Bama (Bama) robertsi, 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 : 31

Bama (Bama) robertsi n.sp.

Figs 5, 6

Type material. Holotype ♀ (unique). Papua New Guinea: Southern Highlands Province: Mount Giluwe [c. 6°05'S 143°50'E], 7.xii.1979, H.R., on ground foliage ( AM K352854 ). On micropin through polyporus.

Description (♀, ♂ unknown). Moderately large, largely metallic black fly, with heavily marked wing.

Coloration. Head largely black; anterior margin of postfrons and frontal lunule tawny-brown.Antenna, including arista, tawny-brown. Prelabrum black; palpus dark brown. Thorax black, largely glossy, with reflections slightly tinted with blue-green. Legs almost entirely dark brown to black; mid coxa with all setulae on anterior plate pale yellow, except for one or two larger lateral black setulae. Wing hyaline, with predominantly dark brown to blackish markings as in Fig. 5 ; halter tawny, with dark brown capitellum. Abdomen black, dorsally largely glossy, with blue- to purple-tinted reflections.

Head. Postfrons almost parallel-sided, near mid-length c. 0.37× as wide as head; height of cheek c. 0.20 of height of eye; two fronto-orbital bristles rather large; ocellar bristles distinct but minute; postvertical bristles very small, closely placed and almost parallel. Antennal segment 3 broadly rounded apically, more than twice as long as deep; segment 4 very short; segment 5 apparently slightly longer than its diameter; segment 6 with short pubescence, except near base. Prelabrum moderately deep, well sclerotised; palpus rather narrow, tapered distally.

Thorax. Mesoscutum bare and glossy between dorsal setulae, pubescent-pruinescent only towards lateral margins; scutellum uniformly pubescent on dorsal surface, except for glossy subapical zone; ventromedial extremity of sternopleuron with numerous slender yellow setulae of various sizes forming a loose brush; dorsocentral and prescutellar acrostichal bristles large; chaetotaxy otherwise generic. Fore femur with moderately developed posteroventral bristles, without posterodorsal bristles. Wing ( Fig. 5 ): first costal cell largely bare, only narrowly microtrichose along distal margin; second costal cell entirely microtrichose; stem vein without dorsal setulae basad of humeral crossvein; vein 2 with only slight curvature; anterior crossvein not more than half as long as penultimate section of vein 4; second section of vein 4 with deeply concave curvature; both anterodistal and posterodistal distal angles of discal cell acute; second basal cell bare on c. basal half; anal cell bare, except towards distal extremity; anal crossvein strongly bent at c. anterior third, with concave curvature posteriorly.

Abdomen ( Fig. 6 ). Compound tergite 1+2 c. 3× as long as exposed part of tergite 3; sternites 1, 2, and 3 rather large; sternites 4, 5, and 6 progressively shorter.

Dimensions. Total length, 7.8 mm; length of thorax, 3.7 mm; length of wing, 8.9 mm.

Notes. Bama robertsi should be readily distinguished by the wing pattern ( Fig. 5 ) in addition to characters given in the key. The remarkably long female compound tergite 1+2 and the absence of dorsal setulae on the stem vein (base of R) are characters not yet observed in other species of the subgenus Bama .

The specific epithet refers to the late Hywel S. Roberts whose collections (AM and FRIL) have significantly increased knowledge of the platystomatids of Papua New Guinea.

Figures

Figures 5, 6. Bama robertsi n.sp., holotype female. (5) Right wing. (6) Abdomen, dorsal view.