Bengalia torosa Wiedemann 1819
Creators: name: Rognes, Knut
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Calliphoridae
Bengalia
Bengalia torosa

description: Key to males of the Bengalia torosa Wiedemann species group
All B. torosa species-group species lack discal setae on T5. This feature is shared with species belonging to the B. labiata Robineau-Desvoidy species-group [equivalent to the subfamily “ Bengaliinae ” of Lehrer (2005)]. All species in the latter group have a ventrally pointed (“gourd-shaped”) greater ampulla (Figs 259, 262) and a pair of strong marginal setae on ST4 (Rueda 1985; Kurahashi & Magpayo 2000), whereas the greater ampulla in the B. torosa species-group is always oval (Figs 151, 172, 195, 256). Species in the torosa -group are in general very similar to one another. Good starting points for identification of male specimens are the shape of the ST5 flap and the pattern of strong ventral setae on the fore tibia. However, the shape of the ST5 flap is variable (especially in B. kanoi, see Figs 138–148) and should be used with caution. Note also that its shape may be difficult to ascertain in dry specimens, because it does not always present itself in its broadest aspect (compare Figs 28 and 30), and the lack of microtrichia close to the margin may obscure its true shape. The anepimeron also provides useful characters. Its vestiture is often all pale, or consists of a bundle of black setulae in the upper part and pale or dark setulae in the lower part. Colour pattern should be used with caution. Very dark specimens may occur in species that normally are rather pale, and the opposite is also sometimes true. As a general rule, the phallus (aedeagus) should always be examined for safe identification. Some females may be identified from the typical external features also found in males (e.g., B. escheri and B. torosa), and with a fair degree of certainty if they have been captured together with males all belonging to a single species. So far, the ovipositor has not been investigated for any species of the B. torosa species-group.
1 Posterior margin of eye with a distinct concavity in profile (Fig. 207); fore tibia ventrally with two groups of spinous setae in a 5+2 pattern (Fig. 209); no strong erect marginal setae on T4; distance between vibrissae equal to or less than distance between vibrissa and eye; transverse line connecting vibrissae separated from lower facial margin by a distance greater than width of first flagellomere (Fig. 208); clypeus strongly projecting below lower facial margin (Fig. 208); anepimeron with pale setulae only (Fig. 212)............................................................... Bengalia torosa (Wiedemann)
- Posterior margin of eye straight, without a concavity in profile (Figs 106, 252); fore tibia with a single group of spinous setae ventrally; strong marginal setae present on T4; distance between vibrissae greater than distance between vibrissae and eye; vibrissa level with lower facial margin; clypeus less strongly projecting below lower facial margin; anepimeron with pale setulae only or at least a group of black setulae in upper part..................................................... 2
2 Anepimeron with pale setulae only (as in Figs 12 and 212)..................................................... 3
- Anepimeron with black setulae all over, or black setulae in a group in upper part in combination with exclusively or several
pale setulae in lower part (as in Fig. 92) (B. kanoi very rarely without black setulae or with a single black setula on anepimeron)............................................................................................... 6 3 Tegula black, sometimes with a pale margin (Fig. 9); mesonotum and mesopleuron bluish grey (Figs 3, 12); T4 and T5 with broad dark marginal bands (Fig. 4), often appearing all dark; T1+2 and T3 mostly yellow with dark marginal bands (Fig. 4), sometimes with middorsal dark stripe; ST5 flap large, triangular-circular (Figs 10–11); bacilliform sclerite process of complex structure (Fig. 20); semidomes forming an almost perfectly circular structure when viewed apically (Fig. 18)........................................................................................... Bengalia chekiangensis Fan
- Tegula yellow; mesonotum and mesopleuron yellowish-brown, not bluish; semidomes not forming an almost perfectly circular structure when viewed apically........................................................................... 4
4 Anepisternum usually dark in upper third (Fig. 242); T5 yellow on disc (Fig. 241); ST5 flap asymmetric (Figs 239–240); cercus with pronounced dorsal projections (Fig. 238), appearing as pale buttons in posterior view (Fig. 237)........................................................................................ Bengalia xanthopyga Senior-White
- Anepisternum usually all yellow; T5 yellow or dark on disc; cercus without such projections......................... 5
