Proctacanthus milbertii Macquart

Dennis, D. Steve, Barnes, Jeffrey K. & Knutson, Lloyd, 2008, Pupal cases of Nearctic robber flies (Diptera: Asilidae), Zootaxa 1868 (1), pp. 1-98 : 78-79

Proctacanthus milbertii Macquart

( Fig. 49 )

The pupal case of Proctacanthus milbertii was described by Malloch (1915, 1917). It is redescribed here based on two male cases in the United States National Museum. These cases are both labeled "E. Lansing, Mich.; SWB, S.W. Bromley Collection 1955" with the dates Aug. 11, 1939 and Aug. 18, 1939.

Redescription: Greatest length, including anterior antennal processes, 27.3–28.5 mm; greatest width of thorax 7.0– 7.3 mm; greatest width of abdomen 5.8–6.0 mm, tapering to 2.8–3.0 mm at greatest width of abdominal segment 8. Integument subshining yellowish brown to golden brown; spines and other processes glistening reddish brown, sometimes darker apically or basally.

Head with pair of dorsally flattened, ventrally wedge­shaped anterior antennal processes not joined at base and group of 3 basally fused posterior antennal processes located ventrolaterally on each side, middle and outer posterior processes fused for greater distance, appearing closer together and slightly shorter than inner posterior process; outer posterior process broad for entire length and broadly rounded apically; inner and middle posterior processes becoming narrow and slightly more acute apically. Labral sheath very rugose, with tubercle­like keel posteriorly. Proboscial sheath rugose on each side of midline, with slight tubercle­like swelling posteriorly on each side of midline and small, ventrally concave tubercle on midline posteriorly. Maxillary sheath rugose, especially around posterior processes and along inner margin; with small, apically rounded process posteriorly and anterior tubercle on each side of labral sheath.

Anterior coxal sheath irregularly rugose, with anterior, median, longitudinal split. Prothoracic spiracle elongate­oval, on large rugose callosity, situated midlaterally at anterior margin of thorax. Anterior mesothoracic spines consisting of pair of subequal, straight to slightly posteriorly curved and apically rounded spines on each side of thorax above bases of sheaths of mid legs. Posterior mesothoracic callosity large, rugose, with apically rounded to acute posterior mesothoracic spine; margin of callosity toward dorsum sclerotized. Wing sheath irregularly rugose, with small tubercle at base and two larger median tubercles; tubercle toward venter usually larger than tubercle toward dorsum. Thoracic area above wing sheath irregularly rugulose. Apex of hind leg sheath reaching to posterior margin of abdominal segment 2.

Abdominal spiracles elongate­oval, light to dark reddish brown, situated along midline laterally.

Abdominal segment 1 with dorsal transverse row of 20 long, apically recurved spurs; dorsolateral bristlelike spines absent; with 8–10 bristle­like spines of irregular size behind each spiracle; venter obscured by wing and leg sheaths.

Segments 2–5 with 2–4 short dorsolateral spines. Segments 6–7 with 1–3 short spines Segment 2 with 13– 14 alternating dorsomedian long spurs and short spines; spines situated slightly anterior to spurs. Segments 3– 7 similar to segment 2, with 11–13 alternating spurs and spines.

Segments 2–6 and 7 with 5–8 and 3–4 dorsolateral bristle­like spines, respectively, and 12–15 bristle­like spines behind each spiracle.

Segment 2 with 7–11 median ventral bristle­like spines on each side of, and sometimes extending under, hind leg sheath; segments 3–6 and 7 with 29–41 and 23–27 ventral bristle­like spines, respectively, several short spines interspersed among long spines.

Segment 8 with 4 dorsomedian spurs on each side of dorsal midline; small, dark brown spiracle at lateral midline; 4–8 lateral bristle­like spines on each side; and 7–9 ventromedian bristle­like spines on each side of ventral midline.

Segment 9 with 2 medium­length dorsal posterolateral processes curved inward toward each other, 2 short ventral posterolateral processes not fused basally to dorsal posterolateral processes, and pair of terminal ventromedian tubercle­like processes slightly anterior to ventral posterolateral processes.

Figures

FIGURE 49. Proctacanthus milbertii Macquart, mouthpart sheaths. Abbreviations: lsh = labral sheath, msh = maxillary sheath, prsh = proboscial sheath.