Nipponocercyon Satô, 1963

Hoshina, Hideto & Fikáček, Martin, 2010, Morphological study and taxonomic revision of the genus Nipponocercyon (Coleoptera: Hydrophilidae: Sphaeridiinae), Acta Entomologica Musei Nationalis Pragae 50 (1), pp. 117-130 : 118-124

Nipponocercyon Satô, 1963

Nipponocercyon Satô, 1963: 267 . Type species: Nipponocercyon shibatai Satô, 1963 (by monotypy). Gender masculine.

Differential diagnosis. Head without distinct interantennal ridge; mentum weakly bisinuate on anterior margin; antennomeres 7–8 with groups of peg-like sensilla ventrally; maxilla with sucking disc in males; posterior tentorial pits minute; pronotum evenly convex, lateral margins not deflexed; transverse row of punctures along posterior margin of pronotum absent; median portion of prosternum elevated, bearing strong setiferous sculpture but not separated from lateral portion by a ridge; antennal grooves not reaching lateral margin of hypomeron; profemur with elongate ventral depression along anterior margin; elytron with 10 punctural series; elytral intervals not costate; lateral margins of elytra not denticulate or serrate; cavities for reception of procoxae large, reaching mesocoxae; preepisternal plate suboval to subrhomboid, widely contacting metaventrite; metaventrite with two short mesal ridges anteriorly; each anterolateral ridge of metaventrite lying along posterior margin of mesocoxa throughout the width of metaventrite, reaching anterolateral corner and not overlapping to lateral margin of metaventrite; lateral portions of metaventrite with coarse setiferous punctation consisting of two differently sized types of punctures; abdominal ventrite 1 pubescent, ventrites 2–5 bare; phallobase much shorter than parameres, slightly asymmetrical, not delimited from manubrium; corona of median lobe situated in basal half; lateral margin of median lobe lacking pubescence; male sternite 9 with large tongue-like projection; male sternite 8 without anterior narrow projection.

The genus is compared with other megasternine genera in the discussion below.

Redescription. Body elongate oval, moderately convex in lateral view. Elytra gradually narrowing posteriad.

Head. Clypeus and frons with coarse setiferous punctures, anterior clypeal margin slightly convex, narrowly rimmed, very indistinctly widened laterad; frontoclypeal suture not visible; interantennal ridge not developed, visible only as small unpunctured area on each side of head. Interocular area not elevated. Eyes small, convex, separated by 9× the width of one eye. Genae without distinct ocular ridge, bearing rugose setiferous microsculpture posteriorly of eyes, smooth in posterior portion. Gula distinct, wide, bearing posteromedian carina and narrow posterior collar; surface with rugose setiferous microsculpture. Posterior tentorial pits minute. Labrum retracted under clypeus, weakly sclerotized; anterior margin trilobate, with median lobe less protruding anteriad than lateral lobes; chaetotaxy not examined. Mandibles not examined. Antenna with nine antennomeres; scapus long and thin, ca. as long as antennal club, longer than antennomeres 2–6 combined; cupula small; antennal club compact, elongate, ca. 2.3 times as long as wide, antennomeres 7 and 8 bearing groups of peg-like sensilla ventrally, antennomere 9 not constricted subapically, forming distal half of antennal club, bluntly rounded at apex. Maxilla with sucking disc in males; maxillary palpomeres 2 and 4 subequal in length, palpomere 3 distinctly shorter than palpomere 4; palpomere 2 strongly widened distally, palpomere 3 slightly widened distally, palpomere 4 spindle-like. Submentum slightly shorter than mentum, bearing sparse setiferous punctures, lacking microsculpture and disc-like fields; mentum 1.7 times as wide as long, slightly narrowing anteriad, anterior margin slightly bisinuate, surface with weak transverse sulcus along anterior margin.

Prothorax. Pronotum arcuately narrowing anteriad, anterior margin slightly bisinuate, posterior margin nearly simply arcuate; lateral margins not deflexed, not explanate, narrowly rimmed, not serrate; surface evenly convex, without elevated ridges or bulges; punctures with minute setae intermixed with those bearing long decumbent setae; posterior pronotal margin without distinct transverse row of punctures; posterior corners obtusely rounded. Hypomeron with very narrow lateral glabrous portion very indistinctly widening posteriad; mesal portion with weakly developed intrahypomeral ridge, whole mesal hypomeral portion with equal rugose setiferous microsculpture; hypomeral process not developed. Prosternum carinate medially, with median part more elevate and bearing very coarse setiferous punctures and minute denticles on interstices, separated from lateral smooth impunctate portion by weak ridge; anterior margin slightly constricted at the border of median and lateral portions; deep pits at the border of lateral and mesal portion absent; posterior part forming prosternal process with large posterior notch. Antennal grooves large but not reaching lateral glabrous hypomeral portion, lateral margins of grooves rounded; notopleural suture indistinct. Coxal cavity closed internally; sclerotized postcoxal bridge reinforced mesally. Accessory ridge below posterior pronotal margin present, distinct even laterally as transverse fold. Profurca protruding outside of prothoracic cavity, composed of short and wide stalk and slightly asymmetrical extension with blunt apex.

