Cercyon (Cercyon) kabaki Ryndevich, 2004

Ryndevich, Sergey K., Jia, Fenglong & Fikáček, Martin, 2017, A review of the Asian species of the Cercyon unipunctatus group (Coleoptera: Hydrophilidae: Sphaeridiinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 57 (2), pp. 535-576 : 545-547

Cercyon (Cercyon) kabaki Ryndevich, 2004

( Figs 4 , 13 )

Cercyon kabaki Ryndevich, 2004a: 59 .

Type locality. China, Sichuan, Qunlaishan Mts., 2700–3000 m a.s.l. [GPS ca. 31.38°N 103.071°E].

Type material examined: HOLOTYPE: ♂, ( ZISP): ‘ CH. Sichuan, Qunlaishan, Mt. R. , WSW of Lixian, W of Mt. “5892”, 2700–3000 m, 10.7.2000, leg. Kabak, Belousov, Davidian’.

Additional examined material. CHINA: SICHUAN: 1 spec. ( CSR): 2.1 km N of Dehgsheng, SE of Balanguan Pass, 3425 m, 30º53’03’’N 102º58’23’’E, 29.viii.2004, Belousov & Kabak leg.; 28 spec. ( NMPC, CSR, KMNH, SYSU, BMNH): Emeishan Mt., Taiziping Temple, mixed forest with Abies and bamboo undergrowth, leaf litter sifting, 2820 m, 29°31’50’’N 103°19’36’’E, 8.vi.2014, J. Hájek & J. Růžička lgt.; 1 spec. ( NMPC): Emeishan Mt., Golden Summit, mixed forest with Abies , Sorbus and bamboo undergrowth, leaf litter sifting, 3030 m, 29°31’23”N 103°20’05”E, 10.vi.2014, J. Hájek & J. Růžička lgt.; 1 spec. ( NMPC): Moxi env., Hailuogou valley, side valley above Cableway station, mixed forest with Betula , Sorbus , Rhododendron and broadleaf trees on steep slope, leaf litter sifting, 3140 m, 29°34’23ʺN 101°59’19’’E, 18–21.vi.2014, J. Hájek & J. Růžička lgt.; 3 spec. ( NMPC): Emeishan Mt., Jieyingdian Temple, forest above temple, secondary mixed forest, leaf litter sifting, 2420 m, 29°32’17’’N 103°19’59’’E, 10.vi.2014, J. Hájek & J. Růžička lgt; 1 spec. ( NMPC): Wolong National Nature Reserve, Namasi vill., side valley above small water dam, shrubs in closed stream valley at base of rocks, baited pitfall trap (fish meat), 2144 m, 31°01’28’’N 103°09’40’’E, 23–25.v.2014, J. Hájek & J. Růžička lgt.

Diagnosis. Head black with yellow anterior margin of clypeus; pronotum black with narrowly yellowish lateral margin; elytra yellow with characteristic dark pattern in pale specimens, dark specimens with elytra more less black with paler spots on base and midlength of intervals 2–3, pale humeral spot and pale elytral apex; maxillary palpi yellow; elytra and pronotum without hairs, elytral intervals flat; mesoventral plate narrowly elongate, ca. 5.4× as long as wide; metaventrite without femoral lines; fifth ventrite not emarginate apically; sternite 9 with rounded base; median lobe widest near middle and base, narrowing apically, with long narrowly rounded apex; gonopore minute, subapical.

Description. Form and color. Body elongate oval ( Fig. 4A ), length 2.1–2.3 mm, width 1.2–1.3 mm. Head black with very small yellow preocular spots and yellow anterior margin of clypeus, pronotum black with lateral margins and anterior side of pronotum narrowly pale (yellow or brownish-yellow), base of pronotum paler near posterolateral angles. Scutellum black. Elytra yellow with black and dark brown spots, forming a characteristic pattern (large lobate central spot, anterior part of intervals 4–7 and nearly complete sublateral intervals darkened), dark specimens with elytra dark brown to black with weakly delimited paler spots on base and midlength of intervals 2–3, pale humeral spot and pale elytral apex. Epipleuron yellow or brownish. Antennae yellowish except for darker club. Maxillary palpomeres yellow. Ventral surface black, prosternum and mesoventral plate brown, posterior margins of abdominal ventrites yellowish-brown or brown. Metaventral pentagon black or dark brown. Legs brown, tarsi yellowish-brown.

