Nipponocercyon satoi, Fikáček, Martin, Jia, Fenglong & Ryndevich, Sergey, 2015

Fikáček, Martin, Jia, Fenglong & Ryndevich, Sergey, 2015, A new aberrant species of Nipponocercyon from the mountains of southeastern China (Coleoptera: Hydrophilidae: Sphaeridiinae), Zootaxa 3904 (4), pp. 572-580 : 573-579

Nipponocercyon satoi sp. nov.

( Figs. 1–21 )

Type material. Holotype: male ( SYSU): CHINA: Zhejiang Prov. Tianmushan Mt., bamboo garden, sifted from leaf litter on the ground, 4.vi.2013, Ma Gu-de lgt. (labelled in English and Chinese). Paratypes: 1 female ( SYSU): CHINA: Jiangxi prov., Jinggangshan Mts., Xiangzhou (forested valley S of the village), 26°35.5′N, 114°16.0′E, 374m, 26.iv.2011; F.-L. Jia lgt.; 1 female ( NMPC): “ CHINA: Jiangxi prov. [MF04] / Jinggangshan Mts., Xiping / 26°33.7ʹN 114°12.2ʹE, / 915 m, 24.iv.2011 / Fikáček, Hájek, Jia & Song // sifting: moist leaf litter / accumulted above the / banks of a stream in a sparse / tree-bamboo bush // DNA isolation: MF533 / isolated by D. Vondráček / ix.2013, isolate deposited in / National Museum, Prague”.

Description. Body widely oval, widest in anterior third of elytra. Body length of the holotype: 2.0 mm. General coloration of dorsal surface dark brown to black, anterior and anterolateral margins of clypeus and lateral portions of frontoclypeal suture reddish, anterior and lateral margins of pronotum and lateral margins of elytra narrowly reddish. Ventral surface dark brown to black, mouthparts reddish brown. Maxillary palpi, antennae reddish brown, legs reddish brown except for brown to dark brown meso- and metafemora.

Head. Clypeus rounded laterally, straight mesally, constricted above antennal bases, with very distinct marginal bead. Clypeus and frons with uniform punctuation consisting of semicircular punctures, bearing a very fine seta each (seen only under SEM), interstices without microsculpture. Frontoclypeal suture apparent only laterally as a non-sculptured stripe directing mesad. Eyes moderately large but not much exposed dorsally, isolated by 9.5× the width of one eye in dorsal view. Mentum with sparsely arranged fine setiferous punctures, those situated on lateral margin and close to it with stouter and longer setae; interstices with strong scale-like microsculpture. Antennal club with distinct groups of peg-like sensilla situated ventrally on distal margin of antennomeres 7 and 8 and in two oval closely adjacent groups in apical third of antennomere 9, the sensilla are intermixed with surrounding setae, not placed in a deep cavity. Maxilla of male with sucking disc ventrally.

Prothorax. Pronotum with sparsely arranged fine setiferous semicircular punctures, larger punctures along posterior margin absent; interstices without microsculpture. Lateral portions of pronotum largely deflexed, but only very narrowly seen in ventral view. Prosternum with well defined median plate 2.1× wider than long, bearing strong rugose sculpture with sparsely intermixed moderately coarse rounded setiferous punctures; the plate without median carina. Anterolateral corners of prosternum (at contact with hypomeron) with small but distinct tooth ( Fig. 11 , prt). Antennal grooves moderately large, not reaching lateral margin of hypomeron. Profemur with a shallow depression on a large portion of ventral surface. Protibia angulate on outer margin in distal third, rounded distally.

Mesothorax. Scutellar shield with few fine semicircular punctures, without microsculpture. Elytra with 10 series of punctures, series 1–2 reaching from elytral base to apex, remaining series very irregular and only reaching subbasally; all series not impressed and consisting of large but very shallow punctures, and hence elytral series very indistinct; elytral intervals flat, interval punctation sparse, consisting of minute V- or Y-shaped punctures, each bearing fine seta; interstices without microsculpture; lateral portions of elytra strongly deflexed laterally (hence, largely visible in ventral view); epipleuron present throughout elytral length, but very narrow in apical half. Mesoventrite with subpentagonal posteromedian elevation, 1.3× wider than long, with rugose setiferous sculpture.

Metathorax. Anteromedian process with very distinct short longitudinal ridges ( Fig. 16 , mtr), postcoxal ridge widely diverging from posterior margin of mesocoxal cavity forming a wide elevated rim behind mesocoxal cavities; median portion of metaventrite not distinctly elevated, bearing sparsely arranged small setiferous punctures; lateral portions of metaventrite with intermixed large and moderately large setiferous punctures; whole surface of metaventrite without microsculpture on interstices. Hind wings well developed.

Abdomen. Abdominal ventrite 1 carinate medially, with dense and coarse punctation; ventrites 2–5 without median carina, bearing sparsely arranged fine punctuation; interstices of all ventrites with fine microsculpture.

Male genitalia. Aedeagus 0.67 mm long. Parameres slender, 1.6× longer than phallobase. Median lobe robust, very wide basally, gradually narrowing apicad, apex rounded; gonopore situated at midlength of median lobe.

Etymology. The species is dedicated to the Japanese specialist on Hydrophilidae and other aquatic beetles Masataka Satô (1937–2006), who discovered and described the genus Nipponocercyon .

