A revision of the Chinese Helochares ( s . str . ) Mulsant , 1844 ( Coleoptera , Hydrophilidae )

Representatives of the subgenus Helochares (s. str.) Mulsant, 1844 of China are revised. One new species, H. (s. str.) songi sp. nov., is described from Guangxi, China. All species known from China are redescribed. A diagnosis and a differential diagnosis are provided for each species. Helochares fuliginosus d’Orchymont, 1932 is recorded for the first time from China and Cambodia. Additional distribution records of H. atropiceus Régimbart, 1903 and H. pallens (MacLeay, 1825) are provided from China. The habitus and aedeagus of all species are illustrated, and a key for the identification of Chinese species of the subgenus is provided.

HEAD. Labrum with fi ne and dense punctures, smooth between punctures, anterior margin broadly emarginate. Clypeus broad, anterior margin clearly broadly emarginate, moderately expanded in front of eyes, with somewhat rounded lateral margin (Fig. 4), clearly impressed in front of eyes (Fig. 4). Ground punctures on clypeus coarser and sparser than those on labrum, surface smooth between punctures. Systematic punctures on clypeus almost same size as ground punctures. Eyes of moderate size, clearly emarginate anteriorly (Figs 1,4), separated by ca 4.0-4.1 × the width of one eye. Frons with slightly coarser and stronger punctures than on clypeus, with clear systematic punctures. Maxillary palps long and slender, ca 1.1-1.2 × as wide as head, second and third palpomeres curved inwards, apical palpomere almost as long as penultimate, asymmetrical (Fig. 4). Antennae with 9 antennomeres, scape ca 1.5 × as long as pedicel, pedicel subequal in length to antennomeres 3-6 combined, club loosely segmented, with dense pubescence. Mentum ca as wide as long, subquadrate, with deep v-shaped impression anteromedially, with coarse punctures and wrinkles posteriorly (Fig. 5). Submentum with a small glabrous area medially and with a few coarse punctures laterally. Maxilla with coarse punctures, smooth between punctures.
THORAX. Pronotum ca 2 × as wide as long, widest posteriorly, posterolateral margins broadly round, anterior margin smooth, with a very fi ne transverse groove, lateral margin with stronger groove, posterior margin without such groove; posterior margin almost straight. Ground punctures slightly coarser than those on head, systematic punctures on pronotum distinct, almost of same size as ground punctures (Figs 4,6). Prosternum bulging in middle, not carinate, pubescent, with transverse groove (Fig. 5), protruding anteriorly. Mesoventrite with a low transverse ridge medially, which does not bear an elevated tooth or projection but with long setae (Fig. 7); behind ridge with a low longitudinal carina. Metaventrite pubescent, with somewhat convex middle portion, without glabrous area. Metepisterna ca 3.5 × as long as wide, subparallel. Scutellum triangular, with similar punctures to elytra. Elytra almost parallel from base to posterior third, somewhat explanate laterally, ground punctures similar to those on pronotum, with 3 distinct rows of systematic punctures (Fig. 3), without sutural stria; epipleuron very broad anteriorly, reaching posterior margin of fi rst visible abdominal sternite, with sparse, coarse punctures. Femora densely pubescent, with apical eighth glabrous (Figs 2,8). Metatarsomeres with dense white hairs ventrally and a few long swimming hairs dorsally. Claws of moderate size, rather strongly curved.