Head. Clypeus with dense, moderately coarse punctures, interstices without microsculpture. Anterior margin of clypeus with narrow bead. Frontoclypeal suture undetectable. Frons without microsculpture on interstices. Eyes small, somewhat protruding, interocular distance 8.0–8.5× the width of one eye in dorsal view. Mentum glabrous, ca. 1.6–1.7× as wide as long, densely and coarsely punctate. Antennae with 9 antennomeres, scapus ca. 1.3× as long as antennomeres 2–5 combined, club compact. Maxillary palpomere 2 strongly swollen, palpomere 4 almost symmetrical, equal to palpomere 3 in length.

Thorax. Elytra and pronotum without hairs. Pronotum ca. 2.3–2.4× as wide as long. Pronotal punctation similar to that on head. Lateral margins of pronotum with narrow bead overlapping anterior and posterior corners, anterior and central part of posterior margins without bead. Prosternum with strong longitudinal carina medially; antennal groove distinct, moderately large, rounded laterally. Mesoventral plate narrowly elongate, ca. 5.4× as long as wide, widest at midlength ( Fig. 4G ). Metaventrite with raised, glabrous, sparsely punctate median pentagonal area; femoral lines absent. Elytra with ten punctate striae, striae 1–9 impressed and reaching base, stria 10 very short. Elytral intervals flat, central part of intervals slightly convex; ground punctures on intervals very fine. Humeral bulge not distinct. Epipleuron flat, horizontal. Femora with sparse and shallow punctures ventrally, with distinct tibial groove. Tarsi with densely arranged white setae ventrally, first metatarsomere about as long as metatarsomeres 2–3 combined.

Abdomen. Abdomen with five ventrites, first ventrite distinctly longer than other ventrites, ca. 1.7× as long as second ventrite, bearing distinct median longitudinal carina, fifth ventrite not emarginate apically.

Male genitalia ( Figs 4C–E ). Phallobase slightly shorter than parameres, asymmetrical basally. Paramere slightly narrowed subapically, almost straight on outer margin, widely rounded apically, apex membranous, apex and inner edge with very short setae subapically. Median lobe narrow, nearly parallel-sided except apical fifth forming very long gradually narrowing apex, basal ароdemes short, apex pointed; gonopore small, situated subapically. Median projection of sternite 9 evenly cut apically, bearing 4 short subapical setae, median portion shorter than lateral struts, base rounded.

Variation. Despite the small number of specimens known, the species seems quite variable in dorsal coloration: the holotype and the additional specimen from Dehgsheng bear a characteristic pattern with very sharply defined yellow-black patterning, whereas all specimens collected in Emeishan Mts. and around Moxi in 2014 are darker, with nearly completely dark elytra with paler (reddish) more vaguely defined spots and a brownish sutural interval. The male genitalia of the dark specimens agree completely with that of the holotype.

Biology. Most known specimens were sifted from litter of mixed forests with Abies , Rhododendron , Sorbus and bamboo, few were also collected in baited pitfall traps in the same habitat.

Distribution. The species is endemic to the mountains in central Sichuan, in altitudes between 2400 and 3500 m.

Figures

Fig. 4. Cercyon kabaki Ryndevich, 2004. A–B – dorsal and lateral habitus (A – pale form from China: Sichuan: north of Dehgsheng; B – dark form from China: Sichuan: Taizping Temple); C–E – male genitalia (C – tegmen; D – median lobe; E – sternite 9); F – meso- and metaventrite; G – detail of mesoventral plate.

Fig. 13. Known distribution of the species of C. unipunctatus species group in Asia.