Pentachaeta pinguis, 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 : 261-263

Pentachaeta pinguis n. sp.

Figs 1 , 40–42

Type material. Holotype ♂. New South Wales: Royal National Park, lower end of Waterfall Creek , 34°09'S 151°01'E, 25.xii.2003, D.K.M. ( AM K310599 ). Glued to card point, postabdomen in genitalia vial on same pin . Paratypes. New South Wales: 2♂♂, 2♀♀, same locality as holotype, Mar., Dec., 2003–2012, D.K.M. ( AM, ANIC) ; 1♂, 2♀♀, [Royal] National Park , Nov. 1960 –1965, D.K.M. ( AM) ; 2♂♂, 12♀♀, Terania Creek, near Lismore , Feb. 1980 – 1983, D.K.M., B.J.D., K.C.K. ( AM) ; 1♂, Whian Whian State Forest, near Lismore , Feb. 1965, D.K.M. ( AM) ; 1♂, Iluka Rain Forest Reserve , Feb. 1965, D.K.M., R.L. ( AM) ; 2♀♀, Mooney Mooney Creek, near Gosford , Dec. 1976, 1978, D.K.M. ( AM) ; 4♂♂, 4♀♀, Springwood [probably vicinity of Sassafras Gully], Jan. 1956, D.K.M. ( AM) .

Other material examined. Queensland: Eungella National Park (near Broken River) ( AM); Olmara Hills, near Dalrymple Heights (or Eungella), c. 1000 m ( AM, QM); Crediton, near Eungella ( AM); Finch Hatton, 180 m ( AM); Finch Hatton Gorge ( AM); 13 km and 17 km S of Ravenshoe ( AM); Edge Hill, near Cairns ( AM); Kuranda ( AM); Paluma ( AM); Austral Forest, near Bulburin, Monto district ( AM).

Description (male, female)

Resembling P. kirkspriggsi in most characters; agreeing with description of that species, except as indicated below.

Coloration. Antenna tawny-yellow as in P. kirkspriggsi (type colour form), or with segments 2 and 3 quite black (dark tropical colour form); palpus tawny yellow with c. distal quarter grey brown (darker in fresh specimens), black in dark tropical form. Fore tibia entirely tawny-yellow (type colour form) or with brownish apical zone (dark tropical form).

Thorax. Tibiae as in P. kirkspriggsi .

Abdomen (male) resembling that of P. kirkspriggsi except as indicated. Surstylus often slightly more slender than in P. kirkspriggsi with smaller setulae; subepandrial process slightly narrower distally than in P. kirkspriggsi , but somewhat variable ( Fig. 42 ); gonostylus with posterodistal group of prominent tubercles and one to three large setulae; cercus slightly variable in shape but differing from that of P. kirkspriggsi in having anterior lobe tapered, not markedly produced and compressed, but slightly variable in shape.

Dimensions. Total length, ♂ 2.3–3.2 mm, ♀ 2.2–3.1 mm; length of thorax, ♂ 1.3–1.5 mm, ♀ 1.3–1.6 mm; length of wing, ♂ 3.0– 3.3 mm, ♀ 3.0– 3.6 mm.

Distribution. Eastern New South Wales: coastal districts and Blue Mountains; Queensland: Monto district in south of state (type colour form), sub-coastal ranges in tropics, from Kuranda to Clarke (Eungella) Range (mainly dark colour form). Map reference 7F, 7J, 7K, 8H ( Fig. 4 ).

Notes

Pentachaeta pinguis differs from other species of the genus except P. impar in having the palpus conspicuously darkened apically, but differs from that species in lacking the brown zone on the upper margin of the sternopleuron. Males resemble those of P. kirkspriggsi and P. physopus in having all tibiae conspicuously thickened but differ in the shape of the cercus (compare Figs 41 , 44 ), whereas the male of P. impar has only the hind tibia thickened and, again, a differently shaped cercus (compare Figs 40 , 35 ).

Tropical populations of P. pinguis differ from all other Pentachaeta forms in having antennal segments 2 and 3 black. This is such a striking feature that I initially assumed these populations to represent a distinct species, but comparison of numerous specimens from both tropical and southern populations reveals no identifiable differences except in coloration. There is slight variation in the shape of the surstylus and cercus in both these populations, but the male cercus is consistently distinct from that of P. kirkspriggsi , and both surstylus and cercus are sharply different from those of P. physopus .

One male specimen of P. pinguis from within its tropical habitat (Eungella National Park) shows tawny-yellow antennae, but was preserved in alcohol before drying and mounting. It shows some bleaching of pigmented cuticle, and it is uncertain if this treatment fully explains the antennal coloration.

The specific epithet is a Latin adjective, obese or fat, in reference to the thickened male tibiae.

Figures

Figure 1. Pentachaeta pinguis, northern form, female (13 km N of Ravenshoe).

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 40–42.Pentachaeta pinguis, Royal National Park (40) pair of cerci, left lateroventral view; scale = 0.1 mm.Pentachaeta pinguis, near Springwood (41) left surstylus, outer view, with basal prominence seen through transparency; scale = 0.1 mm; (42) left gonostylus and subepandrial process; scale = 0.05 mm.

Figures 43, 44.Pentachaeta physopus, Mooney Mooney Creek (43) left surstylus, outer surface view; (44) pair of cerci,

Figures 34, 35. Pentachaeta impar, Wilson River Reserve; (34) surstyli, with subepandrial processes; scale = 0.1 mm; (35) cerci, oblique ventral view; setulae shown only on left surstylus; scale = 0.1 mm.