Trichotichnus (Bottchrus) sikkimensis, 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 : 341-344

Trichotichnus (Bottchrus) sikkimensis sp. n.

( Figs 120 , 124–129 , 152 , 5 )

Type material. Holotype: ♂, “W-Sikkim, Pelling near Gezing [Geyzing], 1900 m 17/ 18.5.98, leg. Ahrens & Fabrizi” (cJS).

Description (male). Habitus as in Fig. 120 . Comparatively robust and convex. Body length 6.8 mm, width 3.0 mm.

Colour: Body black piceous, shiny on dorsum, with light coppery tinge on pronotum and elytra; labrum, very narrow margins of pronotum and apical portion of elytral margins paler, reddish brown; palpi, antennae and legs brownish yellow, femora not infuscate.

Head: Large, with wide neck (HWmax/PWmax = 0.66; HWmin/PWmax = 0.53). Eyes convex (HWmax/ HWmin = 1.26), somewhat wide oval in lateral view. Tempora about half as long as eye, slightly convex, somewhat abrupt to neck. Genae wide, about 1.7 as wide as width of antennomere 1, with few short setae. Lateral margin of head between antenna and eye 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 of 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 and membranose base of labrum visible; clypeus moderately convex basally, flatly sloped to apex, with one setigerous pore at each apical angle. Frons and vertex convex. Mentum and submentum ( Fig. 124 ) separated by thin suture, submentum on each side with one long seta and one short seta laterally of long seta. Left mandible not truncate, slightly blunted at apex. Dorsal microsculpture almost not developed; indistinct, strongly obliterate meshes visible only laterally behind eyes. Antennae comparatively slender, slightly surpassing basal edge of pronotum, with antennomeres 4–8 markedly longer than wide.

Pronotum: Moderately transverse (PWmax/PL = 1.41), widest slightly before the end of anterior third, moderately narrowed posteriad (PWmax/PWmin = 1.17), with one lateral seta inserted markedly before widest point. Sides largely rounded, slightly sinuate near basal angles. Apical margin slightly emarginate, bordered throughout, very finely at middle. Apical angles rounded, slightly protruded anteriad. Basal margin very broadly rounded, bordered almost throughout, distinct laterally and vaguely in middle third, noticeably longer than apical margin and slightly shorter than base of elytra between humeral angles. Basal angles obtuse, sharp at apex, subdenticulate. Pronotal disc convex, strongly sloped to apical angles and moderately so to basal ones, not depressed medio-basally, but with very small latero-basal depression at basal angles. Lateral gutter very narrow basally, slightly widened in apical half. Median line very fine, superficial, crenulate, ended markedly before apical and basal margins. Basal foveae distinct, rounded, slightly deepened. Surface very finely and irregularly punctate along base and in latero-basal area; also with very fine micropunctures at apical margin medially. Dorsal microsculpture evident throughout, consisting of fine transverse meshes.

Elytra: In lateral and caudal view convex, in dorsal view oval, moderately wide (EL/EW = 1.33; EL/PL = 2.31; EW/PWmax = 1.24), widest slightly behind middle, with somewhat acute apex. Humeri prominent, angularly rounded at tip, without denticle. Subapical sinuation week but distinct. Sutural angle acute, slightly blunted at tip. Basal edge slightly sinuate laterally, forming a very obtuse angle with lateral margin. Striae smooth, almost superficial, only slightly impressed, striae 6–8 slightly deeper apically. Parascutellar setigerous pore present, large. Parascutellar striole as long as or slightly longer than distance from parascutellar pore to suture, with apex free. Intervals subconvex along entire length and only slightly narrowed posteriad. Interval 3 with a discal setigerous pore at stria 2 behind middle. Marginal umbilicate series widely interrupted at middle, with 7–8 pores in anterior group and 8 pores in posterior group. Microsculpture hardly visible on two lateral intervals, consisting of obliterate thin lines.

Hindwings: Reduced to tiny scales.

