Helochares obscurus ( Müller, 1776 ), Fikacek et al., 2015

Jia, Fenglong & Tang, Yu-dan, 2018, A revision of the Chinese Helochares (s. str.) Mulsant, 1844 (Coleoptera, Hydrophilidae), European Journal of Taxonomy 438, pp. 1-27 : 12-15

Helochares obscurus ( Müller, 1776)

Figs 26–31 , 53–55

Hydrophilus obscurus Müller, 1776: 69 .

Hydrophilus erythrocephalus Fabricius, 1792: 185 .

Hydrophilus variegatus var. variegatus Herbst, 1797: 304 .

Helochares subcompressus Rey, 1885: 14 .

Helochares erythrocephalus var. substriatus Sahlberg, 1913: 20 .

Helochares griseus a. Mülleri Reitter, 1909: 364.

Hydrophilus griseus var. variegatus – Gyllenhal 1808: 122.

Helophilus lividus var. erythrocephalus – Mulsant 1844: 135.

Philhydrus lividus var. erythrocephalus – Gemminger & Harold 1868: 481.

Philhydrus lividus var. variegatus – Gemminger & Harold 1868: 481.

Helochares (i. sp.) erythrocephalus – Kuwert 1890: 37.

Helochares (s. str.) griseus var. substriatus – Zaitzev 1908: 382.

Helochares (s. str.) obscuus – d’Orchymont 1933: 306.

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 ). Metaventrite without glabrous area medially. Femora densely pubescent except apical eighth ( Figs 27, 31 ). Aedeagus ( Figs 53–55 ) ca 2.4× as long as wide. Apex of paramere 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 that are visible when the median lobe is extended.

Material examined

CHINA: Xinjiang: 1 ♂, Tacheng, Haerdun River dike, 4 Aug. 2005, Ling Zhao leg.; 1 ♀, Yining, Yili River, 5 Aug. 1984, Zhihe Huang leg.

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 ( Figs 27–28 ). Ventral side dark brown, legs with apices of femora, tibiae and tarsomeres yellowish brown ( Fig. 27 ).

HEAD. Labrum with fine 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 ). Prosternum bulging in middle, not carinate, with transverse groove, protruding anteriorly. Mesoventrite with a low transverse ridge medially, which does not bear 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 first 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.

ABDOMEN. All visible abdominal ventrites with dense pubescence; first ventrite not carinate ( Fig. 31 ).

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 figures of Hansen (1987) here for illustration ( Figs 54–55 ).

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.

Distribution

China (Xinjiang); Palearctic: Austria, Azerbaijan, Belarus, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Great Britain, Greece, Hungary, Iran, Israel, Italy, Kazakhstan, Latvia, Lithuania, Luxemburg, Montenegro, Netherlands, Norway, Poland, Russian Fed. ( Russia, West Siberia), Slovakia, Sweden, Switzerland, Turkey, Ukraine ( Fikáček et al. 2015; Hansen 1999).

Figures

Figs 26–31. Helochares obscurus (Müller, 1776). 26–27. Habitus. 26. Dorsal. 27. Ventral. 28. Head and pronotum. 29. Head and prosternum. 30. Mesoventrite. 31. Abdomen.

Figs 47–55. Aedeagi in species of Helochares Mulsant, 1844. 47. H. fuliginosus d’Orchymont, 1932. 48–49. H. songi sp. nov. 50–51. H. atropiceus Régimbart, 1903. 50. From Guangxi. 51. From Hong Kong. 52. H. pallens (MacLeay, 1825). 53–55. H. obscurus (Müller, 1776). 53. From Xinjiang. 54–55. After Hansen (1987).