Pachysternum haemorrhoum Motschulsky, 1866

Fikáček, Martin, Jia, Fenglong & Prokin, Alexander, 2012, A review of the Asian species of the genus Pachysternum (Coleoptera: Hydrophilidae: Sphaeridiinae), Zootaxa 3219, pp. 1-53 : 27-31

Pachysternum haemorrhoum Motschulsky, 1866

( Figs. 9 , 13, 16, 21 , 26 , 31 , 44 , 58)

Pachysternum haemorrhoum Motschulsky, 1866: 168 .

Pachysternum haemorrhoum: Harold (1878: 69, redescription) ; Sharp (1884: 464, catalogue); Knisch (1924: 159, catalogue); Shatrovskiy (1989: 287, identification key); Hebauer (1995: 31, faunistics); Hansen (1999: 307, catalogue); Hansen (2004: 66, catalogue); Hebauer & Ryndevich (2005: 50, faunistics); Ôhara & Jia (2006: 145, faunistics, male genitalia); Short & Kanda (2006: 12, catalogue); Prokin (2009, faunistics).

Megasternum gibbulum Motschulsky, 1866: 169 . Syn. nov.

Megasternum distinctum Sharp, 1873: 66 .

Megasternum distinctum: Harold (1878: 69, synonymized with Pachysternum haemorrhoum) ; Sharp (1879: 278, synonymy with P. haemorrhoum denied); Sharp (1884: 462, 464, catalogue, synonymy with P. haemorrhoum denied); Knisch (1924: 158, catalogue); Orchymont (1926b: 373, synonymy with P. haemorrhoum confirmed).

Pachysternum sibiricum Kuwert, 1890: 172 , 324. Syn. nov.

Pachysternum sibiricum: Knisch (1924: 159, catalogue) ; Balfour-Browne (1947: 457, faunistics); Bellstedt (1985: 140, faunistics); Hebauer (1995: 31, faunistics).

Pachysternum haemorrhoum var. sibiricum : Orchymont (1926b: 373, downgraded to the variety of P. haemorrhoum ). Pachysternum haemorrhoum ssp. sibiricum: Hansen (1999: 307, catalogue); Hansen (2004: 66, catalogue); Ôhara & Jia (2006: 146, faunistics).

Type localities. Pachysternum haemorrhoum : Japan. Megasternum gibbulum : Japan. Megasternum distinctum : Japan. Pachysternum sibiricum : Russia, Vladivostok.

Type material. Pachysternum haemorrhoum : Lectotype (hereby designated): 1 spec. ( ZMUM): “ Pachysternum / haemorrhoum / Motsch. / Japonia [yellow label, in handwritten]” Paralectotype: 1 spec. ( ZMUM): same label data as the lectotype, with additional lectotype label “Lectotypus / Pachysternum haemorrhoum / Motsch. / design. Shatrovskiy 1986” . There are two specimens of P. haemorrhoum in the Motschulsky collection, both corresponding with the original description in the locality data and the characters mentioned (including of the coloration). In contrast to type specimens of P. nigrovittatum and P. apicatum , the specimens do not bear the original indication of the type status. In accordance with A. G. Shatrovkiy who designated one of these specimens as lectotype, and with Hansen (1998), we consider them as a part of the original type series. The lectotype designation by Shatrovskiy was never published and is therefore invalid according to International Code of Zoological Nomenclature ( ICZN 1999). As the specimen bearing Shatrovskiy’s lectotype label is totally disarticulated, we designate here the second, complete specimen as the lectotype.

Megasternum gibbulum : Lectotype (hereby designated): 1 male ( ZMUM): “ Megasternum / gibbulum / Motsch. / Japonia [yellow label, handwritten] // Lectotypus 3 / Megasternum / gibbulum / Motsch . / design. Shatrovskiy 1985 // Pachysternum / haemorrhoum Motsch . / det. Shatrovskiy 1986”. The lectotype designation was never published and is therefore invalid according to International Code of Zoological Nomenclature ( ICZN 1999). Hence, the single available specimen is formally designated as lectotype here.

