Viettherchnus orszuliki, 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 : 591-594

Viettherchnus orszuliki sp. nov.

( Figs. 1 , 5 , 8 , 10, 13, 16 )

Type material. Holotype ♂ ( NMPC), labelled: “ NEPAL. Manaslu env. / Besisahar / 800 m, 23.4.2015 / lgt. Orszulik [p] // HOLOTYPUS ♂ / VIETTHERCHNUS / orszuliki sp. nov. / JelÍnek & Hájek det. 2024 [red label, p]” . Paratypes: 6 ♂, 4 ♀, the same data as holotype ( KOFM, NMPC) ; 1 ♂, 1 ♀, “E-NEPAL, 30/6-1/7.2000, / Kangchenjunga Himal Mts , / CHIRUWA vill. 1260m / 27.29N 87.45E [GPS] env. / David Král lgt. [p] // NEPAL Expedition, / Jan Farkač, David Král / & Jan Schneider, 2000 [p]” ( NMPC) ; 1 ♂, “ NEPAL central / Beni – west of Pokhara / 3.5.- 4.5.2017 / lgt. E.Kučera [p]” ( NMPC). All paratypes with the appropriate printed red label .

Description of male holotype. Habitus broadly oval, convex, glabrous, smooth and shining.

Colouration. Orange, pronotum with four round black spots, two smaller at anterior margin, two larger at basal margin besides scutellum. Each elytron with following black spots: one at humeral bulge, one behind it near mid-length, one round spot at median axis at ca. one third of elytra length; further there are two common spots at suture: one narrow oblong just behind scutellum, and one broad subtriangular one near apex. Legs and antennae yellow, antennal club black-brown ( Fig. 1 ).

Head transverse, eyes on small conical protuberances, with sharp transverse edges between eye and antenna insertion, temples rectilinear, converging posteriad. Vertex and lateral portions of frons feebly convex, median portion of frons between antennae markedly concave, anterior portion as well as clypeus almost horizontal and moderately transversely convex. Sides of frons besides eyes distinctly punctate, punctures almost equal in size to eye-facets, separated by one diameter or more, interspaces smooth and shining. Median portion as well as clypeus smooth and shining with very fine and widely spaced punctures. Anterior margin of clypeus subtruncate, not bordered. Labrum transverse, anterior margin arcuate laterally, subtruncate in middle without distinct incision. Mandibles arcuately dilated laterally with sharp, raised angulate dorsal edge and large, shallowly concave face against eye ( Fig. 5 ). Antennae as long as width of head across eyes (ratio HEAW/ANLE = 1.00); club oblong oval. Scapus almost 3× wider than pedicel, 1.375× longer than wide, widest at base and subrectangular, gradually narrowed distad, with arcuate sharp anterior margin and well defined shallow anteocular concavity on posterior face. Pedicel length/width = 4/3, hardly wider than following antennomeres. Antennomere III ca. twice as long as wide, IV ca. as long as wide, its anterior side angulate, V 1.33× longer than wide, VI and VII as long as wide, VIII transverse. Ratio ANCL/ANCW = 1.78, antennomere XI nearly as long as IX + X combined, X lunular, shorter than neighbouring ones; ratio ANLE/ANCL = 2.60.

Pronotum transverse, strongly transversely convex, widest at posterior angles and strongly arcuately narrowed anteriad. Anterior margin deeply trapezoidally emarginate, indistinctly bordered. Anterior angles broad, prominent, obtuse with more or less rounded tips. Lateral margins broadly arcuate, not explanate, finely bordered, visible simultaneously from above in their entirety. Basal margin not bordered, in front of scutellum with broad truncate projection, besides it broadly arcuate. Posterior angles obtusely angulate. Punctures almost equal in size to eye-facets, separated by several diameters, interspaces smooth and shining. Scutellar shield large, subtriangular, punctate like pronotum.

Elytra widest near base, gradually arcuately narrowed posteriad and simultaneously rounded apically, strongly convex both longitudinally and transversely, without distinct humeral bulges; lateral margins not explanate, not visible simultaneously from above. Surface of each elytron with eight series of punctures nearly equal to those of pronotum and within one row separated by ca. one diameter. Analogous, but diffuse, punctures occur also along apical portion of suture. Sutural lines indistinct. Interstries finely diffusely punctulate with widely spaced punctures corresponding to those of concave median portion of frons. Interspaces smooth and shining.

Pygidium subtriangular, broadly rounded apically. Punctures larger than eye-facets and bearing rudimentary setae, separated by one diameter or less, interspaces obsoletely reticulate, somewhat dull.

