Trichotichnus (Bottchrus) obliquebasalis, Schmidt, 2017

Schmidt, Joachim, 2017, Brachypterous ground beetles of the Trichotichnus subgenus Bottchrus Jedlička (Coleoptera, Carabidae) from the Himalaya, with description of fifteen new species, Zootaxa 4323 (3), pp. 301-358 : 318-320

Trichotichnus (Bottchrus) obliquebasalis sp. n.

( Figs 39 , 47–52 , 151 , 6 )

Type material. Holotype: ♂, “ NEPAL –HIMALAYA, S Khumbu-Himal, leg. Kleeberg 1993”, “Umgeb. Jiri 1707 m, Shivalaya, 1.5., Kimti Khola” (cJS).

Paratypes: 4 ♂, 2 ♀, same data as holotype (cJS, ZIN) ; 1 ♂, 1 ♀, “C NEPAL Dolakha Distr., Tama Koshi vall. Tshet Tshet env., 1000–1400 m, 3.VI.00 lg. Schmidt, 25°51'58"N 86°13'19"E ” (cJS).

Description. Habitus as in Fig. 39 . Body length 4.8–5.4 mm, width 2.1–2.5 mm.

Colour: Body piceous, shiny on dorsum, with distinct bluish or blue greenish tinge on elytra and pronotum; labrum, in some specimens also very narrow margins of pronotum and apical portion of elytral margins slightly paler; palpi, antennae and legs brownish yellow, femora not infuscate.

Head: Comparatively large, with wide neck (in males, HWmax/PWmax = 0.67–0.71, HWmin/PWmax = 0.55– 0.58; in females, these indices 0.69–0.72 and 0.58–0.60, respectively). Eyes moderately or strongly convex (in males, HWmax/HWmin = 1.18–1.24, and in females, 1.19–1.20), in lateral view elongate oval. Tempora about half as long as eye, slightly convex, sloped somewhat abruptly to neck. Genae noticeably wider than width of antennomere 1, with short setae. Lateral margin of head between antenna and eye, like in all the preceding species, slightly protruded laterally, forming an obtuse angle near eyes, distinctly bordered. Area between supraorbital furrow and upper margin of eye approximately as wide as width of antennomere 2 basally. Supraorbital setigerous pore located just behind level of posterior margin of eye, separated from supraorbital furrow approximately by width of antennomere 3 apically. Labrum moderately concave anteriorly. Clypeus slightly emarginate along anterior margin, moderately convex basally, flatly sloped to apex, with a moderately large setigerous pore at each apical angle. Frons and vertex convex. Mentum and submentum completely fused, submentum with one long seta on each side, occasionally also with a short seta laterally of long seta. Left mandible not truncate, blunted at apex. Dorsal surface smooth, highly obliterate meshes evident only laterally behind eyes. Antennae comparatively short, in both sexes not extended to basal edge of pronotum, with antennomeres 4–8 slightly longer than wide.

Pronotum: Comparatively wide (PWmax/PL = 1.37–1.42), widest at the end of anterior third, slightly or moderately narrowed posteriad (PWmax/PWmin = 1.16–1.24), with one lateral seta inserted slightly before the widest point. Sides rounded anteriorly, almost straight to slightly sinuate in basal third. Apical margin very slightly emarginate, bordered only laterally. Apical angles very slightly prominent anteriad, rather widely, but less widely than in T. baglungensis sp. n., rounded at tip. Basal margin nearly straight in the middle portion, oblique laterally, more or less distinctly bordered except for the short middle portion, slightly longer than apical margin and slightly shorter than base of elytra between humeral angles. Basal angles very obtuse, each with a sharp, subdenticulate apex not or slightly protruded laterad. Pronotal disc moderately convex, strongly sloped to apical angles and moderately so to basal ones, not depressed basally. Lateral gutter very narrow, very slightly widened in apical half. Median line fine, superficial, ended markedly before apical and basal margins. Lateral depressions absent; basal foveae distinct, small, elongate and very shallow. Surface sparsely, somewhat coarsely and irregularly punctate in basal and latero-basal areas, finer punctures also present at apical margin. Microsculpture not evident even at high magnification.

Elytra: In lateral and caudal view convex, in dorsal view oval, moderately wide (in male, EL/EW = 1.30–1.31; EL/PL = 2.32–2.45; EW/PWmax = 1.27–1.32), widest slightly behind middle, with somewhat acute apex. Humeri prominent, angularly rounded at tip, with a small acute denticle at tip visible from behind. Subapical sinuation very shallow. Sutural angle acute, sharp or slightly blunted at tip. Basal edge noticeably curved at humerus, forming a somewhat sharp, slightly more than right angle with lateral margin. Striae slightly impressed along entire length. Intervals slightly convex, weakly narrowed posteriad. Parascutellar setigerous pore present, large. Parascutellar striole short, occasionally interrupted, in most specimens shorter than distance from parascutellar pore to suture, with apex free. Interval 3 with a very small discal setigerous pore at stria 2 behind middle. Marginal umbilicate series widely interrupted at middle, with 6–8 pores in anterior group and 8–10 pores in posterior group. Microsculpture not evident even at high magnification.

Hindwings: Reduced to tiny scales.

