Cercyon (Cercyon) verus Shatrovskiy, 1989

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 : 563-565

Cercyon (Cercyon) verus Shatrovskiy, 1989

( Figs 10 , 12 , 13 )

Cercyon (Cercyon) verus Shatrovskiy, 1989: 282 .

Cercyon (Cercyon) verus: SHATROVSKIY (1992) : 364 (detailed redescription).

Type locality. Russia, Far East, Kuril Islands, Kunashir.

Type material examined. PARATYPES: 1 spec. ( ZISP):‘ O. Kunasir, bl. Mendeleevo, 22.VI.1985, Nikitskiy [in Russian] ’; 1 spec. ( ZISP): ‘Novoaleksandrovsk, Yuzh. Sakhalin, leg. Kerzhner, 7.IX.1973 [in Russian] ’.

Additional material examined. RUSSIA: KEMEROVO OBLAST: 1 spec. ( CSR): W Siberia, Kemerovo reg., Lipovyy ostrov, 17.vii.1994, leg. A.B. Ryvkin ,. SAKHALIN OBLAST: 1 spec. ( CSR): 15 km Yu Sernovodsk, Kunashir , [Kunashir Is., 15 km S of Sernovodsk], 7.vi. [19]93, Kerzhner leg. ; 4 spec. ( CAP): Kunashir Is., Yu.V. oz. Peschanoe [southwest of Peschanoe Lake], 8.vii.2008, Makarov leg. ; 1 spec. ( MPU): Kunashir isl., sea foreland Ivanovskiy , 18–21.ix.2014, Yu. Sundukov leg. ; 2 spec. ( CSR): Kunashir isl., lower reaches of river Saratovka , 14–15.vii.2014, Yu. Sundukov & L. Sundukova leg. ; 4 spec. ( MPU, CSR): same data but 10–16.vii.2014 ; 22 spec. ( MPU, CSR): same data but 12–18.vii.2014 ; 2 spec. ( MPU): same data but 14–15.vii.2014 ; 1 spec. ( CSR): Kunashir Is., volcanic caldera near Goryachee lake, 14–17.vii.2015, Yu . Sundukov & L. Sundukova leg. ; 1 spec. ( MPU): Kunashir Is., foreland Ivanovskiy , 2 km S of Grozovoe, 2.vi.2015, Yu. Sundukov leg. ; 1 spec. ( CSR): Kunashir Is., volcanic caldera near Goryachee lake, 14–17.vii.2015, Yu . Sundukov & L. Sundukova leg. ; 1 spec. ( MPU): Kunashir Is., foreland Ivanovskiy , 2 km S of Grozovoe, 2.vi.2015, Yu. Sundukov leg. ; 3 spec. ( MPU, CSR): Kunashir isl., near cordon Saratovskiy, 2–4.vii.2014, Yu . Sundukov & L. Sundukova leg. ; 2 spec. ( NMPC): Urup Is., 46º01.29’N 149º51.67’E, Rybnaya River, Smugly Bay , under leaves of Petasites japonica , hand collecting, 24.viii.1995, M. Ôhara leg. (UR95MO055) ; 1 spec. ( NMPC): Urup Is., 46º12.84’N – 150º12.89’E, Novo-Kurylsk bay, near mouth of Bystraya River , 8.viii.1995, cow dung, hand collected, M. Ôhara leg. (UR95MO-8) ; 2 spec. ( NMPC): Simushir Is., 46º51.36’N – 151º47.19’E, hills near the shore at Kitoboynaya Bay , feces of pig, 11.viii.1995, M. Ôhara leg. (SI95MO011) .

Published records. RUSSIA: SAKHALIN OBLAST: Sakhalin Is.: Novoaleskandrovsk ( SHATROVSKIY 1989, 1992); Kunashir Is.: Lagunnoe, Filatova river, klyutsh Zolotoi, Mendeleevo ( SHATROVSKIY 1989, 1992; ÔHARA & JIA 2006); Shikotan Is.: coastal shrubs of Rosa rugosa ( SHATROVSKIY 1992) ; Iturup Is.: Rubetsu [= Pioner] ( ÔHARA & JIA 2006); Urup Is. ( ÔHARA & JIA 2006); Simushir Is. ( ÔHARA & JIA 2006).

Diagnosis. Head black with very small preocular spot; pronotum black with widely reddish lateral margin; elytra reddish-yellow to brownish, with or without central dark spot; maxillary palpi yellowish, last palpomere darker; lateral part of elytra with very sparse short pale hairs; elytral intervals flat; mesoventral plate elongate, ca. 3.3–4.0× as long as wide; metaventrite without femoral lines; pentagonal area of metaventrite with coarse and dense punctation, distance between individual punctures in lateral parts ca. 1–3 diameters of puncture ( Fig. 10F ), fifth ventrite emarginate apically; median lobe widest near base, almost parallel-sided, strongly narrowing apically, lateral margins with very short setae in apically part; sternite 9 wider in apical half, bearing four short subapical setae.

