Bama (Bama) brevitarse, McAlpine, 2015

McAlpine, David K., 2015, Signal Flies of the Genus Bama (Diptera: Platystomatidae) in Papua New Guinea, Records of the Australian Museum 67 (2), pp. 25-53 : 33-36

Bama (Bama) brevitarse n.sp.

Figs 11–16

Type material. Holotype ♂ (unique). Highlands of Central Province: Murray Pass , N of Woitape, 2800–2900 m, 11.xi.1965, J.S., M.S. ( BPB). Impaled on large pin. Perhaps somewhat discoloured through exposure to moisture, but not mouldy. Abdomen in genitalia tube on pin.

Description (♂, ♀ unknown). Moderate-sized robust fly, with poorly defined wing markings.

Coloration. Generally brownish appearance perhaps partly due to fading. Head tawny-brown; postorbital silverypruinescent zone apparently extending on to cheek.Antenna tawny-yellow; arista slightly darker. Prelabrum brown; palpus tawny-yellow. Thorax brown to tawny-brown, largely shining, less so on mesoscutum. Legs: coxae brown to tawnybrown; femora dull tawny-yellow; tibiae tawny-brown; tarsi somewhat darker brown. Wing markings ( Fig. 11 ) irregular and partly nebulous, though widely distributed over anterior part of wing and crossveins. Halter tawny basally, with yellow capitellum. Abdomen brown to brown-black.

Head. Postfrons slightly narrowed anteriorly; width near mid-length 0.38 of total width of head; height of cheek 0.35

tibia and tarsus. (13) Right mid coxa and associated parts.

of height of eye; face with slight depression across midlength, slightly convex below; both fronto-orbital bristles probably moderately developed (damaged). Antennal segment 3 c. 2.8× as long as deep, apically narrowly rounded; segment 4 short and rounded; segment 5 only slightly larger; segment 6 only slightly thickened basally, loosely pubescent beyond base. Prelabrum small for genus; palpus rather slender.

Thorax apparently mainly as described for B. gressitti (some details of surface and chaetotaxy difficult to interpret). Marginal comb of mid coxa ( Fig. 13 ) with several noncrowded black setulae and less conspicuous finer, mostly pale setulae; fore femur with both slender and moderate posteroventral bristles and fairly stout posterodorsal bristles; mid tibia with one moderate-sized terminal spur; mid basitarsus cylindrical, much shorter than in B. bickeli (and in female of B. gressitti ); length of hind basitarsus ( Fig. 12 ) c. 0.26 of length of hind tibia, c. 0.39 of total length of tarsus. Wing: first and second costal cells entirely microtrichose; discal cell almost entirely microtrichose, not much narrowed basally; vein 2 with gentle sigmoid curvature beyond basal third; distal sections of veins 3 and 4 both slightly arched, subparallel; penultimate section of vein 4 slightly longer than anterior crossvein, slightly more than half as long as discal crossvein; discal crossvein strongly curved, its general orientation almost transverse; anal crossvein subangularly bent near anterior third of length.

Abdomen. Abdominal sternites 3 to 5 ( Fig. 14 ) increasingly broad in that order; sternite 4 broader than long, neither divided nor incised; sternite 5 large, flat, with deep median posterior incision; cercus rather large, distally inflated and posteriorly curved; aedeagus ( Fig. 16 ): preglans more heavily sclerotized than stipe, with oblique distal margin and terminal prominence, without spinules; flexible section subcylindrical, its length c. 0.35 of that of glans; glans irregularly ovoid- cylindrical, with large mainly transparent distal lobe bearing dense micropubescence near apex; bulb elongate, thickened at apex; apparent right terminal filament stout, scarcely tapering, nearly 3× as long as glans; apparent left filament much smaller with very fine apex and no visible pore.

Dimensions. Total length, 6.2 mm; length of thorax, 2.7 mm; length of wing, 7.7 mm; length of glans of aedeagus 0.46 mm.

Notes. The irregular and roughly defined wing markings in the male of B. brevitarse ( Fig. 11 ) are unlike those of any other known Bama species, but it is conceivable that they are highly sexually dimorphic. The hind basitarsus is shorter relative to adjacent parts than in other Bama species, and the mid basitarsus is also unusually short. The shape and proportions of abdominal sternites 4 and 5 of the male ( Fig. 14 ) appear to be distinctive, but these characters are unknown in some species, as are those of the aedeagus. The general condition of the holotype makes me uncertain if the tawnybrown coloration of the thorax is natural or due to fading.

The specific epithet is treated as a Latin compound adjective, indicating the unusually short tarsi.

Figures

Figures 11–13. Bama brevitarse n.sp., holotype male. (11) Right wing. (12) Right hind

Figures 14–16. Bama brevitarse n.sp., holotype male. (14) Abdominal sternites 2–5. (15) Genital segment and associated structures, anterolateral view.(16) Distal part of aedeagus; scale = 0.5 mm.bu, bulb; fs, flexible section of aedeagus; g, glans;lg, distal lobe of glans; st, stipe; tf, terminal filaments.