Pentachaeta gilliesi, 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

Pentachaeta gilliesi n. sp.

Figs 30–33

Type material. Holotype ♂. South Australia: Mount Bonython, near Mount Lofty , c. 34°58'S 138°42'E, 12.iv.1967, D.K.M. ( AM K310596 ). Glued to card point, postabdomen in genitalia tube on same pin . Paratypes. South Australia: 1♂, summit, Mount Lofty , Apr. 1967, D.K.M. ( AM) ; 4♂♂, “Sunders”, near Hackham, Adelaide district , May 1975, H.A. ( SAM, AM) ; 1♂, “Kurlge”, Blackwood , 850 feet [c. 259 m], May 1958, N.B.T. ( SAM) .

Other material examined. Males. Australian Capital Territory: Black Mountain, near Canberra ( ANIC, AM). Some female specimens from the following localities are associated with males of P. gilliesi and perhaps may be conspecific: Sunders, near Hackham ( SAM); Blackwood ( SAM); Black Mountain ( ANIC).

Description (male)

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, with some details as in description of P. edwardsi .

Abdomen. Epandrium with only one pair of well differentiated dorsal bristles; surstylus ( Fig. 31 ) less elongate than in P. edwardsi and P. inserta , somewhat narrowed distally, but very obtuse, on outer surface with many short microtrichia and very few small macrotrichia, on inner surface near apex with macrotrichia of very diverse sizes ( Fig. 32 ), near base on inner surface without usual fascicle of setulae, but with one to three long setulae in a series approaching subepandrial process; subepandrial process forming short, broad setulose tubercle; gonostylus bilobed, anterior lobe with few large setulae, posterior lobe separately prominent, with few minute setulae but no scabrous or pustulose zone; bulb of aedeagus without invaginated teeth; cercus ( Fig. 30 ) scarcely produced posteriorly, anteriorly very prominently elongate, almost parallel-sided, towards anterior apex obtuse, minutely setulose, posterior half of cercus setulose, with many of larger setulae in a single series.

Dimensions. Total length 2.6–2.9 mm; length of thorax, 1.2–1.3 mm; length of wing, 3.2–3.6 mm.

Distribution. Only known from the Adelaide Hills district, South Australia, and the Canberra district, Australian Capital Territory. These two districts, about 900 km apart, are of similar latitude (around 35°S). They are drier than most Pentachaeta habitats, and other Pentachaeta species are not recorded for the districts. It is conceivable that P. gilliesi may yet be found in intermediate localities. Map references 1K, 6K ( Fig. 4 ).

Notes

Pentachaeta gilliesi closely resembles P. edwardsi and related species and is at present only distinguishable from these on male postabdominal characters. The long, narrow cerci ( Fig. 30 ) are so distinctive that males with these exposed are easily identified. Another distinctive feature is the presence of only one pair of stout dorsal bristles on the epandrium, and the form of the surstylus ( Fig. 31 ) is fairly distinctive, though somewhat resembling that of P. skusei .

This species is dedicated to William Gillies, whose elementary but thoughtfully prepared book (c. 1909) served as my childhood introduction to entomology.

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 30–33.Pentachaeta gilliesi, Mount Bonython (30) epandrium with cerci, showingright subepandrial process and basal prominence of right surstylus; scale = 0.2 mm; (31) pair of surstyli, posteroventral view; setulae shown only on left surstylus; scale = 0.2 mm; (32) apex of left surstylus, inner surface view; scale = 0.05 mm; (33) left gonostylus, lateral view; scale = 0.05 mm.