5 Abdominal tergites with broad hind marginal bands, occupying about a third of tergite length; ST5 flap longer than wide, with a nick in the distal edge and with a narrow projection, almost as long as the flap itself, alongside it on both sides (Figs 42, 45); bacilliform sclerite process long, thin and pointed (Fig. 38); distal lip process (dlp) large, like a half cylindrical tube directed apically, with a distal nick (Figs 39–41).............................................. Bengalia concava Malloch
- Abdominal tergites with very narrow black marginal bands (Fig. 196), T5 all pale or with a narrow dark marginal band; ST5 flap very short, much shorter than wide (Figs 186, 197–198, 203–204, 206), without narrow projections alongside it; bacilliform sclerite process with a backward projection (Figs 185, 202, 205); distal lip projection bifid (Figs 187–188, 191)...................................................................................... Bengalia recurva Malloch
6 Wing with pale area around r-m crossvein (Figs 61, 67, 95) (easier to see on actual specimens than in the photographs); distal lip process apparently bifid in anterior view (Figs 57, 86).................................................... 7
- Wing without pale area around r-m crossvein; distal lip process different......................................... 8
7 Pale species. ST5 flap as in Figs 80, 83, 91, 96. Narrow black marginal bands on T1+2–4 (Figs 94, 99). Fore tibial vestiture as in Fig. 90. Femora yellow. Anepimeron with a bundle of dark setulae in upper part, and with pale setulae in more than lower half (Fig. 92). Bacilliform sclerite process distally with an apically rounded projection directed towards hypandrium, and a narrow pointed projection directed towards base of cercus; lower edge of bacilliform sclerite process strongly concave (Figs 78– 79)........................................................................... Bengalia fuscipennis Bezzi
- Dark species. ST5 flap as in Figs 51–52, 68. Usually with broad black marginal bands on T1+2–4 (Figs 61–62). Fore tibial vestiture as in Figs 59, 64, 73–74. Femora dark in distal half (Fig. 60). Anepimeron usually with dark setulae all over, sometimes with some pale setulae in much less than lower half (Fig. 70). Bacilliform sclerite process distally without rounded projection directed towards hypandrium, only with the narrow pointed projection directed towards base of cercus; lower edge of bacilliform sclerite process straight (Figs 49–50, 75–76)......................................... Bengalia escheri Bezzi
8 ST5 flap as in Figs 107 and 116, broad with hind edge straight or very slightly concave, with rounded lateral angles; distal lip process complex, broader than long and with broad lateral wing-like projecting membranes in dorsal view (Figs 103, 105)................................................................................. Bengalia jejuna (Fabricius)
- ST5 flap as in Figs 28, 30, 138–148, 168, 177–178; distal lip process different (Figs 31–34, 134, 154, 156–157, 162–164).. 9
9 ST5 flap with broad and evenly convex distal edge (Figs 28, 30); pregonite elongate with a distal bifid tip (Fig. 24), postgonite with a broad tip, shaped as a bird’s head with a beak (Fig. 24); distal lip process a prominent trough or gutter with parallel edges and with low lateral walls at a right angle to floor of trough, with a narrow distal excavation (Figs 31, 33); semidomes with a horizontal upper edge forming an angle with lateral edge, as seen in apical view (Fig. 34).................................................................................... Bengalia chiangmaiensis Kurahashi & Tumrasvin
- ST5 flap with a concave or straight distal edge (Figs 138–148), or distal edge with a small convex projection with concave sections on each side (Figs 168, 177–178); pre- and postgonite of the normal type (Figs 136, 181); distal lip process different, with lateral and ventral dentate keels (Figs 134, 154, 156–157, 162–164); semidomes different, upper edge rounded (Fig. 154, 165).................................................................................................. 10
10 Distal edge of ST5 flap varying from concave to straight (Figs 138–148)........... Bengalia kanoi Kurahashi & Magpayo
- Distal edge of ST5 flap with a small convex projection with concave sections on each side (Figs 168, 177–178).................................................................................. Bengalia martinleakei Senior-White
description: Published as part of Rognes, Knut, 2018, Revision of the Bengalia torosa Wiedemann, 1819 species-group (Diptera: Calliphoridae), with notes on the systematic position of B. robertsi Kurahashi, 1987 and B. subnitida James, 1964, pp. 1-71 in Zootaxa 4391 (1) on pages 9-10, DOI: 10.11646/zootaxa.4391.1.1, http://zenodo.org/record/1193860