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

Pentachaeta bassiana n. sp.

Figs 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 . Paratypes. Tasmania: 2♂♂, same data as holotype ( AM) ; 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 ) 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 ) 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 ) 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 ).

Notes

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 ), 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.

Figures

Figure 4. Reference map for distribution of Pentachaeta species in eastern Australia. Numbers in each rectangle (2° longitude by 2° latitude) are numbers of recorded species. Map references are given under Distribution for each species.

Figures 23–25. Pentachaeta bassiana (23) pair of surstyli, posteroventral view (Marakoopa Caves); structure on inner surface of basal half seen through transparency; scale = 0.1 mm; (24) pair of cerci, oblique ventral view (Belgrave); setulae shown only on left cercus; scale = 0.2 mm; (25) left gonostylus, subepandrial process and associated parts (Marakoopa Caves); scale 0.1 mm.