Mesothorax. Scutellar shield triangular, slightly longer than wide, with few punctures present on surface. Elytron with 10 series of punctures, series 1–5 and 9–10 reaching elytral base, series 6–8 arising subbasally. Series 7 and 8 as widely separated from each other as other series; serial punctures with minute setae (indistinct under binocular microscope); elytral interstices flat to weakly convex, bearing fine setiferous punctures; alternate elytral intervals not more convex than adjacent ones; elytral margin slightly deflexed laterally, without denticulation or serration. Pseudepipleuron much wider than epipleuron subbasally, nearly horizontal, glabrous, reaching elytral apex; epipleuron pubescent, very narrow, oblique, reaching metathorax. Mesoventrite fused with anepisternum 2, anepisternal suture absent. Cavities for reception of procoxae deep and large, lacking pubescence, reaching mesocoxae. Preepisternal elevation not subdivided into short anterior and long posterior portion, bearing subrhomboid to suboval plate widely contacting but not overlapping anterior margin of metaventrite; posterolateral portion of preepisternal elevation with large tooth-like bulges separating the elevation from coxal lobe. Mesofurca not examined.

Metathorax. Metanotum not examined. Metaventrite with slightly raised subpentagonal median portion bearing finer punctures without setae, not depressed in both sexes; lateral portions except for narrow posterior part bearing very coarse setiferous punctation with punctures of two different sizes and without microsculpture, posterior part along metacoxae with a few smaller punctures without setae and with weak scale-like microsculpture. Anteromedian part of metaventrite slightly projecting anteriad, reaching ca. posterior third of length of mesocoxal cavities. Anterior margin of metaventrite with very distinct anterolateral ridge along posterior margin of mesocoxal cavities, reaching but not overlapping anterolateral corner of metaventrite; mesal portions of anterolateral ridges bending posteriad, forming two short longitudinal mesal ridges on anterior part of metaventrite; posterior margin of anterolateral ridges weakly crenulate. Femoral lines absent. Anepisternum 3 narrow, 7.5 times as long as wide. Epimeron 3 with minute but distinct ventral portion. Metafurca not examined. Hind wings present, well developed, venation not examined.

Legs. Procoxae moderately transverse, narrowly separated; mesocoxae transverse, moderately separated by preepisternal elevation and anteromedian part of metaventrite; metacoxae transverse, contiguous medially. Proximal part of trochanters concealed by coxae, surface bearing few setiferous punctures. Profemur with very distinct tibial groove delimited by dorsal and ventral ridges; meso- and metafemora with weaker tibial grooves delimited throughout ventrally and in distal half dorsally; profemur with very distinct elongate depression on ventral surface along anterior margin, bearing dense mesh-like microsculpture, remaining surface bearing few setae and weak scale-like microsculpture; meso- and metafemur with sparse punctation bearing stiff semierect setae, surface with fine microsculpture consisting of elongate meshes. Protibia slightly widened apically, without lateral or laterodistal emargination, bearing two rows of stout setae along lateral margin and one row of fine setae along mesal margin, dorsal surface with three rows of fine setae, ventral surface with one oblique row of stout setae and weak, strongly sculptured tarsal groove. Mesotibia with one row of stout setae along lateral margin, three rows of partly fine and partly stout setae on ventral surface and one row of fine setae mesally, apical portion with a series of stout setae and moderately long tibial spurs; metatibia similar to mesotibia but with four ventral series of setae. Tarsi slightly shorter than tibiae, pro- and mesotarsomeres 1–4 short, subequal in length, tarsomere 5 ca. twice as long as tarsomere 4; metatarsomere 1 ca. as long as tarsomeres 2–3 combined, tarsomeres 2–5 subequal in length. All tarsi with rather sparse and short pubescence ventrally and few longer setae on each tarsomere dorsally. Claws small, arcuate.

Abdomen with five ventrites; ventrite 1 carinate medially, bearing coarse punctation with long setae; ventrites 2–5 not carinate, with finer punctation lacking setae and bare microdenticulate portion along posterior margin; additional mesal ridges absent on all ventrites.

Male genitalia. Phallobase much shorter than parameres, asymmetrical, lacking median ridge, with weakly developed manubrium. Parameres slender, lacking median projections, each paramere bearing one seta at apex. Median lobe reaching deeply into phallobase, bearing distinct apophyses, not attached to bases of parameres and therefore freely movable within phallobase in anteroposterior direction; corona situated in basal half; lateral margins and apex lacking pubescence. Sternite 9 with long tongue-like posterior projection on median part. Sternite 8 without anterior projection.

Female genitalia. Not examined.