Borboroides Malloch, 1925

McAlpine, DK, 2007, Review of the Borboroidini or Wombat Flies (Diptera: Heteromyzidae), with Reconsideration of the Status of Families Heleomyzidae and Sphaeroceridae, and Descriptions of Femoral Gland-baskets, Records of the Australian Museum 59, pp. 143-219 : 157-158

Genus Borboroides Malloch

Borboroides Malloch, 1925: 85 . Type species (original designation) B. atra Malloch.

Description. Minute to moderately small flies (length of wing c. 1–5 mm), often of slender build, but some of smallest species relatively robust, of blackish to yellow-brown body colour; wing faintly pigmented, without darker markings.

Head. Postfrons usually with more or less proclinate setulae on anterior median part; frontal lunule at most narrowly exposed; ptilinal suture on each side ventrally extended towards vibrissa, well below level of lower margin of eye; face uniformly sclerotized, more or less concave in profile, but often with median region slightly convexly raised on upper part; cheek region (“gena”) with single series of peristomial setulae only; postvertical bristles markedly convergent; small paravertical bristle present between postvertical and outer vertical; ocellar bristle well developed; fronto-orbital bristles two (except when anterior one is much reduced), both close to eye margin, posterior one reclinate and, to variable degree, sloped outwards, anterior one reclinate, eclinate, or proclinate, sometimes vestigial or undifferentiated from adjacent setulae; vibrissa well differentiated; central cheek bristle absent.Antenna: segment 2 with distal articular surface facing obliquely downwards (least so in B. doreenae ), with well-developed conus inserted into segment 3; segment 3 usually almost horizontally oval with oblique base fitted to segment 2, in atra group more nearly circular and slightly decumbent; segment 5 generally elongate, at least 4× as long as maximum diameter (less elongate in B. doreenae ); segment 6 with many short hairs on entire length. Prelabrum in most species larger in female than in male; proboscis with moderately developed labella.

Thorax. Prosternum rather short, anteriorly broadened, but remote from propleuron on each side (broader than in general condition of Allophylopsini ), without setulae; scutellum shorter than in Allophylopsini , without setulae; subscutellum variable in size and degree of convexity, generally less prominent and convex than in Heleomicra . Fore femur usually with seriate posterodorsal and posteroventral bristles; mid femur with seriate anterior bristles, which are sometimes rather small, in B. parva reduced to single distinct bristle; hind femur usually with one preapical anterodorsal bristle, usually without anterior and anteroventral bristles; fore and hind tibiae each with one preapical dorsal bristle or none; mid tibia with two more or less approximated preapical dorsal bristles and usually one to three longitudinally aligned slightly more basally located anterior bristles (absent in B. parva ), also the following subapical spurs: one large anterior, often one smaller posterior, one ventral spur, latter often large, but absent in males of some species; hind tibia sometimes with anteroventral apical or subapical spur; mid basitarsus longer than other basitarsi; fore basitarsus of male without apicoventral process (present in such heteromyzid genera as Borborillus Duda ; Leriopsis McAlpine , Fig. 167; Pseudoleria Garrett ; and Zachaetomyia Malloch ). Wing: costa with well-developed anterodorsal and anteroventral costagial bristles, with humeral break usually visible as a short, little sclerotized region, without spaced anterior or anteroventral spines among the numerous weaker setulae or spinules; subcosta well sclerotized for some distance beyond humeral crossvein, distally either not reaching costa but terminating freely in membrane near vein 1, or traceable to costa but sclerotized to variable degree, often with visible weakening opposite humeral break of costa; fork of vein 2+3 slightly basad of basal extremity of discal cell; basal section of vein 4 at least 0.7× length of second section (before anterior crossvein); distal section of vein 6 not reaching wing margin as a visible trace, either long, short, or (in B. parva which has anal cell open distally) absent; vein 7 absent without trace beyond alular incision.

Abdomen. Sternite 1 subquadrate and well sclerotized, or reduced and sclerotized only at sides. Male postabdomen: tergite 6 quite small but usually distinguishable, without setulae; sternite 6 primitively sclerotized mainly on left side of postabdomen, with dark, sclerotized anterior marginal stripe, dorsally joined to compound protandrial sclerite, in B. atra and allied species becoming more or less symmetrical, with thickened marginal strip encircling postabdomen or almost so; segment 8 more or less lengthened and petiolelike (least so in B. parva ), with sternite 8 extending round ventral surface as a sclerotized bridge; posterior extremity of sternite 8 generally with pair of lateral prominences for hinge-like articulation with epandrium; epandrium usually narrowed anteriorly, with contracted foramen connecting to protandrium, with sclerotized anteroventral bridge separated from hypandrial structures by window-like prehypandrial membrane; surstylus articulated with margin of epandrium; hypandrium of very diverse form and armature, without sclerotization anterior to base of aedeagus (except in B. parva ); aedeagus variable, but never of the very elongate flexible type (as seen in Prosopantrum spp. , Malloch, 1933), usually with long apodeme (shorter in a few species) unconnected to hypandrium; cerci usually separate, but often connected by narrow sclerotized strip. Female postabdomen moderately extensile; tergites and sternites 6 and 7 separately sclerotized, not spinose; cerci separate, ovoid or somewhat elongate; spermathecae three, with dark cuticularized vesicles, two of them sharing a common duct.

Distribution. Most less arid parts of temperate Australia; extending to tropics on Atherton Tableland, Queensland ( B. atra Malloch ). This is an addition to the tropical Australian “heleomyzid” records summarized by Sinclair & D. McAlpine (1995).

Notes

I have, over a long period, considered the problem as to whether the stewarti group (including six species) forms a sister group to the rest of the genus Borboroides as here constituted, and, if so, whether it should be separated as another genus. I think there is some evidence for the first proposition, as the presence of upwardly directed setulae on the mesopleuron (or anepisternum, see Fig. 81) in the other five species groups provides a distinctive synapomorphy. However, various other diversely distributed apomorphies cut across such a division, and the one species of the perkinsi group shows a combination of the wing characters, which strongly differentiate the stewarti group on one hand from the staniochi , helenae , parva , and atra groups on the other. The wide diversity in certain male postabdominal characters does not particularly support the division into two genera, but various postabdominal and other characters strongly support monophyly of Borboroides s.l. as distinct from Heleomicra ; for example, the presence of the ventral bridge of sternite 8 and the anteroventral bridge of the epandrium is not known to me in other heteromyzid genera. For these reasons I maintain a broad genus Borboroides consisting of six possibly monophyletic species groups.

The generic name is feminine, as originally treated by its author, under Article 3.1.4.4 of the ICZN (1999).