On the Identity of Eurytoma oleariae Maskell.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 55, 1924, Page 687

On the Identity of Eurytoma oleariae Maskell. By A. B. Gahan, of the U.S. Department of Agriculture, Bureau of Entomology. Communicated by David Miller. [Read before the Wellington Philosophical Society, 29th October, 1923; received by Editor, 5th November, 1923; issued separately, 28th August, 1924.] In January, 1922, the Bureau of Entomology of the United States Department of Agriculture received from E. S. Gourlay, of the Biological Department, Canterbury College, Christchurch, New Zealand, fifteen specimens of a small hymenopteron which he had determined as Eurytoma oleariae Maskell. According to the correspondent, these specimens were reared from galls on Olearia furfuracea, which were also inhabited by a species of Cecidomyid. Samples of the galls were also received. Comparison of the specimens and the galls with Maskell's description and figures (Trans. N.Z. Inst., vol. 21, 1888, p. 255, pl. xi, figs. 1–16) left no doubt that the species had been correctly identified. This species is not an Eurytoma, however, nor even a Chalcidoid, but belongs to the Serphoidea and to the family Platygasteridae, where it agrees best with the genus Metaclisis Foerster of the tribe Inostemini. Metaclisis is said to have the scutellum flat and the antennal club of the female three-jointed. In the present species the scutellum is not wholly flat, but transversely pillow-shaped as in many species of the genus Platygaster, while the antennal club is not very well defined but appears to be six-jointed. One might with justice, perhaps, propose a new genus for it, but the relation to Metaclisis is apparently close, and it is deemed best to place it in that genus for the present. Maskell's description is obviously inaccurate in some respects. The following descriptive notes will aid in recognition of the species.

♀. Length, 2.3 mm. Head transverse, narrower than thorax; vertex entirely and temples above granularly sculptured and pilose; frons smooth and glabrous (sometimes with a narrow orbital line faintly granular) with a very small but distinct median tubercule in front of median ocellus; face, cheeks, and temples below smooth and sparsely hairy; occiput distinctly margined; viewed from front the head is subtriangular and broader than high; antennae ten-jointed, weakly clavate; scape moderately long and somewhat curved; pedicel fully twice as long as thick; third joint as long and about as thick as pedicel; fourth approximately two-thirds as long as third and about as thick; fifth not quite as long as fourth and slightly thicker, about as broad as long; sixth to ninth subequal and subquadrate or very slightly longer than thick; tenth conical and very slightly longer than preceding joint. Thorax ovoid, broadest before tegulae; pronotum rounded in front and deeply and broadly emarginate behind; parapsidal grooves complete and sharply impressed; scutellum slightly convex and about twice as broad as long; axillae transverse, deeply depressed or sunken and meeting on median line; pronotum, mesoscutum, and scutellum finely granular and closely pilose; propodeum with a shallow median channel bounded on each side by prominent carina, transversely rugose between carinae and very faintly granular and pilose laterally; mesopleura glabrous and polished with three of four distinct longitudinal striae near dorsal margin; metapleura pilose but practically smooth; legs moderately long and slender, posterior tibiae with two unequal spurs; forewings with a complete basal cell, the submarginal, basal, and median veins distinct though more or less vestigial, the submarginal faintly traceable for nearly half length of wing and terminating in a nearly obsolete knob; whole surface of wing ciliated, basal portion a little more sparsely so than remainder; hindwing with a non-ciliated area extending obliquely basad from hooklets to posterior margin. Abdomen as long as head and thorax or a little longer, as broad as thorax, broadest at apex of second tergite, and distinctly margined laterally; first tergite broader at apex than long down middle and strongly longitudinally striated; second tergite a little more than twice as long as first, much broader at apex than at base, with a large ovate and well-defined depressed area on each side of middle at base, surface of tergite mostly smooth and glabrous but with several elongate punctures or short striations at basal middle, the depressed areas very finely punctured and pilose within, and lateral margins of tergite sparsely hairy; tergites beyond second, short, weakly punctate, and hairy; ovipositor concealed. Black; antennae black; coxae concolorous with thorax; legs, except coxae, reddish-testaceous; marginal carina of abdomen reddish beneath; forewings faintly fuscous, the infuscation not uniform but more intense on median portion of wing; hindwing also faintly fuscous with hyaline spot behind hooklets. ♂. Similar in every way to female except in antennae. These are not at all clavate, third and fourth joints are subequal and each a little longer than pedicel, fifth a little longer than thick, sixth to ninth subequal and distinctly longer than thick, tenth ovate and about one and a half times as long as ninth; all flagellar joints cylindrical and very shortly petiolate but not serrate. Described from fifteen specimens received, as already stated, from E. S. Gourlay. The species is without much doubt parasitic upon a Cecidomyid, possibly Cecidomyia oleariae Maskell. It seems highly probable that more than one species of Cecidomyidae has been confused under this name by Maskell.