Tausternus Fedorenko, 2020

Fedorenko, D. N., 2020, New taxa of Pterostichini (Coleoptera: Carabidae) from Vietnam, Russian Entomological Journal 29 (1), pp. 38-52 : 39-40

Subgenus Tausternus Fedorenko , subgen.n.

Figs 1–13 .

Type species: Pterostichus hoii Fedorenko, sp.n.

DIAGNOSIS. A subgenus of Pterostichus recognizable in having prosternum with a very deep T-shaped sulcus, combined with metatibiae and metatarsi incrassate in male. Other features are as follows: Body apterous, medium-sized for the genus, shiny, metallic, violaceous blue. Head medium-sized, microphthalmic, with long genae; frontal foveae impunctate, in form of long and very deep round brackets; terminal palpomeres subfusiform. Mandibles moderately long, slender, nearly straight, with ventral scrobal ridge sinuate in dorsal view. Mentum tooth triangular and blunt. Antennomeres 4–11 pubescent, scape and pedicel unisetose, segment 3 without setae other than verticellate ones. Pronotum subcordate, with two basal sulci on each side, inner long, outer vestigial; disc convex up to lateral bead, without explanate lateral margin. Elytra connate, oblong, with apices blunt and narrowly separated along suture by an oblong fissure; humeri distinct, humeral angle obtuse, basal ridge outside stria 4. Elytral parascutellar striole missing. Prosternal process conspicuously beaded. Abdominal sternite VII with a long horn-like process in male. Legs slender; tarsomeres neither sulcate nor carinate laterally. Body on each side with fixed setae as follows: head: 2 supra-ocular, 1 clypeal; submentum — 2; mentum — 1; penultimate labial palpomere — 2; maxillary stipes — 2; pronotum — 2; elytra: parascutellar seta in stria 2, discal setae missing, apical setae — 2 in stria 7; abdominal sternites IV– VII — 1, sternite VII — 1 (♂) or 2 (♀); legs: trochanter — 1; metacoxa — 3; profemur — 3, posterior; mesofemur — 2, anteroventral; metafemur — 1, anteroventral basal; metatibia without outer setae; tarsomere 5 glabrous ventrally .

Aedeagus with right paramere small, apical orifice of median lobe left dorsolateral. Female reproductive tract similar to that of Pterostichus (Morphohaptoderus) Tscitschérine, 1898 , except that spermathecal duct is extremely long and medially balled (receptacle subcylindric, gradually broadened apicad, meeting spermathecal duct at acute angle, with spermathecal gland duct entering just the corner).

DESCRIPTION. Body ( Fig. 1 ) apterous, oblong, medium-sized.

Head medium-sized, without neck constriction, each side with a deep supra-ocular groove slightly surpassing eye; eyes small yet moderately convex, dorsolateral; genae long; posterior supra-ocular seta midway between posterior margin of eye and the angle. Frontal foveae C-shaped, long and deep. Antennae nearly filiform, length ratio of antennomeres 1–4 (1.13: 0.6: 1: 0.8), scape with dorsal seta, pedicel with ventral seta.

Mandibular scrobe medially with a deep longitudinal sulcus reaching its apex. Mentum with two close setae at base of a simple and blunt median tooth. Genae ventrally just behind submentum deeply transversely grooved. Terminal labial palpomeres subfusiform.

Pronotum rather long, base and apex truncate, basal angles slightly obtuse and blunt, apical angles acute and porrect; basal bead missing, apical bead obliterate in middle third, lateral bead reaching posterolateral seta; basal and apical transverse impressions rather shallow. Inner basal sulci disappearing a third from base, diverging on each side of basal transverse impression and almost reaching base; outer sulcus half as long, running close to and anteriorly joining lateral bead, reaching and rather deep at basal margin; basal fovea impunctate. Posterolateral seta distinctly in front of base.

Elytron with a slight preapical sinuation and narrowly rounded apex, preapical plica well-developed yet internal and invisible in lateral view. Base truncate and narrow, without humeral tooth; humeri distinct yet apically rounded; sides diverging and straight in basal 1/2–2/5. Reflexed lateral margin finely beaded up to apex, neither costate nor carinate, about as wide as interval 9. Striae deep impunctate or indistinctly crenulate. Intervals subequally wide, 9 th with 15–18 US (mostly 16) arranged into anterior group in basal 1/3–1/4 (6–7 US, mostly six), posterior group behind middle, and one intermediate US.

Underside nearly smooth. Prosternal T-shaped sulcus very deep and almost reaching apex of prosternal process; this process apically rounded or subtruncate and conspicuously beaded; inclination posteriorly flat, wide dorsally, less so ventrally, constricted in between. Metepisternum ca. 0.83 times as long as wide. Abdomen entirely beaded laterally, sternite III with a wide and rather shallow median groove broadened slightly apicad.