Differential diagnosis
This species is very similar to H. fuliginosus d 'Orchymont, 1932, but may easily be distinguished from the latter by its larger size (3.6-4.3 mm in H. fuliginosus), lateral margin of clypeus and elytra with same colour as disc (Fig. 4), pronotum and elytra more coarsely punctate, and maxillary palps dark brown or black, each palpomere with light colour apically . Aedeagus slender, parameres ca 10 × as long as width of apex (Fig. 48), apex with a small inwardly directed tooth ; median lobe slightly projecting beyond parameres apically (Fig. 48). It can be distinguished from H. atropiceus , H. ciniensis Hebauer, 1999and H. taprobanicus Sharp, 1890, occurring in the Oriental, by its slender aedeagus, parameres ca 10× as long as width of apex, without branches, not concave outside, apex with a small inwardly directed tooth . Hebauer (1995) described Helochares fulgurans based on a unique female from Thailand. Helochares songi sp. nov. can be distinguished from H. fulgurans by its larger size (3.5 mm in H. fulgurans), dark colour (bright yellow brown, only dark between eyes, with two dark basal spots on pronotum in H. fulgurans) and maxillary palps dark brown or black, each palpomere with light colour apically (yellow in H. fulgurans). From H. vitalisi d 'Orchymont, 1919 (Fig. 45) it differs in having the head, pronotum and elytra with coarser punctures (ground punctures very fi ne in H. vitalisi), each maxillary palpomere with light colour apically, clypeus moderately expanded laterally, with somewhat rounded lateral margin, clearly impressed in front of eyes (clypeus not expanded laterally and not impressed in front of eyes in H. vitalisi) and elytra almost parallel from base to posterior third (widest at middle in H. vitalisi), somewhat explanate laterally (not explanate in H. vitalisi, as in Enochrus).

Biology
Lives along the sides of rivers with a sandy bottom and stagnant water. The female carries the egg case under the abdominal ventrites.

Remarks
The density is very high at the type locality, but no specimen was collected at light in July. It is probable that this species can be collected at light during its reproductive period.

Distribution
China (Guangxi), so far only known from the Shiwandashan National Park and its surroundings.

Diagnosis
Length 3.6-4.3 mm. Dorsum with dense and fi ne punctures that are fi ner than in H. songi sp. nov. Clypeus somewhat impressed in front of eyes (Figs 12,14). Maxillary palps ca 1.2 × as long as width of head, each palpomere uniformly yellowish brown . Pedicel subequal in length to antennomeres 3-6 combined. Submentum with a small glabrous area medially and with a few coarse punctures laterally (Fig. 16). Elytra almost parallel from base to posterior third, somewhat explanate laterally, with distinct systematic punctures (Fig. 9). Mesoventrite with a low transverse ridge medially and a low longitudinal carina (Fig. 15). Metaventrite without glabrous area medially. Femora densely pubescent except apical eighth (Figs 10,17). Length of parameres ca 6.5 × as long as width of apex, subparallel, slightly expanded subapically and round apically, apex without inwardly directed tooth; median lobe expanded subapically, abruptly narrowed apically (Fig. 47).
HEAD. Labrum with fi ne and dense punctures, smooth between punctures, anterior margin broadly emarginate. Clypeus broad, anterior margin clearly broadly emarginate, moderately expanded in front of eyes, lateral margin somewhat rounded, clearly impressed in front of eyes . Punctures on clypeus coarser and sparser than those on labrum, smooth between punctures, systematic punctures almost of same size as ground punctures (Fig. 14). Eyes of moderate size, clearly emarginate anteriorly , separated by ca 4.0 × the width of one eye. Ground punctures on frons similar to those on clypeus, with clear systematic punctures in front of eyes. Maxillary palps long and slender, ca 1.2 × as wide as head, second and third palpomeres curved inwards, apical palpomere almost as long as penultimate, asymmetrical (Fig. 16). Antennae with 9 antennomeres, scape ca 1.5 × as long as pedicel, pedicel subequal in length to antennomeres 3-6 combined, club loosely with dense pubescence. Mentum ca as wide as long, subquadrate, with strong v-shaped impression anteromedially, with coarse punctures and wrinkles posteriorly (Fig. 16). Submentum with a small glabrous area medially and with a few coarse punctures laterally. Maxilla with coarse punctures, smooth between punctures.

Differential diagnosis
This species is closest to H. songi sp. nov., from which it can easily be distinguished by its smaller size; clypeus yellowish brown laterally ; elytra with yellowish or reddish brown margin laterally (Fig. 11); maxillary palps uniform yellow or yellowish brown ; pronotum and elytra more fi nely punctate; parameres ca 6.5 × as long as width of apex, apex without a small, inwardly directed tooth (Fig. 47).

