Machimus occidentalis ( Hine, 1909 )

Dennis, D. Steve & Barnes, Jeffrey K., 2013, Pupal cases of three Nearctic species of Machimus (Diptera: Asilidae), Zootaxa 3683 (5), pp. 561-570 : 564-567

Machimus occidentalis ( Hine, 1909)

( Figs. 4–5 )

Asilus occidentalis Hine, 1909: 147

The pupal case of a male M. occidentalis was described by Dennis and Lavigne (1976; as Machimus sp., either callidus (Williston) or occidentalis (Hine)) with additional comments in Dennis et al. (2008a). The following description is based on a pupal case and associated pinned female labeled, “Arroyo Seco, Monterey Co., Calif. III- 25-56, Emerged IV-22-56, D. Bundick Coll., Machimus occidentalis Hine det. J. Wilcox. USNMENT00876154”.

Description. Pupal case mostly straight. Greatest length, including anterior antennal processes 15.0 mm; greatest width of thorax 3.5 mm; greatest width of abdomen 3.0 mm, tapering to 1.0 mm at greatest width of abdominal segment 8. Subshining golden brown, smooth to rugose. Spurs, dorsal spines, and processes uniformly reddish brown; some spurs and dorsal spines darker apically, antennal processes and processes of abdominal segment 9 darker apically; dorsolateral, postspiracular, and ventral bristlelike spines pale yellowish.

Head with pair of basally rugose, dorsally rounded to flattened, ventrally wedge shaped anterior antennal processes not joined at base; with group of 3 basally fused, rugose posterior antennal processes located ventrolaterally on each side; innermost (anterior) process widely separated from outermost (posterior) process ( Figs. 4–5 ); 2 outermost processes fused basally for greater distance, thus appearing shorter than innermost process; one side of processes dorsally rounded to flattened, other side wedge shaped; innermost and outermost processes apically rounded to acute, middle process apically more acute; basal sensory pore present on proximal side of outer process, in slightly flattened, elongate oval area ( Fig. 5 ). Facial area lacking median and lateral spines. Labral sheath short, rugose along and on either side of midline, with posterior rugose tubercle extending slightly over proboscidal sheath. Proboscidal sheath about three times length of labral sheath, smooth, with slight posterior, medial furrow. Maxillary sheaths smooth, extending 2/3 length of proboscidal sheath, lacking apical processes or tubercle-like swellings. Palpal sheaths not visible between maxillary sheath and labral sheath.

Anterior coxal sheaths smooth to slightly rugulose, with anterior median longitudinal split. Posterior coxal sheath not visible, folded inward. Paired elongate oval prothoracic spiracles, tilted posteriorly, elevated on flattened area of callosity with sclerotized ridge, situated midlaterally at anterior margin of thorax. Pair of anterior mesothoracic spines present on each side of thorax above bases of mid leg sheaths; spines mostly straight, basally rugose, dorsally rounded, ventrally wedge shaped; anterior spine slightly shorter, narrower, apically recurved and more pointed than posterior spine which is more straight. Posterior mesothoracic callosity at base of wing sheath medium to large, rugose; with apically rounded posterior mesothoracic spine with sclerotized edge. Wing sheath smooth to rugulose with posterior elongate grooves, lacking basal and medial tubercle like projections. Thoracic area above wing sheaths smooth to slightly rugulose. Apex of hind leg sheath (leg sheath 3) reaching to posterior half of abdominal segment 3, with apical median groove. Leg sheaths smooth to slightly rugulose, apically slightly bilobed with small medial projection.

Abdominal segment 1 with dorsal transverse row of apically recurved spurs divided by median space. Abdominal segments 2–7 lacking dorsomedian space, with or without median bifurcate spine, with transverse rows of alternating long, apically recurved spurs and short, straight spines; some spines slightly anterior to spurs, and some lateral spurs and spines becoming shorter. Dorsolateral, postspiracular, and ventral bristlelike spines about equal in length from anterior to posterior segments. Some bristlelike spines short or indistinct and not equally spaced.

Abdominal segments 1–7 with spiracles situated along midline laterally, shining light yellowish brown to reddish brown, spherical to oval, slightly raised to flush with cuticle, generally not on callosities.

Abdominal segment 1 with anterodorsal transverse row of 4–7 long, equal, apically recurved spurs on each side separated by narrow dorsomedian space; lacking dorsolateral bristlelike spines; with 3 mostly long postspiracular bristlelike spines; venter obscured by wing and leg sheaths.

Abdominal segment 2 with short, broad, deeply bifurcate dorsomedian spine flanked on each side by 5–7 alternating long recurved spurs and short spines; with 6 long, subequal bristlelike spines; with 6 mostly long postspircular bristlelike spines; with 6 mostly long ventral bristlelike spines extending under wing and leg sheaths on each side.

Abdominal segment 3 with dorsomedian transverse row of 13 alternating short spines and long spurs; with 4–6 mostly long, equal dorsolateral bristlelike spines; with 6–7 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 14 or more (some missing) mostly long bristlelike spines.

Abdominal segment 4 with dorsomedian transverse row of 13 alternating short spines and long spurs; with 5–6 mostly equal dorsolateral bristlelike spines; with 7 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 21 mostly long bristlelike spines.

Abdominal segment 5 with dorsomedian transverse row of 13 alternating short spines and long spurs; with 4–5 mostly long dorsolateral bristlelike spines; with 7 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 25 mostly long bristlelike spines.

Abdominal segment 6 with dorsomedian transverse row of 13 alternating short spines and long spurs; with 4–6 mostly long dorsolateral bristlelike spines; with 5–6 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 18 mostly long bristlelike spines.

Abdominal segment 7 with deeply bifurcate dorsomedian spine flanked on each side by 2–3 long, apically recurved spurs alternating with short spines; with 4 mostly long dorsolateral bristlelike spines; with 6 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 16 mostly long bristlelike spines.

Abdominal segment 8 with 2 dorsal spurs on either side of midline, inner spurs larger and slightly longer than outer spurs; with 0–1 dorsolateral bristlelike spines; with 5–6 mostly long postspiracular bristlelike spines; laterally with small, spherical, reddish brown spiracle flush with cuticle; ventrally on each side of midline with 1 long inner bristlelike spine curved towards midline and 1 shorter outer, bristlelike spine straight to slightly recurved.

Abdominal segment 9 with pair of long, apically recurved, dorsally rounded, ventrally wedge shaped dorsal posterolateral processes and pair of shorter, straight, rounded ventral posterolateral processes; with 2 short, wide, rugose tubercles between dorsal processes; with 2 short, tapered, basally rugose tubercles between ventral processes and small medial midventral callosity anterior to tubercles.

Figures

FIGURE 4. Machimus occidentalis female pupal case, facial sheath and adjacent structures. acsh = anterior coxal sheath, lsh = labral sheath, msh = maxillary sheath, pcsh = area of posterior coxal sheath (with sheath folded inward), prsh = proboscidal sheath.

FIGURE 5. Machimus occidentalis, posterior antennal processes, left side, dorstlateral view.