Ventral surface: Prosternum and metasternum finely pubescent. Metepisternum ( Fig. 47 ) approximately as wide as long as or slightly wider than long, strongly narrowed posteriad. Apex of last visible (VII) abdominal sternite in male rounded ( Fig. 48 ), in female widely angularly rounded ( Fig. 49 ).

Legs: Protibia longitudinally sulcate on upper surface. Profemur with usually four, occasionally three or five, setae on anterio-ventral margin. Tarsi short, metatarsus noticeably shorter than HWmin, with metatarsomeres (particularly 2–4) markedly widened posteriad, metatarsomere 1 approximately as long as metatarsomeres 2+3. Tarsomere 5 with two pairs of ventro-lateral setae. In male, pro- and mesotarsi only slightly widened.

Female genitalia: Laterotergite (hemisternite) symmetrical, with two or three thick setae apically. Basal stylomere with one preapical spine on external margin. Apical stylomere moderately curved, with a peg-like spine at both ventral and dorsal edges of outer margin.

Male genitalia: Median lobe of aedeagus ( Figs 50–52 ) in lateral view arcuate, C-shaped, more strongly bent ventrad just after basal bulb, with almost straight, slightly convex middle portion of ventral margin and with apex curved ventrad; in dorsal view almost straight, comparatively strongly narrowed to apex in distal third. Terminal lamella moderately short, acute at tip, without apical capitulum ( Fig. 50–51 ). Internal sac with spiny folded formation at middle.

Etymology. The specific name is derived from the Latin obliquus meaning “oblique” and basalis meaning “basal”, and referring to the oblique lateral portions of the basal margin of the pronotum.

Comparison. This new species is similar to T. (B.) holzschuhi and all the other preceding species in general appearance, short metepisternum, and arcuate aedeagal median lobe, but may be readily recognized by very small size [4.8–5.4 mm, equal only to that of T. (B.) parvulus sp. n.], very distinctive pronotum with basal margin wide and distinctly oblique laterally, and with lateral gutter narrow throughout, by presence of a small denticle in humerus and a longitudinal sulcus on dorsal side of protibia, and by absence of apical capitulum in the median lobe of the aedeagus ( Figs 50–51 ). In the latter character T. (B.) obliquebasalis sp. n. is dissimilar to all the other brachypterous Himalayan species of Bottchrus , the median lobe of which has more or less developed apical capitulum. This new species is also distinct in very shiny dorsum without microsculpture, in brownish yellow legs, with femora not infuscate, in comparatively narrow metepisternum (approximately as long as wide), in elytral basal edge noticeably curved at humerus, forming somewhat sharp, slightly more than right angle with lateral margin, and in comparatively coarse punctation of pronotum, with finer punctures present also at apical margin.

Distribution ( Fig. 151 , 6 ). Western Solu Khumbu mountain range of eastern Central Nepal, Dolakha District. Up to today only known from the Khimti Khola Valley and the upper Tama Koshi Valley at altitudes of approximately 1400–1700 m (based on field notices of J.S., in the upper Tama Koshi river gorge the specimens were sifted from accumulations of dead plants at an altitude of 1400 m).

Figures

FIGURE 151. Distribution of the Himalayan species of Trichotichnus subgenus Bottchrus. 1, T. holzschuhi Kirschenhofer, 1992; 2, T. baglungensis sp. n.; 3, T. parvulus sp. n.; 4, T. bubsaensis sp. n.; 5, T. schawalleri sp. n.; 6, T. obliquebasalis sp. n.; 7, T. panchhaseensis sp. n.; 8, T. siklesensis sp. n.; 9, T. pusillus sp. n.; 10, T. ganeshensis sp. n.; 11, T. minutus sp. n.; 12, T. cyanescens Ito, 1998; 13, T. martensi sp. n.; 14, T. opacus Ito, 1998.

FIGURES 38 – 41. Himalayan species of Trichotichnus subgenus Bottchrus, photographs of habitus. 38, T. schawalleri sp. n., holotype; 39, T. obliquebasalis sp. n., paratype, male; 40, T. siklesensis sp. n., paratype, male; 41, T. panchhaseensis sp. n., paratype, male.

FIGURES 47 – 52. Trichotichnus (Bottchrus) obliquebasalis sp. n. (47 – 49, paratypes; 50 – 52, holotype). 47, left metepisternum; 48, apex of last (VII) abdominal sternite, male; 49, same, female; 50, 52, median lobe of aedeagus; 51, apex of aedeagus. 47 – 49, ventral view; 50, lateral view; 51, caudal view; 52, dorsal view. Scale bars = 0.25 mm (A: Figs 47 – 50, 52; B: Fig. 51).

FIGURES 5 – 13. Trichotichnus (Bottchrus) holzschuhi Kirschenhofer, 1992 (5 – 7, paratype; 8 – 13, specimens from Sete). 5, terminal lamella of aedeagus; 6 – 8, 11, median lobe of aedeagus; 9, apical capitulum; 10, left metepisternum; 12, apex of last (VII) abdominal sternite, male; 13, same, female. 5, 7, 8, dorsal view; 6, 11, lateral view; 9, caudal view; 10, 12, 13, ventral view. Scale bars = 0.25 mm (A: Figs 5 – 8, 10 – 13; B: Fig. 9).