Legs fairly slender and lightly armed with spiniform setae. Protibia slightly dilated apicad, apically with one posterior and two posterolateral spinules. Metatrochanter rounded apically, less than half as long as metafemur. Mesofemur with two subequally spaced anteroventral setae and two anterodorsal setae in apical two fifths; mesotibia with three outer setae, distal seta inserted closer to anterior ridge. Tarsomeres 1–4 each with one pair of latero-apical setae, tarsomeres 1–2 each with one pair of dorso-apical setae; meso- and metatarsomeres 1–4 with ventral setae rather sparse, being totally reduced in inner (posterior) row, except for 1–3 short setae survived on mesotarsomeres 1–4 and/or on metatarsomere 1 in some specimens.

Aedeagus ( Figs 10–13 ) characteristic of Pterostichus .

Female genitalia and reproductive tract. Laterotergite with dense marginal setae; gonosubcoxite setulose along inner margin, with a few (four) strong setae along latero-apical margin. Gonocoxite falcate, with a double nematiform seta near apex and three ensiform setae, two ventral (outer) and one dorsal (inner), and 1–2 smaller additional setae at inner margin. Bursa copulatrix with three large yet fairly weak, contiguous, subtriangular sclerites, and a nodule, sphincter, near base of seminal canal. Spermatheca geniculate, seminal canal sclerotized at base, extremely long, serpentine, medially rolled into an incompact ball, meeting receptacle at acute angle; duct of spermathecal gland enters the corner; receptacle straight, subclavate, gradually broadened apicad.

Secondary sexual differences (of male): protarsomeres 1– 3 dilated and biseriately squamose on ventral side as usual in the genus; abdominal sternite VII ( Fig. 5 ) strongly modified, with a shallow round impression at middle and a fine longitudinal carina at its bottom that gives rise to a large, slightly flattened, horn-like process; meso- and metatibia ( Figs 6–9 ) plurituberculate along both inner ridges, anterior and posterior; metatibia and metatarsus incrassate, tarsomeres cordiform.

NAME. Masculine, combination of Greek letter ‘τ’ [tau] and ‘ sternum ’, referring to the very deep T-shaped impression of the prosternum.

DISTRIBUTION. The only species of the subgenus is known to occur in the Ngoc Linh Mt., Central Vietnam.

HABITS AND HABITATS. All specimens of Pterostichus hoii sp.n. were collected by pitfall traps in a monsoon forest at 1600–2150 m altitudes, together with some species of the subgenera Vietosteropus and Steropanus of Pterostichus .

COMMENTS. This subgenus is monobasic. It is very distinctive in body appearance, including colouration; deeply transversely sulcate prosternum; frontal sulci unusual in shape, deep and wide; mandibles long and sinuate laterally; elytra apically separated and lacking discal setae; hind two leg pairs sexually dimorphic, with tarsi scarcely setose ventrally; abdominal sternite VII strongly modified in male; etc. On the other hand, there is only a little difference between this and some other subgenera of Pterostichus from Southeast Asia in body setation and female genital apparatus. Among them, Morphohaptoderus and probably also Tschitscherinea Berg, 1898 and Jedlickaia Sciaky, 1997 seem be closest to Tausternus subgen.n., all having the metacoxa trisetose (vs. bisetose in others).

Figures

Figs 1–9. Pterostichus (Tausternus) hoii sp.n.: 1 — habitus of paratype ♀; 2, 3 — head and pronotum; 4 — variant form of pronotum; 5 — body apex; 6–9 — left metatibia of male (6, 8) and female (7, 9); 1, 4 — dorsal aspect; 2 — ventral aspect; 3, 5, 8–9 — left lateral aspect; 6–7 — caudal aspect. Рис. 1–9. Pterostichus (Tausternus) hoii sp.n.: 1 — габитус дорЗально, паратип ♀; 2, 3 — голова и переднеспинка; 4 — вариант формы переднеспинки; 5 — верШина тела; 6–9 — ЗаднЯЯ леваЯ голень самца (6, 8) и самки (7, 9); 1, 4 — дорЗально; 2 — вентрально; 3, 5, 8–9 — слева; 6–7 — каудально.

Figs 10–13. Pterostichus (Tausternus) hoii sp.n.: 10–11 — median lobe of aedeagus; 12 — right paramere; 13 — female genitalia and reproductive tract (spermathecal gland and major part of spermatheca removed), ventral aspect; 10 — left lateral aspect; 11 — dorsal aspect; bc — bursa copulatrix; gsc — gonosubcoxite; LTIX — laterotergite IX; ov — common oviduct; sbs — spermathecal basal sclerite; sc — seminal canal. Scale bars: 1 mm. Рис. 10–13. Pterostichus (Tausternus) hoii sp.n.: 10–11 — среднЯЯ долЯ Эдеагуса; 12 — праваЯ парамера; 13 — половой аппарат самки (больШаЯ часть сперматеки и желеЗа сперматеки удалены), вентрально; 10 — слева; 11 — дорЗально; bc — копулЯтивнаЯ сумка; gsc — гоносубкоксит; LTIX — латеротергит IX; ov — обЩий Яйцевод; sbs — баЗальный склерит сперматеки; sc — семенной канал. МасШтаб: 1 мм.