Biology. Terrestrial species. Both female specimens from Jinggangshan Mts. were sifted from leaf litter in the forest close to a small stream, in one case with many bamboo plants. The holotype was sifted from the leaf litter in bamboo undergrowth.

Distribution. Known from two mountain systems in Southwest China situated ca. 640 km from each other: Tianmushan Mts. in Zhenjiang Province, and Jinggangshan Mts. in Jiangxi Province ( Fig. 21 ). It may be more widely distributed in the mountains of SW China, but seems to be generally rare on the localities based on our intensive field work in Jinggangshan Mts.

N. satoi sp. nov. N. shibatai N. sichuanicus Differential diagnosis. The new species may be easily recognized as a member of Nipponocercyon based on the presence of two short ridges on anteromedian portion of the metaventrite (i.e. on metaventral process, Fig. 16 : mtr), which is unique for the genus within the Megasternini . In addition, it bears a subpentagonal mesoventral plate ( Figs. 2 , 16 ), mesoventral grooves for reception of procoxae reaching to mesocoxal cavities ( Fig. 16 : grp) and prosternum with differentiated median plate and anterolateral corner projecting into a “tooth” ( Fig. 11 , prt). It differs from the remaining two species of the genus on the first view by the small highly convex body and the absence of impressed elytral series ( Figs 1–3 , 21 ). For a detailed comparison of the three species, see Table 1 .

By the general habitus, i.e. small shiny globular body seemingly without distinct elytral series, N. satoi is easily confused with the megasternine genera Megasternum and Pacrillum (both also occurring in China / Japan) rather than with other species of Nipponocercyon . Both genera differ from N. satoi by large antennal grooves reaching to lateral portion of hypomeron, absence of ridges on the metaventral process, absence of a profemoral depression and anepisternum 3 narrowing from base and hence extremely narrow anteriorly. Pacrillum also differs e.g. by the rhomboid strongly carinate prosternal plate and mesoventral plate longer than wide. Megasternum differs e.g. by hexagonal ecarinate prosternal plate which is as wide as long, mesoventral plate wider than long and anterolaterally excised protibiae.

Figures

FIGURE 21. Distribution and general habitus of known species of Nipponocercyon. Habitus photos shown to scale. Figure of N. sichuanicus adopted from Fikáček et al. (2012), that of N. shibatai from Hoshina & Fikáček (2010).

FIGURES 1 – 6. Nipponocercyon satoi sp. nov. 1 – 4: general habitus of the female paratype (1: dorsal view, 2: ventral view, 3: lateral view, 4: frontal view). 5 – 6: aedeagus of the holotype (5: phallobase and parameres, 6: median lobe).

FIGURES 7 – 14. Morpology of Nipponocercyon satoi sp. nov., SEM micrographs of female paratypes. 7: head in dorsal view; 8: head in ventral view; 9: anterior tibia, dorsal view; 10: antenna in ventral view; 11: prosternum; 12: prothorax and anterior leg in ventral view; 13: whole body in lateral view; 14: detail of the punctation of the pronotum. Abbreviations: ang: antennal grooves of prothorax; aps: antennal peg-like sensilla; prt: the free prosternal “ tooth ” on prosternum-hypomeron border; pfd: profemoral depression.

FIGURES 15 – 20. Morpology of Nipponocercyon satoi sp. nov., SEM micrographs of female paratypes. 15: meso- and metathorax in ventral view, detail; 16: detail of mesoventral plate and metaventral process; 17: meso- and metathorax in ventral view, general view; 18: posterior leg, ventral view; 19: elytron, lateral view; 20: detail of basal portion of elytron and scutellat shield. Abbreviations: grp: grooves for reception of procoxae; mtr: ridge of the metaventral process.

Tables

TABLE 1. Diagnostic characters of the Nipponocercyon species.

Dorsal surface: microsculpture on interstices	absent	absent or very weak	present, strong and mesh-like
Maxilla: sucking disc in male	present	present	absent
Prosternal plate: median carina	absent	present	present (but partly obscured by coarse punctation)
Antennal club: cavities with peg-like sensilla (seen under SEM only!)	absent	present	present
Antennal grooves of prothorax	not reaching lateral margin of hypomeron	not reaching lateral margin of hypomeron	reaching lateral margin of hypomeron
Mesoventral plate	as long as wide	as long as wide to much longer than wide	slightly longer than wide
Elytra: coloration (Fig. 21)	uniformly dark	pale with dark transverse stripe	uniformly dark
Elytra: series of punctures	not impressed	impressed	impressed
Metaventrite: pair of ridges anteromesally	present, very distinct	present, very distinct	present, but partly obscured by coarse punctuation
Metaventrite: punctation of lateral portion	with mixed large and small setiferous punctures	with mixed large and small setiferous punctures	with large punctures only
Abdominal ventrite 1: punctation	punctures only slightly larger than on other ventrites	punctures only slightly larger than on other ventrites	punctures much larger than on other ventrites
Protibia: shape distally	rounded	rounded	angulate
Aedeagus: length of median lobe	shorter than paramere	longer than paramere	longer than paramere
Aedeagus: width of median lobe	very wide basally	moderately wide basally	moderately wide basally