Biology
This species occurs in small stagnant pools and on wet stones on ground with grass or leaf litter near rivers or streams, but never collected in habitats where Oocyclus spp. occur. It is occasionally collected at light. The female carries the egg case under the abdominal ventrites.

Material examined
HEAD. Labrum with fi ne and dense punctures, smooth between punctures, with distinct systematic punctures, anterior margin broadly emarginate. Clypeus broad, with coarser and sparser punctures than those on labrum, smooth between punctures, systematic punctures distinct; anterior margin clearly emarginate, at most slightly expanded in front of eyes, never impressed in front of eyes (Figs 20-21). Eyes of moderate size, not emarginate anteriorly (Figs 20-21), separated by ca 4.0 × the width of one eye. Frons with as coarse and strong punctures as clypeus, with clear systematic punctures. Maxillary palps long and slender, ca 1.6 × as wide as head, second and third palpomeres curved inwards, apical palpomere ca 0.85 × as long as penultimate, asymmetrical. Antennae with 9 antennomeres, scape ca 1.5 × as long as pedicel, pedicel ca ⅔ × as long as antennomeres 3-6 combined, club loosely segmented with dense pubescence. Mentum ca as wide as long, subquadrate, with strong v-shaped impression anteromedially, with coarse punctures, with wrinkles posteriorly (Fig. 22). Submentum without a small glabrous area medially and with even, dense, coarse and strong punctures, smooth between punctures (Fig. 22). Maxilla with a few punctures that are fi ner than those on submentum (Fig. 22).
THORAX. Pronotum ca 2 × as wide as long, widest posteriorly, posterolateral margin broadly round, anterior and posterior margins smooth, with a very fi ne transverse groove, lateral margin with stronger groove; posterior margin slightly bisinuate, with median portion widely curved, punctures slightly coarser than those on head, with distinct setiferous systematic punctures (Figs 20-21, 23). Prosternum bulging in middle, not carinate, pubescent, with transverse groove, protruding anteriorly (Fig. 22). Mesoventrite with a stout, backwardly pointing projection, rising to level of mesocoxae, apex of projection with a few long setae (Fig. 24). Metaventrite without glabrous area medially; metepisterna ca 3.5 × as long as wide, subparallel. Scutellum triangular, with similar punctures to those on elytra. Ground punctures on elytra similar to those on pronotum and clearly with three distinct rows of systematic punctures (Fig. 20); epipleura very broad anteriorly, reaching posterior margin of fi rst visible abdominal sternite, with sparse, coarse punctures. Femora densely pubescent with apical eighth glabrous (Figs 19,25). Metatarsomeres with dense golden hairs ventrally and some long swimming hairs dorsally. Claws of moderate size, rather strongly curved.
AEDEAGUS. Very broad. Parameres somewhat wider than widest part of median lobe, each paramere with 3 branches: inner branch short and strongly curved inwards; median branch knife-formed, sharp apically, almost as long as outer branch; outer branch narrower than other two branches, apical third curved inwards, sharp apically. Median lobe with broad basal half, gradually narrowed apically. Basal strut very short (Figs 50-51).

Differential diagnosis
It is very easy to distinguish this species from other species known from China by its large size, dark brown to black colour, pronotum and elytra fi nely punctate, mesoventrite with a stout, backwardly pointing projection, rising to the level of the mesocoxae, the apex of the projection with a few long setae, each paramere with 3 branches. For the differences between H. atropiceus and allied species, see Hebauer (2001).

Biology
Living in natural ponds with leaf litter or water grass, can sometimes be collected on wet ground with plenty of grass. It can be collected at light in May and June in South China. It has never been collected from the edges of rivers and streams. The female carries the egg case under the abdominal ventrites.

