Asiocnemis colombicus Muona, 2022

Muona, Jyrki, 2022, New fossil false click-beetles from the Americas (Coleoptera: Eucnemidae), Insecta Mundi 2022 (912), pp. 1-11 : 9-10

Asiocnemis colombicus Muona , new species

Figures 8–11 .

Etymology. Named after the Republic of Colombia.

Holotype. Embedded in a flat, quadratic Colombian resin piece, 55 mm × 30 mm, 4 mm thick, female.

Diagnosis. The elongated, parallel-sided and flat shape, wide smooth frontoclypeal area, slender tarsi with tarsomere 4 feebly bilobed, simple, minute claw and slender antennae separate this species from all previously known neotropical Dromaeolus species as well as all American Asiocnemis Mamaev species.

Description. Length 5.5 mm. Elateroidea synapomorphy: pro-mesocoxal clicking mechanism present.

Eucnemidae synapomorphies: pedicel attached subapically to scape, labrum hidden, elytral striae with apical excretory punctures. Macraulacinae synapomorphy: hypomera with basally open lateral antennal grooves ( Fig. 9 ). Macraulacini diagnostic other characters: tibiae with lateral spine-combs.

Form narrow, parallel sided, flat ( Fig. 8 ). Head rounded, densely punctate, eyes medium-sized, frontoclypeal region wide, 1.3 times as wide apically as between antennal sockets, apical margin slightly rounded, mandibles short, bifid. Pronotum elongated, about as wide as long, with short, deep basal median groove converging craniad and ending before middle, with acute non-carinate hind angles, roughly and very densely punctate, scutellum strongly transverse, fairly large, parallel-sided, slightly bilobed caudally, elytra densely and roughly punctate with strong sutural striae and apical excretory punctures, disk without striae. Antennal sockets round, antennae moderate long, slender, f8–f9 reaching past pronotal hind angles, scape long, elongate, pedicel shorter than f1, all flagellomeres longer than wide, becoming more elongated towards apex, f4 twice as long as wide, f9 longest of all, 1.5 times longer than f8 ( Fig. 9 , 10 ). Hypomeron densely punctate with sharply delimited non-punctate lateral antennal grooves ( Fig. 9 , 10 ), prosternal peg parallel-sided, apically pointed, prosternum very densely punctate, metasternum very densely and roughly punctate. Metacoxal plates triangular, very densely punctate, widest close to midline, three times as wide as on sides, less so at midline, caudal angle rounded. Legs long, elongate, protarsi shorter than protibiae, tarsomeres 2–4 increasingly narrower and tarsomere 5 small, delicate, meso- and metatibiae long, slender, longer than tarsi, with strong spine-combs on lateral surfaces, meso- and metatarsomere 1 as long 2–4 combined, 4 excavated, slightly wider than previous one, claws small, simple ( Fig. 11 ). Abdominal ventrites connate, very densely punctate.

Remarks. As pointed out by Muona (2000), Dromaeolus is an artificial assemblage of species waiting for a phylogenetic analysis. Such an attempt requires the inclusion of all Macraulacini genera, a gargantuan task. The present species does not fit any previously known Dromaeolus in the only “complete” key available ( Bonvouloir 1871), nor does it fit any species described from South America. It is also clear that it is not congeneric with the European Dromaeolus barnabita Villa , the type-species of this genus ( Muona 1987). The genus Asiocnemis differs from Dromaeolus by conspicuous larval characters but it has not been satisfactorily defined with external adult characters. The present species with slender, parallel form, delicate tarsi, basally strongly grooved elongate pronotum and rough surface sculpture fits the known species well and it has been placed in Asiocnemis . There are seven previously reported Asiocnemis species from the Americas, distributed in the western mountains from Washington to Ecuador and French Guiana. It is assumed that several South American slender black Dromaeolus species belong here as well. Whether this newly described species is a recent one or an extinct creature from the past, cannot be determined at this time. A somewhat similar one, Asiocnemis sp. , was reported from Baltic amber ( Muona 1993a).

Figures

Figure 8. Asiocnemis colombicus n. sp., holotype, dorsal view.

Figure 9. Asiocnemis colombicus n. sp., holotype, ventral view of side of fore body showing flagellomeres 2–9 and the basally open, medially sharply defined antennal groove.

Figure 10. Asiocnemis colombicus n. sp., holotype, ventral view of side of fore body showing scape, pedicel and flagellomeres 1–7 and the basally open, medially sharply defined antennal groove.

Figure 11. Asiocnemis colombicusn. sp., holotype, dorsal view of mesotibia and mesotarsus. Because of the shooting angle of the image tibia appears shorter than tarsus, right proportions are shown in Figure 8.