Trilophidius planophthalmus, Balkenohl, 2018

Balkenohl, Michael, 2018, Notes on Oriental Clivinini and the description of two new species (Coleoptera: Carabidae: Clivinini), Linzer biologische Beiträge 50 (1), pp. 197-215 : 202-205

Trilophidius planophthalmus nov.sp. ( Figs 3-6 )

T y p e m a t e r i a l: Holotype: ♂, with label and data: yellow, black printed: "N LAOS iv. 1993 10 km N Luang-Prabang Mekhong river , 240km N Vientiane, hills ca. 250m poor settlem., prim. veget. lux, leg. Insomsay Somsy " ( MFNB) . Paratypes: 2♂♂, 2♀♀, 6 specs., same data as holotype ; 2 specs., same data as holotype but iii. 1993 ( MFNB, CBB) .

R e m a r k s: In the holotype, the right antennae is glued at joint four but complete. Most of the paratypes are more or less damaged, e.g. with missing parts of legs, crashed pronotum, and in one case a missing elytron. One of them could not be included in the measurements.

E t y m o l o g y: The name is derived from the flattened eyes and is a composite from the Latin ‘planus’ and the Greek ‘ophthalmos’ (ophthalmus in Latin).

D i a g n o s i s: A distinctly brown Trilophidius species with subelongate elytra having the maximum width behind middle, six setigerous punctures on the third interval, an incomplete fold-like carina in the channel at the apex of the elytra, and a broadly interrupted series umbilicata in the marginal channel of the elytron. Distinguished directly from all other Oriental species by the black and conspicuously flattened eyes and the distinctly convex frons of the head.

D e s c r i p t i o n:

Measurements: Length 2.22-2.45 mm (ẍ = 2.31 mm *), width 0.71-0.83 mm (ẍ = 0.79 mm *), ratio length/width of pronotum 1.0-1.05 (ẍ = 1.02*), ratio length/width of elytra 1.68-1.82 (ẍ = 1.76*); (*n = 10).

Colour: Uniformly fuscus. Palpi leoninus. Eyes piceus. Wings of clypeus and supraantennal plates slightly translucent. Pronotum towards base, disc of elytron, and antennae somewhat more pale.

Head ( Fig. 3, 4 ): A third smaller than pronotum. Clypeus and wings finely reflexed margined; clypeus indistinctly excised to straight anteriorly, meshed with transverse reticulation; wings tooth-like projecting, fused with clypeus, divided from supraantennal plates by distinct obtuse-angled notches; supraantennal plates amargined, convex, prolonged posteriorly as blunt supraorbital-carina, interrupted at mid-eye level;

triangular-like tubercle on vertex elongated posteriorly into a sharp keel, with isodiametric reticulation posterior tubercle. Clypeus and frons divided from supraantennal plates by deep and broad longitudinal furrows with roughly meshed reticulation. Furrows diverging posteriorly. Frons distinctly convex, smooth and with few minute punctures. Neck constriction distinct at posterior-eye level, composed of small to medium sized irregularly arranged band of punctures, more or less interrupted at middle. Eyes distinctly flattened; ommatidiae distinct, slightly convex; genae and temporae small. Labrum slightly excised, with irregular reticulation, five-setose. Mandibles distinctly acute at apex. Apical segment of maxillary palpomere conspicuously securiform, with four setae ventrally; terminal segment of labial palpomere bottle-like, penultimate segment bisetose. Mentum and submentum divided by deep furrow, with two pairs of setae each, median tooth triangular, acute at apex, lobes moderately elongate, longer than tooth, rounded anteriorly, with longitudinal reticulation. Gula nearly smooth at middle, with irregular reticulation laterally. Antennae short, just reaching posterior setigerous puncture of pronotum, segment five to ten moniliform.

Pronotum ( Fig. 3 ): Outline subglobose, as long as wide, maximum width at middle. Disc convex. Anterior margin nearly straight. Reflexed lateral border distinct anteriorly, prolonged finely to posterior setigerous puncture. Proepisternum distinctly tumid laterally and well visible in dorsal view, most distinct in posterior third. Anterior angles distinct, obtuse-angular, bent downwards. Anterior transverse line visible at anterior angles. Median line distinct, sharp, deeper and broader towards base, not reaching anterior margin, not reaching channel of basal constriction. Surface with some fine irregular transverse wrinkles at median line towards base, basal impression absent. Ring-like flange convex, three times as broad as channel of deep basal constriction.

