Bulirschius ruiterbos 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 : 114-115

Bulirschius ruiterbos Borovec , sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:754FB435-839B-4635-ADBC-07F381609F65

Figs (6, 21, 22, 27, 32, 38)

Type locality. South Africa, Western Cape, Ca 3 km S of Robinson Pass.

Type material. Holotype: ♂, South Africa, Western Cape, ca 3 km S of Robinson Pass , 33°53.8′ S, 22°01.3′ E, 17.x.2017, 720 m, fynbos, J. Janák lgt. ( TMSA) . Paratypes: 3 specs., same data as holotype ( JJRC) ; 11 specs., RSA, Western Cape, Robinson Pass , 33°52.377′ S, 22°01.871′ E, 25.x. 2019, 858 m, R. Borovec lgt., sifting of roots under ground leafs of different small plants in fynbos ( BMNH, CMNC, NMPC, RBSC, SANC) ; 3 specs., South Africa, Western Cape, 2-4 km S of Robinson Pass , 33°54′ S, 22°02′ E, 6.xii.2009, fynbos sifting, J. Janák lgt. ( JJRC) ; 5 specs., S. Afr. [Western Cape], Outeniqua Mt., Ruitersbos , 33.53 S – 22.01 E, 15.viii.1979, E-Y: 1646, 1000 m, sifted, leg. Breytenbach ( TMSA) .

Diagnosis. Rostrum slender, in dorsal view with distinctly concave sides; eyes not prominent from outline of head; elytra elongate; spermatheca with ramus and collum subequal in length, subparallel.

Description. Body length 1.75–2.53 mm, holotype 2.19 mm. Body ( Fig. 6 ) blackish, basal part of scapes and tarsi slightly paler, brown. The entire dorsal part of body densely covered with regularly rounded appressed scales, fully covering integument, 4 across width of one interstria. Elytra with one regular row of inconspicuous, semi-appressed setae on each interstria, setae visible mainly in lateral view, subspatulate, about as long as half width of one interstria, distance between two setae about twice longer than length of one seta. Pronotum and head with rostrum with similar setae as those on elytral disc, densely irregularly scattered. Vestiture dark, marbled with light rusty brown and dark brown scales, elytral interstriae 4–7 with small, scattered spots of white scales, pronotum with only several small spots of white scales, forming three incomplete longitudinal slender stripes, semi-appressed setae dark brown with only several scattered grey scales.

Rostrum ( Figs 21, 22 ) 1.04–1.09× as wide as long, at base subequal in width as at apex, with distinctly concave sides, tapering from base to midlength and then distinctly rounded around antennal insertions. Epifrons narrow, slightly tapering basad, at base narrowest and here 0.5× as wide as rostrum in relevant part, dorsally longitudinally depressed, posteriorly with shallow transverse furrow at level of anterior eyes margins. Frons moderately long, deepened, matt, finely punctate. Eyes in dorsal view not prominent from outline of head. Head under scales with regular longitudinal ridges converging towards median ridge separated by narrow grooves, giving vertex a lirate appearance.

Antennal scape ( Fig. 6 ) short, 4.43–4.88× as long as wide at apex, in apical part 0.9× as wide as club. Funicle moderately robust, article 1 1.6–1.7× as long as wide and 1.1–1.2× as long as article 2, this is 1.6–1.8× as long as wide; articles 3–6 1.2–1.3× as wide as long; article 7 1.4× as wide as long; club 1.6–1.7× as long as wide.

Pronotum ( Fig. 6 ) moderately narrow, 1.28–1.32× as wide as long, widest at midlength with regularly rounded sides, slightly more tapering anteriad than posteriad; disc regularly domed; base arched.

Elytra ( Fig. 6 ) long oval, 1.32–1.37× as long as wide, widest at midlength, with slightly regularly rounded sides; striae narrow; interstriae flat; subhumeral calli missing.

Tibiae short, moderately robust, 5.4–5.8× as long as at midlength wide; protibiae apically rounded with fringe of short and fine brown setae, indistinctly finely denticulate on inner margin in apical half; all tibiae with long slender mucro. Tarsi with tarsomere 2 1.5–1.6× as wide as long; tarsomere 3 1.4× as wide as long and 1.3–1.4× as wide as tarsomere 2; onychium of protarsi 0.9–1.0× as long as tarsomere 3, of metatarsi 1.2–1.3×.

Abdominal ventrites ( Fig. 27 ) 1.03–1.06× as wide as long, glabrous, finely, sparsely punctured. Metaventral process 1.5× as wide as transverse diameter of metacoxa.

Penis ( Fig. 32 ) medium long, subparallel-sided along entire length with slightly rounded sides, short apical portion subtriangular with slightly concave sides before narrowly rounded tip; in lateral view slightly curved and tapering apicad, tip slightly curved outside; endophallus with two slender sclerites, different in length. Tegmen with two short, translucent, hardly visible parameres.

Sternite VIII with short apodeme widest at midlength, 1.7–1.9× as long as plate; plate slender, long, subtriangular, pointed, 1.3–1.4× as long as wide. Gonocoxites short and wide with long apical styli. Spermatheca ( Fig. 38 ) Ushaped; cornu straight; corpus slender, elongate; ramus and collum subequal in width and length, subparallel to each other.

Derivation of name. The Latin name refers to the locality where the majority of the type material was collected, to the historical name of Robinson Pass, which was amended to Ruiterbos Pass (Ruiterbosch Pass, or Brandwaghoogte), because Ruiterbos was regarded as the start of the pass.

Biology. This species apparently lives in fynbos. Part of the type material was collected by sifting of detritus below ground leaf rosettes of various plants and the remaining part of the type material stated “fynbos” on locality labels.

Distribution. South Africa (Western Cape).

Differential diagnosis. Bulirschius ruiterbos is similar to B. inconspicuus and B. densatus in the elytra lacking subhumeral bumps, rostrum in apical portion at most as wide as at 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 of these species by having a slender rostrum with distinctly concave sides, eyes not prominent from the outline of the head, elongate elytra, metaventral process distinctly wider than transverse diameter of metacoxa and spermatheca with equally long, subparallel ramus and collum.

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.