MSRG REPORTS:

Inostemma californica Ashmead

The species of Inostemma that are found in the United States have not been illustrated. For the last 20 years I have had an unidentified species of Inostemma from North Dakota, parasitic on sunflower midges. It remains undescribed because of my uncertainty about the habitus of the other species of Inostemma, and the fact that it closely resembles the few types that I have seen.

Lately I have had an opportunity to re-examine some of the types of American species, and to make notes and sketches of them. The information derived is somewhat minimal because the wasps are point mounted in dark glue, probably brown varnish, and are not well suited to illustration. I have drawn what I could with a camera lucida mounted on a B&L antique dissecting microscope, using 15 and 20x oculars with ocular micrometers and 24 mm objectives. This provides limited knowledge of the topographical features, some of which are presented here.

Inostemma californica is one of the shorter - horned species, in which the horn of abdominal tergite I of the females extends over only about 2/3 of the mesoscutum. It is also in the group that has a longitudinal depression on the vertex, though this is not nearly as deep as that of Inostemma horni Ashmead. Most, if not all, of the species have very wide laterotergites (the ventro-lateral portion of the abdomen that is sharply folded under) and deep striation on the basal portion of the first and second sternites. The last tergite is also sculptured.

For the most part, it is difficult to find significant diagnostic characters or character states in the genus, and it becomes a matter of finding minute details to differentiate species.There appear to be numerous sibling species, at least among the groups in which the female has a horn. In some instances, the males may provide better characters. The alternative may be that there are a few quite variable species, but that is a matter of much more study.

The following description is an OCR version of Ashmead's original text (1893), reformatted enough to make it more readable. I add here that some of the very old descriptions are not amenable to easy optical recognition by current programs, perhaps because the type styles and sizes used in the 1800's vintage linotype machines are not exactly like their modern counterparts.

Length, 1 mm. to 1.6mm. Black, subopaque, closely finely punctulate, the mesonotum less distinctly punctate, shining.

Head transverse,the vertex at the middle posteriorly impressed. Antennae 10-jointed, black, the scape one-third shorter than the flagellum; pedicel longer than the first funicular joint, first funicular joint almost as long as the second and third together, second, third and fourth joints all small, the last the smallest, club 4-jointed, the first the narrowest, second and third quadrate, the last conical, longer than the preceding. In the male the club is 5-jointed the flagellum nearly twice as long as the scape, the pedicel as long as the first two funiclar joints, the third being minute.

Thorax with 2 faint furrows. Mesopleura with a deep, glabrous impression on the disk, extending to the middle coxae. Metapleura finely rugose. Tegulae rufo-piceous. Wings hyaline, not fringed, the submarginal vein with the knobbed tip, black. Legs piceous-black, the trochanters, anterior tibiae beneath and at tips, base of middle and posterior tibiae and all tarsi pale brownish-yellow.

Abdomen slightly longer than head and thorax together, pointed fusiform, smooth and shining; the basal segment very rugose, in female with a large horn extending forward over the thorax to the vertex of head [author's note: certainly not in the type that I studied], striated at base; the second segment is long, slightly longer than the five following segments united (in the male), with a fovea and some faint striae at base. In the male the basal segment has no horn and is longitudinally striated.

Habitat.-Los Angeles, Cal.

Types in National Museum

Bred by A. Koebele, from a Cecidomyiid gall on Telypodium integrifolium*

* Thelypodium integrifolium (Nutt.). Cruciferae. Hitchcock, C. L. .and A. Cronquist. 1964. Vascular plants of the Pacific Northwest.: 549 - 551 (incl. fig.). Univ.Wash. Press, Seattle.

Reference:

Ashmead, W.H. 1893. Monograph of the North American Proctotrypidae. Bul.U. S. Nat'l. Mus. 45:259.

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