Pentachaeta impar, McAlpine, 2014

McAlpine, David K., 2014, Review of the Australian Genus Pentachaeta (Diptera: Heleomyzidae), with Descriptions of Nine New Species, Records of the Australian Museum 66 (5), pp. 247-264: 258-260

publication ID 10.3853/j.2201-4349.66.2014.1631

persistent identifier

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scientific name

Pentachaeta impar

n. sp.

Pentachaeta impar   n. sp.

Figs 34–36 View Figures 34, 35 View Figure 36

Type material. Holotype ♂. New South Wales : Wilson River Reserve, near Bellangry, [c. 31°12'S 152°29'E], 24.ix.1981, D.K.M., B.J.D. ( AM K310597). Glued to card point, postabdomen not dissected GoogleMaps   . Paratypes. New South Wales   : 112♂♂, 69♀♀, same locality as holotype, Jan. , Mar. , Sept. , Nov., Dec., 1966–1986, D.K.M., B.J.D., D.J.B. ( AM, ANIC, USNM) GoogleMaps   ; 6♂♂, 2♀♀, Cambridge Plateau , Kyogle district, Jan. 1993, S.F.M. ( AM)   ; 1♂, 2♀♀, Terania Creek , Lismore district, Feb. 1980, D.K.M., B.J.D. ( AM)   ; 4♂♂, Whian Whian State Forest , Lismore district, Feb. 1965, 1980, D.K.M., B.J.D. ( AM)   ; 10♂♂, 8♀♀, Huonbrook , near Mullumbimby , Jan., Feb., Mar. 1961 –1965, D.K.M., R.L. ( AM, QM)   ; 3♂♂, 2♀♀, Mount Gibraltar National Park, c. 64 miles [103 km] W of Grafton, Feb. 1965, D.K.M. ( AM)   ; 19♂♂, 15♀♀, Bruxner Park , near Coffs Harbour , Feb. , Oct., Nov., 1962–1965, D.H.C., D.K.M., M.S.U. ( AM, ANIC)   ; 3♂♂, 4♀♀, near N.W. Jolly Memorial Grove , Moonpar State Forest, Dorrigo district, Mar. 1987, D.K.M., B. J.D., R.d.K. ( AM)   ; 4♂♂, 2♀♀, Dorrigo National Park , Jan. Mar., 1960, 1961, D.K.M. ( AM)   ; 2♂♂, The Dome (McGrath’s Hump), near Dorrigo, Mar. 1960, D.K.M. ( AM)   ; 2♀♀, Middle Brother State Forest , near Kendall, Feb. 1990, D.K.M. ( AM)   ; 1♂, Lorien Wildlife Refuge , near Lansdowne, Sept. 2010, G.A.W. ( AM)   .

Other material examined. Queensland: Summer Creek, Little Yabba Forestry Road, near Kenilworth ( AM); Mount Glorious, near Brisbane ( AM); Mount Tamborine ( AM); Binna Burra, Lamington National Park ( AM); Cunningham’s Gap, near Maryvale ( ANIC).

Description (male, female). General characters as for genus.

Coloration of head, body, and wings, as for genus. Antenna predominantly tawny-yellow, with segment 3 slightly suffused with light brown; palpus tawny-yellow with brown apex. Sternopleuron tawny-yellow; with upper margin suffused with brown. Fore femur entirely brown; mid and hind femora tawny-yellow, with brown apices, tibiae tawny-yellow, hind tibia with brownish base and apex; fore and hind tarsi brown; mid tarsus tawny-yellow, becoming brownish apically.

Thorax. Hind tibia thickened in male only, other tibiae slender, normal.

Abdomen (male). Epandrium with two pairs of large dorsal bristles and numerous setulae, produced into a marginal tubercle anteriorly to base of surstylus; surstylus ( Fig. 34 View Figures 34, 35 ) elongate, almost parallel-sided in part, rounded apically, slightly broadened at extreme base, densely microtrichose on most of outer surface, with several large setulae, some nearly half as long as surstylus, and minute apical setulae, without inner basal prominence; subepandrial process large and prominent with few small setulae and minute tubercles distally, dorsobasally with two or three larger setulae; gonostylus compact, simple, with two to four large setulae; distiphallus long, tapered, channelled, with membranous oblong ventral lobe; bulb of aedeagus of unusual shape with pair of apertures on funnel-like anterior processes; cercus ( Fig. 35 View Figures 34, 35 ) moderately elongate, extensively microtrichose on both inner and outer surfaces, with relatively few large posteriorly directed setulae, and rather short subcylindrical, blunt, non-microtrichose anterior process, usually somewhat gibbous ventrally at base of process.

Dimensions. Total length, ♂ 2.0– 2.4 mm, ♀ 2.4–2.8 mm; length of thorax, ♂ 1.1–1.3 mm, ♀ 1.3–1.4 mm; length of wing, ♂ 2.8–3.1 mm, ♀ 3.2–3.7 mm.

Distribution. Mainly coastal and subcoastal districts of southern Queensland and northern New South Wales, from Kenilworth district in north to Taree district in south. Map references 8G, 8H, 8I ( Fig. 4 View Figure 4 ).


Pentachaeta impar   is distinct from all other species of the genus in that the male has only the hind tibia markedly thickened, the other tibiae being slender as in the female. The aedeagus is peculiar in the structure of the distiphallus and the presence of a pair of funnel-like openings on the bulb. Both sexes can generally be distinguished from other Pentachaeta   species by presence of a brown suffusion on the upper margin of the sternopleuron (katepisternum).

The specific epithet is a Latin adjective, impar   , unequal, in reference to the difference in thickness between the hind tibia and the other tibiae in the male.


Australian Museum


Australian National Insect Collection


Smithsonian Institution, National Museum of Natural History


Queensland Museum