Ventral surface. Postmentum ca. 2.5× wider than long, its anterior margin feebly concave, punctures larger than eye-facets, shallow, separated by one diameter or less, interspaces smooth and shining. Antennal furrows well defined with raised margins, converging posteriorly. Prosternum short with sharp mediolongitudinal carina gradually vanishing on prosternal process; punctures fairly twice as large as eye-facets, flat, separated by less than one diameter, interspaces shining. Prosternal process with blunt arcuate apical margin behind procoxae, its apical wall convex, obliquely sloping dorsad, with subtruncate apical margin. Hypomera broad, concave, impunctate, smooth and shining, postcoxal pieces punctate like prosternum. Mesoventrite situated markedly lower than metaventrite (ventral view), transversely convex, mediolongitudinally carinate. Anterior portion of mesepisternum (prepectus) flat, indistinctly punctate, alutaceous, dull; posterior portion concave, punctate like mesoventrite, shining. Mesocoxal axillary lines in median half transverse, running near posterior margins of mesocoxal cavities, their outer recurrent portion arcuate, meeting metasternopleural suture before its mid-length. Metaventrite almost flat except for large concavities in front of metacoxae, its anterior intercoxal margin concave, extending over intercoxal piece of mesoventrite, posterior intercoxal margin truncate. Discrimen absent. Punctures in median portion indistinct, very fine and widely spaced, becoming larger laterally, at sides fairly equal in size to eye-facets and separated by nearly one diameter. Metacoxal axillary lines running close to posterior margins of metacoxal cavity all along its length, axillary space not developed. Abdominal ventrite I as long as II–IV combined, punctures of all ventrites equal, nearly equal in size to eye-facets, but very shallow, separated by nearly one diameter and bearing long semirecumbent yellow setae; interspaces smooth and shining. Hypopygium transverse, flatly rounded apically ( Fig. 8 ).

Legs. Distances between pro-, meso- and metacoxae as 7: 16: 16. Profemur twice as long as wide, dorsal anterior margin almost rectilinear, ventral one in distal half arcuately emarginate. Posterior margin subrectilinear, in apical portion arcuate. Protibia shorter than femur (33/45), 3.3× longer than wide, subparallel-sided, only in basal fifth arcuately narrowed proximad; outer margin densely crenulate, outer subapical angle subrectangular. Mesofemur broad (length/width= 45/25), its posterior margin almost rectilinear, in ca. 2/3 of its length abruptly curved and then again as subrectilinear running towards distal end of femur. Mesotibia 2.69× longer than wide, mesofemur 1.34× longer than mesotibia, subparallel-sided in two distal thirds, in basal third arcuately narrowed towards base. Metafemur 1.83× longer than wide, widest at two thirds of its length, its posterior margin in two basal thirds subrectilinear, in distal third arcuate. Metatibia as long as femur, subparallel-sided, in basal third arcuately narrowed proximad. Meso- and metatarsomeres I–III bilobed, tarsomere V as long as I–IV combined. Tarsal claws simple.

Male genitalia. Penis broad and short, apical margin broadly rounded with short rounded apical protuberance ( Fig. 10 ). Tegmen 1.25× longer than wide, broadly rounded apically ( Fig. 13 ).

Female. Externally similar to male except for absence of secondary sexual characters. Frons almost flat, situated approximately at the same level as clypeus and separated from it by shallow transverse impression between antennal insertions. Entire frons punctate with punctures almost equal in size to eye-facets, separated by one diameter or more, interspaces smooth and shining. Clypeus smooth and shining with very fine and widely spaced indistinct punctures. Mandibles dorsoventrally flattened, not extended laterally, outer margin sharp, but not raised. Scapus ca. twice as long as wide, base not angulate, anterior face convex, posterior one with well defined shallow anteocular concavity. Ovipositor serrate in apical third, apex acutely pointed, without styli ( Fig. 16 ).

Variation. Colour pattern variable, in specimens with most extended black pigmentation pronotum mostly black with orange borders at sides and lateral portions of basal margin, as well as with more or less interrupted zigzag transverse bar on disc; elytra black, each with large orange ellipse in sutural half, reaching from basal margin to ca. two thirds of elytra length and projecting shortly laterad; also humeral angle orange.

Measurements. Body length 2.4–3.0 mm (holotype 2.95 mm), width 1.7–2.0 mm (holotype 1.95 mm), height 1.0– 1.4 mm (holotype 1.40 mm).

Differential diagnosis. The combination of a marked orange and black colour pattern, antennal club shorter than antennomeres II–VIII combined and distinct serial punctation on elytra suggest close relation of V orszuliki sp. nov. to Viettherchnus plagiatus Kirejtshuk & Kirk-Spriggs, 1996 from Malaysia.

The peculiar colour pattern of the new species resembles that of some Cyllodes species like Cyllodes literatus ( Reitter, 1878) , C. multimaculatus Grouvelle, 1914 or C. nakanei Hisamatsu, 1961 . Female of Viettherchnus orszuliki sp. nov. differs from them in the abrupt boundary between distinctly punctate frons and indistinctly, finely punctate clypeus (in Cyllodes species punctation of frons becomes gradually finer towards clypeus) and blackish pygidium (in mentioned Cyllode s species pygidium as well as entire ventral surface red).

Name derivation. The new species is dedicated to Kamil Orszulik (Frýdek-Místek, Czech Republic), an enthusiastic amateur entomologist and collector of the most specimens of the new species. The specific epithet is a noun in the genitive case.

Distribution. Viettherchnus orszuliki sp. nov. is known from several localities in central and eastern Nepal.

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 8–9. Ventral habitus of Viettherchnus. 8. V. orszuliki sp. nov. (paratype ♂); 9. V. helferi sp. nov. (paratype ♀; Kalimantan). Scale bar 1 mm.

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.