Antitrogus batesii (Olliff, 1890) Allsopp, 2022

Allsopp, Peter G., 2022, Australian Melolonthini (Coleoptera: Scarabaeidae: Melolonthinae): reclassification of eight species to Antitrogus Burmeister, 1855 and Barryfilius new genus, Zootaxa 5213 (5), pp. 513-545 : 516-517

Antitrogus batesii (Olliff, 1890) , new combination

( Figs. 7–9 )

Othnonius batesii Olliff, 1890: 6 .

Othnonius batesi: Blackburn 1911: 182 ; Britton 1978: 37, figs. 114–116 (aedeagus), fig. 275F (head and pronotum); Weir et al. 2019: 495, fig. 155 (pygidium and metathoracic leg), plate 63L (dorsum).

Type series. Allsopp (2020b) concluded that all of the type series of this species were lost, but, as the species is well characterised, there is no need to designate a neotype. There is a specimen from Mossgiel in ANIC that might be a syntype, but it has no other identifying label. Weir et al. (2019) attributed publication of Olliff’s paper to 1891, but part 1 of the Proceedings of the Linnean Society of New South Wales is marked as issued on 16 June 1890.

Other material examined. More than 50 males and females from localities across the Darling Downs of southeastern Queensland and south through inland New South Wales ( Fig. 9 ) in ANIC, PMH, QDAF, QM and UQIC .

Diagnosis ( Figs. 7–8 ). Body 14–17 mm long; head, pronotum, and scutellum black to dark red-brown, elytra redbrown or yellow-brown, propygidium yellow-brown, pygidium brown to black, ventral surface of thorax, metacoxae and legs dark brown to black, ventral abdomen brown but more yellow laterally, antennomeres 1–4 red-brown, antennomeres 5–10 pale yellow. Terminal palpomere of maxillary palp larger than 3 basal palpomeres together, elongate-elliptical (length:width 2.5:1), with an elongate depression on the outer dorsal side. Antennae with 10 antennomeres, antennomere 3 cylindrical, antennomere 4 sublamellate, antennomeres 5–10 forming long (about 3 mm), curved lamellae in males, short (0.7 mm), straight lamellae in females. Clypeus with anterior face deep, length 4.5–5.0x width, surface microreticulate between larger setose punctures; width of upper surface 2x length, anterior margin evenly rounded, with rounded angles; upper surface strongly concave, coarsely and closely punctured, each broad, flat-bottomed puncture with a minute, white seta contained within the puncture. Frons with a low transverse ridge at about two-thirds length marked with a band of long, yellow-white setae grading to very short setae to anterior and posterior margins, anterior two-thirds coarsely punctured, posterior third with finer punctures; laterally with numerous, white, long setae above each eye and on ocular canthi. Pronotum strongly transverse, greatest width 1.5x length; anterior margin with a raised edge; lateral edges curved before half-length and with a few, long, yellow setae, then only slightly wider and glabrous towards posterior margin, widest just before posterior margin; posterior margin with groove except across middle; anterior and posterior angles obtuse; surface evenly punctured, each puncture with a minute, white seta never more than 2x long as diameter of the puncture. Scutellum with scattered punctures with setae longer than those on pronotum. Elytra with fringe of yellow setae on lateral margins, intervals 1, 3, and 5 narrow and convex in contrast to intervening intervals that are broad, flat and more densely punctate, each puncture with minute, white setae contained within their puncture. Propygidium and pygidium clothed with fine, short, pale, semierect setae, apex of pygidium with slight indentation. Abdominal ventrites sparsely clothed with short, pale, semierect setae. Ventral surface of thorax densely clothed with long, fine, yellow setae. Teeth on outer edge of protibia long and acute; spurs of metatibiae broad and flat. Sutures between abdominal sternites distinct across the middle; terminal ventrite without lateral lobes. Aedeagus symmetrical, elongate spoon shaped in ventral view ( Fig. 8 ).

Distribution ( Fig. 9 ). Known from areas of self-mulching, black clays on the Darling Downs of southeastern Queensland and into inland New South Wales and further west on the grey and brown calcareous clays that tend to gilgai (a small, ephemeral lake formed from a depression in the soil surface in expanding clay soils) and that carry brigalow ( Acacia harpophylla F. Muell. ex Benth. ; Fabaceae ), wilga ( Geijera parviflora Lindl. ; Rutaceae ) and belah ( Casuarina cristata Miq. ; Casuarinaceae ) scrub ( Turner & Shaw 1969); Köppen-Geiger classification Cfa humid subtropical. Two of the four localities given by Olliff (1890) (Wilcannia and Mossgiel) are far to the southwest of the main distribution ( Fig. 9 ) and are not on the same soil type or climate classification (Köppen-Geiger Bsk/Bsh semi-arid); these localities appear doubtful, and I know of no further specimens from those areas.

Natural history. Common name: Black soil scarab. Larvae damage crops and pastures on the Darling Downs and in inland New South Wales. Reports of damage date from 1911 to recently, particularly during drought years ( Turner & Shaw 1969; Turner & Roubicek 1970; Goodyer 1977; Britton 1978; Brier & Miles 2022).

Turner & Shaw (1969) and G.K Waite (personal communication of undated manuscript about 1970) found that A. batesii has a two-year life cycle with adults flying after about 13 mm of rain in early summer to as late as March. Eggs are 3.5 mm long and 2.5 mm wide and take 35.4 days at 22.2 °C and 22.2 days at 28.8 °C to hatch. Mean headcapsule width is 2.3 mm for instar I, 3.7 mm for instar II, and 5.5 mm for instar III. At 29.4 °C the prepupal stage takes about nine days and the pupal stage takes 21 days. Females with well-developed wing muscles lay 10– 14 eggs and those with less developed muscles that do not fly lay a mean of 21 eggs and up to 35 eggs.

Carne (1974) reported observations by T.V. Bourke that “the male, which has greatly enlarged antennal clubs, flies actively and seeks out females as they emerge from the ground. The female apparently releases a pheromone that attracts males to her vicinity. Females rarely fly and, hence, are less well represented in collections than males”. This antennal structure and behaviour appear to be typical of Antitrogus ( Allsopp 1990b , 1993d).

Goodwin & Filshie (1969) described an entomopoxvirus from larvae of A. batesii and the molecular weight of its DNA was determined by Langridge & Roberts (1977). From field collections, Milner & Lutton (1975) suggested that the pathogenicity of the virus was low and in laboratory experiments infection had little effect of mortality and no significant effect on duration of first instars, food intake or larval growth. Milner (1974) described a milky disease Paenibacillus popilliae var. rhopaea (Paenibacillaceae) from A. batesii and other melolonthines but concluded ( Milner 1976) that it also was unlikely to be of value in the control of larvae of A. batesii .

Figures

FIGURE 9. Known distributions of Antitrogus batesii (Olliff, 1890) and Antitrogus ciliatus (Britton, 1978) in eastern Australia.

FIGURES 7–8. Antitrogus batesii (Olliff, 1890), male. 7, Dorsal view; 8, aedeagus, ventral, dorsal and lateral views. Fig. 7 reproduced from Weir et al. (2019) (CSIRO, used with permission). Fig. 8 reproduced from Britton (1978) (CSIRO, used with permission).