Diagnosis
Length 5.0-6.4 mm. Yellowish brown to reddish brown with dark head (Fig. 26). Dorsum with dense and coarse punctures. Systematic punctures on clypeus of the same size as ground punctures. Clypeus never impressed in front of eyes (Fig. 28), lateral margin distinct narrowed anteriorly. Eyes somewhat emarginate anteriorly (Fig. 28). Maxillary palps yellowish brown with infuscate apex (Figs 28-29), ca 1.3 × as long as width of head. Antennae with pedicel slightly shorter than antennomeres 3-6 combined. Submentum with small glabrous areas medially and with uneven, dense, coarse and strong punctures (Fig. 29). Elytra usually with some longitudinal rows of black spots (Fig. 26), systematic punctures on pronotum and elytra indistinct (Figs 26,28). Mesoventrite with a low transverse ridge medially, which does not bear an elevated tooth or projection but with a tuft of long setae (Fig. 30 Redescription FORM AND COLOUR. Body length 5.0-6.4 mm, width 2.4-3.1 mm, oval, moderately convex. Head yellowish to dark brown, labrum dark brown or black. Pronotum yellowish to reddish brown (Figs 26,28). Elytra with same colour as pronotum but with some longitudinal rows of black spots (Fig. 26). Maxillary palps yellowish brown with last palpomere black apically (Figs 28-29). Antennae yellowish brown with somewhat dark club. Labial palps reddish or yellowish brown and dark apically . Ventral side dark brown, legs with apices of femora, tibiae and tarsomeres yellowish brown (Fig. 27).
HEAD. Labrum with fi ne punctures, systematic punctures detectable. Clypeus broad, anterior margin broadly emarginate, lightly expanded in front of eyes, not impressed in front of eyes (Fig. 28), with moderately coarse and dense punctures, systematic punctures of same size as ground punctures (Fig. 28). Eyes moderate in size, emarginate anteriorly; interval between eyes ca 4 × as wide as one eye. Ground punctures on frons similar to those on clypeus, systematic punctures only slightly coarser than ground punctures. Maxillary palps long and slender, ca 1.3 × as long as width of head, 1 st and 2 nd palpomeres curved inwards, apical palpomere a little shorter than penultimate, slightly bending inwards. Antennae with 9 antennomeres, scape ca 1.5 × as long as pedicel, pedicel almost as long as antennomeres 3-6 combined, club loosely segmented, bearing dense pubescence (Figs 27, 29). Mentum ca 1.3 × as wide as long, subquadrate, moderately impressed anteromedially, with coarse punctures and wrinkles (Fig. 29). Submentum with uneven, coarse punctures and small, glabrous areas medially (Fig. 29).
THORAX. Pronotum ca 2 × as wide as long, widest medially; anterior margin and posterior margin almost straight; with punctures as on head, systematic punctures arranged as two transverse oblique rows, almost of same size as ground punctures (Fig. 28 an elevated tooth or projection but with a tuft of long setae, behind the ridge, with a low, longitudinal carina between mesocoxae (Fig. 30). Metaventrite pubescent, with somewhat convex middle portion, without glabrous area; metepisterna ca 3.5 × as long as wide, subparallel. Scutellum triangular, with similar punctures to those on elytra. Ground punctures on elytra similar to those on pronotum, with 2 or 3 rows of indistinct systematic punctures (Fig. 26). Epipleura very wide anteriorly, gradually narrowed, reaching level of fi rst visible abdominal sternite. Femora densely pubescent with apical eighth glabrous. Metatarsomeres with dense white hairs ventrally and a few long swimming hairs dorsally. Claws of moderate size, rather strongly curved.
AEDEAGUS. Ca 2.4 × as long as wide. Apex of parameres dilated inwards, rounded near apex, not distinctly angular (dorsal view). Membranous inner sac with several small dentiform bulges on each side, corresponding to a number of sclerotized spines of median lobe, visible when median lobe is extended. Median lobe with spine-formed apex (Figs 53-55). Apex of median lobe of aedeagus ( Fig. 53) damaged during our dissection of the unique male. We used the fi gures of Hansen (1987) here for illustration .

