Viettherchnus apriculus, Jelínek & Hájek, 2024

Jelínek, Josef & Hájek, Jiří, 2024, Three new species of the genus Viettherchnus Kirejtshuk, 1985 (Coleoptera: Nitidulidae: Nitidulinae: Cyllodini), Zootaxa 5519 (4), pp. 590-600 : 595-596

Viettherchnus apriculus sp. nov.

( Figs. 2 , 6 , 11, 14 )

Type material. Holotype ♂ ( NMPC), labelled: “ MALAYSIA, Perak / Cameron Highlands / BATU [= MILE] 19 vill. env. / 04°22.2′N, 101°20.0′E, 590 m / JiřÍ Hájek leg. 5.- 15.5.2009 [p] // HOLOTYPUS ♂ / VIETTHERCHNUS / apriculus sp. nov. / JelÍnek & Hájek det. 2024 [red label, p]”.

Description. Habitus. Broadly oval, convex, glabrous, smooth and shining.

Colouration. Head black with minute orange spots at insertions of antennae, pronotum black with narrow orange borders, somewhat wider at basal margin and vaguely delimited reddish-brown mediolongitudinal area. Scutellar shield and elytra orange, wider border along lateral half of base and lateral margins of elytra, as well as apical portion of elytra brown-black. Legs and antennae brown-yellow, antennal club infuscate ( Fig. 2 ).

Head transverse, temples rectilinear, converging posteriad. Frons almost flat, diffusely punctate, its anterior portion between antennal insertions sloping down, almost impunctate. Punctures almost equal in size to eye-facets, separated by 2–3 diameters, interspaces smooth, strongly shining. Clypeus separately vaulted, at base separated from antennal insertions by deep perpendicular furrows, anterior margin subtrapezoidal, surface with very small and widely separated punctures, interspaces smooth and shining. Labrum almost semicircular with narrow median incision. Mandibles with strong pointed protuberances curved outwards ( Fig. 6 ). Antennae somewhat shorter than width of head across eyes, antennal club oblong, obovate, occupying ca 0.4 antennal length, 1.5× longer than wide, widest at base of antennomere XI. Scape almost semicircular, its anterior (dorsal) side with two sharp parallel longitudinal edges, between them canaliculate. Pedicel twice, antennomere III 1.66× as long as wide, antennomeres IV, VI and VII nearly as long as wide, V slightly longer than neighbouring ones.

Pronotum transverse, convex both transversely and (less so) longitudinally, widest at posterior angles and strongly curved anteriad. Ratio WPR1/WPR3 =1.91, WPR2/LEPR = 1.82. Anterior margin with trapezoidal emargination, arcuate, not bordered; anterior angles obtusely rounded. Lateral margins broadly arcuate, in posterior half subrectilinear (vertical view), finely bordered, not explanate. Basal margin not bordered, with broad truncate lobe opposing scutellar shield, besides it broadly arcuate. Posterior angles obtuse. Punctures equal in size to those of frons, separated by more than one diameter; interspaces smooth and shining, with sparsely intermixed microscopic punctures bearing short indistinct rudimentary setae. Scutellar shield subtriangular, partly concealed by basal lobe of pronotum, punctate more densely than pronotum.

Elytra widest near base, arcuately narrowed posteriad and simultaneously rounded apically.Disc strongly convex both longitudinally and transversely, lateral margins finely bordered, not explanate, not visible simultaneously from above in their entirety. Surface of elytra seriate punctate, punctures in series nearly equal in size to those of pronotum, neighbouring punctures in one series separated by ca. one diameter, punctures on interstries diffuse, of somewhat variable size, but generally smaller and sparser than those in series. Sutural lines absent.

Ventral surface. Prosternum mediolongitudinally carinate, apical margin flatly arcuate. Mesoventrite situated beneath metaventrite (ventral view), mediolongitudinally carinate. Metaventrite flatly convex, in posterior half with punctures nearly equal to eye-facets and separated by 1.0–1.5 diameters, becoming larger and closer laterally and finer in anterior half; interspaces smooth and shining. Diverticulum absent. Mesocoxal axillary lines reaching metasternopleural suture at ca. one third of its length. Abdominal ventrites with larger punctures separated by one diameter or less. Metacoxal axillary lines closely bordering posterior margin of coxal cavities.

Legs. Profemur 1.5×longer than wide, its anterior margin rectilinear, proximal anterior angle rectangular. Protibia ca. 2.5× longer than wide, subparallel-sided; outer subapical angle rectangular, outer margin densely denticulate. Protarsomeres I–III 0.75× the width of protibia, V as long as I–IV combined. Mesofemur subtrapezoidal, 1.74× longer than wide. Metafemur almost oval, posterior margin in basal half rectilinear, 1.93× longer than wide. Tarsal claws simple.

Male genitalia. Penis subparallel-sided, broadly rounded apically ( Fig. 11 ). Tegmen broadly rounded apically ( Fig. 14 ).

Female unknown.

Measurements. Body length 2.45 mm, width 1.70 mm, height 1.20 mm.

Differential diagnosis. Large antennal club, shape of scapus and seriate punctation of elytra suggest its close relation to Viettherchnus sulawesiensis Kirejtshuk & Kirk-Spriggs, 1996 from the Indonesia (Sulawesi) and Philippines. The new species differs from the latter in its brightly orange elytra with black apex and sides, and in striking acute lateral projections on mandibles in male. Large mandibular projections occur also in the sympatric V. plagiatus , in which they are directed anteriad, subparallel-sided and rounded apically.

Name derivation. Latin noun apriculus , -i, m, is diminutive of aper (boar), referring to characteristic modification of male mandibles resembling the projecting teeth of a wild boar. The specific epithet is a noun in the nominative case, standing in apposition.

Distribution. Viettherchnus apriculus sp. nov. is only known from the type locality in Cameron Highlands, Perak, Peninsular Malaysia.

Figures

FIGURES 1–4. Dorsal habitus of Viettherchnus. 1. V. orszuliki sp. nov. (holotype ♂); 2. V. apriculus sp. nov. (holotype ♂); 3. V. helferi sp. nov. (paratype ♀, dark form; Kalimantan); 4. V. helferi sp. nov. (holotype ♂). Scale bar 1 mm.

FIGURES 5–7. Head of male Viettherchnus. 5. V. orszuliki sp. nov.; 6. V. apriculus sp. nov.; 7. V. helferi sp. nov. Not in scale.

FIGURES 10–17. Genitalia of Viettherchnus. 10–12. penis with internal sac in dorsal view; 13–15. Tegmen; 16–17. Ovipositor. 10, 13, 16. V. orszuliki sp. nov.; 11, 14. V. apriculus sp. nov.; 12, 15, 17. V. helferi sp. nov. Scale bar 0.5 mm.