Constricticollis Hutchinson & Allsopp, 2023

Allsopp, Peter G. & Hutchinson, Paul M., 2023, Philcarneum new genus and Constricticollis new genus, two distinctive rhinoceros beetles (Coleoptera: Scarabaeidae: Dynastinae: Pentodontini) from opposite sides of Australia with a revised key to the Australian dynastine genera, Zootaxa 5351 (3), pp. 322-340 : 328-330

Constricticollis Hutchinson & Allsopp , new genus urn:lsid:zoobank.org:act:EF5C0AE1-7A83-4E9C-BAEE-18ED919F04D1

Type species. Constricticollis clunis Hutchinson & Allsopp new species, here designated.

Description of female. Body 15.0 mm long. Mentum not dilated and not concealing the bases of the maxillary palps, not compressed. Mandibles visible from above aside clypeus, bidentate, inner tooth narrow. Maxillary palps short, longer than labial palps; galea strongly toothed, without a conical process. Antenna with 10 antennomeres, apical 3 antennomeres forming a lamellate club, lamellae widest at midlength, club equal to length of shaft, scape not expanded or wedge-like, not concealing funicular antennomeres. Head without armature. Clypeus with anterior margin transverse, glabrous, strongly contracted towards apex with sides linear; clypeofrontal suture ridge-like, linear, angled anteriorly, depressed at midpoint. Pronotum unarmed, with medio-longitudinal concavity; highly transverse width:length 2:1; anterior margin deeply arcuately concave; posterior margin slightly concave across midlength. Elytral punctures arranged in lines, sutural striae linear punctate. Hind wings fully developed. Propygidium not enlarged, with dispersed stridulatory ridges. Apical pygidial ridge glabrous. Postcoxal process forming a vertical columnar process. Last abdominal ventrite non-sulcate. Protibiae tridentate, apical tooth acute. Meso- and metatibiae bicarinate, their apices expanded and truncated faces with cilia. Meso- and metatarsomere 1 asymmetrical. Claws simple and symmetrical.

Male. Unknown.

Etymology. From the Latin word “constrictus” meaning constricted and “collis” meaning neckband or collar (a term used for pronotum in coleopterology) referring to the pronotum whose both anterior and posterior margins are concave thus constricting the longitudinal length and making this species very distinct. The name is masculine in gender.

Placement. Use of the key to Australian dynastine genera of Weir et al. (2019) to place Constricticollis is difficult as that key is mainly based on males. However, some characters of the female point to a probable placement.

As for Philcarneum , Constricticollis cannot be placed in five of the six tribes of Australian dynastines (Cyclocephalini, Dynastini, Oryctini, Phileurini and Oryctoderini), nor in the Central and South American Agaocephalini nor the Madagascan Hexodontini.

The Pentodontini have the mentum narrowed towards the ligula, the postcoxal process forming a vertical columnar process, and the mesothoracic and metathoracic legs with small claws; all characters found in Constricticollis . Of the four Australian subtribes recognised by Weir et al. (2019), Constricticollis does not conform to three of these:

• Pseudoryctina—the mentum is not compressed, the mandibles and labrum are not exposed beyond the clypeus, and the labrum does not have a deeply truncated face and is not at considerable angles to the plane of the frons.

• Dipelicina—the apical labial palpomere is not securiform, the clypeus is not truncate and bearing a vertical plate, and the propygidium is not enlarged.

• Cheiroplatina—the mandibles are not evenly rounded distally, the ocular canthi bears only a few apical setae, the clypeofrontal ridge is not transverse or posteriorly arcuate but depressed medially and not giving rise to a median tubercle or horn, and the terminal abdominal ventrite is without a transverse sulcus.

The Pentodontina are recognised ( Carne 1957; Weir et al. 2019) by: the mandibles are toothed and are visible beyond the clypeus; the ocular canthi usually glabrous; the clypeus is narrowed or truncate and the anterior margin is bisinuate or bidentate; clypeofrontal ridge more-or-less transverse, usually elevated, bituburculate, rarely with median horn; pronotum usually evenly convex or with an anterior tubercle and impression, rarely with major excavation; propygidium with stridulating ridges either short and scattered or as a pair of paramedian bands, last abdominal ventrite without a transverse sulcus. The majority of these characters are shared with Constricticollis and it is best place here.

Within the Pentodontina, Constricticollis is distinct from other Australian genera as it has the anterior and posterior margins of the pronotum conspicuously concave and because from:

• Hyphoryctes Blackburn, 1895 as the ligula not bilobed, the clypeus does not have concave sides and the apex is not bisinuate, the clypeofrontal ridge is not posteriorly arcuate nor does it give rise to a median tubercle, and the metatibiae do not have cilia on the distal truncate surface.

• Pimelopus Erichson, 1842 as clypeus does not have concave sides nor a bisinuate, truncate apex, and the clypeofrontal suture is not posteriorly angulate nor does it give rise to a swelling.

• Carneodon Özdikmen, 2009 as the ligula is not apically acute, the mandibles are not tridentate, the clypeus does not have concave margins nor the apex with a pair of tubercles or marginal sinuations, and the clypeofrontal ridge is not transverse nor does it give rise to a pair of paramedian tubercles.

• Metanastes Arrow, 1911 as the ligula not bilobed, the clypeus does not have concave sides nor the apex with a pair of tubercles, and the pronotum does not have acute anterolateral angles.

• Neonastes Carne, 1957 as the ligula is not bilobed, the mandibles are not tridentate, the apex of the clypeus is not rounded nor weakly bisinuate, and the pronotum does not have acute anterolateral angles.

• Papuana Arrow, 1911 as the head and pronotum are not armed, the concavities of the pronotum are not limited to the anterior portion nor is the floor of the concavity rugose, and the protibiae do not have secondary denticles.

• Heteronychus Burmeister, 1847 (one African species established) as the mentum is not feebly notched in front, the mandibles are not trilobed on the outer edge, the head is not armed, and the protibiae do not have secondary denticles.

• Temnorhynchus Hope, 1837 (one African species established) as the clypeus does not have a vertical plate, and the metatibiae are not strongly dilated.

• Pentodon Hope, 1837 and Phyllognathus Eschscholtz, 1830 were recorded from Australia from single specimens ( Allsopp & Hutchinson 2019), indicating that these genera have not established in Australia.