Pentachaeta bassiana, 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: 256-257

publication ID 10.3853/j.2201-4349.66.2014.1631

persistent identifier

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scientific name

Pentachaeta bassiana

n. sp.

Pentachaeta bassiana   n. sp.

Figs 23–25 View Figures 23–25

Type material. Holotype ♂. Tasmania: Marakoopa Caves, near Mole Creek , c. 41°35'S 146°17'E, 10.i.1960, D.K.M. ( AM K310594). Glued to card point, surstyli exposed, postabdomen not dissected GoogleMaps   . Paratypes. Tasmania: 2♂♂, same data as holotype ( AM) GoogleMaps   ; 2♂♂, Hellyer Gorge, upper (eastern) Arthur River district , Feb. 1967, E.F.R. ( ANIC)   ; 2♂♂, 2 miles [c. 3 km] E of Tonganah, near Scottsdale , Jan. 1960, D.K.M. ( AM)   ; 1♂, near Russell Falls, Mount Field National Park , Jan. 1960, D.K.M. ( AM)   .

Other material examined. Males. Victoria: Belgrave, near Melbourne ( AM, MV).

Description (male, females not yet identifiable)

Resembling P. edwardsi   and related species without sexual dimorphism of tibiae; agreeing with description of that species, except as indicated below.

Coloration generally as for genus; details as given for P. edwardsi   .

Abdomen. Surstylus ( Fig. 23 View Figures 23–25 ) with basal foot extended narrowly on margin of epandrium posteriorly, much broadened near and beyond mid-length but contracted to short, narrow apical section, on most of outer surface densely microtrichose but with few minute macrotrichia, apically with several larger macrotrichia on inner surface, basally on inner surface with compact sclerotized tubercle bearing few short macrotrichia; subepandrial process ( Fig. 25 View Figures 23–25 ) somewhat resembling that of P. edwardsi   ; gonostylus more nearly resembling that of P. bickeli   , with typically three long macrotrichia and scabrous zone which varies from slightly convex to slightly concave; aedeagus without invaginated teeth; cercus ( Fig. 24 View Figures 23–25 ) somewhat elongate, but expanded anteriorly to mid-length, with the pair of anterior lobes strongly diverging, each apically compressed, rounded and slightly twisted, outer surface with large macrotrichia posteriorly, minute ones anteriorly, and with general covering of microtrichia, but without distinctly angular outline and tubercle.

Dimensions. Total length 3.3–3.6 mm; length of thorax, 1.5–1.8 mm; length of wing, 4.1–4.6 mm.

Distribution. Tasmania: probably widely distributed. Victoria: vicinity of Melbourne. Map references 4L, 4N, 5N, 5O ( Fig. 4 View Figure 4 ).


Pentachaeta bassiana   belongs among those species without sexual dimorphism of the tibiae and with entirely dark male fore tarsus. Among these, the male has the surstylus with quite distinctive shape ( Fig. 23 View Figures 23–25 ), and the cercus is also characteristic. The specimen examined from Belgrave, Victoria, differs from the Tasmanian specimens (Marakoopa Caves and Hellyer Gorge) in having the surstylus slightly broader, the anterior lobe of the cercus shorter, and the setulae on the subepandrial process and gonostylus more numerous. These differences are slight, and study of more material is needed before significant divergence between the Victorian and Tasmanian populations can be accepted.

The specific epithet has the form of a Latin adjective and refers to the occurrence of the species on both sides of the Bass Strait.


Australian Museum


Australian National Insect Collection


University of Montana Museum