Eurocrossotus, Vitali, 2021

Vitali, Francesco, 2021, Eurocrossotus alekseevi gen. n., sp. n. (Coleoptera: Cerambycidae) from Baltic amber, the first fossil member of the tribe Crossotini Thomson, 1864, Baltic Journal of Coleopterology 21 (2), pp. 221-228 : 222

Eurocrossotus gen. n.

Differential diagnosis

Eurocrossotus gen. n. shows all characters of Crossotini already stated in the introduction. In addition, it shows some characters not contemporaneously present in any extant genus: prosternal process narrow and lower than procoxae, frons parallel-sided, scape short, pronotum with a lateral tooth, elytra tapered posteriorly, without tubercles or hair fascicles but with long erect pubescence.

Most of these characters are present in the Malagasy genera Lasiocercis Waterhouse, 1882 and Tlepolemoides Breuning, 1957 and in the South African genera Tlepolemus Thomson, 1864 and Paratlepolemoides Breuning, 1962 . Nonetheless, the prosternal process is wide in the first two genera ( Breuning, 1957) and as high as procoxae in the third genus ( Breuning, 1942a, b), while the antennae are not as fringed as in the fourth genus ( Hunt & Breuning, 1959).

Eurocrossotus gen. n. also resembles some members of the Neotropical tribe Compsosomatini Thomson, 1857 , especially, Eusphaerium Newman 1838 , the only genus covered with long pubescence, but which differs in the divergent claws (tribal character).

Description

Habitus minute, stout; everywhere covered with long dense pubescence.

Mandibles arcuate, without peculiar features; labium sub-trapezoidal, densely covered with recumbent pubescence; frons parallel-sided, convex, densely covered with fine punctures; eyes strongly reniform and finely facetted; lower eye lobes squared, as long as genae; vertex wide, marked with dense strong punctures.

Antennae almost thick, possibly a bit shorter than body (female), not fossate, internally fringed with dense erect setae, one-half as long as the antennomere carrying it; scape short, club-shaped, everywhere covered with long erect pubescence; pedicel elongate, antennomere III bowed, slightly longer than scape; VII-X subequal, feebly decreasing in length apically; XI straight, scarcely longer than X; antennomere proportions according to the formula: 3.6: 1: 4.6:?:?: 2.6: 2.4: 2.3: 2.0: 1.8: 2.

Pronotum feebly transverse, 1.3 times as wide as long, finely furrowed at both apical and basal margin, armed with an obtuse large conical tooth at each side, which are connected on the disc with two large obtuse bulges delimiting a arcuate impression at apex and at base; surface sparsely covered with strong punctures. Scutellum widely semicircular, transverse, 2.5 times as wide as long.

Elytra short (each elytron about 3 times as long as wide at base), dorsally flat, regularly tapered to the apex; humeri almost prominent; sides slightly convex; apices widely rounded; disk covered with long erect pubescence and a strong dense punctation, twice as strong as that on the pronotum, nearly subseriate at base and along the suture, sparse in the middle and extremely fine or lacking at the sides and on the apical third.

Legs relatively short covered with long erect pubescence; femora club-shaped; protibiae arcuate; meta- and mesotibiae straight; mesotibiae without pre-apical furrow; tarsi short; claws opposite.

Prosternal process narrow, lower than procoxae; mesocoxal cavities open; mesepisterna narrow; last visible urosternite posteriorly rounded.

Etymology

From Euro - and the genus name Crossotus in reference to the past distribution of this fossil species.

Type species

Eurocrossotus alekseevi sp. n. (monobasic).