Omotrachelus geiseri 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 : 503-506

Omotrachelus geiseri Borovec sp. nov.

Figs (1, 6, 11, 17)

http://zoobank.org/ urn:lsid:zoobank.org:act:5E340577-341F-49E3-800C-0A629CF5B9A8

Type locality. Guinea, Ditinn , Chute de Ditinn .

Type material. Holotype: ♁, Guinea, Ditinn, Chute de Ditinn (Guinea Savannah & Gallery forest), N 10°49′08″, W 12°11′30″, 771 m, 18–25.xi.2019. General Coll. Geiser, M., Leno, M., Koivagui, S., Miles, W., Mulvaney, L., Safian, Sz. leg., BMNH(E) 2020-19 ( BMNH) . Paratypes: 1 ♀, same data as holotype ( BMNH) ; 1 ♀, Mali: Kéniéroba , 70 km SW Bamako, 12°06′ N, 8°20′ W, vi–vii.2014, V. Kravchenko [lgt.] ( RBSC) .

Description. Body length holotype 4.69 mm, paratypes 3.94–4.69 mm. Body densely regularly covered by regularly rounded, longitudinally striate appressed scales, 4–5 across width of one interstria, leaving only short interspaces. Elytral interstriae with one regular row of erect setae, only interstria 5 in apical half with two irregular rows; setae slightly shorter than half width of interstria, narrow, parallel-sided, apically rounded, at apex narrower than diameter of one appressed scale. Pronotum and head with rostrum with the same setae, densely irregularly scattered, on pronotum arise from punctures. Inner side of scapes, femora and tibiae with semi-erect, short, narrow setae. Vestiture dark brown, lateral and apical parts of elytra with several inconspicuous light brown small spots, from which only spot on subhumeral bump and behind middle of interstria 5 are more conspicuous.

Rostrum ( Fig. 6 ) short and robust, at base 1.06–1.13× as wide as long and 1.13–1.17× as wide as at apex, evenly tapering apicad, in basal half slightly more than in apical half with almost straight sides; in lateral view flat, vaulted downwards only in apical portion. Epifrons wide, at base slightly narrower than base of rostrum, in basal two thirds parallel-sided with straight sides, in apical third distinctly tapered apicad, thus at base 1.31–1.38× as wide as at apex, dorsally flat with swollen margins, with slender longitudinal stria along entire length reaching to posterior margins of eyes level. Frons short, mat, with fine microsculpture. Epistome distinct, V-shaped. Antennal scrobes in dorsal view invisible; in lateral view somewhat enlarged posteriad with dorsal margin S-shaped and directed to middle of eye and ventral margin curved, directed below eye. Vertex wide and flat, subequal in width as basal two thirds of epifrons. Eyes large, weakly vaulted, not prominent from outline of head; in lateral view dorsally placed.

Antennae ( Fig. 1 ) slender; scape 5.6–6.2× as long as wide and 1.2–1.3× as long as funicle, evenly enlarging apicad, slightly curved at middle, at apex 0.9× as wide as club. Funicle segments 1 and 2 slender, conical, equally long, segment 1 1.6–1.7× as long as wide; segment 2 1.8–1.9× as long as wide; segments 3 and 4 1.1× as long as wide; segments 5 and 6 isodiametric; segment 7 1.1× as wide as long; club 1.5–1.7× as long as wide.

Pronotum ( Fig. 1 ) short and wide, 2.18–2.28× as wide as long, widest at base and distinctly, evenly tapering apicad with almost straight sides; the entire area roughly punctured, space between punctures subequal to their diameter, 4–5 punctures across length of pronotum; pronotum in lateral view flat. Base V-shaped, prominent posteriad.

Elytra ( Fig. 1 ) oval, 1.12–1.18× as long as wide, behind base weakly constricted, with regularly rounded sides, apically broadly rounded. Interstriae slightly vaulted, equally wide, wider than densely and distinctly punctured striae; interstria 9 with small posthumeral bump, hardly visible in dorsal view. Base V-shaped. Elytra in lateral view slightly vaulted.

Protibiae somewhat slender, 5.3–5.6× as long as at middle wide, at apical quarter curved inside, apically fringed by yellow setae with long mucro, inner margin in apical third sparsely and finely denticulate. Tarsi slender; segment 2 isodiametric; segment 3 1.3x as wide as long and 1.6–1.7× as wide as segment 2; onychium 1.2–1.3× as long as segment 3.

Penis ( Fig. 11 ) 2.9–3.3× as long as wide, widest near the base, at basal third with distinctly rounded sides, at middle third narrowly subtriangular, evenly tapering apicad, in apical third narrow, parallel-sided, tube-shaped, apically rounded; in lateral view narrow, curved, apical part almost straight, tip rounded; temones about as long as body of penis; endophallus not recognizable because penis is teneral.

Spermatheca ( Fig. 17 ) U-shaped, cornu regularly curved; corpus elongated; ramus very short, rounded; collum as long as wide, weakly tapering apicad, rounded. Sternite VIII with moderately large, subtriangular plate, as long as wide. Gonocoxites flat, subtriangular, with slender and long apical styli.

Biology. Unknown.

Etymology. The newly described species is dedicated to my friend and colleague, Michal Geiser (BMNH), one of the collectors of the type specimens, participant in several expeditions to West Africa, who prepared very interesting material of broad-nosed weevils for my study.

Remarks. Omotrachelus geiseri is similar to three species described from Ivory Coast ( O. stachi Kania, 2004 , O. stelmahersi Kania, 2004 and O. tomczyki Kania, 2004 ) in having a moderately large body with the base of elytra only slightly constricted. From all three species O. geiseri is easily distinguishable by the following characters: epifrons at base only slightly narrower than base of rostrum, in basal two thirds parallel-sided; antennal scrobes in dorsal view invisible; interstriae 9 with one small posthumeral bump, hardly visible in dorsal view; and interstriae 3 lacking tubercle behind midlength. The other three species have the epifrons at base distinctly narrower than base of rostrum, tapering apicad just from base; antennal scrobes in dorsal view clearly visible; interstriae 9 with several irregular tubercles clearly visible in dorsal view; and interstriae 3 with tubercle behind midlength.

Figures

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 1–4. Dorsal habitus. 1. Omotrachelus geiseri. 2. O. kaniai. 3. O. longirostris. 4. O. parallelus. Not to scale.

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.