Wongaroo amplipectorale, 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

Wongaroo amplipectorale sp. n.

( Figs. 1–6 )

Description. Body length ca. 6.0– 6.5 mm, width across both elytra at base ca. 2.0– 2.1 mm; head dimensions not measurable; pronotum length 1.4–1.6 mm, width 1.8–1.9 mm; elytra length 4.2–4.5 mm, width 1.1–1.3 mm; abdomen length not measurable, width approximately 2.4 mm at base.

Head indistinct, only two small fragments visible in holotype, approximately 0.3 times as broad as pronotum; antennae ca. 2.6 mm long, 0.1 mm wide. Prothorax anterolaterally broadly rounded, dorsal surface smooth. Elytral intervals slightly raised, almost as broad as strial punctures. Abdominal ventrites flat, surface smooth, apparently glabrous. Other characters as in generic description.

Material examined (2 specimens). Holotype: part (AM F. 140884; Figs. 1, 3 ), almost flat compression of white cuticular remains showing dorsal aspect of head, antennae, parts of profemora, left elytron and basal part of right elytron; counterpart (AM F. 140885; Fig. 2 ), impression of cuticular remains of part, with white cuticular remains of parts of left antenna and abdomen; Talbragar Fish Bed ( Upper Jurassic : Kimmeridgian-Tithonian, 151 ±4 Ma), Gulgong, N.S.W., Australia , April 2015, coll. M. Frese. Deposited in the Australian Museum, Sydney. Paratype: part only (AM F. 110530; Fig. 4 ), three-dimensional preserve of body showing dorsal aspect of partial head, prothorax and elytra and impression of ventral surface of metaventrite and abdomen, with some white cuticular fragments, at edge of block; Talbragar Fish Bed ( Upper Jurassic : Kimmeridgian-Tithonian, 151 ±4 Ma), Gulgong, N.S.W., Australia , December 2011, coll. R. Oberprieler. Deposited in the Australian Museum, Sydney.

Name derivation. The specific name is an adjective derived from the Latin adjective amplus , -a, -um (large) and noun pectus (genitive: pectoris) (chest), referring to the large, convex pronotum.

Remarks. Part and counterpart of the holotype together preserve the cuticular remains of the dorsal aspect of the head, both and complete antennae, the prothorax, parts of the profemora, the left elytron and the basal part of the right, and the abdominal ventrites. Complete preservation of the antennae is unusual among the Talbragar beetle fossils, probably because they are easily lost after the death of the specimens, and it is also difficult to completely expose them between the multiple fine layers of the surrounding sediment. The paratype shows more three-dimensional details than the compressed holotype but preserves almost nothing of the cuticular remains, which is presumably lifted away with the counterpart, which has not been found. The paratype retains the convex structure of the pronotum and preserves detailed imprints of the right elytron, metaventrite, parts of the right hindleg and the abdomen. The right metacoxa is complete but its structure unclear; it is possibly displaced from the coxal cavity. The proximal part of the right metafemur is concealed beneath the metacoxa, whereas the distal part is exposed but only with a fragment of cuticle preserved. The right metatibia is almost completely visible. No tarsi are preserved, and the abdominal apex is also missing. The paratype is very similar in size and structure to the holotype, and as we can find no substantial differences between the two specimens, we regard them as being conspecific. The elytra of both specimens clearly show the deep strial pits at the base of the elytra that are also present in extant cerophytid genera.

Figures

FIGURES 1 – 4. Wongaroo amplipectorale gen. et sp. n. 1, holotype, part (AM F. 140884); 2, holotype, counterpart (AM F. 140885); 3, holotype, part, antennae and thorax enlarged (AM F. 140884); 4, paratype (AM F. 110530). Scale bars 1 mm.

FIGURES 5 – 8. Wongaroo amplipectorale gen. et sp. n. and Cerophytum elateroides (Latreille, 1804). 5, Wongaroo amplipectorale, holotype, combined drawing of part and counterpart; 6, Wongaroo amplipectorale, paratype, drawing; 7, Cerophytum elateroides, dorsal habitus; 8, Cerophytum elateroides, ventral habitus. Scale bars 1 mm.