Tyrannothroscus, Muona, 2019

Muona, Jyrki, 2019, Throscidae (Coleoptera) relationships, with descriptions of new fossil genera and species, Zootaxa 4576 (3), pp. 521-543 : 529-530

Tyrannothroscus new genus

Type species: Tyrannothroscus rex new species

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 ( Fig. 6 ). Synapomorphies of Rhomboaspis + Tyrannothroscus + Potergini + Throscini : antennal grooves and proleg impressions separated by septum, metaventrite with tarsal grooves, abdomen with tarsal grooves. Synapomorphies of Rhomboaspis + Tyrannothroscus : elytra with strong and sharp, at most minutely punctate striae, body form very wide. Tyrannothroscus apomorphies: head with strong carinae above antennal insertions ( Fig. 7 ), metasternal discrimen well developed, meso- and metatarsomeres 4 lobed beneath ( Fig. 8 ).

Diagnostic other characters: pronotal lateral carinae complete, head without median carina, antennal insertions located in fossae, antennae with apical, symmetrical club, prosternal process basally straight in lateral view.

Description. Body wide, flattened, pronotum strongly narrowing anteriorly ( Figs. 6 , 9 ). Head with strong supraocular ridges uniting in mid-line, frontoclypeus narrow, elongate, eyes large, antennae stout, a1 wide and short, a2 shorter than a3 and a4 but as wide, a9–a11 forming a club. Clypeus well slerotized, small. Anterior edge of prosternum strongly developed, projecting downwards as a wide arched extension. Metaventrite large and wide, cavity for pro- and mesolegs well-developed, ridged around and with separate sections for both legs, proleg area exceptionally wide, metatarsal grooves long, lateroposteriorly directed ( Fig. 6 ). Prosternal process slightly narrowed in middle, diverging strongly posteriorly, lateral carniae complete and apex rounded ( Figs. 1 , 6 ). Metacoxae with prominent median apex, abdominal tarsal grooves extending to ventrite four. Elytral striae sharp, interstices flat, wide. Tibiae simple, without tarsal grooves, tarsi delicate, t4 lobed below.

Etymology. Tyrannothroscus refers to the relatively large size of this throscid, the largest known.

Figures

FIGURE 1. Pactopus horni LeConte. Head and thorax, ventrolateral view. A = antennal groove; F = depression for mesofemur; M = mesothoracic tarsal groove; mc = mesocoxa; pc = procoxa; S = septum; T = depression for mesotibia.

FIGURE 6. Tyrannothroscus rex n. sp., ventral view. A = antennal groove; MtG = metathoracic groove; AtG = abdominal tarsal groove, SAR = supra-antennal ridge.

FIGURE 7. Tyrannothroscus rex n. sp., head, ventrolateral view, slightly frontally. A = antennal groove; E = eye; F = frontoclypeal region; C = labrum; PL = ventrally bent fron margin of prosternum; PP = prosternal process; SAR = supraantennal ridge.

FIGURE 8. Tyrannothroscus rex n. sp., metatarsus. t4 = lobed tarsomere 4.

FIGURE 9. Tyrannothroscus rex n. sp., dorsal view.