Megasternum distinctum : Lectotype (hereby designated): 1 spec. ( BMNH): “Lecto- / type [round label with violet margin] // Type [round label with red margin] // Japan [printed label with yellow stripe] // Sharp Coll / 1905– 131 // Japan [round yellow label, handwritten] // Megasternum / distinctum / Type D. S. [in handwritten] // Lectotypus Ƥ / Megasternum / distinctum Sharp / design. Shatrovskiy 1984 [red label, partly handwritten]” . The species was described according to two specimens ( Sharp 1873). Only one of these specimens is deposited in BMNH, bearing the lectotype label by A. Shatrovskiy. However, the lectotype designation was never published and is therefore invalid according to International Code of Zoological Nomenclature ( ICZN 1999). Hence, the specimen is formally designated as lectotype here.

Pachysternum sibiricum : Lectotype (hereby designated): 1 spec. ( HNHM): “ Siberia or. / Wladiwostock [printed] // coll. Reitter [printed] // Holotype 1890 / Pachysternum / sibiricum / Kuwert [white label with red border]”. On our request we have received the only specimen labeled as holotype from HNHM. However, the holotype label corresponds with those attached routinely to the type specimens in this museum and its handwriting does not correspond with Kuwert’s handwriting. Number of type specimens is not indicated in the original description, therefore we must consider the single available specimen as a part of type series. For this reason, we hereby designate this specimen as the lectotype.