Elytra ( Fig. 3 ): Convex in lateral and apical view. Anterior half slightly flattened for a short distance (lateral view). Subelongate, sides slightly rounded anterior middle and diverging, evenly rounded in apical third. Maximum width behind middle. Base slightly obliquely truncated. Marginal channel narrowed at middle of elytron, series of umbilical setigerous tubercles distinctly interrupted at middle, fold-like carina at apex incomplete, indistinct in the holotype and most of the paratypes. Humeral tooth small, situated in extended projection of seventh interval. With two basal tubercles with setigerous punctures adjoining lateral margin at humerus, a distinct tubercle in the extended projection of the second stria. Scutellar stria visible as very fine line. First stria deep up to tip of apex, stria two and three fairly deep, punctuate, other striae developed as rows of punctures, becoming fine apically; stria four shortened at base. Intervals slightly convex, eights forming obtuse overhanging carina in apical two-fifths, third with series of five to six fine setigerous punctures situated at the third stria in anterior half and towards the middle of the interval posteriorly.

Hind wings: Fully developed.

Ventral surface: Proepisternum with few transverse wrinkles and minute punctures, fine submarginal furrow visible in anterior quarter, furrow between prosternum and proepisternum invisible in anterior third. First and second abdominal sternites with isodiametric reticulation.Legs: Protibia: Surface with fine longitudinal reticulation, nearly smooth; lateral upper spine curved ventrally. Movable spur smaller than spine, nearly straight, apically curved. Praeapical lateral denticle robust, sharp, second one smaller. Profemur dorso-laterally with distinct coriaceous notches. Intermediate tibia with indistinct preapical tubercle furnished with seta. Hind legs: Tarsomere one nearly as long as two and three combined.

Sexual dimorphism: Terminal segment of abdominal sternite nearly smooth in the male, and with irregular reticulation in apical half in the female (160 times).

Male genitalia ( Fig. 5 ): Median lobe slightly arcuate in the middle part, distinctly arcuate in apical quarter. Nearly straight in lateral view, with wrinkles laterally anterior basal opening. Apex acute and flattened, with nodules laterally. Endophallus with two teeth. Parameres somewhat distorted, both of them with two long setae at apex, petioles short, nearly right-angled.

Female genitalia ( Fig. 6 ): Coxostylus one and two fused. Distinctly broadened basally, conspicuously curved, slender and acute at apex, with 4 dorsal and 5 ventral nematiform setae in the basal half and one big peg-shaped ensiform seta.

Variation: In the 13 specimens investigated the number and the arrangement of punctures of the neck constriction varies and the interruption at middle is more or less distinct. The number of setae on the labrum is usually five but four in three specimen and three on one specimen. Some of the paratypes have one of the eyes slightly more convex than on the other side. In all of these cases the convexity is developed to a degree less than 50% as in the other species of the genus. In few paratypes only five setigerous punctures are visible on the interval three of the elytron.

D i s t r i b u t i o n: The species was collected at light in Laos North of Vientiane at an altitude of 250 m.

R e m a r k s: The key to the Oriental species provided in BALKENOHL (2017a) can simply be enriched by the first question: ‘eyes distinctly convex as it is in the type species of the genus ( Fig. 7 ), or flattened ( Fig. 4 )’. The second option leads directly to the species described in this contribution. And indeed, out of the eight known species T. planophthalmus nov.sp. is the only one not exhibiting globose or distinctly convex eyes. But although the eyes of T. planophthalmus nov.sp. are flattened the diameter of the eyes is not much smaller. The eyes seem to work well because the specimens were collected at light.

Figures

Figs 3-7: Trilophidius planophthalmus nov.sp.: (3) Holotype, habitus; (4) Head dorsal view; (5) Holotype, aedeagus (a) and parameres (b, c) dorsal view, aedeagus lateral view (d); (6) Female coxostylus; (7) Trilophidius impunctatus PUTZEYS, head, dorsal view.