Differential diagnosis
This species can easily be distinguished from other species occurring in China by its having the pronotum and elytra yellow brown, head only dark between the eyes, elytra with some longitudinal rows of black spots, aedeagus with a membranous inner sac, median lobe with a number of sclerotized spines and with a spine-formed apex. For the differential characters between it and H. pallens (McLeay, 1825) see the Differential diagnosis of that species. This species is close to the Palaearctic H. punctatus Sharp, 1869. The differential characters were given by Hansen (1987).

Remarks
This species seems to live in water at the edge of dams and the margins of rivers. Other biological characters are unknown.
HEAD. Labrum with fi ne punctures, systematic punctures detectable. Clypeus broad, anterior margin broadly emarginate, slightly expanded in front of eyes, not impressed in front of eyes (Fig. 35) as wide as one eye. Ground punctures on frons similar to those on clypeus, systematic punctures conspicuous in front of eyes. Maxillary palps long and slender, ca 1.2 × as long as width of head, 1 st and 2 nd palpomeres curved inwards, apical palpomere a little shorter than penultimate, slightly bending inwards. Antennae with 9 antennomeres, scape ca 1.5 × as long as pedicel, pedicel slightly shorter than antennomeres 3-6 combined, club loosely segmented, with dense pubescence. Mentum ca 1.2 × as wide as long, subquadrate, lightly impressed anteromedially, with coarse punctures, never with wrinkles (Fig. 37). Submentum with coarse punctures (Fig. 37).
THORAX. Pronotum ca 2 × as wide as long, widest basally; posterior margin slightly bisinuate with median portion widely curved; ground punctures on pronotum similar to those on head, systematic punctures arranged in two transverse rows (Figs 35-36). Prosternum slightly bulging in middle, not carinate (Fig. 38), pubescent, with transverse groove, protruding anteriorly. Mesoventrite only simply convex posteromedially, without a low transverse ridge (Fig. 39). Metaventrite pubescent, with somewhat convex middle portion, without glabrous area. Metepisterna ca 3.5 × as long as wide, subparallel. Scutellum triangular, with similar punctures as on elytra. Ground punctures on elytra similar to those on pronotum, with three conspicuous rows of systematic punctures, dorsal surface without striae but 8-9 striae on underside of elytra usually visible from dorsal side (Figs 41-42) (continuous dark lines with black spots on ventral surface of the elytra, not corresponding with real punctures on dorsal elytral surface, and sometimes not clear in old specimens). Epipleura very wide anteriorly, gradually narrowed, reaching level of fi rst visible abdominal sternite. Femora densely pubescent with apical eighth glabrous (Figs 33,40). Metatarsomeres with dense white hairs ventrally and some long swimming hairs dorsally. Claws of moderate size, rather strongly curved.
AEDEAGUS. Apex of parameres not dilated inwards, somewhat narrowly rounded near apex. Membranous inner sac with several small dentiform bulges on each side. Median lobe with sharp apex, apex spineformed (Fig. 52).

Differential diagnosis
This species may be closest to H. obscurus (Müller, 1776) based on form and colour. It can be distinguished from H. obscurus by its smaller size, dorsum with fi ne punctures, striae on the underside of the elytra usually visible in dorsal view, mesoventrite only simply convex posteromedially, without a transverse ridge or process pointed posteriorly, apex of parameres not dilated inwards and median lobe with a spine-formed apex.

Habitat
Wingspread and occupying typical aquatic habitats such as ponds with rotting leaves, margins of puddles and edges of rivers. It usually fl ies when it is collected from water and its body surface becomes drier during the daytime. Adults have strong photokinesis and sometimes hundreds of individuals appear at light.  (Müller, 1776). 53. From Xinjiang. 54-55. After Hansen (1987).
North and Northeast China, as well as north of the Yangtze River in Central and East China, even though many expeditions have been conducted there by the senior author. Helochares pallens may be expected to be found from north of the Yangtze River in the future.
The purpose of this manuscript is to contribute to our understanding of the fauna of Helochares (s. str.) in China. However, a phylogenetic analysis or a re-assessment of the subgenus are far beyond the scope of this work.