Walkeromyia plumipes Philippi 1873

Walkeromyia plumipes (Philippi, 1873)

(Figs. 1–3)

Anthrax plumipes Phillippi, 1873: 307. Type locality: Argentina, Mendoza. Type lost in MNNC.

Redescription. Male (Fig. 1 a–c). Body length: 13–16 mm; wing length: 14–15 mm.

Head: Eyes separated by twice the width of ocellar triangle. Frons with black pile and black tomentum. Face brown, rounded, with black hairs and black tomentum, some whitish pile near oral cavity. Scape brown, rectangular, with black hairs at apex, three times as long as pedicel; pedicel brown, twice as wide as long, bare; flagellomere brown, as long as scape and pedicel combined; conical, slightly flattened; stylus minute, terminal. Proboscis short, not projecting beyond oral margin. Palpi fulvous, reduced, with black hairs. Occiput with short white hairs and black scales.

Thorax: Anterior margin of mesonotum with white pile, with scattered black hairs; tomentum on disc entirely black, with scattered white scales; longer white scales on posterior margin, near scutellum; black bristles on postalar corners. Mesopleuron with black pile, not tomentose. Proepimeron with white hairs on anterior half and black hairs on posterior half. Coxae with black pile, not tomentose. Legs fulvous, tarsi yellow, fore and mid femora black with short black scales, hind leg with a band of long flattened black scales covering the whole leg; bristles black. Halter steam brown, knob fulvous. Scutellum brown, with black tomentum; bristles black. Setulae on basicosta fulvous with black tips. Wing brownish darker along veins, cell centers hyaline or fainted pigmented (Fig. 1 c); r-m cross-vein behind middle of cell dm; no cross-vein between R4 and R2+3; cell r5 slightly narrowed towards wing margin; vein CuA1 with first and second sections each twice the length of r-m cross-vein, third section as long as two first sections combined; cell a as wide as cell cup; alula well developed.

Abdomen: Dorsum with black pile on center of tergite one, except white hair on sides of tergite one, remainder with black pile; black tomentum with some white scales laterally on tergite six. Venter with black pile, not tomentose. Genitalia brown with black hairs; epandrium in lateral view, trapezoid, dorsal portion wider, cercus well exposed, epandrium subtriangular in dorsal view (Fig. 2 a), posterior tip rounded, anterior corners elongated forward; gonocoxite in lateral view wider at middle with anterior hooked extension and posterior narrow tip; gonocoxite in ventral view (Fig. 2 b) distinctly subquadrate, narrowing apically, anterior corners extending forward, medially divided; gonostylus with a basal process narrowing toward tip, tip slightly hooked in ventral view; epiphallus in lateral view slightly curved (Fig. 2 c), apex swollen, hooked antero-dorsally; epiphallus in ventral view medially divided (Fig. 2 d), united only in apical third, basal half separated in two, wide at base narrowing toward apex, swollen near tip; aedeagus spine-like, slightly longer than epiphallus; gonopore terminal.

Pupal stage (Figs. 1 d): Integument of pupa yellowish hyaline with yellow setae and reddish brown blacktipped tubercles. Cephalic tubercles formed almost in straight line, medial tubercle situated slightly outside line between apices of anterior and posterior tubercles and closer to posterior tubercle. Tubercles broad basally, tapering to sharp apex, with sharp ventrolateral and dorsolateral ridges. Posterior tubercle short. Anterior facial tubercles compressed anteroposteriorly, connected by mesal ridge, with acute lateral apices. With a row of long curved bristles at the junction of the thorax and abdomen. Abdominal tergites two to six with a dorsal row of strong spines adhering to the cuticle except at their tips, tergite seven with a row of simple smaller spines, tergite eight without spines dorsally; sides of segments two to seven with a row of six wide, long flattened outgrowths, four in pleurites, two on sides of sternites. Anal tubercles about four times longer than medial width of one lobe, separated, broad basally, tapering to sharp apex, sclerotized at tip, slightly swollen dorsally before apex.

Female. Not collected in this study.

Material examined. ARGENTINA. 13, Buenos Aires, La Plata (34°53'S 50°01'W, 12 mts), II-2009, L. Álvarez; 23 and pupal case, Santiago del Estero, Dpto. Atamisqui (28°38'54''S 64°04'58''W, 120 mts), 21-III-2009, M. Lucia & L. Álvarez. All in the nests of X. splendidula.

Host. Xylocopa (Schonnherria) splendidula Lepeletier.

Distribution. Argentina: Buenos Aires, Mendoza and Santiago del Estero provinces.

Biological observations. The larva of W. plumipes developed in a cell of a nest of Xylocopa splendidula built in the dead culms of Arundo donax L. The sequence of images in figure 3a shows the development of a larva located in the right-hand cell that corresponds to the parasitoid, we assume that it is the final non-feeding larval stage. There are two pre-pupal stages of the Xylocopa splendidula in the remaining cells and located to the left near the entrance of the nest is the last empty cell. Figures 3 b–c show the beginning of the pupation of the larval bee and parasitoid bee fly. The following images (Fig. 3. d–i) show the development of the pupal stage of bees and parasitoid fly. On the last pre-emergence day, the bee fly pupa was observed to move to the nest entrance for adult emergence. The last image (Fig 3 j) shows the emergence of the adult W. plumipes bee fly and the two remaining bees with their still-in-progress cycle. The two adults of carpenter bees were males. The observation of the pupal stage of the parasitoid lasted 28 days. This clearly shows the unsynchronized development of the adult parasitoid with emergence prior to that of unparasitized bees.