Additional material examined. CHINA: Heilongjiang: 1 spec. ( FMNH): Hsiolin Station , 60 miles W of Harbin [coordinates ca. 45°48.5'N 125°16'E], 10–25.vii.1938, lgt. M. Weymarn. Jilin: 1 spec. ( BMNH): “ Chengchin , Lesser Khingan , Manchukuo ” [= Changchun , coordinates 43°49'N 125°19.5'E], 20.iv.2038, lgt. M. Weymarn. Inner mongolia: 2 spec. ( SYSU): Hailar City [coordinates ca. 49°12'N 119°42'E], 23–26.vii.2003, lgt. F. L. Jia; 7 spec. ( SYSU): Yitulihe , without date, lgt. F.L. Jia. JAPAN: Hokkaido: 3 spec. ( BMNH): Otaru [coordinates ca. 43°11.5'N 141°0'E], without date, lgt. G. Lewis. Honshu: 4 spec. ( IRSNB): Kyoto [coordinates ca. 35°1'N 135°46'E], without date and collector; 1 spec. ( IRSNB): Nagano, Mt. Yatsu , 24.vii.1955, lgt. M. Sato; 3 spec. ( BMNH): Nara, “ft of Mt. Kasuga ” [coordinates ca. 34°41'N, 135°51'E], 20.viii.1980, lgt. P. M. Hammond. Kyushu: 1 spec. ( BMNH): Nagasaki [coordinates ca. 32°45'N 129°52'E], 20.ii.1881, lgt. C. Lewis. Shikoku: 2 spec. ( FMNH) Ehime , Ishizuchi Mtn. NP Omogo Valley , elev. 700 m [coordinates ca. 33°43'N 133°6'E], 18– 25.viii.1980, lgt. S. & J. Peck. Unspecified localities: 2 spec., 1 male ( BMNH, IRSNB): “ Japan ”, without date and collector; 3 spec. ( BMNH): “ Japan ”, without date, lgt. C. Lewis. MONGOLIA: Arkhangai: 1 spec. ( NHMW): Ugij-nur, Aimak Arkhangai , elev. 1340 m, 47°48'N 102°48'E, 7.vi.1964, lgt. Mongolian-German biological expedition. RUSSIA: Amur: 1 spec. ( HNHM): Chitaizki-Sterena [= Khitayskiy-Storona , Blagoveshchensk env., coordinates ca. 50°15'42''N 127°31'56''E], without date, lgt. B. v. Bodemeyer. Buryatia: 4 spec. ( HNHM): Quellgebiet des Irkut [= spring area of the Irkut River , coordinates ca. 51°38.5'N 101°29'E], without date, lgt. Leder . Chita: 2 spec. ( FMNH): Chita [coordinates ca. 52°3'N 113°30'E], without date, lgt. Jul. Isaak ; 2 spec. ( IRSBN, NHMW): same locality, without date, lgt. H. Frieb; 1 spec. ( NMPC): Strjetensk [= Sretensk , coordinates ca. 52°15'N, 117°43'E], without date, lgt. von Bodemeyer . Altay Republic: 1 spec. ( MPU): “okr. Gorno-Altayska ” [= near Gorno-Altaysk ], elev. 500 m, 28.v.1996 [coordinates ca. 51°57'N 86°58'E], lgt. A.Matalin & A.Brinev. Khakassia: 1 spec. ( MPU): Zap. Sayany , per. Zapadnosyanskiy [ West Sayan Mts. , Zapadnosayanskiy pass; situated on the road from Tashtyp to Bolshoy On ( Makarov ., pers. comm.), coordinates ca. 52°26ʹN 89°48ʹE], elev. 2200 m, alpine, brook shore, 8.viii.1989, lgt. S. Bugrov. Evreyskaya Avtonomnaya Oblast: 8 spec. ( NHMW, NMPC): O. Siberien, Sotka-Gora [= Pompeyevka env., coordinates ca. 48°21'N 130°48'E], without date, lgt. B. v. Bodemeyer; 1 spec. ( MPU): okr. st. Bira [= near station Bira ], 14.vii – 2.viii.1993, lgt. P.Udovichenko; 1 spec. ( MPU). Irkutsk: 1 spec. ( ASHC): Shelekhov [coordinates ca. 52°12'32''N 104°5'30''E], 28.v.1992, lgt. A. Shavrin; 3 spec. ( ASHC, NMPC): same locality, 9.vi.1992, lgt. A. Shavrin; 2 spec. ( ASHC): same locality, 19.vi.1992, lgt. A. Shavrin; 9 spec. ( ASHC, NMPC): same locality, 29.vi.1992, lgt. A. Shavrin; 4 spec. ( ASHC): same locality, 27.viii.1992, lgt. A. Shavrin. Primorsky krai: 1 spec. ( NHMW): Arsenev [= Arsenyev , coordinates ca. 44°9'40''N 133°17'6''E], vi.1991, lgt. Štrba ; 1 spec. ( NHMW): same locality, vii.1991, lgt. Šauša ; 3 spec. ( NHMW): Novochiguievka [= Novochuguyevka , coordinates ca. 44°13'37''N 133°50'33''E], 26–31.vii.1992, lgt. D. Boukal; 2 spec. ( NHMW): Sergeyevka by Chanka [coordinates ca. 44°18'10''N 131°46'E], 28–30.vii.1990, lgt. D. Boukal; 33 spec. ( NHMW): Sergeyevka, 70 km NW of Ussuriysk [coordinates ca. 44°18'10''N 131°46'E), 27.vii.1990, lgt. S. Bečvář sen.; 1 spec. ( NHMW): “ Ussuri ”, without date, and collector; 7 spec. ( IRSNB): Vladivostok [coordinates ca. 43°6'27''N 131°52'50''E], without date, lgt. H. Frieb; 3 spec. ( NMPC): same locality, 1919, lgt. Jureček ; 2 spec. ( NHMW): same locality, 23.viii.1919, lgt. H. Frieb; 1 spec. ( ZMUM): V. Primorye, Kamenushka bliz Ussuriysk [= East Primorye , Kamenushka near Ussuriysk , coordinates ca. 43°37'N 132°13'E], 24.vi.1982, lgt. Nikitskiy ; 1 spec. ( ZMUM): same locality and collector, 20.vi.1982; 3 spec. ( ZMUM): same locality and collector, 24–27.vi.1984; 2 spec. ( ZMUM); same locality and collector, 3.vii.1982; 2 spec. ( ZMUM): Primorye, Shkotovskiy rayon, okr. g. Bol. Kamen [= Primorye , Shkotovo district, near Bolshoi Kamen Mt. , coordinates ca. 43°11'N, 132°39'E], dung on a pasture, 17–18.viii.1988, lgt. I. V. Melnik; 4 spec. ( MPU): U. Primorye , Khasanskiy rayon, okr. buh. Perevoznaya [ South Primorye , Khasanskiy district, near Perevoznaya bay, coordinates ca. 43°3'N, 131°34'E], on mushrooms, 25.vi.1990, lgt. I. Melnik; 1 spec. ( NMPC): Lazovsky Reserve, Urochishche Amerika, [coordinates ca. 43°00''N 133°52'E], 17–20.vii.2006, lgt. V. Shokhrin. Tomsk: 3 spec. ( HNHM): Tomsk [coordinates ca. 56°29'19''N 84°58'E], without date and collector. Kuril islands: 2 spec. ( MPU): Kunashir Is. , dolina ruchiya Asin U. Tretiyakovo [floodplane of the brook Asin , south Tretiyakovo ], coordinates ca. 43°59'03''N 145°37'33''E, 2.viii.2009, lgt. K. Makarov & A.Zaitsev; 2 spec. ( MPU): Kunashir Is., Alekhinskaya zastava [border station ” Alekhinskaya ”], coordinates ca. 43°55'06''N 145°31'34''E, lgt. I. Melnik; 1 spec. ( MPU): Iturup Is., vulk. Atsu-Napuri , zal. Dobroe nachalo [ Atsu-Napuri volcano, Dobroe Nachalo gulf], dry meadow on hillocks, on a surface, 15.viii. [19]75, lgt. Kuznetsov . Unspecified localities: 39 spec. ( IRSNB, NMPC): “ Siberia orient.”, without date, lgt. B. v. Bodemeyer; 1 spec. ( NMPC): same locality, without date, lgt. Reitter.

