Omotrachelus thoracomimus Borovec, 2023

Borovec, Roman, 2023, New data on Omotrachelus Kolbe, with description of five new species (Coleoptera; Curculionidae; Entiminae; Cneorhinini), Zootaxa 5357 (4), pp. 502-514 : 511-512

Omotrachelus thoracomimus Borovec sp. nov.

Figs (5, 10, 16)

http://zoobank.org/ urn:lsid:zoobank.org:act:6B47F7AB-BEB2-404D-AF8D-1EC59DABD7BC

Type locality. Democratic Republic of the Congo, Kwango: Feshi .

Type material. Holotype: ♁, [ Democratic Republic of the Congo] Kwango: Feshi, rive g. Kwenge , III-1959, B. 70, Mme J. Leleup [lgt.], I. R.S.A. C.- Mus. Congo, Biot. No 70, tête de source de la Mvula Myeji, forêt ( RMCA) . Paratype: 1 ♁, same data holotype ( RMCA) .

Description. Body length 3.81–4.18 mm, holotype 3.81 mm. Elytra with interstriae densely covered with small, regularly rounded appressed scales, 4–5 across width of one interstria, with feeble goldish or cupreous metallic sheen, striae glabrous. Head with rostrum and pronotum densely covered with greyish brown, small, irregularly rounded appressed scales with several short fringes. All elytral interstriae with one dense row of semi-erect, slender, piliform setae, slightly shorter than width of one interstria, distance between them subequal to their length. Erect setae on head with rostrum and pronotum slightly shorter than half length of elytral setae, densely irregularly scattered. Scapes, femora and tibiae with identical appressed scales as those on pronotum, and with short, slender, moderately dense erect setae.

Rostrum ( Fig. 10 ) 1.18–1.22× as long as at base wide, at base weakly enlarged apicad, then subparallel-sided along entire length, at apex 1.06–1.08× as wide as at base; in lateral view regularly curved. Epifrons wide, at base as wide as rostrum, in basal half slightly tapering apicad with straight sides, in apical half distinctly tapering apicad, at base 1.64–1.78× as wide as at apex, between antennal insertions narrower than space between eyes, dorsally shallowly longitudinally depressed. Frons very short, glabrous. Epistome small, V-shaped. Antennal scrobes in dorsal view hardly visible only in short apical part as narrow furrows; in lateral view straight, narrow, directed below ventral margin of eye and teaching it. Vertex flat. Eyes moderately large, slightly convex and prominent from outline of head; in lateral view oval, almost reaching dorsal margin of head. Head enlarged posteriad.

Antennae ( Fig. 5 ) somewhat robust; scape slightly regularly curved, slightly evenly enlarging apicad, 5.2–5.8× as long as wide, at apex 0.8× as wide as club. Funicle segment 1 robust, conical, 1.3–1.4× as long as wide and 1.2–1.3× as long as short segment 2, this is 1.1–1.2× as long as wide; segment 3 1.4–1.5× as wide as long; segments 4–6 1.5–1.6× as wide as long; segment 7 1.7–1.8× as wide as long; club 1.4–1.5× as long as wide, with first segment as long as two thirds of entire club length, shiny, sparsely setose, the others very short, mat, densely setose.

Pronotum ( Fig. 5 ) very short and wide, 2.69–2.81× as wide as long, widest at base and evenly tapering apicad with almost straight sides; disc with rough punctures partly concealed under appressed scales, 3–4 across length of pronotum, distance between punctures shorter than their diameter; pronotum in lateral view slightly vaulted.

Elytra ( Fig. 5 ) long oval, 1.36–1.44× as long as wide, behind base distinctly constricted and here subequal in width to pronotum, constriction as long as length of pronotum, elytra from basal constriction obliquely subtruncate posteriad to widest point at basal third, then slightly evenly tapering posteriad with almost straight sides, apically broadly rounded; base straight; interstriae 8 and 9 with low subhumeral bump visible mainly in dorso-lateral view; interstriae 7–10 except of short subhumeral bump portion glabrous, smooth; sutural interstriae in short basal part slightly swollen. Striae moderately wide, sparsely punctured; interstriae slightly vaulted. Elytra in lateral view distinctly vaulted in short distance just from base, then flat.

Protibiae short and robust, 4.7–4.9× as long as at midlength wide, apically broadly rounded and fringed with rusty brown setae, with dark brown mucro and in short apical portion denticulate with 5–6 small, pointed brownish spines; inner margin bisinuate. Tarsi with segment 2 1.3–1.4× as wide as long; segment 3 1.1–1.2× as wide as long and 1.2–1.3× as wide as segment 2; onychium short, 0.7–0.8× as long as segment 3.

Penis ( Fig. 16 ) 2.71–2.83× as long as wide, subparallel-sided in basal two thirds, evenly tapering in apical third with slightly concave sides, tip narrowly rounded; in lateral view narrow, regularly curved, tip narrow, apically narrowly rounded.

Biology. The type specimens were collected in forest habitat.

Etymology. The Latin name refers to the curious and exceptionally, long basal constriction of the elytra, the basal portion subequal in width to the pronotum.

Remarks. Omotrachelus thoracomimus shares no obvious characters of the distinctive elytra with any currently known species in the genus Omotrachelus . Its long basal constriction, including the oblique sloping part reaching the basal third of the elytral length is unique. Similarly, the three lateral interstriae glabrous and smooth and dorsal part of elytra distinctly vaulted just behind base in lateral view are also unique within the genus.

Figures

FIGURE 5. Dorsal habitus. 5. Omotrachelus thoracomimus.

FIGURES 6–10. Head with rostrum in dorsal and lateral view. 6. Omotrachelus geiseri. 7. O. kaniai. 8. O. longirostris. 9. O. parallelus. 10. O. thoracomimus. Scale 0.50 mm.

FIGURES 11–21. 11–16: penis in dorsal and lateral view. 11. Omotrachelus geiseri. 12. O. kaniai. 13. O. angulatus. 14. O. longirostris. 15. O. parallelus. 16. O. thoracomimus. 17–21: spermatheca. 17. O. geiseri. 18. O. kaniai. 19. O. angulatus. 20. O. longirostris. 21. O. parallelus. Scale 0.125 mm for 20, 21; 0.25 mm for 17–19; 0.50 mm for 11, 12, 14–16; 1.00 mm for 13.