Ommatius gemma Brimley, 1928

Dennis, D. Steve, Barnes, Jeffrey K. & Knutson, Lloyd, 2008, Pupal cases of Nearctic robber flies (Diptera: Asilidae), Zootaxa 1868 (1), pp. 1-98 : 48-50

Ommatius gemma Brimley

( Fig. 28 )

This description is based on a male pupal case from the United States National Museum. It is labeled "Manhattan, KS; 3–VI–32; emerged 14–VI–32; R. H. Painter Collector." According to Martin & Wilcox (1965) this species occurs in Arkansas, Florida, Mississippi, North Carolina, Okalahoma, and Virginia. Wilcox (1936) also reported it from Arkansas, Mississippi, North Carolina, and Oklahoma. The label information for the described specimen indicates a slightly wider distribution than previously reported.

Description: Greatest length, including anterior antennal processes, 9.0 mm; greatest width of thorax 2.0 mm; greatest width of abdomen 1.5 mm; tapering to 0.5 mm at greatest width of abdominal segment 8. Integument subshining golden brown; spines and other processes glistening reddish brown, darker apically, except for abdominal spines, which are uniformly reddish brown.

Head with pair of long, dorsoventrally flattened, medially fused anterior antennal processes and group of 3 basally fused posterior antennal processes located ventrolaterally; middle and third posterior processes closer together and fused for greater distance, appearing shorter than inner or first process; outer or third posterior process apically rounded and ridge­like; first and second posterior processes apically acute. Labral sheath bulbous, composed mostly of large, rugose, apically rounded, dorsoventrally flattened processes. Proboscial sheath smooth, except for slight rugoseness posteriorly. Maxillary sheath mostly smooth with small median tubercle.

Anterior coxal sheath smooth, with anterior, median, longitudinal split. Prothoracic spiracle elongateoval, directed posteriorly, on medium to large, smooth to slightly rugose callosity, situated midlaterally at anterior margin of thorax. Anterior mesothoracic spines absent. Posterior mesothoracic callosity large, smooth, with sclerotized ridges, especially posteriorly. Wing sheath smooth, except for rugoseness on poste­ rior third to half. Thoracic area above wing sheath smooth, with yellowish dorsomedian bristle behind posterior mesothoracic callosity. Apex of hind leg sheath reaching to about middle of abdominal segment 3.

Abdominal spiracles upraised and stalk­like, reddish brown, round to elongate­oval, along midline laterally.

Abdominal segment 1 with dorsal transverse row of 14 mostly long, apically recurved spurs on anterior margin of segment; lacking dorsolateral bristle­like spines; with 3 lateral bristle­like spines behind each spiracle; venter obscured by wing and leg sheaths.

Segments 2–7 with dorsal transverse row of 6 long, straight to slightly apically recurved spurs alternating with 7 short spines; with 2–4 dorsolateral bristle­like spines of unequal size on each side and 3–5 lateral bristle­like spines of unequal size behind each spiracle.

Segment 2 with 4–5 ventral bristle­like spines on each side of hind leg sheaths. Segments 3–7 with complete transverse row of 16–21 bristle­like spines of unequal size; median 2–3 bristle­like spines usually shorter than spines on each side.

Segment 8 with dorsal row of 3 long spurs alternating with 2 short spines on each side of midline, small spiracle along midline laterally, 5–7 lateral bristle­like spines below spiracle, and 15 ventral bristle­like spines of unequal length.

Segment 9 with pair of long, dorsally curved, dorsal posterolateral processes; pair of shorter, dorsally flattened, ventrally curved ventral posterolateral processes; pair of ventral posteromedian acuminate processes; and pair of ventral, posteriorly diverging, elongate swellings.

Figures

FIGURE 28. Ommatius gemma Brimley, lateral view with enlarged dorsolateral view of thoracic region. Abbreviations: lesh 1 = leg sheath 1, lesh 2 = leg sheath 2, pmc = posterior mesothoracic callosity, pthsr = prothoracic spiracle.