Bulirschius inconspicuus Borovec, 2025

Borovec, Roman, 2025, Two new and one enigmatic genus of Oosomini from South Africa with description of seven new species (Coleoptera: Curculionidae: Entiminae), Zootaxa 5642 (2), pp. 101-126 : 113-114

Bulirschius inconspicuus Borovec , sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:BF376C2B-8E79-4510-B70B-BA941DB4E448

Figs (5, 19, 20, 31, 37, 41)

Type locality. South Africa, Western Cape, Cederberg Mts., Jeep track.

Type material. Holotype: ♂, S. Afr., Cape [ South Africa, Western Cape], Cederbg. [ Cederberg Mts .], Jeep track, 32.24 S – 19.10 E, 1380 m, 1.ix.1981, E-Y: 1878, groundtraps, 63 days, leg. Endrödy-Younga, groundtrap with feces bait ( TMSA) . Paratypes: 6 specs., same data as holotype; 3 specs., S. Afr., Cape [ South Africa, Western Cape], Cederbg. [ Cederberg Mts .], Jeep track, 32.23 S – 19.08 E, 1550 m, 1.ix.1981, E-Y: 1875, groundtraps, 63 days, leg. Endrödy-Younga, groundtrap with feces bait (all TMSA, 1 spec. RBSC) .

Diagnosis. Body small, up to 2.2 mm, narrow; rostrum and epifrons subparallel-sided, at base as wide as at apex, with straight sides; furrow between head and rostrum at level of posterior eyes margins; abdominal ventrites squamose; metaventral process narrow; female sternite VIII with longitudinal sclerites.

Description. Body length 1.88–2.19 mm, holotype 1.91 mm. Body ( Fig. 5 ) dark brown to blackish, antennal funicles, tibiae and tarsi slightly paler, reddish brown. The entire body densely covered with rounded appressed scales, very shortly fringed on circumference, completely covered integument, 4 across width of one interstria. Elytra with one regular row subspatulate, inconspicuous setae, semi-appressed on disc and semi-erect on posterior declivity, on declivity slightly longer than half width of interstria, distance between two setae 3–4x as long as length of one seta. Pronotum and head with rostrum with distinctly shorter, spatulate, semi-appressed setae, irregularly scattered. Vestiture light brownish, setae dark brown.

Rostrum ( Figs 19, 20 ) short, 1.31–1.35× as wide as long, subparallel-sided, at base as wide as at apex, with straight sides. Epifrons narrow, subparallel-sided, at base 0.5× as wide as rostrum in relevant part, dorsally flat, with deep transverse furrow at level of posterior eyes margins. Frons very short, matt, densely punctate, forming narrow stripe behind epistome. Eyes in dorsal view slightly prominent from outline of head. Head and epifrons under scales densely punctured, furrow between rostrum and head deep, well visible also in lateral view, but with ill-defined margins.

Antennal ( Fig. 5 ) scape short, 4.67–4.83× as long as at apex wide, in apical part 0.9× as wide as club. Funicle robust, article 1 1.4–1.5× as long as wide and 1.8–2.0× as long as short article 2, this is 1.1–1.2× as long as wide; article 3 1.6–1.7× as wide as long; articles 4–6 1.8–1.9× as wide as long; article 7 2.1–2.2× as wide as long; club 1.5–1.7× as long as wide.

Pronotum ( Fig. 5 ) 1.16–1.22× as wide as long, widest at posterior third, with regularly rounded sides, weakly constricted behind anterior margin; disc regularly domed; base arched; pronotum in lateral view slightly vaulted, flattened behind anterior margin.

Elytra ( Fig. 5 ) long oval, 1.28–1.32× as long as wide, widest at midlength, with regularly rounded sides; striae narrow; interstriae flat; subhumeral calli missing.

Tibiae short, 5.5–5.8× as long as at midlength wide; protibiae apically obliquely subtruncated with sparse fringe of short blackish setae, indistinctly finely denticulate on inner margin in apical half; all tibiae with long, slender light brown mucro. Tarsi with tarsomere 2 1.6–1.7× as wide as long; tarsomere 3 1.4–1.5× as wide as long and 1.3–1.4× as wide as tarsomere 2; onychium short, 0.8–0.9× as long as tarsomere 3.

Abdominal ventrites 1.08–1.11× as long as wide, densely squamose. Metaventral process narrow, slightly narrower than transverse diameter of metacoxa.

Penis ( Fig. 31 ) short, widest at base, slightly evenly tapering apicad with straight sides; apex subtriangular with distinctly concave sides; tip rounded; in lateral view slightly curved, widest at apical quarter, tip narrow, destinctly elongate. Endophallus with two sclerites, one V-shaped, second slightly shorter, straight. Tegmen with short parameres.

Sternite VIII ( Fig.41 ) with short apodeme, widest at middle, 1.3–1.4× as long as plate; plate slender, subtriangular, distinctly pointed, 1.5–1.6× as long as wide with distinct, V-shaped longitudinal sclerites. Gonocoxites short, subtriangular, with long apical styli. Spermatheca ( Fig. 37 ) with regularly curved slender cornu; corpus slender, elongate; ramus short, slightly longer than wide; collum straight, perpendicular to ramus, longer than ramus and twice as long as at base wide, narrowing apicad.

Derivation of name. The small body size, inconspicuous colour of the vestiture and shape of setae and also the lack of any other striking character suggested the Latin name of this new species.

Biology. Type material was collected to pitfall traps in mountain fynbos.

Distribution. South Africa (Western Cape).

Differential diagnosis. Bulirschius inconspicuus is similar to B. ruiterbos and B. densatus in the elytra lacking subhumeral bumps, rostrum in apical portion at most as wide as the base, dense, regularly rounded appressed scales, erect setae short, subspatulate, not prominent from the outline of the body in dorsal view. It differs from both these species by having a transverse furrow between head and rostrum at level of posterior eye margins, abdominal ventrites squamose and plate of female sternite VIII with longitudinal sclerites. From B. ruiterbos it differs by a short and wide rostrum with straight sides, eyes prominent from the outline of the head and a narrow metaventral process; from B. densatus it differs by longer and more slender pronotum and elytra, sparse erect elytral setae and short onychium.

Figures

FIGURES 5–8. 5–7: Dorsal habitus. 5. Bulirschius inconspicuus 6. B. ruiterbos. 7. B. tesinskyi. 8: Ventral habitus. 8. Kostalius rotundisetis. Not to scale.

FIGURES 13–24. 13–24: Head including rostrum in dorsal and lateral view. 13, 14. Andringitrabius polymitus. 15, 16. Bulirschius densatus. 17, 18. B. dysommatiformis. 19, 20. B. inconspicuus. 21, 22. B. ruiterbos. 23, 24. B. tesinskyi. Scale 0.50 mm.

FIGURES 25–43. 25: Right protibia. Bulirschius tesinskyi. 26–28: Abdominal ventrites. 26. B. densatus. 27. B. ruiterbos. 28. B. tesinskyi. 29–33: Penis in dorsal view. 29. B. densatus. 30. B. dysommatiformis. 31. B. inconspicuus. 32. B. ruiterbos. 33. B. tesinskyi. 34: Tegmen. B. tesinskyi. 35–39: Spermatheca. 35. B. densatus. 36. B. dysommatiformis. 37. B. inconspicuus. 38. B. ruiterbos. 39. B. tesinskyi. 40–42: Female sternite VIII. 40. B. densatus. 41. B. inconspicuus. 42. B. tesinskyi. 43: Ovipositor. B. tesinskyi. Scale 0.50 mm for 25–28, 34, 40–43; 0.25 mm for 29–33, 35–39.