Ramussia captiosum Kurbatov, 2022

Kurbatov, S. A., 2022, Notes on Pselaphinae (Coleoptera: Staphylinidae) of the Sakhalin Region, Russia, Russian Entomological Journal 31 (1), pp. 36-41 : 38-39

Ramussia captiosum Kurbatov , sp.n.

Figs 21–22, 26 .

MATERIAL. Holotype ♂: SW Sakhalin, 14 km East of Nevelsk , 46°44´33.8´´N 142°03´04.5´´E, rotten Picea , 22.07.2021, S. Kurbatov ( ZIN). Paratypes: 3♂ with holotype; 1 ♂, SW Sakhalin, 15 km East of Nevelsk, 46°44´37.5´´N 142°03´35.0´´E, rotten Abies , 24.07.2021, S. Kurbatov ( MHNG, ZIN, ZMUM, PCSK) .

DESCRIPTION. Body 1.35–1.4 mm long, light brown, in fairly fine, dense decumbent pubescence.

Head 0.21 mm long, 0.27–0.29 mm wide. Vertexal foveae quite large, distance between them slightly greater than distance from edge of fovea to inner edge of eye at this level. Frontal sulcus intermediate between U- and V-shaped. Anterior edge of the front angular. Eyes large, convex, their diameter in lateral view slightly longer than length of temples. Temples widely rounded. Head dorsally with some minute punctures on frontal anterior edge and on lateral edge above eyes. Antennal tubercles weakly protruding. Antennae with scape subcylindrical; pedicel 1.5 times as long as wide, hardly narrower than scape; antennomeres 3–8 subequally wide, distinctly narrower than pedicel; antennomere 3 slightly longer than wide; antennomeres 4–8 subequal, hardly wider than long, sometimes antennomere 4 as long as wide; antennomere 9 transverse, distinctly wider and hardly longer than 8; antennomere 10 transverse, more than twice as wide as long, barely longer and wider than 9; antennomere 11 more or less conical, wider than 10, longer than 8–10 combined.

Pronotum more or less as long as wide (0.29/ 0.30 mm), widest between anterior third and quarter length. Disc variable, either with thin shallow median longitudinal sulcus (in this case pronotal punctuation fine) or without sulcus (then there are several large points there). Short oblique, indistinct sulcus anteriorly from lateral fovea reaching pronotal mid-length.

Elytra (0.39–0.40/ 0.43–0.47 mm) with three basal foveae; discal stria not reaching elytral mid-length.

Male secondary sexual characters on head and legs not expressed. Sternite 6 (VIII) emarginate at apex, notch covered by penial plate (IX sternite), 0.130 mm long ( Fig. 26 ).

Aedeagus ( Figs 21–22 ) 0.230 –0.235 mm long.

COMMENTS. The new species differs from R. parabile in the proportions of the 9–10 antennomeres, which are at least twice as wide as long (less than twice as wide as long in parabile ), in the absence of pronounced secondary sexual characters on the front and legs (present in parabile ), in the shape of penial plate ( Figs 25–26 ) and of aedeagus ( Figs 19– 22 ). Another species, Ramussia camponoti ( Lea, 1912) , transferred to this genus by Chandler and unknown to us is easily distinguished by the shape of the aedeagus [see Chandler, 2001, P.217–220, Fig. 85].

Figures

Figs 15–26. Details of the Ramussia spp: 15–16, 23 — R. lovtsovae sp.n.; 17–18, 24 — R. svetlanae sp.n.; 19–20, 25 — R. parabile; 21–22, 26 — R. captiosum sp.n.; 15–22 — aedeagi, dorsally and laterally; 23–26 — IX sternite. Рис. 15–26. Детали строениЯ Ramussia spp: 15–16, 23 — R. lovtsovae sp.n.; 17–18, 24 — R. svetlanae sp.n.; 19–20, 25 — R. parabile; 21–22, 26 — R. captiosum sp.n.; 15–22 — Эдеагусы, дорсально и латерально; 23–26 — IX стернит.