Rhopalomma stefaniae Ashman, Oberprieler & Ślipiński, 2015

Ashman, Lauren G., Oberprieler, Rolf G. & Ślipiński, Adam, 2015, Rhopalomma stefaniae gen. et sp. n., the first ommatid beetle from the Upper Jurassic in Australia (Coleoptera: Archostemata: Ommatidae), Zootaxa 3980 (1), pp. 136-142 : 138-139

Rhopalomma stefaniae Ashman, Oberprieler & Ślipiński sp. n.

Description. Body length 7.0 mm, maximum width across elytra 2.8 mm; head length 1.4 mm, width slightly less than length but not exactly measurable; pronotum length 1.0 mm, width 1.1 mm; elytra length 4.5 mm, maximum width 2.8 mm. Cuticle of head, pronotum and elytral flanges tuberculate (leaving fine punctures on CP), surface below cuticle finely punctate; vestiture not visible. Head poorly preserved, apparently 1.2–1.4 times longer than wide but lateral edges unclear; anterior margin of clypeus and trace of labrum visible on P ( Fig. 3 ); possible fragments of mouthparts visible on CP ( Fig. 4 ); eyes not preserved. Antennae visible on CP, extending to posterior margin of head ( Fig. 4 ); club of right antenna (left side of CP) 3-segmented, club segments about twice as broad as funicle segments; club of left antenna missing (incomplete). Pronotum with anterior and posterior margins distinct, lateral margins unclear. Both prothoracic legs partially visible on CP, apical half of both femora distinct, right tibia (left side of CP) entire and extended, left tibia partial and folded towards femur ( Fig. 4 ); apices of tibiae not discernible, protarsi and meso- and metathoracic legs not preserved. Elytral apex poorly preserved. Ventral sclerites of metathorax and abdomen not visible.

Material examined (1 specimen). Holotype: part (AM F.139992; Figs. 1 , 3 , 5 ) and counterpart (AM F.139993; Figs. 2 , 4 , 6 ); dorsal view showing head, prothorax with partial legs and elytra preserved as white layer with impressions on rock surface above and below, on rock with leaf fragment; Talbragar Fish Bed (Upper Jurassic: Kimmeridgian-Tithonian, 151 ±4 Ma), Gulgong, N.S.W., Australia; December 2013, coll. S. Oberprieler. Deposited in the Australian Museum, Sydney.

Etymology. The species is named after Stefanie Oberprieler, who found the single specimen during the December 2013 excavation at the site and has described several other insect fossils from the Talbragar Fish Bed.

Remarks. The part (P) contains most of the white cuticular cover, but sections are missing or were lifted with the counterpart (CP); the latter is an imprint of the specimen in petrified mud. The head and prothoracic legs are preserved mostly on the CP; the P shows an imprint of the surface underneath the cuticle. The prothorax is mostly preserved on the P, with an imprint of the dorsal surface on the CP. The elytra are mostly on the P, but two sections of the right elytron were lifted with the CP, leaving imprints of the surface underneath the cuticle on the P.

Figures

FIGURES 3 – 4. Rhopalomma stefaniae gen. et sp. n., details of head and prothorax. 3. part (AM F. 139992); 4. counterpart (AM F. 139993), after further exposure of structures, with antennal club and pronotum labelled. Scale bars are 1 mm.

FIGURES 1 – 2. Rhopalomma stefaniae gen. et sp. n. 1. part (AM F. 139992); 2. counterpart (AM F. 139993). Scale bars are 1 mm.

FIGURES 5 – 6. Rhopalomma stefaniae gen. et sp. n. line drawings. 5. part (AM F. 139992); 6. counterpart (AM F. 139993).