Pseudothroscus, Muona, 2019

Muona, Jyrki, 2019, Throscidae (Coleoptera) relationships, with descriptions of new fossil genera and species, Zootaxa 4576 (3), pp. 521-543 : 527-528

Pseudothroscus new genus

Type species: Pseudothroscus balticus new species

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

Throscidae synapomorphies: a2 as wide as a3 and a4, antennal grooves running along notosternal suture and bending laterally along proleg cavity.

Synapomorphies of clade Throscidae without Jaira : metasternal discrimen absent, metacoxae with posteriorly projecting median apex.

Diagnostic other characters: pronotal lateral carinae complete, head without median carina, eyes large, antennal insertions located in fossae, antennal grooves posteriorly partly separated from proleg impressions by septum, pro- and mesoleg impressions only faintly indicated, tibiae simple, slender.

None of the characters used in the analysis turned out to be apomorphies for Pseudothroscus .

Pseudothroscus and Potergosoma share several plesiomorphies: complete lateral pronotal carinae, no tarsal grooves, simple t4, simple tibiae, poorly developed pro-mesoleg impressions, antennal fossae and strong serial elytral punctures. Pseudothroscus lacks the Potergosoma apomorphies (reduced eyes, strong frontal keel) and has unique delicate ridges around the antennal fossae. This combination of characters places it in a genus of its own.

Description. Body fairly elongate, flattened, venter convex, dorsum somewhat less so ( Fig. 4 ). Head with small antennal fossae, these with delicate ridges, frontoclypeus small, wide and short, front margin slightly arched, eyes large, labrum well sclerotized, fairly large ( Fig. 5 ). Antennae slender, all antennomeres longer than wide, a2 as wide as a3 and a4, a9–a11 forming a club ( Fig. 5 ). Prosternum apically parallel-sided, sides diverging rectilinearily posteriorly, lateral carniae complete, apex quite narrow, rounded, anterior edge produced ventrally, curved ( Fig. 5 ). Antennal grooves partly separated from proleg impressions by septum, pro- and mesoleg impressions only faintly indicated, metathorax and abdomen without tarsal grooves. Elytral striae wide, deep, with large punctures, interstices slightly convex ( Fig. 4 ). Tibiae simple, without tarsal grooves, tarsi delicate, t4 simple.

Etymology. Superficially similar to Trixagus , Throscus being its junior synonym previously in wide use.

Figures

FIGURE 4. Pseudothroscus balticus n. sp., dorsal view.

FIGURE 5. Pseudothroscus balticus n. sp., ventral view. AC = antennal club; AF = antennal pit boarded by delicate ridge; L = labrum; LC = complete lateral pronotal ridge; MsT = simple mesotibia.