Beattieellus, Oberprieler, Rolf G., Ashman, Lauren G., Frese, Michael & Ślipiński, Adam, 2016

Oberprieler, Rolf G., Ashman, Lauren G., Frese, Michael & Ślipiński, Adam, 2016, The first elateroid beetles (Coleoptera: Polyphaga: Elateroidea) from the Upper Jurassic of Australia, Zootaxa 4147 (2), pp. 177-191 : 181-182

Genus Beattieellus gen. n.

Type species: Beattieellus jurassicus sp. n.

Description. Body elongate, approximately 3.3 times longer than wide. Head small, partly retracted under pronotum, only shortly visible in dorsal view; anterior margin arcuate. Antennae not preserved. Prothorax inversely parabolic in outline, anteriorly broadly rounded, lateral margins feebly arched; postero-lateral corners strongly and sharply projecting, evidently without carina; surface not evidently sculptured or punctate. Scutellar shield not discernible. Elytra flat dorsally, declivous laterally, apex acute; each with apparently nine striae of shallow cell-like punctures extending from base to apex, diminishing in size towards apex; striae 1–7 on disc, number of punctures not countable, striae 8–9 on lateral declivity; intervals narrow, about half as wide as striae, apical confluences not discernible. Procoxae indicated but not clear, apparently subglobular, separated by about their width, by a short broad prosternal process; forelegs not discernible. Mesanepisterna and mesepimera not discernible; metanepisterna long, narrow, subparallel; metepimera evidently not exposed. Mesoventrite short; mesocoxae subcircular in outline, anteriorly separated by broad round concavity (evidently part of clicking apparatus) flanked by a pair of short conical protuberances; mesofemora short, anteriorly slightly rounded, evidently flattened; mesotibiae apparently short, narrow, flat, retractable against femora; tarsi 5-segmented, slender. Metaventrite long, navicular, without distinct discrimen; metacoxae long, narrow, slanting anteriad, medially contiguous, with coxal plate covering femora and tibiae in repose; metafemora long, slender, flattened, anterior margin curved, almost reaching side of body; metatibiae shorter than metafemora, slender, straight, narrow, flattened, folding against metafemora, apical spurs not discernible; tarsi 5-segmented, slender, straight, as long as metafemora. Abdomen strongly convex, with five ventrites but their outlines and sutures not clearly discernible.

Name derivation. The genus is cordially named for our colleague Robert Beattie, who has led the palaeoentomological excavations at the Talbragar Fish Bed for many years and discovered numerous magnificent specimens in the process, including most of the ones described here. His dedication to the project and his inextinguishable enthusiasm in exploring this Jurassic entomofauna on every excursion have been a great inspiration to us. The gender of the name is masculine.

Remarks. The salient characters of Beattieellus (the general fusiform body form, the acutely projecting posterolateral angles of the prothorax embracing the elytral humeri, the mesoventrite with an apparent clicking apparatus and the metacoxae with well-developed coxal plates) indicate that it is an elateroid belonging in either the family Elateridae or Eucnemidae . These two families differ mainly in the following characters: in Elateridae the labrum is free, the pedicel of the antennae is inserted apically into the scape, the posterolateral pronotal angles are usually dorsally carinate and the last two abdominal ventrites are freely articulated, whereas in Eucnemidae the labrum is concealed (except in Anischiinae ), the pedicels are inserted apicolaterally into the scapes, the pronotal angles have no carina and the last two abdominal ventrites are fused. All these features are difficult to ascertain in compression fossils, and the only one indicated in Beattieellus is the lack of a carina on the posterolateral pronotal angles. However, the structure of its clicking apparatus, featuring a broad and short mesoventral cavity flanked by a pair of prominent tubercles, is also characteristic of Eucnemidae . In eucnemids the lateral rims of this cavity are generally angled in about the middle, the anterior part sloping upwards, and the angle is often strengthened into a short flange, callus or tubercle ( Fig. 13 , arrow), whereas in Elateridae the cavity is typically longer and narrower and its lateral rims are not angled or produced in the middle. We therefore assign Beattieellus to the Eucnemidae . Among the Australian eucnemid fauna, a comparable development of the clicking apparatus as in Beattieellus occurs in Fornax Laporte, 1835 and Nematodes Berthold, 1827 . The former genus contains some species of similarly small size, but they have a relatively larger prothorax and do not appear to be represent the same genus as Beattieellus , which we therefore place in a new one. Assignment of Beattieellus to a eucnemid subfamily is not possible due to the lack of the relevant diagnostic characters ( Muona 1993a) being visible in the fossil.

Figures

FIGURES 13 – 16. Eucnemidae, clicking apparatus and Genus and species 1 & 2. 13, Nematodes sp., clicking apparatus showing anterior tubercles of mesoventral cavity (arrow); 14, Genus and species 1, part (AM F. 140888); 15, Genus and species 2, part (AM F. 137138); 16, Genus and species 2, counterpart (AM F. 137139). Scale bars 1 mm.