Allothnonius Britton 1978

Allothnonius Britton, 1978

Allothnonius Britton, 1978: 38.

Type species: Allothnonius brooksi Britton, 1978, by original designation.

Diagnosis. Labial palp with terminal palpomere about as long and wide as penultimate palpomere. Terminal maxillary palpomere slender, as long as the proximal 3 palpomeres together, upper side with a shallow, dull-surfaced depression. Antenna with 10 antennomeres, club with 6–7 lamellae in male. Labrum convex, not protruding beyond face of the clypeus, with long setae. Clypeus with anterior face wide, ratio of greatest width to mid depth about 4–5:1, with numerous scattered setiferous punctures including some longer setae, upper surface broadly rounded, without an emargination. Surface of frons, pronotum, and scutellum either with long, pale-yellow, backwardly directly setae, sometimes interspersed with elongate, adpressed, white setae; or only with adpressed white setae. Elytra sometimes with a few, long setae close to the base, otherwise with minute, stout setae; lateral margin with fringe of longer, stout, brown setae. Pygidium with uniform but sparse clothing of short setae or adpressed, elongate, white scales. Thorax with long, fine setae beneath. Spurs of metatibia long (1.2 mm) and uniformly tapered to apex. Claws long and sharply curved, with a strong tooth beneath the base.

In the most recent key to Australian Melolonthini sensu lato (Weir et al. 2019), Allothnonius separates from Othnonius Olliff, 1891 at couplet 11. Allothnonius have the metatibial spurs long and uniformly tapered (short, broad and flattened in Othnonius), and have at least a few broad or elongate, adpressed, white scales or flattened, adpressed setae on the anterior faces of the prefemora and/or protibiae (setose in Othnonius).

Distribution. Known from northeastern Queensland (Einsleigh Uplands and south of Townsville) and northwestern Northern Territory in areas dominated by savannah vegetation (Fig. 18). The area south of Townsville where A. brooksi occurs is the Burdekin Gap, an area of tropical savannah and the largest dryland biogeographical barrier on Australia’s east coast (Bryant & Krosch 2016) – it separates the Wet Tropics from the moist Central Mackay Coast. Given the predominance of this vegetation type and the uniformity of climate types across the intervening area between the Queensland and Northern Territory distributions (Fig. 18), it would not be surprising if additional species were discovered. As with many other Australian Melolonthini, adults probably emerge only over a few days each year, and this has restricted collection opportunities.