Leptoplectus perperus Kurbatov, 2022

Kurbatov, S. A., 2022, Notes on Pselaphinae (Coleoptera: Staphylinidae) of the Sakhalin Region, Russia, Russian Entomological Journal 31 (1), pp. 36-41 : 40-41

Leptoplectus perperus Kurbatov , sp.n.

Fig. 27 .

MATERIAL. Holotype ♂: SW Sakhalin, 7 km NNE of Nevelsk, near Yasnomorskoye , rotten Betula , 18.07.2021, S. Kurbatov ( ZIN). Paratypes: 1♂, SW Sakhalin, 15 km East of Kholmsk , 47°02´16.7´´N 142°12´09.6´´E, rotten Betula , 17.07.2021, S. Kurbatov ; 1♂, SE Sakhalin, 25 km East of Yuzhno-Sakhalinsk, near Lesnoye , rotten Betula , 27.07.2021, S. Kurbatov ; 1♂, S Sakhalin, near Yuzhno-Sakhalinsk, the foothills of Mount Chekhov , rotten Betula , 17.07.2011, S. Kurbatov ; 1♂, SW Kunashir Is., cordon Ivanovsky , rotten Abies , 20.07.1989, S. Kurbatov ; 1♂, SW Kunashir Is., near Mendeleevo , rotten Alnus , 29.06.1991, S. Kurbatov ; 2♂, SW Kunashir Is., near Mendeleevo , rotten Alnus , 04.07.1991, S. Kurbatov ; 2♂, SW Kunashir Is., cordon Ozerny , rotten Betula , 26.07. and 27.07.2011, S. Kurbatov ; 1♂, SW Kunashir Is., cordon Ozerny , rotten Phellodendron , 27.07.2011, S. Kurbatov ; 1♂, NE Kunashir, lower course of Saratovka River, F.I.T., 12– 18.07.2014, Yu. Sundukov ( ZIN, ZMUM, MHNG, PCSK) .

DESCRIPTION. Body 1.15–1.30 mm long, yellowish brown (elytra sometimes darker), in fine decumbent pubescence.

Head (0.17–0.19/ 0.24–0.26 mm) entirely in dense fine punctation. Occipital impression long and narrow. Distance between vertexal foveae less than twice the diameter of the individual fovea and approximately equal to the distance between edge of the fovea and lateral edge of the head. Frontal sulcus with lateral branches short, not reaching the transversal branch; the latter with weak medial longitudinal elevation. Antennae short, longer than wide (seems to be wider than long when appended to the head); antennomere 2 as long as wide or slightly longer, as wide as 1; antennomeres 3–8 as wide as long or slightly wider, much narrower than 2, antennomeres 5 and 7 hardly larger than neighboring segments; antennomere 9 transverse, distinctly wider than 8; antennomere 10 transverse, wider than 9; antennomere 11 a little wider than 10, elongated, as long as 7–10 combined.

Pronotum (0.21–0.23/ 0.22–0.24 mm) narrower than head, with the same punctation. Elytra (0.33–0.34/ 0.30–0.31 mm) less distinctly punctated than pronotum. Abdominal tergites 1–2 (IV–V) each with pair of longitudinal basal carinae; carinae of tergite 1 about 3/4 the length of the tergite, carinae of tergite 2 about 2/3 the length of the segment.

6 (VIII) sternite of male with point-shaped medial impression.

Aedeagus ( Fig. 27 ) 0.16–0.18 mm long. There are specimens with both normal and inverted aedeagus, and the variability of its apical lobe is much less than that in the previous species.

COMMENTS. The new species is very close to L.spinolae (Aubé, 1844) . Despite some difference (poorly formalized) in the structure of the upper part of the head the new species differs reliably from the latter only in the structure of the apical lobe of the aedeagus, which in addition to the long spike (as in L. spinolae ) has an additional long acute denticle on the other side of the apical lobe ( Figs 27–28 ). There is a surprising coincidence here. The image of the aedeagus of L. spinolae in “Die Käfer Mitteleuropas” [ Besuchet, 1974: 323] also shows a minute denticle on the same spot of the apical lobe. When the author examined the collection of MHNG, among the males of L. spinolae was found exactly the specimen whose aedeagus is depicted in “Die Käfer Mitteleuropas”. It turned out that the aedeagus preparation had the inclusion of a fine dust particle, which gave an optical distortion, giving the impression of a denticle. In fact, there is no any denticle. Examination of other males of this species also revealed the absence of a denticle in this location.

The above difference between the two species seems relatively insignificant. However, on the one hand, it is stable and there is not even a hint of the existence of transitional forms. One species is distributed in Western Europe, the other occurs only in the insular part of the Far East (Sakhalin and Kunashir). In addition, the significance of this difference is indicated by another Far Eastern species Leptoplectus falcifer Kurbatov, 1992 , which is very close to the two compared species. The male of this species has a characteristic peculiar modification of the frontal sulcus, which immediately allows to recognize this species. Its aedeagus is very similar to that of the two compared species, having a slight difference in the structure of the same part of the apical lobe of the aedeagus ( Fig. 29 ).

Figures

Figs 27–39. Details of the Leptoplectus spp: 27 — L. perperus sp.n.; 28 — L. spinolae; 29 — L. falcifer; 30, 32–39 — L. similis; 31 — L. illex; 27–31 — aedeagi; 32–39 — variability of the apical lobe of the aedeagus (32 — Vladivostok, S Primorye; 33 — Kholmsk, Sakhalin Isl.; 34 — Venevitinovo, S Primorye; 35–37, 39 — Nevelsk, Sakhalin Isl.; 38 — Mendeleevo, Kunashir Isl.). Рис. 27–39. Детали строениЯ Leptoplectus spp: 27 — L. perperus sp.n.; 28 — L. spinolae; 29 — L. falcifer; 30, 32–39 — L. similis; 31 — L. illex; 27–31 — Эдеагус; 32–39 — иЗменчивость вершинной доли Эдеагуса (32 — Владивосток, Ю Приморье; 33 — Холмск, о. Сахалин; 34 — Веневитиново, Ю Приморье; 35–37, 39 — Невельск, о. Сахалин; 38 — Менделеево, о. Кунашир).