Ventral surface: Prosternum and metasternum finely pubescent. Metepisternum ( Fig. 125 ) almost as long as wide, strongly narrowed posteriad. Last visible (VII) abdominal sternite (in male) subtruncate at apex ( Fig. 126 ).

Legs: Protibia with very thin, indistinct longitudinal sulcus in basal quarter. Profemur with six setae on anterioventral margin. Tarsi short, metatarsus noticeably shorter than HWmin, with metatarsomeres (particularly 2–4) moderately widened posteriad, metatarsomere 1 approximately as long as metatarsomeres 2+3. Tarsomere 5 with two pairs of ventro-lateral setae. Pro- and mesotarsi (of male) weakly widened.

Male genitalia: Median lobe of aedeagus ( Figs 127–129 ) relatively large, in lateral view nearly S-shaped, with convex ventral margin in apical half; in dorsal view median lobe almost straight, evenly narrowed to apex in distal half. Terminal lamella in dorsal view short and narrow, with sides converging apicad. Apical capitulum in lateral view ( Fig. 127 ) somewhat transverse, much more prominent ventrally than dorsally, in caudal view ( Fig. 128 ) oval, with acute apex. Internal sac with a group of small spines behind middle.

Etymology. The specific name refers to the Indian state Sikkim where the single specimen of this new species was found.

Comparison. This new species is very similar to T. (B.) loebli from Darjeeling District, India, in size, external morphology, and particularly in male genitalia. Based on the original description (Ito 1 998), the latter species differs in shorter antennae, not reaching pronotal basal edge, pronotum with sides almost straightly converging basad, not sinuate, and with basal angles angularly rounded at tip, pronotal microsculpture not evident, and aedeagal median lobe more markedly curved at middle; its apical capitulum in lateral view more strongly rounded along distal margin and with markedly projecting dorsal flange. Trichotichnus (B.) cyanescens is distinguished from T. (B.) sikkimensis sp. n. in having mentum and submentum fused laterally and separated by suture medially, elytra with fine, obliterate microsculpture on disc, and median lobe of aedeagus more strongly sinuate and hooked at apex ( Figs 117–119 ).

Distribution ( Fig. 152 , 5 ). Known only from Pelling near Geyzing (Gyalshing), West Sikkim, India, at altitude of approximately 1900 m.

Figures

FIGURE 152. Distribution of the Himalayan species of Trichotichnus subgenus Bottchrus. 1, T. gupchiensis sp. n.; 2, T. brancuccii sp. n.; 3, T. manasluensis sp. n.; 4, T. loebli Ito, 1998; 5, T. sikkimensis sp. n.; 6, T. hingstoni Andrewes, 1930.

FIGURES 120 – 123. Himalayan species of Trichotichnus subgenus Bottchrus, photographs of habitus. 120, T. sikkimensis sp. n., holotype; 121, T. martensi sp. n., holotype; 122, T. hingstoni Andrewes, 1930, male from Kechu Pheri Lake; 123, T. birmanicus Bates, 1892, male from the Kali Gandaki, Tatopani.

FIGURES 124 – 129. Trichotichnus (Bottchrus) sikkimensis sp. n. (holotype). 124, mentum and submentum; 125, left metepisternum; 126, apex of last (VII) abdominal sternite, male; 127, 129, median lobe of aedeagus; 128, apical capitulum. 124 – 126, ventral view; 127, lateral view; 128, caudal view; 129, dorsal view. Scale bars = 0.25 mm (A: Figs 124 – 127, 129; B: Fig. 128).

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).

FIGURES 115 – 119. Trichotichnus (Bottchrus) cyanescens Ito, 1998 (specimen from Dhabeli). 115, left metepisternum; 116, apex of last (VII) abdominal sternite, male; 117, 119, median lobe of aedeagus; 118, apical capitulum. 115 – 116, ventral view; 117, lateral view; 118, caudal view; 119, dorsal view. Scale bars = 0.25 mm (A: Figs 115 – 117, 119; B: Fig. 118).