Chrysolina (Pleurosticha) borisi, Bieńkowski, 2023

Bieńkowski, A. O., 2023, Two new species of the subgenus Pleurosticha of the genus Chrysolina (Coleoptera: Chrysomelidae) from the mountains of southern Siberia (Altai and Tyva), Zoosystematica Rossica (China) 32 (1), pp. 75-84 : 79-83

Chrysolina (Pleurosticha) borisi sp. nov.

( Figs 6–8, 25–30)

Holotype. Male, Russia, Republic of Tyva, Western Tannu-Ola Ridge, upper reaches of Kady River , mountain tundra, 2.VIII.1979, B.A. Korotyaev leg. ( ZIN).

Paratype. Female, with same labels ( ZIN) .

Description. Holotype (male). Body 6.3 mm long, 3.7 mm wide, elongate oval, 1.7 times as long as wide, convex; elytron 2.5 times as long as high. Body dorsally sericeous shining because of distinct microreticulation, black with bronze reflection ( Figs 25, 26), antennae piceous with antennomeres 1 and 2 rufous ventrally, mouth parts, femora, tibiae, and underside black with bronze reflection, tarsi piceous.

Last maxillary palpomere broadly oval,obliquely truncate, 1.3 times as long as wide, 1.2 times as wide as previous palpomere and 1.5 times as long as latter. Antenna inserted 2.0 times as close to clypeus as to eye.

Pronotum ( Fig. 28) 1.9 times as wide as long (length measured from anterior to posterior bor- der along middle), with maximum width just before base, roundly narrowed anteriorly, with anterior and posterior angles more than 90 °, slightly rounded. Pronotal lateral calli convex, narrow, 0.1 times as wide as pronotal width (in dorsal view), separated from disc by deep narrow furrow in basal half and by narrow, shallow, gently sloping impression with wrinkled punctures in anterior half. Pronotal disc and lateral calli covered by distinct microreticulation (cells rounded) and micropunctules (diameter about 0.02 mm). Pronotum entirely marginated and ciliate anteriorly. Anterior setiferous pore of pronotum absent.

Prothoracic hypomeron weakly convex, with irregular wrinkles laterally; basal fold wide and deep. Prosternal intercoxal process convex, wrinkled. Metasternum entirely marginated anteriorly.

Two elytra combined 1.3 times as long as wide; elytral base as wide as pronotal base. Elytron with obsolete humeral callus, without scutellar puncture row, with ten rows of dense, moderately large punctures (diameter 0.05 mm); rows distinct up to apex. Puncture rows regular, slightly wavy here and there. Sutural interval as wide as second interval. Intervals slightly convex, covered by numerous punctures as large as those on pronotal disc. Elytral microreticulation and micropuncturation similar to those on pronotum. Elytral epipleuron inclined outside, visible along entire length in lateral view, densely ciliate apically. Hind wings strongly reduced, as long as metathorax.

Tarsomeres 1–3 very broad, with entire sole. In fore tarsi, first tarsomere as wide as third and 1.2 times as wide as second. Claw tarsomere without denticles beneath.

Pygidium without distinct longitudinal medi- an impression. Last abdominal sternite with high transverse tubercle in basal third and with distinct impression in apical third ( Fig. 27).

Aedeagus ( Figs 6–8, 29, 30) flattened dorsoventrally, curved in lateral view, constricted laterally at level of alae; dorsal side with shallow impression before alae, laterobasal border of membranous part not visible in lateral view; lateral side of aedeagus at attachment place of alae drawn towards base and forming a narrow long protrusion; alae narrow, directed basally; apex of aedeagus slightly bent ventrally; flagellum absent.

Variability. Paratype (female) 7.2 mm long, 4.4 mm wide. Elytral rows 6 and 7 irregular in basal half. Tarsomeres 1–3 narrow, with entire sole beneath. Last abdominal sternite evenly convex.

Comparison. A combination of such features as a convex body and its small size, black coloration of the dorsal side, femora and tibiae, regular puncture rows of the elytra, with slightly convex intervals, clearly distinguishes the new species from other members of the subgenus Pleurosticha . The unique feature of the new species is the shape of the lateral side of the aedeagus at the place of attachment of the alae: it is drawn towards base and forms a narrow long protrusion ( Figs 7, 8, 29, 30). No other known species of the subgenus Pleurosticha has such a protrusion.

Etymology. The new species is named after Boris A. Korotyaev (ZIN, St Petersburg), a well-known Russian entomologist who collected the type specimens of the new species during an expedition to Tyva.

Distribution. Russia, Tyva: Western Tannu-Ola Ridge.

Habitat. According to the personal communication by B.A. Korotyaev, the type locality is a steep grassy slope at about 2500 m a.s.l., a mountain meadow steppe with a dense cover of cereal grasses and possibly sedges.