Anthophorula (Anthophorula) completa, (COCKERELL)

Rozen, Jerome G., 2011, Immatures of Exomalopsine Bees with Notes on Nesting Biology and a Tribal Key to Mature Larvae of Noncorbiculate, Nonparasitic Apinae (Hymenoptera: Apidae), American Museum Novitates 2011 (3726), pp. 1-52 : 24-28

ANTHOPHORULA (ANTHOPHORULA) COMPLETA (COCKERELL)

Table 2

I discovered a single nest of Anthophorula completa at Desert Station on the east side of the Tucson Mountains in Pima Co., Arizona, and excavated it on April 28, 1993. A year later to the day I found two more close by. The entrance to one of these was at the overhanging edge of a piece of rhyolite on the side of the sloping surface of a small ravine .

NEST ARCHITECTURE: One of the nests discovered in 1994 had its main open burrow descending at about 45° following an irregularly curved path. First cells were encountered about 15 cm from the entrance and all others, about 20 total, were found from there to 22 cm beyond the entrance. The burrow branched many times and all cells were clumped side by side and apparently end to end, presumably because of limited space created by rock inclusions. Cell inclination seemed variable. Although the cells appeared fresh, most were vacated, but at least one contained fresh provisions, two or three held feeding larvae, and several more had postdefecating larvae. Two other cells contained feeding larvae of Triopasites penniger (Cockerell) ( Nomadinae : Brachynomadini ). The second nest was similar but had fewer cells.

Cells preserved in the collection show that cell walls, up to 0.5 mm thick, are more consolidated than the substrate and have a shiny lining that is highly water repellent when tested with a water droplet. Obviously coated with a smooth semitransparent material, walls show a faint longitudinal ripple pattern. Cells are elongate ovals, with their top surface more curved than the slightly flatter lower surface holding the provisions. Their anterior end is more elongate than the rear, so that the maximum diameter is about 2 mm from the rear end. Cell closures have a nearly flat inner surface showing a well-defined spiral of soil in some samples consisting barely of three coils to the radius, although others have four coils; the outer surface of the closure is concave and smooth, but not shiny. The closure thickness at the center on one specimen is somewhat less the 0.5 mm. When tested with water, the inner surface of closures is relatively water retardant, and the outside surface slowly absorbs a droplet.

PROVISIONING AND DEVELOPMENT: Provisions of Anthophorula completa (figs. 45, 46) were loaflike with an unusually flat upper surface, and a backward slanting, flattened front that ended below in a ventral projection, a “foot” (as illustrated in Rozen and MacNeill, 1957: figs. 1, 2). The rear of the provisions is apparently attached to the lower curved rear of the cell, and the foot apex either just nearly reach the cell floor at the front. Eggs were deposited on the top surface, somewhat toward the front, as judged from exuviae found on provisions stored in the museum (fig. 46). The widest part of the loaf was in the posterior part, when viewed dorsally or laterally (figs. 45, 46).

Almost all feces are deposited against the closure and the front wall of the cell for about one mm behind the closure. When torn apart the feces seem to incorporate fibers of silk, suggesting cocoons are initially started during defecation, although the walls of the cocoon elsewhere contain no feces, an indication that the body of the cocoon is spun after defecation is complete. Most of the cocoon fabric is a semitransparent, extremely thin parchmentlike sheet of silk closely applied to the cell surface, so that one can see the position of the feces through the cocoon from inside the cell. However, the cocoon incorporating the feces at the cell closure is thicker and its texture of the inner surface is more fibrous.

When examined with an SEM, a cocoon wall was a single sheet partly imbedding silk strands with other free strands partly covering the inner surface. Whether the sheet was composed solely of fused silk or of another secretion that was deposited during silk spinning is

A. (Isomalopsis) H 2.8–3.5 (1) 7.0–7.5 (2) 3.8–4.0 (3) 1 45–75° 3.5–4.0 2.2–2.5 2.4–2.7 5 Yes Current study uncicornis

Eremapis parvula H 1.75–3.0 (4) 4.0–5.0 (8) 2.5–2.9 (10) 1–2 0–30° 2.3–2.6 1.7–1.8 1.8–2.0 5 No Current study

Chilimalopsis parvula F 1.5–2.0 (2) 3.8–4.2 (10) 2.4–2.8 (11) 1–3 0–80° 2.0–2.2 1.0–1.9 1.6 c 2 No Current study

Teratognatha modesta F 2.0–2.2 (4) 4.0–4.6 (10) 2.6–2.8 (12) 1–3 2.0–2.3 1.4–1.7 1.8 c 3 Nod Current study

Exo. ( Exomalopsis ) H 4.0 (2) 10.0 (1) 5.0 (1) 1 90° No Zucchi, 1973 auropilosa

Exo. ( Exomalopsis ) H 4.0–4.5 (2) 7.0-8.0 (?) 5.0 (?) 1 20–80° 4.4–4.7 3.1–3.2 3.0–3.2 3 No Rozen, 1997

bruesi

Exo. ( Exomalopsis ) H 8.8 1 40° No Raw, 1977 pulchella

E. ( Exomalopsis ) H & F 8.8 1 ≈0° No Raw, 1977

similis

Exo. (Stilbomalopsis) H 8.0–9.5 (31) 5.0–5.6 (35) 1 5.0 3.3 3.2 1 No Rozen, 1984;

solani Norden et al., 1994

Exo. (Stilbomalopsis) H 4.5 (1) 7.5–8.5(8) 5.0–5.5 (8) 1 35–80° 5.0–6.1 2.9–3.5 3.2–4.0 8 Yes Rozen, 1984 solidaginis

a New data, from single food mass store in AMNH or from notes.

b 3 data.

c Single datum.

d See text for explanation.

unknown. It was, however, extremely thin (somewhat less than 5 µm, fig. 62) on the sides of the cocoon wall and had no openings or fenestrations, except at the anterior pole (fig. 58). There a large, more or less circular hole (diameter <1 mm) occurred, screened by an open but dense webbing of silk strands (figs. 59, 60). This feature presumably allows gas exchange between inside and outside of the cocoon, which is necessary because the immature bee must survive until the next blooming of its food plants, perhaps 10 months away. It seems likely that the thin cocoon fabric elsewhere protects the bee from desiccation while the screening at the opening helps prevent parasite/predator invasion. Although no external protrusion is noticeable on the outside of the cocoon, this structure corresponds to the nippled end of megachilid cocoons that serves similar functions ( Rozen and Hall, 2011).

The cocoon of Anthophorula completa is similar to that described for Anthophorula sidae ( Rozen, 1984) in that most of the feces of A. sidae are applied to the front end of the cell, and elsewhere the cocoon fabric is semitransparent. With A. completa all the feces are applied only to the front end, but A. sidae also applies a thin layer of feces to the entire cell wall where it is loosely held in place by fine open strands of silk spun before the semitransparent layer. The cocoons A. chionura and A. nitens are opaque, matte, and dense with feces applied to all surfaces during cocoon construction ( Rozen and MacNeill, 1957; Rozen and Snelling, 1986). Hence, their cocoons have a very different appearance from the semitransparent, thin, seemingly delicate cocoon of A. completa .

PARASITISM: As indicated above, the cleptoparasite Triopasites penniger successfully attacked these nests; its larval feces were broadly smeared against much of the cell wall, not unlike the habits of its tribal partner Brachynomada sidaefloris (Cockerell) , which attacks Anthophorula sidae (Cockerell) ( Rozen, 1984: figs. 31, 32). Triopasites penniger also parasitizes nest of Anthophorula compactula ( Rozen, 1977) .