Stenus ascendor, Puthz, 2012

Puthz, V., 2012, On the Stenus LATREILLE 1797 from Taiwan with non-spotted elytra (Coleoptera, Staphylinidae) (327 Contribution to the Knowledge of Steninae), Linzer biologische Beiträge 44 (2), pp. 1431-1475 : 1432-1433

Stenus ascendor nov.sp. ( Figs 13, 15 )

Type material: Holotype () and 4 - paratypes: Taiwan: Hualien Hsien: near Juisui , 29.III.1984, Y. Shibata . Paratypes: 2: ibidem, 400m, 26.III.1980, idem ; 1: ibidem, 3.VIII.1981, idem ; 2: Taipei Hsien: Wulai , 24.-30.IV.1972, A. Yoshii. - HT and PTT in coll. Shibata (Tokyo), PTT also in cP .

Description: Black, strongly shiny, coarsely and densely punctuate, pubescence long, dense, semierect on forebody, erect on abdomen. Antennae, maxillary palpi and legs reddish yellow. Clypeus blackish, labrum brown, anterior margin lighter, both densely pubescent.

Length: 4.2-5.0mm (forebody: 2.3-2.5mm).

PM of the HT: HW: 34.5; DE: 15; PW: 22; PL: 27; EW: 31; EL: 32; SL: 25.

Male: Sternites 3 and 4 simple, sternite 5 with a shallow and short posteromedian impression with sparser punctation than laterally, sternite 6 with a distinct posteromedian impression, which is finely and sparsely punctate, posterior margin shallowly emarginate, sternite 7 shallowed along middle, finely and very densely punctate and pubescent anteriorly, much sparser posteriorly. Sternite 8 (fig. 13). Sternite 9 serrate at posterior margin. Tergite 10 very broadly rounded at smooth posterior margin. Aedeagus (fig. 15), apical portion of median lobe truncate; parameres about as long as median lobe, with about 20 apical setae, which are of different breadth.

Female: Sternite 8 at posterior margin broadly rounded. Valvifer serrate apically. Tergite 10 as in the male.

Head slightly broader than elytra, frons narrow, concave, with two shallow longitudinal furrows, median portion nearly flat; punctation moderately coarse and moderately dense, diameter of punctures about as large as basal cross section of antennal segment 3, interstices larger than half diameter of punctures, often also larger than punctures. Antennae slender, when reflexed the last two segments exceeding beyond the posterior margin of pronotum, penultimate segments 2x as long as broad. Pronotum distinctly longer than broad, sides moderately convex; no impressions; punctation coarse and very dense, diameter of punctures as large as apical cross section of antennal segment 2 or slightly larger, interstices distinctly smaller than half diameter of punctures. Elytra subquadrate, shoulders prominent, sides slightly divergent posteriad, posterior margin deeply emarginate; no impressions; punctation as on pronotum, interstices in average very slightly larger. Abdomen cylindric, basal furrow of anterior segments very deep, tergite 7 with a distinct membranous fringe apically; punctation on tergites 3-6 coarse, on the first tergites about as dense as on frons, on tergite 6 somewhat sparser; tergite 7 with the punctation anteriorly moderately fine, becoming much finer posteriad, interstices twice and more as large as punctures, tergite 10 very finely and very sparsely punctate. Legs slender, metatarsi three fifths as long as metatibiae, segment 1 slightly longer than the three following segments combined, much longer than the last segment; segment 4 deeply and broadly bilobed. The whole insect without groundsculpture.

Comparative notes: This new species belongs to the group of Stenus cylindricollis BOHEMAN ( PUTHZ 1973a: 83), in which it resembles many species. From the relatives with long erect abdominal pubescence it may be distinguished as follows: from S. angusticollis EPPELSHEIM by smaller, less coarsely punctate elytra, from S. bhutanus PUTHZ and S. cylindricollis FAUVEL by much smaller elytra and sparser punctation of frons, from S. crinitus L. BENICK furthermore by less dense abdominal punctation. Regarding the aedeagus the new species resembles strongly S. thanonensis ROUGEMONT from Thailand, but has a broader head, slightly different ventral characters of male, a median lobe with a broader apical portion and more stout setae at the parameres. From exosceletal characters also S. plagiocephalus L. BENICK (which recently was discovered on Ishigaki Island) is similar, but has a very different aedeagus (see PUTHZ 2012b) and a distinctly coarser punctate tergite 7.

Etymology: This species lives on bushes, therefore I name it " ascendor " = ascender.

Figures

Figs 1-16: Sternite 8 of male (1-8, 13, 14) and of female (9, 10), posterior portion of sternite 9 of male (11, 12), anterior portion of aedeagus (15, 16) of Stenus hirtellus SHARP (1), S. piliferus MOTSCHULSKY (2), S. perpastus nov.sp. (3, PT), S. perpinguis nov.sp. (4, PT), S. perpropinquus nov.sp. (5, PT), S. persimplex nov.sp. (6, PT), S. perturbator nov.sp. (7, PT), S. pervilis nov.sp. (8, PT), S. persculptus nov.sp. (9, PT), S. perspicabilis nov.sp. (10, PT), S. sugayai nov.sp. (11, PT), S. perodiosus nov.sp. (12, PT), S. ascendor (13, 15, PT), S. hanami HROMÁDKA (14, 16, HT). – Scale bar = 0.1mm (1= 2-10; 11=12; 13=14; 15=16).