Heteropogon macerinus (Walker)

Dennis, D. Steve, Barnes, Jeffrey K. & Knutson, Lloyd, 2008, Pupal cases of Nearctic robber flies (Diptera: Asilidae), Zootaxa 1868 (1), pp. 1-98 : 39-41

Heteropogon macerinus (Walker)

( Figs 20–22 )

The following description is based on five female and three male pupal cases with pinned adults from the Charles A. Triplehorn Insect Collection, Ohio State University, Columbus. They are labeled "Rockymount, VA., 6 miles East; Sept. 3, 1956; R. E. Woodruff. " Also, one female from the United States National Museum is labeled "Rockville, Pa.; larva coll. IV­21­12, Champlain; pupated VI –25, emerged VII–8–12," which indicates that this species may remain in the pupal stage for approximately two weeks .

Description: Greatest length, including anterior antennal processes, ♂ 13.6–15.5 mm, ♀ 13.6–16.0 mm; greatest width of thorax ♂ 3.7–4.4 mm, ♀ 3.9–4.1 mm; greatest width of abdomen ♂ 3.1–3.6 mm, ♀ 3.5–3.6 mm, tapering to ♂ 1.2–1.9 mm and ♀ 1.2–1.6 mm at greatest width of abdominal segment 8. Integument subshining, faded, yellowish brown; spines and other processes glistening reddish brown, darker apically except for uniformly colored or basally darker dorsal abdominal spines and spurs.

Head with pair of dorsally flattened, ventrally wedge­shaped anterior antennal processes not joined at base and group of 3 basally fused, subequal posterior antennal processes located ventrolaterally on each side; mid­ dle and outer posterior processes closer together, fused for greater distance; outer or third posterior process at least twice as wide as inner and middle processes, with straight sides, truncate or with 1–3 apical teeth; inner and middle posterior processes with either straight sides or curved outer sides, apically narrow and rounded or more acute. Labral sheath usually smooth, with very slight keel posteriorly. Proboscial sheath smooth; shallow median furrow extending two­thirds to three­fourths length of sheath; posterior tubercle absent. Maxillary sheath smooth, posterior process absent, inner edge extending slightly posterior to labral sheath on each side at juncture with proboscial sheath, forming very small tubercle.

Anterior coxal sheath smooth, with anterior, median, longitudinal split. Prothoracic spiracle oval, on small, cone­shaped callosity with slight anterior ridge, situated midlaterally at anterior margin of thorax. Anterior mesothoracic spines paired, subequal, on each side of thorax, above bases of sheaths of mid legs; anterior spine apically rounded to acute, slightly curved posteriorly; posterior spine more broadly rounded or with median tooth, straight to slightly curved posteriorly. Posterior mesothoracic callosity small, smooth to slightly grooved, with indistinct, broadly rounded, heavily sclerotized posterior margin. Wing sheath smooth to irregularly rugulose with broad anterior­posterior ridge; basal and median tubercles absent. Thoracic area above wing sheath smooth to slightly grooved or rugulose. Apex of hind leg sheath reaching between posterior margin of abdominal segment 2 and middle of abdominal segment 3.

Abdominal spiracles small, almost round, reddish brown, flush with surface, along midline laterally.

Abdominal segment 1 with dorsal transverse row of 12–13 long recurved spurs; median and lateral spurs shorter than others.

Segments 2–6 with dorsal median row of 12–13 alternating short, acuminate spines and long, acuminate spurs.

Segment 7 similar to segments 2–6, but with dorsal row of 9–10 spines and spurs.

All abdominal segments smooth or with numerous shallow grooves; dorsolateral, lateral, and ventral spines absent.

Segment 8 with 2 dorsal spurs on each side of midline; spiracle not visible.

Segment 9 with pair of long, dorsally curved dorsal posterolateral processes and pair of short, dorsally curved ventral posterolateral processes. Male with small, indistinct ventromedial callosities converging anteriorly.

Figures

FIGURES 20–22. Heteropogon macerinus (Walker), 20. ventral view, 21. lateral view, 22. dorsal view.