Dioxys cincta (Jurine)

ROZEN, JEROME G. & ÖZBEK, HIKMET, 2003, Oocytes, Eggs, and Ovarioles of Some Long-Tongued Bees (Hymenoptera: Apoidea), American Museum Novitates 3393, pp. 1-36 : 5-8

Dioxys cincta (Jurine)

We presume that the surface bearing the thick, nodular chorion is dorsal and that the thin, smooth chorion typical of most bee eggs is ventral. The mature oocytes of this species tend to be variably misshaped because the anterior end at least on some specimens is obliquely pressed (in some cases, nearly side by side) against the preceding oocyte in the ovariole; figures 1–6 illustrate specimens that seemed less modified than others and had nearly full chorionic development.

MATURE OOCYTE (figs. 1–6): Length 1.00– 1.38 mm; maximum width, lateral view 0.40 –0.58 mm; maximum width, dorsal view, 0.40–0.73 mm (N = 12); egg index 0.39 (dwarf). Shape bilaterally symmetrical;

TABLE 1 Comparative Data on Number and Sizes of Mature Oocytes / Eggs and Number of Ovarioles of Bees Treated in This Study (Taxa arranged by family and subfamily according to Michener [2000]. Numbers in the first three columns are means if more than one specimen was examined.)

long axis presumably straight; maximum width, dorsal view, either anterior or posterior to midpoint; either front end or rear end more broadly rounded than opposite end; dorsal surface of egg extending over ventral surface because of thickness of dorsal chorion as seen in lateral view; micropyle at cen­ ter of elevated radiating lines close to anterior edge of ventral surface (fig. 3); under SEM examination, micropyle consisting of numerous closely grouped pores (fig. 4). Ovum seemingly symmetrical along its axis, rounded at both ends. Dorsal chorion extremely thick on fully developed oocyte (roughly 10 times thicker than ventral chorion), when submerged in alcohol appearing glassy (figs. 5, 6), distinctly amber tinted, and clear, when critical­point dried, satiny tan above but frosted on border to attachment of ventral chorion; dorsal surface coarsely, seemingly irregularly nodular although nodules indistinctly arranged in linear rows on sides (fig. 2); earlier mature oocytes with nodules more closely set and sharply pointed and with less mass than those of later oocytes; ventral chorion mostly smooth, colorless, reflective under stereoscopic examination; under SEM examination dorsal chorion without surface sculpturing except for nodules, although early mature oocytes with ridges between nodules; frosted area bordering ventral chorion pitted and with faint polygonal pattern; ventral chorion smooth.

MATERIAL STUDIED: Two females, Turkey: Erzurum: 22 km WSW Oltu, VI­23–2001 (J.G. Rozen) ; two females, same except VI­ 25–2001.

REMARKS: As is more fully explained with the respect to the oocytes of Biastes brevicornis , described below, the chorion of Dioxys cincta was in different stages of deposition on the mature oocytes within the same female. Compared with fully developed oocytes, earlier mature oocytes had a thinner dorsal chorion, from which the follicular tissue was more difficult to dissect.

The thick, amber­tinted chorion provides the oocyte a dark border when seen from above or below (fig. 5), contrasting with the pale ovum. The amber chorion can easily be identified through the ovariole tissue before dissections.