Redescription. Form and color. Body elongate oval ( Figs 10A–B ), length 2.6–2.9 mm, width 1.5–1.7 mm. Head black with very small yellowish or brownish preocular spot. Pronotum black to dark brown, lateral margins widely pale (reddish), anterior margin very narrowly pale, base very narrowly pale near posterolateral angles. Scutellum dark. Elytra and epipleura reddish yellow to brownish; sutural interval of elytra in apical half dark brown or black; central part of elytra with or without darker spot. Antennae yellowish except for darker club. Maxillary palpomeres yellowish, last palpomere darker. Ventral surface dark brown to black, mesoventral plate and metaventral pentagon brown to dark brown, posterior margins of abdominal ventrites yellowish or brownish. Legs brownish-yellow to brownish.

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 ca. 6.0× the width of one eye in dorsal view. Mentum glabrous, ca. 1.6× as wide as long, densely and coarsely punctate, with clear dense transverse wrinkles ( Fig. 10I ).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. Pronotum ca. 2.2–2.5× 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 margin without bead. Prosternum with strong longitudinal carina medially; antennal groove distinct, moderately large, rounded laterally. Mesoventral plate elongate, ca. 3.3–4.0× as long as wide, widest at midlength, with almost evently convex margins. Metaventrite with raised, glabrous, sparsely punctate median pentagonal area; femoral lines absent. Pentagonal area with coarse and dense punctation, distance between individual punctures in lateral parts ca. 1–3 diameters of puncture ( Fig. 10F ). Elytra with ten punctate striae, striae 1–9 impressed and reaching base, stria 10 very short. Intervals slightly convex in medial and apical parts. Ground punctures on intervals very fine. Humeral bulge not distinct. Lateral part of elytra with very sparse, short, pale hairs. Epipleura 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 ones, ca. 2× as long as second ventrite, with distinct median longitudinal carina; fifth ventrite arcuate, not emarginate apically.

Male genitalia ( Figs 10C–E ). Phallobase slightly longer than parameres, asymmetrical basally. Paramere narrow basally, narrowly rounded apically, with slight subapical constriction, apex membranous, with setae. Median lobe widest near base, almost parallel-sided, strongly narrowing apically, with long ароdemes basally, lateral margins with very short setae in apical part, apex obtusely pointed; gonopore small, situated subapically. Median projection of sternite 9 wider in apical half, pointed apically, bearing 4 short subapical setae, base strongly rounded; median portion shorter than lateral struts.

Variation. Cercyon verus varies strongly in coloration ( Figs 12E–J ); some specimens have a totally pale sutural interval of the elytra, lack a central sutural spot, and the last palpomere of the maxillary palpi is pale yellowish.

Diagnosis from C. unipunctatus and C. quisquilius . By coloration, pale specimens of C. verus are very similar to C. quisquilius , and typically colored specimens of C. verus resemble C. unipunctatus with a weakly developed central elytral spot. Pale specimens of C. verus differ from C. quisquilius by the wider pale (reddish) lateral part of the pronotum (narrower in C. quisquilius ). Typically colored C. verus differ from pale C. unipunctatus by the more rounded body form, wider pale lateral margins of the pronotum, pentagonal area of the metaventrite with coarse and dense punctation (distance between individual punctures in lateral parts ca. 1–3× their diameters, mentum with distinct dense transverse wrinkles). In contrast, Cercyon unipunctatus has a more elongate body form, narrower pale lateral margins of the pronotum, pentagonal area of the metaventrite with shallow and sparse punctation (distance between individual punctures in lateral parts ca. 4–6 × their diameters), and the mentum with barely developed transverse wrinkles.

Biology. Coprophagous species inhabiting mammal excrements (cows, pigs). It comes to light.

Distribution. Cercyon verus is only known from Kuril Islands. A single specimen from Western Siberia is a female, but otherwise fully corresponds to the Far Eastern specimens; the occurrence in continental Far East and Siberia would however need further confirmation.

Figures

Fig. 10. Cercyon verus Shatrovskiy, 1989.A–B – dorsal and lateral habitus of specimens from Kuril Islands; C–E – male genitalia (C – tegmen; D – median lobe; E – sternite 9). F–I – ventral morphology (F – meso- and metaventrite; G – detail of mesoventral plate; H – prosternum and antennal groove; I – mentum).

Fig. 12. Variability of elytral coloration. A–D – Cercyon unipustulatus Nakane, 1982. E–J – Cercyon verus Shatrovskiy, 1989.

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