Potergus superbus, 2019

Muona, Jyrki, 2019, Throscidae (Coleoptera) relationships, with descriptions of new fossil genera and species, Zootaxa 4576 (3), pp. 521-543 : 530

Potergus superbus new species

Fig. 11

Type material. Holotype labeled: Potergus superbus n. sp. / HOLOTYPE / J. Muona des. 10-2015. Found from Kaliningrad. Embedded in Baltic Amber piece, 23 mm x 15 mm, 7 mm thick, sex unknown. Age 50 Mya. Numerous minute, hirsute remains of plant matter are present as well ( Fig. 24 ) .

Diagnosis. Elateroidea synapomorphy: pro-mesothoracic joint with clicking mechanism.

Throscidae synapomorphies: a2 as wide as a3–a4, antennal grooves running along notosternal suture and then bending laterally along proleg cavity. Synapomorphy of Potergini + Throscini : tibiae flattened, with tarsal grooves apically. Synapomorphy of Potergus : keeled frons. This in combination with abdominal tarsal grooves is diagnostic for the genus. The extant Potergus species and the Eocene fossil P. frohi Muona are parallel-sided and much narrower than P. superbus . P. superbus resembles P. logei Muona in shape, but has longer abdominal tarsal grooves than that species, these extending to v4. In addition, the metathoracic tarsal grooves are more distant from the metanepisterna in P. superbus that in P. logei . The metallic shine of P. superbus is diagnostic as well. Because of the strong pronotal punctation, the lateral carina is obscure cranially.

Description. Length 4.3 mm. Venter shiny with conspicuous metallic sheen, blue to slightly purple. Dorsum poorly visible. Pronotum and venter coarsely and densely punctate, head densely and slightly less coarsely punctate than pronotum, medially keeled. Elytral striae hardly indicated, serial punctures orderly placed, large, interstices with minute punctation, epipleura faintly and very densely punctate.

Antennae short and robust, a2–a8 about as long as wide and of even width, a9–a11 forming a distinctly wider club. Position and length of tarsal grooves as in Fig. 11 .

Etymology. Contrary to other known throscids, the dorsum of this species is faintly metallic blue.

Figures

FIGURE 11. Potergus superbus n. sp., ventrolateral view. AtG = abdominal tarsal groove; MtG = metathoracic tarsal groove.

FIGURE 24. Potergus balticus n. sp., holotype.