae. Scale bars:1 mm.

FIG. 7.— Lateralviews ofterminal-instar eurytomidlarvae:A,Eurytoma aspila (Walker,1836) ex Phanacis caulicola; B, E.brunniventris Ratzeburg, 1852 ex Cynips quercus (A); C, E. cynipsea Boheman, 1836 ex Phanacis hypochoeridis; D, E. infracta Mayr, 1904; E, E. mayri Ashmead, 1887; F, E. pediaspisi Pujade i Villar,1994; G, E. robusta Mayr, 1878; H, E. rosae Nees, 1834 ex Diplolepis rosae. Scale bars:1 mm.

FIG. 9. — Anterior views of the head of terminal-instar eurytomid larvae: A, Eurytoma aspila (Walker, 1836) ex Phanacis caulicola; B, E. brunniventris Ratzeburg, 1852 ex Cynips quercus (A); C, Eurytoma infracta Mayr, 1904; D, Eurytoma mayri Ashmead, 1887; E, Eurytoma pediaspisi Pujade i Villar, 1994; F, Eurytoma robusta Mayr, 1878. Scale bars: A, B, D, F, 400 μm; C, 300 μm; E, 200 μm.

FIG. 12. — Anterior views of mouthparts of terminal-instar eurytomidae larvae:A, Eurytoma robusta Mayr,1878; B, E. rosae Nees,1834 ex Diplolepis rosae; C, E. rufipes Walker,1832;D, E.sp.cf.aspila; E, E. sp. cf. jaceae; F, E.strigifrons Thomson,1876; G, E.timaspidis (Mayr, 1904). Scale bars: A-E, 100 μm; F, G: 200 μm.

FIG. 13.— Anterior views of the right mandible of terminal-instar eurytomid larvae:A, Eurytoma aspila (Walker,1836) ex Phanacis caulicola; B, E. brunniventris Ratzeburg, 1852 ex Cynips quercus (A); C, E. cynipsea Boheman, 1836 ex Phanacis hypochoeridis; D, E. infracta Mayr, 1904; E, E. mayri Ashmead, 1887; F, E. pediaspisi Pujade i Villar, 1994; G, E. robusta Mayr, 1878; H, E. rosae Nees, 1834 ex Diplolepis rosae; I, E. rufipes Walker, 1832; J, E. sp. cf. aspila; K, E. sp. cf. jaceae; L, E. strigifrons Thomson, 1876 (right mandible); M, E. strigifrons (left mandible); N, E. timaspidis (Mayr, 1904). Scales bars: A, D-G, I-N, 50 μm; B, 20 μm; C, H, 100 μm.

FIG. 14. — A, terminal-instar larva of Eurytoma aspila (Walker, 1836) ex gall of Aulacidea tragopogonis; B, larval cells of Phanacis centaureae with terminal-instar larvae of E. aspila; C, cross-section of Cynips quercus (A) leaf gall showing terminal-instar larva of E. brunniventris Ratzeburg, 1852, with debris of adult host; D, ventral view of terminal-instar larva of E. brunniventris ex gall of C. quercus (A);E, cross-section of a gall of Cynips divisa (A) showing fully-grown larva of E. brunniventris; F, terminal-instar larva of E.brunniventris ex gall of Plagiotrochus australis (S);G, anterior view of head of fully-grown larva of E.brunniventris ex gall of P.australis (S); H, larval cells of Aulacidea pilosellae with terminal-instar larva of E. cynipsea Boheman, 1836; I, larval cell on Silybum marianum with terminal-instar larva of E. cynipsea feeding on gall tissue; J, terminal-instar larva of E. robusta Mayr, 1878 in cell of Isocolus leuzeae gall; K, cross-section of Diplolepis centifoliae leaf gall showing terminal-instar larva of E. rosae Nees, 1834; L, lateral view of fully-grown larva of E. rosae ex gall of D. centifoliae.