Promachus bastardii (Macquart)

Dennis, D. Steve, Barnes, Jeffrey K. & Knutson, Lloyd, 2008, Pupal cases of Nearctic robber flies (Diptera: Asilidae), Zootaxa 1868 (1), pp. 1-98 : 62-64

Promachus bastardii (Macquart)

( Fig. 38 )

The following description is based on six pupal cases with pinned adults from the United States National Museum collection. Four males are labeled "Agawam, Mass.; 8 VII 15; H.E. Smith Coll.; W. Springfield No. 915339; W. R. Walton Coll.," "Agawam, Mass.; 10 VII 15; H.E. Smith Coll.; W. Springfield No. 915297," "Agawam, Mass.; 5 VII 15; H.E. Smith Coll.; W. Springfield No. 91510; W. R. Walton Coll.," and " W. Springfield No. 9159; 5 VI 16 ; W. R. Walton Coll." Two females are labeled " Agawam , Mass.; 8 VII 15; H.E. Smith Coll.; W. Springfield No. 915293," and " Cass Co., Minn.; Cass Lake, Minn.; from soil; May 21, 1937; pupated June 22, 1937, emerged July 11, 1937; R. H. Nagel. " The latter label indicates that under some circumstances the pupal stadium for this species can be 19 days .

Description: Greatest length, including anterior antennal processes, ♂ 18.5–21.0 mm, ♀ 21.0–22.0 mm; greatest width of thorax, ♂ 5.0– 5.5 mm, ♀ 5.5 mm; tapering to ♂ 2.0– 2.5 mm and ♀ 1.5 mm at greatest width of abdominal segment 8. Integument subshining golden brown; spines and other processes glistening reddish brown, darker apically.

Head with pair of dorsally flattened, ventrally wedge­shaped anterior antennal processes not joined at base and group of 3 basally fused posterior antennal processes ventrolaterally on each side; middle and outer posterior processes fused basally for a greater distance and appearing shorter than inner posterior process; middle and outer posterior processes rounded apically, inner and middle posterior processes acute. Labral sheath very rugose, with slight keel to apically rounded tubercle often surrounded by 2–3 dark, sclerotized concentric rings. Proboscial sheath usually with 2 tubercles on each side of midline posteriorly, outer tubercles rounded or concave apically, inner tubercles more concave apically; with larger posterior tubercle on midline, rugose around tubercles and to each side of midline. Maxillary sheath with posterior, apically rounded, rugose process, often with minute median processes, rugulose on either side of labral sheaths.

Anterior coxal sheath smooth to rugulose along side and posteriorly; anterior third with median, longitudinal split. Prothoracic spiracle difficult to see in rugose ring of thickened cuticle nearly flush with thoracic area, situated midlaterally at anterior margin of thorax. Anterior mesothoracic spines subequal, acuminate, on each side of thorax above bases of sheaths of mid legs. Thoracic area above spines rugulose. Posterior mesothoracic callosity large, rugose, located at base of wing sheath, often with minute, median, posterior mesothoracic spine toward dorsum. Wing sheath rugulose posteriorly and along edges, with short tubercle near base and 2 minute tubercles medially, often hidden in rugulose area. Thoracic area above wing sheath smooth to rugulose. Apex of hind leg sheath usually reaching to middle of abdominal segment 3 or slightly beyond.

Abdominal spiracles C­shaped, shining reddish brown, located along midline laterally.

Abdominal segment 1 with dorsal transverse row of 12–14 dorsally flattened, apically recurved spurs along anterior margin; outermost spurs shorter than others; median spur one­fourth to one­third as long as others, some spurs fused basally; with 3 bristle­like spines behind spiracles; venter obscured by wing and leg sheaths.

Segments 2–3 with dorsomedian row of 14–15 alternating straight to slightly apically recurved long spurs and straight, short spines; 2 outer spines sometimes bifurcate; all other spines bifurcate to quadrifurcate, with teeth of unequal size, except for unforked median spine; spurs sometimes bifurcate, with teeth of unequal size.

Segments 4–6 similar to 2–3, but with fewer short spines and more single­toothed spines posteriorly.

Segment 7 usually with 6 long dorsal spurs, but sometimes with alternating short spines. Segments 2–7 with 4–7 dorsolateral bristle­like spines and 5–9 lateral bristle­like spines behind each spiracle; spines sometimes bifurcate.

Segment 2 with 5–8 long ventral bristle­like spines on each side of hind leg sheath. Segments 3–6 with complete transverse row of 22–29 ventral bristle­like spines. Segment 7 with 12–17 ventral bristle­like spines.

Segment 8 with 2 dorsal spurs on each side of dorsal midline, small spiracle at lateral midline, 3–5 lateral bristle­like spines, and 4 ventral spines in males; ventral spines absent in females.

Segment 9 with pair of long dorsal posterolateral processes and pair of very short ventral posterolateral processes fused basally to dorsal posterolateral processes, pair of small median tubercles midventrally on posterior part of segment 9 and pair of midventral median tubercles.

Figures

FIGURE 38. Promachus bastardii (Macquart), lateral view with enlarged ventral view of facial area. Abbreviations: acsh = anterior coxal sheath, lsh = labral sheath, msh = maxillary sheath, prsh = proboscial sheath, psh = palpal sheath.