Acanthoglyptus, Alekseev & Vitali, 2020

Alekseev, Vitalii Igorevich & Vitali, Francesco, 2020, Description of the first extinct member of the tribe Anaglyptini (Coleoptera: Cerambycidae) from European Tertiary, Zootaxa 4816 (1), pp. 135-143 : 136-137

Genus Acanthoglyptus gen. nov.

Type species. Acanthoglyptus picollus sp. nov., here designated.

Differential diagnosis. The specimen under consideration is assigned to the tribe Anaglyptini on the basis of the following combination of morphological characters: 1) eyes finely facetted, 2) procoxae rounded, 3) procoxal cavities narrowly open, 4) elytra gibbose at base and without transverse raised ivory-like ridges, 5) antennomeres 3–5 distinctly spinose.

The new genus could be associated to the tribe Tillomorphini , which nevertheless, shows closed procoxal cavities. Exceptionally, they are narrowly open in the, possibly polyphyletic, American genus Euderces LeConte, 1850 , which, in turn, shows evident transverse raised ivory-like ridges (peculiar character of Tillomorphini ), a cribrose elytral disc, divided eyes, antennomere III more than twice as long as IV, etc.

Acanthoglyptus gen. nov. differs from the representatives of extant genera with spined antennomeres ( Anaglyptus Mulsant, 1839 , Oligoenoplus Chevrolat, 1863 , Paraclytus Bates, 1884 , and Cyrtophorus LeConte, 1850 ) in the stout elytra and the longer first metatarsomere. For these characters, it resembles the Chinese Yoshiakioclytus Niisato, 2007 , which nevertheless, has unarmed antennomeres ( Huang & Chen 2016).

Considering the species included in Baltic amber, Tillomorphites Vitali, 2011 ( Tillomorphini Lacordaire, 1868 ) is the only genus characterised by spined antennae. It differs from Acanthoglyptus gen. nov. for the not gibbose elytra, much longer and finer antennal spines on antennomeres (in contrast to three shortly spined antennomeres in the new genus), shorter and more robust legs, and elytral pattern formed by transverse reddish band(s). From Clytus (Xylotrechus) pici Piton , the newly described fossil genus can be distinguished by the smaller body size (9.0 mm compared with 15.0 mm in C. (Xylotrechus) pici ), the elytra gibbose at base, the antennae longer and apparently spined, and absence of frontal carina.

Description. General habitus small, relatively stout, convex dorsally.

Head oblique, slightly elongated; frons with longitudinal furrow; antennal tubercles rather elevated and widely separated; eyes shallowly emarginated, finely facetted; last maxillary palpomere elongate, truncate at apex, as long as two previous palpomeres combined; antennae 11-segmented, hardly as long as body in female; antennomeres III–V with long spine at inner side decreasing in length to antennomere III; pedicel and antennomeres III–V with a few semierect setae.

Pronotum distinctly narrower than elytral base, elongate, with maximal width in anterior third, sides without lateral tubercle or spine, narrowed posteriorly; base straight, disc moderately convex, covered with dimorphic pubescence; pronotal surface double punctured.

Elytra comparatively short (about twice as long as wide, and nearly two and a half times longer than pronotum); base straight with a distinct elongate gibbosity bearing a sparser and finer punctation; humeri rounded; sides slightly constricted in middle, apex rounded; disc covered with obliterate punctation on apical half, and pattern consisting of a recumbent light pubescence.

Legs long and slender, covered with recumbent fine pubescence; femora slightly clubbed; tibiae almost straight, with two apical spurs of equal length; procoxae rounded, narrowly separated by prosternal process; procoxal cavities narrowly open posteriorly; mesocoxal cavities open; metatarsi one-half as long as tibiae; metatarsomere I long, hardly twice as long as tarsomeres II and III combined; claws simple.

Etymology. The name is a combination of the old Greek word ἄκανθα (ákantha, i.e. thorn, spine) and the Greek root γλυπτός (glyptus, i.e. carved, graved) referring to the tribal type-genus Anaglyptus . Gender masculine.

Composition. The new genus is monotypic, represented by the type species only.