Published records. KAZAKHSTAN: East Kazakhstan: Dzhungarskiy Alatau, area of river Musdybulak ( Hebauer & Ryndevich 2005). RUSSIA: Khabarovsk, Amur, Primorsky Krai, Chita: without specified locality ( Shatrovskiy 1989). Kemerovo: Novokuznetsk distr., Lipoviy Ostrov ( Hebauer & Ryndevich 2005). Kuril islands: Shikotan Is., Kunashir Is. ( Shatrovskiy 1989, Ôhara & Jia 2006). Sakhalin: without specified locality ( Shatrovskiy 1989). Unspecified: Sayan Mts., Altay Mts. ( Shatrovskiy 1989). “ KOREA ”: unspecified record from “Korean Peninsula” ( Shatrovskiy 1989).

Differential diagnosis. Pachysternum haemorrhoum is characteristic by continually arcuate outer margin of anterior tibiae ( Fig. 44 ), rather large body size and uniformly dark coloration with elytra becoming largely pale reddish apically ( Fig. 58). By these characters it may be distinguished from all remaining species of Asian Pachysternum except the species of the P. apicatum complex ( P. apicatum , P. c u r v a t u m and P. sandacanum ). However, it differs from all species including those of the P. apicatum complex by the lateral portions of the metaventrite being of the same appearance as the median portion (i.e. shiny and without pubescence ( Fig. 21 ); in all remaining species the lateral portions bear coarse sculpture and dense pubescence) and by the morphology of its male genitalia (especially by large and very distinctly detached manubrium of the basal piece and by widely rounded apex of the median lobe ( Fig. 31 )). The species is also the only eastern Palaearctic species of Pachysternum and does not cooccur with any other Asian species of the genus.

Redescription. Body widely oval, shape of elytra sexually dimorphic, female with slightly pronounced humeral portion of elytra. Body length 2.6–3.5 mm (lectotype: 2.9 mm); body width 1.9–2.3 mm (lectotype 2.0 mm).

Coloration ( Fig. 58). Head black, only with dark reddish narrow transverse ridge. Pronotum black, with vaguely defined dark reddish spot in anterolateral corners. Elytra black to dark brown basally, elytral interval 1 dark throughout, remaining portions of elytra becoming gradually paler towards brown to reddish brown apex. Ventral surface of head and thoracic sclerites black to dark brown, abdominal ventrites 2–5 largely reddish brown, legs pale reddish with darker basal portions of femora.

