Machimus prairiensis ( Tucker, 1907 )

Dennis, D. Steve & Barnes, Jeffrey K., 2013, Pupal cases of three Nearctic species of Machimus (Diptera: Asilidae), Zootaxa 3683 (5), pp. 561-570 : 567-568

Machimus prairiensis ( Tucker, 1907)

Tolmerus prairiensis Tucker, 1907: 93

The following description is based on one pupal case with an associated pinned adult female labeled, “A.C. 4934 Sp., Manhattan, Kan., McColloch-Hayes, Reared as 10705, Asilus prairiensis Tucker ’69 det. J. Wilcox. USNMENT00876155”.

Description. Pupal case straight to abdominal segment 3 and then gently curving. Greatest length, including anterior antennal processes 16.5 mm; greatest width of thorax 3.75 mm; greatest width of abdomen 3.0 mm, tapering to 1.25 mm at greatest width of abdominal segment 8. Subshining light yellowish brown, mostly rugose. Spurs, dorsal spines, antennal processes, and processes of abdominal segment 9 uniformly light reddish brown, processes darker apically; dorsolateral, postspiracular, and ventral bristlelike spines pale yellowish, most darker basally.

Head with pair of basally rugose, dorsally rounded to flattened, ventrally wedge shaped anterior antennal processes not joined at base; with group of 3 subequal, basally fused posterior antennal processes located ventrolaterally on each side; 2 outermost processes widely separated from innermost process, closer together; innermost and middle processes tapered, dorsally rounded, ventrally wedge shaped; outermost process wide for entire length, dorsoventrally flattened, apically rounded; basal sensory pore located on proximal side of outer process, in flattened, elongate oval, sclerotized area. Facial area lacking median and lateral spines. Labral sheath short, rugose on either side of midline, with posterior rugose, almost vertical tubercle extending slightly over proboscidal sheath. Proboscidal sheath about twice length of labral sheath, rugulose on either side of midline, with posterior, almost vertical tubercle extending slightly over anterior coxal sheath; with short longitudinal groove anterior to tubercle. Maxillary sheaths smooth to rugulose, extending 1/2–2/3 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 rugulose, with anterior median longitudinal split. Posterior coxal sheath not visible, folded inward. Paired elongate oval prothoracic spiracles, raised on small callosity, situated midlaterally at anterior margin of thorax. Pair of anterior mesothoracic spines present on each side of thorax above bases of mid leg sheaths; anterior spine dorsally rounded to ventrally wedge shaped; posterior spine dorsally concave, dorsoventrally flattened; spines equal in size, basally rugose, straight. Posterior mesothoracic callosity at base of wing sheath medium size, rugose; with apically rounded posterior mesothoracic spine with sclerotized edge. Wing sheath smooth to rugose with posterior elongate grooves, lacking basal and medial tubercles. Thoracic area above wing sheaths smooth. Apex of hind leg sheath (leg sheath 3) reaching to anterior end or middle of abdominal segment 3, with apical median groove. Leg sheaths 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, recurved spurs and short, straight spines; spines generally slightly anterior to spurs, and some lateral spurs and spines becoming shorter. Dorsolateral and postspiracular bristlelike spines generally about equal in length from anterior to posterior segments; ventral bristlelike spines generally becoming longer from anterior to posterior segments. Some bristlelike spines short or indistinct, apically, and not equally spaced.

Abdominal segments 1–7 with spiracles situated along midline laterally, shining light to dark reddish brown, elongate oval, on stalk or flush on mostly smooth callosity.

Abdominal segment 1 with anterodorsal transverse row of 13 long, subequal, strongly recurved spurs; lacking dorsolateral bristlelike spines; with 5 mostly long postspiracular bristlelike spines; venter obscured by wing and leg sheaths.

Abdominal segment 2 with broad, short, deeply bifurcate dorsomedian spine, flanked on each side by 3 alternating long, apically recurved spurs and 2 straight, short spines, and 2–3 outer short spines; with 6–7 equal, mostly long dorsolateral bristlelike spines; with 9–10 mostly long postspircular bristlelike spines; with 8 mostly long ventral bristlelike spines extending under wing and leg sheaths on each side, becoming shorter towards midline.

Abdominal segment 3 with short, apically bifurcate dorsomedian spine, flanked on each side by 3 alternating long straight to apically recurved spurs and short, straight spines, and 2–3 outer short spines; with 5–7 mostly long, equal dorsolateral bristlelike spines; with 7–8 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 28 mostly long bristlelike spines.

Abdominal segment 4 with apically bifurcate dorsomedian spine, flanked on each side by 3 alternating, straight to apically recurved long spurs and straight, short spines; with 6–7 mostly equal dorsolateral bristlelike spines; with 9 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 27 mostly long bristlelike spines, one pair basally fused.

Abdominal segment 5 with short, apically bifurcate dorsomedian spine, flanked on each side by 3 alternating long, straight to apically recurved spurs and 2–3 straight, short spines; with 5–6 mostly long dorsolateral bristlelike spines; with 8–9 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 27 mostly long bristlelike spines.

Abdominal segment 6 with short, apically bifurcate dorsomedian spine, flanked on each side by 3 alternating straight to apically recurved long spurs and straight, short spines; with 4–5 mostly long dorsolateral bristlelike spines; with 6–7 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 22 mostly long bristlelike spines, some short spines indistinct.

Abdominal segment 7 with dorsomedian, transverse row of 13 alternating straight, long spurs and straight, short spines; with 4 mostly long dorsolateral bristlelike spines; with 7 mostly long postspiracular bristlelike spines; with ventromedian transverse row of 22 mostly long bristlelike spines.

Abdominal segment 8 with dorsomedian row of 4 short, subequal spurs divided by median space; lacking dorsolateral bristlelike spines; with 4 mostly long lateral bristlelike spines; with small, reddish brown, spherical, lateral spiracle, flush with cuticle; lacking ventral bristlelike spines.

Abdominal segment 9 with pair of long, mostly straight, dorsally rounded, ventrally wedge shaped dorsal posterolateral processes and pair of shorter, dorsally rounded, ventrally wedge shaped ventral posterolateral processes curved toward midline; with rugose bulbous area on each side of dorsal midline; with pair of short, tapered, basally rugose ventral tubercles between ventral processes; lacking midventral swellings, callosities, and tubercles.