Proctacanthus rufus Williston

Dennis, D. Steve, Barnes, Jeffrey K. & Knutson, Lloyd, 2008, Pupal cases of Nearctic robber flies (Diptera: Asilidae), Zootaxa 1868 (1), pp. 1-98: 81-82

publication ID 10.11646/zootaxa.1868.1.1

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Proctacanthus rufus Williston


Proctacanthus rufus Williston  

The pupal case of Proctacanthus rufus   was briefly described by Hine (1922). The following, more detailed description is based on four pupal cases from the United States National Museum. One male case with associated pinned adult is labeled " Ocean Grove, N.J.; issued July 11, '93; S.N. Dunning through C.V. Riley." Another male case is labeled "Clemson College, S.C.; VII, 17, '26; S.W. Bromley Collection 1955." One female case is labeled the same as the latter male case and another female case is labeled "Hampden, Conn.; VII, 8, '21; in sandy (soil); S.W. Bromley Collection 1955."

Redescription: Greatest length, including anterior antennal processes, ♂ 27.0– 29.5 mm, ♀ 27.5–28.0 mm; greatest width of thorax, ♂ 5.5–6.5 mm, ♀ 6.5–7.0 mm; greatest width of abdomen, ♂ 5.0– 5.5 mm, ♀ 5.0– 6.5 mm, tapering to ♂ 2.5–3.0 mm and ♀ 2.5–3.0 mm at greatest width of abdominal segment 8. Integument subshining light to dark golden brown; processes light reddish brown, spines and spurs darker; processes, spurs, and spines darker apically; bristle­like spines uniformly light or dark reddish brown.

Head with pair of narrow, 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 closer together and fused for greater distance, appearing shorter than inner posterior process; inner and outer posterior processes about same diameter; middle posterior process usually smaller; middle and inner posterior processes usually apically recurved more than outer posterior process. Labral sheath small, rugulose, with small keel posteriorly. Proboscial sheath slightly rugulose to rugose, with 2 bulbous, tubercle­like projections and small median tubercle posteriorly. Maxillary sheath with very small, apically rounded process posteriorly, posterior half rugose; rarely with rugulose area on each side of labral sheath.

Anterior coxal sheath irregularly rugose with anterior, median, longitudinal split. Prothoracic spiracle elongate­oval, on large, rugulose callosity midlaterally at anterior margin of thorax. Anterior mesothoracic spines consisting of pair of long, narrow, posteriorly curved and apically pointed spines above base of sheath of mid legs; posterior spine usually longer than anterior spine. Posterior mesothoracic callosity large, rugulose to almost smooth, with apically rounded to acute posterior mesothoracic spine and usually small anterior reddish­brown tubercle. Wing sheath irregularly rugose on anterior half, mostly rugose posteriorly, with or without small basal tubercle and with 1–2 small median tubercles. Thoracic area above wing sheath irregularly rugose. Apex of hind leg sheath reaching between posterior margin of abdominal segment 2 and middle of abdominal segment 3.

Abdominal spiracles semi­circular, light reddish brown, situated along midline laterally.

Abdominal segment 1 with dorsal transverse row of 14–15 long, straight to apically recurved spurs in male, 17–18 spurs in females; dorsolateral bristle­like spines absent; with 3–4 bristle­like spines behind each spiracle; venter obscured by wing and leg sheaths.

Segments 2–6 usually with dorsal transverse row of 11–15 alternating long, narrow, straight to apically recurved, acute spurs and short, broad, straight, bifurcate to quadrifurcate spines; with median pair of short spines sometimes fused basally; short spines becoming longer on more posterior segments.

Segment 7 with 9–10 alternating long spurs and shorter, narrow spines and 1–2 short median spines.

Segments 2–6 with 6–9 long dorsolateral bristle­like spines and 11–13 long lateral bristle­like spines of irregular size, but mostly long, behind each spiracle. Segment 7 with 5–6 dorsolateral bristle­like spines on each side and 8–10 bristle­like spines of uniform size behind each spiracle.

Segment 2 with 12–15 long and short ventral bristle­like spines on each side of and sometimes extending under hind leg sheath; segments 3–6 and 7 with 31–41 and 24–34 long, straight to apically curved or recurved ventral bristle­like spines, respectively; 2–3 ventral bristle­like spines often very close together basally and crossing over each other apically, especially on posterior segments.

Segment 8 with 1 very small, dorsomedian spur on each side of midline on male cases; dorsal spurs absent on female; cases of both sexes with bulbous posterior area on each side of midline; with small spiracle at lateral midline; 10–12 lateral bristle­like spines on each side; 7–12 and 3–5 ventrolateral bristle­like spines on male and female cases, respectively; female cases with pair of large, median, rugose tubercles very close together between ventrolateral bristle­like spines; tubercles absent from male cases.

Segment 9 often with small dorsomedian tubercle on each side of midline, pair of long, straight dorsal posterolateral processes and usually pair of minute, rugose ventral posterolateral callosities; male with pair of large ventromedian tubercles; female with pair of very small ventromedian tubercles.