Cavonus fovealacus Hutchinson & Allsopp, 2020

Hutchinson, Paul M. & Allsopp, Peter G., 2020, Cavonus Sharp, 1875 (Coleoptera: Scarabaeidae: Dynastinae: Pentodontini Pseudoryctina) in Western Australia with description of a new species and the female of Cavonus sculpturatus Blackburn, 1888, Zootaxa 4852 (4), pp. 449-460 : 455-458

Cavonus fovealacus Hutchinson & Allsopp , new species

( Figs. 17–28 )

urn:lsid:zoobank.org:act:27E8992D-0EF2-4729-BE2A-EBD5EEE97910

Types. AUSTRALIA. WESTERN AUSTRALIA. Holotype male: ♂ LAKE PALLARUP (STRANDLINE) WEST. AUST. 12.Feb.2008 P. HUTCHINSON | lake strandline // PMH Coll. # Dyn 0473 // genitalia on card [in WAM] ( Fig. 17 ).

Paratype ♂: ♂ Lake Carmody West. Aust. Dead 23.Oct.2001 edge saltlake P. Hutchinson | dead. edge saltlake // PMH Coll. # Dyn 0474 // genitalia on card [in PMH] .

Description. Male ( Figs. 17–25 ). Body black, palps brown, antennomeres 2–10 black with dark-brown suffusion, 15.7 mm long, 9.3 mm wide. Mentum wide at base, deflexed, narrowed to globular apex, reflexed at acute angle and constricted to ligula exposing labial palp insertions, surface setose; ligula margins straight, apex with narrowly expanded arcuate ridge; mandibular palps distinctly exposed beyond clypeus, palpomeres 2 and 3 subequal, palpomere 4 conical and widest at truncate apex, bearing slight dorsolateral fovea in basal half. Antenna with 10 antennomeres, scape and pedicel setose, club long, subequal to length of stalk, inner face setose, outer face unitexturous. Clypeus at 45° to plane of frons, transverse, subcircular in outline with apex broadly arcuate, anterior margin reflexed, lateral margins raised, surface with medial third slightly convex, finely and sparsely punctate, anterior face deep, oblique, glabrous; clypeofrontal ridge strongly raised, transverse, slightly flattened in middle, declivous to frons. Frons medially flattened, concentrically rugulose; ocular canthi short, coarsely punctate, anterior margin at slight angle to line of clypeus, straight, bearing short stout setae, apex rounded and not surpassing lateral margin of eye. Pronotum with anterior margin membranous, anterolateral angle at 90°, posterolateral angle distinct, obtuse, lateral margins evenly arcuate, widest at midlength, anteromedian tubercle stout, erect, slightly recurved, preceding a Y-shaped moderately deep impression, impression anteriorly highly transverse in anterior half reaching lateral margins, with broad moderately deep longitudinal depression interrupting basal convexity, laterally borders rounded, surface with fine, sparse punctation, coarser and denser along lateral and posterior margins, impression with incomplete punctures becoming denser and rugulose anteriorly, posterior ridge continuous. Scutellum with disc coarsely punctate. Each elytron with epipleural setae confined to humeral calli, sutural costa linear-punctate, disc with moderately to deeply impressed coarse punctures in well-defined striae, striae 3 and 4 finer anterior to apical calli, intervals impunctate except for a cluster at base of stria 6. Pygidium strongly convex, disc sparsely punctate, denser across base, setose basolaterally, scarcer across middle, apical ridge moderately broadened and sparsely setose. Postcoxal prosternal process long, narrow, evenly arcuate posteriorly, setose, apex tapering with surface glabrous. Abdominal sternites 2–6 punctate across posterior margin, medially narrowly glabrous. Protibiae quite stout, tridentate, denticles equidistant; protarsomere 5 longer than protarsomere 1; metafemora stout, unisulcate; metatibiae moderately stout with length about 2.5x apical width, bicarinate, basal carina bearing long setae, medial carina bearing long, acute cilia set 1 width apart, apical spurs tapering, smaller slightly curved, larger straight; metatarsomere 5 longer than metatarsomere 1. Genitalia with parameres curving inwards from about half length and apices at right angles to basal portion.

Female. Unknown.

Etymology. The specific name is a combination of fovea (Latin for pitfall) and lacus (Latin for lake), in recognition of the many naturally occurring salt lakes that dot the Western Australian landscape and that act as ‘Nature’s pitfall traps’. Both known specimens of the new species were collected from salt-lake strandlines ( Figs. 26–27 ).

Diagnosis. Cavonus fovealacus males can be distinguished from its congeners by the following combination of characters: clypeus rounded; mandibular palps with apical palpomere conical, widest and truncate at apex; pronotum with single tubercle preceding a deep Y-shaped depression and basal ridge continuous; pygidium with apical ridge setose.

Habitat. Lake Carmody and Lake Pallarup are amongst a series of lakes that are arranged in a north-south orientation between Hyden and Ravensthorpe, Western Australia ( Fig. 28 ). Both natural salt lakes are surrounded by mallee ( Eucalyptus ) ( Myrtaceae ), with an understorey composed of Melaleuca (Myrtaceae) , Allocasuarina (Casuarinaceae) , Acacia (Fabaceae) , and Banksia (Proteaceae) over white sand ( Figs. 26–27 ). The area has a Köppen-Geiger climate of BSk (cold, semi-arid, Beck et al. 2018) with an average annual rainfall of 340–430 mm. Most adult specimens of Cavonus were recorded from September to November and March ( Carne 1957) and the condition of the specimens with quite minor deterioration of colour by sun bleaching and mostly intact appendages is of similar stage of decomposition to other strandline coleopteran specimens where emergence times thus age of specimens are known and suggests it emerges in September–November.

Figures

FIGURE 28. Collection localities of Cavonus fovealacus new species and C. sculpturatus Blackburn, 1888 in Western Australia and South Australia.

FIGURES 17–25. Cavonus fovealacus new species, holotype male. 17, Dorsum; 18, venter; 19, lateral; 20, head, lateral; 21, head, dorsal; 22, pygidium; 23, parameres; 24, aedeagus, lateral; 25, labels.

FIGURES 26–27. Collection areas of Cavonus fovealacus new species. 26, Lake Pallarup (holotype); 27, Lake Carmody (paratype).