Helosciomyza driesseni, McAlpine, 2012

McAlpine, David K., 2012, Notes and Descriptions of Australian Helosciomyzidae or Comb-winged flies (Diptera: Schizophora), Records of the Australian Museum 64 (1), pp. 51-70 : 67

Helosciomyza driesseni n.sp.

Figs 25 , 27

Type material. Holotype ♂. Tasmania: Flood Creek, near Lake Saint Clair , 42.102°S 146.113°E, button grass moorland, 16–17.ii.2004, M.M.D. ( AM K264371 ). Doublemounted on micro-pin through polyporus after preservation in ethanol, postabdomen in micro-vial on pin . Paratypes. Tasmania: 2♂♂, 2♀♀, same data as holotype ( AM, ANIC) ; 2♀♀, Rufus Canal Road East , 42.10°S 146.75– 146.86°E, Feb. 2004, M.M.D. ( AM) ; 1♀, “ Bedlam ”, 42.73°S 146.10°E, Feb. 2004, M.M.D. ( AM) ; 2♂♂, Dove Lake, Cradle Mountain National Park , Dec. 2003, S.A.M. ( AM, TDPI) .

Description (male, female). Resembling other species of the fuscinevris group in most characters; agreeing approximately with description of H. bickeli except as indicated below, but because most specimens have been immersed in ethanol for five years before drying and mounting, some details of coloration are imperfectly preserved.

Coloration. Occipital region with broad dark cuticular mark of characteristic shape ( Fig. 27 ). Antennal segment 3 with large brown zone between aristal insertion and apex, tawny-orange basally and ventrally. Palpus tawnyyellow, sometimes faintly browned apically. Fore femur tawny-orange, on anterior surface with broad brown zone extending from near apex almost to base, on posterior surface with posterodorsal dark grey-pruinescent diffuse zone of variable length, usually becoming narrower and more distally restricted or fading distally, but without separate dark brownish subapical mark centred on posterior surface as in H. macalpinei .

Head. Cheek c. 0.39 as high as eye.

Thorax. Pteropleuron and hypopleuron without setulae; proepimeral bristle minute or absent. Fore tarsal segment 4 often shorter and broader than in corresponding sex of H. macalpinei .

Abdomen. Sternite 1 vestigial, without setulae. Male postabdomen: surstylus ( Fig. 25 ) relatively slender, curved, not distally broadened, with large, setulose posterobasal tubercle and moderately developed setulae posteriorly and on medial surface.

Dimensions (most specimens not accurately measurable). Total length, ♂ 5.2 mm, ♀ 5.7 mm; length of thorax, ♂ 2.6 mm, ♀ 2.6 mm; length of wing, ♂ 6.2 mm, ♀ 6.4 mm.

Distribution. Tasmania: northern to south-central highlands.

Notes

Helosciomyza driesseni , together with H. macalpinei and H. obliqua , belongs with those species of the fuscinevris group having no pteropleural setulae, antenna 3 strongly infuscated in part, and the fore femur with brown zone on anterior surface extending near base. Helosciomyza driesseni differs from related species in having a broad dark mark of characteristic shape just above the occipital foramen ( Fig. 27 ). This mark is due to dark cuticular pigment and, though partly obscured by pale pruinescence, is demonstrably present in nine of the ten available specimens of H. driesseni . Other species of the fuscinevris group have at most a more restricted dark zone, more or less surrounding the supracervical setulae. In the male of H. driesseni the form of the surstylus is distinct from that of H. obliqua and H. macalpinei (compare Fig. 25 with Figs 24, 26 ). The two latter species are only known from mainland Australia, whereas H. driesseni is from the Tasmanian highlands, but it is possible that the distributions are incompletely known.

Michael Driessen indicates that his material of H. driesseni was collected by sweeping vegetation on button grass moorland. This is a low vegetation community dominated by the sedge Gymnoschoenus sphaerocephalus , and is characteristic of certain parts of the Tasmanian highlands.

The specific epithet refers to Michael M. Driessen, who collected type material.

Figures

Figure 27. Helosciomyza driesseni, upper part of occiput, showing characteristic dark mark, most setulae omitted.

Figures 19–26.(19) Helosciomyza steyskali, protandrogram.(20) H.australica, epandrium and associated structures, posterior view, semi diagrammatic, setulae omitted. (21) H. neboissi (Pelion), left surstylus, outer view, scale = 0.2 mm. (22). H. australica (Picton Lakes), left surstylus, outer view. (23). H. steyskali (Boyd River), left surstylus, outer view. (24). H. obliqua (Mount Donna Buang), left surstylus, outer view. (25). H. driesseni (holotype), left surstylus, outer view. (26). H. macalpinei (holotype), left surstylus, outer view. Figs 21–26 all to same scale. c, cercus; ep, epandrium; pbf, posterobasal foot of surstylus; ss, surstylus; s5–s8, sternites 5 to 8; t5, t6, tergites 5 and 6.