Nipponocercyon sichuanicus (Ryndevich, 2005) Ryndevich, 2005

Fikacek, Martin, Ryndevich, Sergey & Jia, Fenglong, 2012, An aberrant species of Nipponocercyon from Sichuan, China (Coleoptera, Hydrophilidae, Sphaeridiinae), ZooKeys 214, pp. 13-27 : 17-21

Nipponocercyon sichuanicus (Ryndevich, 2005) comb. n. Figs 1 –47–1219–2123– 24

Cryptopleurum sichuanicum Ryndevich, 2005: 244

Cryptopleurum sichuanicum : Short and Hebauer (2006: 348, catalogue).

Type material examined.

Paratype: 1 female (CSR): 'CH, S Sichuan, near / Bijishan Village, left / tr. of Lianhegou River / 2500-3200 m, 19.6.2000 / Belousov, Kabak, Davidian // Paratype / Cryptopleurum / sichuanicum / Ryndevich S. K. // Coll. / SKR // Cryptopleurum / sp.n. / det HEBAUER'.

Additional material examined.

CHINA: Sichuan: 2 males, 1 spec. (CSR, NMPC): 2.1 km N of Dengsheng, SE of Balanguan Pass, elev. 3455 m, 30°53'3"N, 102°58'23"E, 29.viii.2004, lgt. Belousov & Kabak; 1 spec. (NHMW): 20 km N Sabdȇ, elev. 3300 m, 29°35'N, 102°23'E, 14.vii.1998, lgt. A. Smetana (C82); 1 spec. (CSR): S of Musu village, elev. 2850 m, 31°56'53"N, 103°15'11"E, 19.viii.2007, lgt. Belousov & Kabak; 1 male (NMPC): N Sichuan, SW of Baima, elev. 2980-3040 m [ca. 27°55'N, 101°56'E], 23.vi.2006, lgt. I. Kabak; 5 spec. (CSR, NMPC, SYSU, KSEM): SW of Jiabi, elev. 3240 m, 31°30'40"N, 102°43'43"E, 8-13.viii.2007, lgt. Belousov & Kabak; 1 male, 3 spec. (NHMW, NMPC): Ganzi, Daxue Shan, Mugecuo, ca. 26 km NW Kangding, elev. 3200-3400 m, 30°06'36"N, 101°31'12"E, 21.v.1997, lgt. A. Pütz.

Redescription.

Body widely oval, widest in anterior third of elytra. Body length 2.2-2.9 mm, body width 1.4-1.7 mm.

General coloration of dorsal surface dark brown, anterior and anterolateral margins of clypeus and lateral portions of frontoclypeal suture pale reddish, anterior margin of pronotum widely reddish, each elytron slightly paler in humeral area and at elytral apex. Ventral surface dark brown, mentum, mouthparts and posterior portions of temporae reddish brown. Maxillary palpi, antennae and legs pale reddish brown.

Head. Clypeus widely rounded, constricted above antennal bases, with very distinct marginal bead. Dorsal surface of clypeus and frons with strong scale-like microsculpture obscuring the punctation, sparsely arranged punctures not apparent among microsculpture, only evident according to long thin setae arising from punctures. Frontoclypeal suture apparent as a non-sculptured stripe directing mesad, strongly bent posteriad submesally. Mentum with sparsely arranged fine setiferous punctures medially and posteriorly, interstices with strong scale-like microsculpture. Antennal club without distinct groups of peg-like sensilla dorsally or ventrally. Maxilla of male without sucking disc ventrally.

Prothorax. Pronotum with sparsely arranged fine setiferous punctures, larger punctures along posterior margin absent. Whole dorsal surface with mesh-like microsculpture, microsculpture strong along anterior and posterior margins and on lateral portions of pronotum, obsolete on pronotal disc; pronotal disc with irregular longitudinal striae. Lateral portions of pronotum slightly deflexed (and hence seen in ventral view). Prosternum with well defined median plate 2.0 × wider than long, bearing strong rugose sculpture, indistinctly carinate mesally. Anterolateral corners of prosternum (at contact with hypomeron) with small but distinct tooth. Antennal grooves large, but not quite reaching lateral margin of hypomeron. Profemur with a rather shallow sculptured depression on a large portion of ventral surface. Protibia angulate distally.

Mesothorax. Scutellar shield with sparse fine punctation, without microsculpture. Elytra with 10 punctural series, all series deeply impressed, lateral striae deeper than median ones; serial punctures minute and rather inconspicuous; elytral intervals highly convex, bearing sparsely arranged fine setiferous punctation, interstices with strong microsculpture consisting of small bumps; lateral portions of elytra deflexed laterally (hence, visible in ventral view); epipleuron present only on elytral base, reduced to extremelly narrow stripe behind level of mesocoxae. Mesoventrite with pentagonal posteromedian elevation, the elevation 1.3 × wider than long, with rugose setiferous sculpture.

Metathorax. Anteromedian process with very weakly developed short longitudinal ridges, in many individuals completely obscured by microsculpture; median portion of metaventrite slightly elevated bearing densely arranged coarse setiferous punctures separated by 0.5 –1.2× puncture diameter; lateral portions of metaventrite with extremelly large setiferous punctures; whole surface of metaventrite except its posterom edian portion with mesh-like microsculpture on interstices, microsculpture stronger laterally than medially. Hind wings well developed.

Abdomen. All abdominal ventrites with strong scale-like microsculpture, punctation of ventrite 1 consisting of extremelly large setiferous punctures similar to that on lateral portions of metaventrite; punctation of ventrites 2-5 sparse and very fine, nearly completely obscured by microsculpture.

Male genitalia. Parameres slender, 1.8 × longer than phallobase. Median lobe robust, very wide and parallel-sided in basal 0.35, slighly and continually narrowing apicad in apical 0.65, apex widely rounded; gonopore situated in basal 0.4 of median lobe. Stenite 9 with slightly asymmetrical median projection.

Differential diagnosis.

See the identification key above for characters distinguishing Nipponocercyon sichuanicus from Nipponocercyon shibatai . Nipponocercyon sichuanicus may be confused with some species of Cryptopleurum , Pachysternum or Cyrtonion (the latter not occurring in Asia, however)which are also characterized by large antennal grooves and strongly sculptured dorsal surface. Nipponocercyon shibatai may be easily distinguished from them by the combination of following characters: (1) metaventrite without femoral lines (femoral lines present in Cryptopleurum , Pachysternum and Cyrtonion , see e.g. Fig. 22, feml); (2) metanepisternum wide throughout (Fig. 20) (reduced anteriorly and widening posteriad in the above genera as well as in all other genera of the Megasternum group characterized by large antennal grooves, see e.g. Fig. 22, aes3); (3) gonopore situated in basal portion of the median lobe (Fig. 4; this character distinguishes both species of Nipponocercyon from all other Megasternini ); (4) mesoventral plate only slightly wider than long, without acute angles (Fig. 19) (mesoventral plate large and distinctly transverse in Cryptopleurum , see e.g. Fig. 22); (5) anterolateral corners of mentum not sharply angulate (Fig. 10) (sharply angulate in Cryptopleurum , as in Fig. 16).

Biology.

No details on the biology are known. The terrestrial habits of Nipponocercyon shibatai (Hoshina & Fikáček 2010) as well as the vast majority of the megasternine taxa suggest that Nipponocercyon sichuanicus is a terrestrial species.

Distribution.

The species occurs in the mountains of the Sichuan province in South China, at altitudes between 2500-3500 m a.s.l. (Fig. 24).