Machimus paropus (Walker)

Dennis, D. Steve, Barnes, Jeffrey K. & Knutson, Lloyd, 2008, Pupal cases of Nearctic robber flies (Diptera: Asilidae), Zootaxa 1868 (1), pp. 1-98 : 88-89

Machimus paropus (Walker)

Scarbrough & Kuhar (1995) described the pupal case of Machimus paropus based on one case with pinned female labeled "Agawan [sic], Mass.; 20. VI.15; W. Springfield; H. E. Smith Coll., No 915348." The following, more detailed description is based on 16 pupal cases from the United States National Museum. Two male cases are labeled "Sioux City, Ia.; C.N. Ainslie Collector; A.E. Pritchard collection 1962" and " Lincoln Co., Me.; 18­VII­39; D. J. Borror; S. W. Bromley Collection 1955." Three male cases from Agawam , Massachusetts, collected by H. E. Smith, are further labeled "21 VI 15 ; W. Springfield No. 915274," "29 VI 15 ; W. Springfield No. 915262," and "15 VII 15; W. Springfield No. 915337." One female case is labeled "Beach, ND; Aug. 10, 1924; C.N. Ainslie Collector; A.E. Pritchard Collection 1962." Ten female cases from Agawam, Massachusetts, collected by H.E. Smith, are further labeled "15 VI 15 ; W. Springfield No. 915341," "21 VI 15 ; W. Springfield No. 915266," "21 VI 15 ; W. Springfield No. 915273," "21 VI 15 ; W. Springfield No. 915294," "21 VI 15 ; W. Springfield No. 915299," "21 VI 15 ; W. Springfield No. 915322," "24 VI 15 ; W. Springfield No. 915344," "2 VII 15; W. Springfield No. 915283," "5 VII 15; W. Springfield No. 915264, and "5 VII 15; W. Springfield No. 915329."

Redescription: Greatest length, including anterior antennal processes, ♂ 12.0– 14.5 mm, ♀ 13.0– 16.5 mm; greatest width of thorax ♂ 3.0 mm, ♀ 2.8–3.3 mm; greatest width of abdomen ♂ 2.5 mm, ♀ 2.5–3.0 mm, tapering to ♂ 1.0– 1.3 mm and ♀ 0.8–1.3 mm at greatest width of abdominal segment 8. Integument subshining, light yellow tan; head and thorax darker than abdomen; wing sheath often darker apically; spines and other processes glistening reddish brown, darker apically except for uniformly colored dorsal abdominal spurs and spines; bristle­like spines faded yellowish to light reddish brown.

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; middle and outer posterior processes fused for greater distance than inner posterior process; outer posterior process usually wider than other processes, straight, apically rounded, with small, oval, flattened outer area basally toward dorsum; inner and middle posterior processes sometimes slightly curved posteriorly, apically rounded to acute. Labral sheath small, mostly smooth or slightly rugulose near small tubercle­like keel and posterior margin. Proboscial sheath smooth or slightly rugulose medially on each side of midline, with shallow median groove posteriorly and small tubercle separated from groove by flattened area of cuticle. Maxillary sheath smooth or slightly rugulose on inner margins; posterior tubercles absent; sometimes with swellings below junction of labral and proboscial sheaths.

Anterior coxal sheath smooth or slightly rugulose, especially on margins, with anterior, median, longitudinal split. Prothoracic spiracle elongate­oval, directed posteriorly on small callosity with small anterior ridge, situated midlaterally at anterior margin of thorax. Anterior mesothoracic spines consisting of pair of long, subequal, apically acute, posteriorly curved spines above bases of mid leg sheaths; spines usually of same shape, but posterior spine sometimes broader and straighter than anterior spine. Posterior mesothoracic callosity small, smooth to slightly rugulose on margin, with small apically rounded posterior mesothoracic spine, situated at base of each wing sheath. Wing sheath mostly smooth to rugulose on apical third, otherwise irregularly rugulose; median and basal tubercles absent. Apex of hind leg sheath reaching between posterior margin of abdominal segment 2 and middle of abdominal segment 3.

Abdominal spiracles elevated, reddish brown, elongate, similar to thoracic spiracles, situated along midline laterally.

Abdominal segment 1 with dorsal transverse row of 10–11 long, apically recurved spurs, each with anterobasal ridge; sometimes 2–3 spurs bifurcate; often with short spur on 1 or both sides or between long spurs; dorsolateral bristle­like spines absent; with 3–5 (usually 4–5) lateral bristle­like spines behind each spiracle; venter obscured by wing and leg sheaths.

Segments 2–6 with 1–2 short outer spines and dorsal transverse row of 6 long, straight to apically recurved spurs alternating with 5–7 short, straight spines; some short spines bifurcate or in pairs, especially on segments 2–3; with 4–9 (usually 4–7) dorsolateral, curved bristle­like spines on each side and 6–8 lateral, curved bristle­like spines behind each spiracle.

Segment 7 similar to 2–3, with row of alternating long spurs and short spines; with 3–5 dorsolateral bristle­like spines and 4–6 lateral bristle­like spines.

Segment 2 with 5–9 ventral bristle­like spines on each side of and often extending under hind leg sheaths; segments 3–6 and 7 with 21–26 and 15–20 ventral bristle­like spines, respectively; spines straight to apically recurved, sometimes bifurcate apically or shorter than surrounding bristle­like spines, appearing to be about equidistant from one another.

Segment 8 with 2–4 (usually 3–4) dorsal spurs on each side of dorsal midline, minute yellowish­brown spiracle at lateral midline, and 3–6 (usually 3–4) lateral bristle­like spines on each side; some spurs and spines apically recurved and sometimes bifurcate apically; female with 1 long, strongly recurved dorsolateral bristlelike spine and often 1–3 (usually 1–2) short outer dorsolateral bristle­like spines on each side; male venter highly variable, with 1 median spine or row of 5–9 spines.

Segment 9 of male and female cases similar to M. snowii , but female cases with slight swelling anterior to terminal posteroventral tubercles.