Protoxaea gloriosa

Rozen, Jerome G., 2018, Nesting Biologies and Mature Larvae of Oxaeine Bees (Apoidea: Andrenidae), American Museum Novitates 2018 (3893), pp. 1-32 : 16

EGG OF PROTOXAEA GLORIOSA

Figures 19 , 29–32

Eggs of only P. gloriosa were available for study.

DESCRIPTION: Form (fig. 19) elongate, strongly curved, sausage shaped; length 3.75 to 4.0 mm (average 3.84 mm) and 0.75 to 0.875 mm (average 0.83 mm) in maximum diameter, nearly parallel sided, with front and posterior ends similar in appearance except front end slightly smaller when viewed with stereoscope. Chorion surface smooth, faintly shiny, and mostly transparent, thereby revealing off-white color. Micropyle area not identifiable even under maximum stereoscopic magnification; with SEM, this structure small, low bulge (figs. 29, 30) on narrower front end of egg surrounded by radiating lines in chorion; bulge bearing numerous small porelike indentations, some of which presumably penetrate chorion. Under very high magnification chorion appears to be composed of wrinkled interconnecting fibers of changing thicknesses (fig. 31), features that have not been observed in other bee eggs by this author. Various views of chorion seem to demonstrate that fiber density responsible for various surface textures shown in micrograph (fig. 29).

MATERIAL STUDIED: Three eggs: NEW MEXICO: Hidalgo Co., 1 mi north of Rodeo , VIII- 20-1970 (J.G. Rozen) .

DISCUSSION: What appeared to be a partly eclosed egg (fig. 32) revealed the underlying integument of the presumed first instar seems to have possessed stout spicules resembling those termed “hatching spines” found in a number of families of bees (Rozen et al., 2017). If this can be confirmed, this would be the first evidence of these structures being involved with eclosion in the Andrenidae .

Figures

FIGURES 16–19. Diagrams of cells and egg of Protoxaea gloriosa. 16. Demonstrating exact shape of lumen and entrance tunnel as well as approximation of cell and tunnel wall. 17. Cell with provisions showing position of egg on provisions with subsurface bubbles presumably of gas. 18. Cell with postdefecating larval of P. gloriosa with moldy fecal material applied to upper end. 19. Egg, lateral view, anterior end to left.

FIGURES 29–32. SEM micrographs of egg of Protoxaea gloriosa. 29. Anterior end showing apical mound of micropyle.30. Close-up of micropyle. 31. Close-up of pits in micropyle demonstrating texture of chorion. 32. Close-up of partly eclosed egg showing spiculelike structures suggestive of hatching spines (arrows).