External morphology. Clypeus with coarse and rather dense punctation consisting of uniformly-sized rounded punctures separated from each other by ca. by puncture diameter. Punctation of frons similar to that on clypeus but slightly sparser, punctures separated by ca. 1–2× puncture diameters and becoming slightly transverse at least laterally. Interstices on head without microsculpture. Larger punctures on pronotum rounded, moderately impressed, slightly larger than small punctures; small punctures fine, slightly transverse, rather deeply impressed, divided from each other by ca. 2–3× puncture diameter. Pronotal interstices without microsculpture. Prosternum with very distinct median carina. Elytral series consisting of large, shallow punctures; interval punctation with rather fine semicircular punctures much smaller than serial ones, with sparsely intermixed slightly larger setiferous punctures of the same shape; interstices without microsculpture. Elytral series 1–7 not impressed, series 8–10 only very weakly impressed. Preepisternal elevation of mesothorax without posterolateral pits. Femoral lines on metaventrite continually arcuate, median portion of metaventrite bearing rather dense and coarse setiferous punctation, interstices without microsculpture; punctation of lateral portions similar to that of median portion, lacking dense pubescence. Anterior tibia rather wide, outer margin continually arcuate, outer series of spines only indistinctly interrupted.

Male genitalia ( Fig. 31 ). Tegmen 1.1 mm long, median lobe 1.1 mm long. Phallobase 1.5× as long as parameres, bearing large asymmetrical, very distinctly detached basal manubrium. Median lobe rather wide, nearly parallel-sided throughout except apically, abruptly triangularly narrowing apically; gonopore subapical, rather indistinct; lateral pubescent lobes wide, forming a rounded rim of apical portion of the lobe. Sternite 9 very narrow, without V-shaped apical emargination.

Variation. The species varies slightly in the coloration of elytra and in structures of the metaventrite. The elytra of paler specimens may be nearly uniformly dark reddish brown, without the black bases ( Fig. 58c). Interstices of the metaventrite may bear shallow but rather distinct mesh-like microsculpture laterally (some specimens from Irkutsk province: Shelekhov). Femoral lines may be more or less elevated anteriorly, and relatively more or less distinct posteriorly; variation in this character is rather narrow and is not influenced geographically. Specimens with variable development of the femoral lines, with presence/absence of microsculpture on the metaventrite, as well as with described variations of elytral coloration agree with “typical” specimens in all other external characters including of the shape of anterior tibia and the male genitalia, and the variation is therefore considered as intraspecific.

Discussion. The strength of the femoral lines was used as diagnostic character distinguishing the Japanese P. haemorrhoum from the mainland P. sibiricum . The variation of this character is very low, is not affected by the geography and the character vary even in the specimens from a single locality. We therefore consider P. sibiricum as a synonym to P. haemorrhoum . This also agrees with the opinion by Shatrovskiy (1989) and Hebauer & Ryndevich (2005) who published the mainland specimens under the name P. haemorrhoum and refrained from distinguishing P. sibiricum as a distinct taxon (F. Hebauer, pers. comm.).

Distribution. Widely distributed from the eastern Kazakhstan and western Siberia through southern parts of eastern Siberian and Russian Far East, northern China and Korean peninsula to Japan. The record from the Philippines by Shatrovskiy (1989) is very probably based on misidentified specimens of P. c u r v a t u m and is not considered here.

Figures

FIGURES 1 – 11. General morphology of Asian Pachysternum. 1: mentum of P. nigrovittatum; 2: maxillary palpus of P. n i g ro - vittatum; 3: maxillary sucking disc of male of P. nigrovittatum; 4: head of P. curvatum, ventral view; 5: antenna of P. c u r v a t u m; 6 – 8: prothorax of P. nigrovittatum (6: posterior view, 7: lateral view, 8: ventral view); 9 – 11: prosternal plate (9: P. h a e m o rrhoum, 10: P. rugosum, 11: P, sulawesicum).

FIGURES 12 – 25. General morphology of the Asian Pachysternum. 12 – 14: pronotal punctation (12: P. nigrovittatum, 13: P. haemorrhoum, 14: P. r u g o s u m); 15: meso- and metathorax of P. nigrovittatum, ventral view; 16 – 19: preepisternal elevation of mesothorax (16: P. haemorrhoum, 17: P. s u l a w e s i c u m, 18: P. apicatum, 19: P. rugosum); 20 – 21: surface sculpture of metaventrite mesally and laterally of femoral line (20: P. nigrovittatum, 21: P. haemorrhoum); 22: elytral punctation of P. nigrovittatum; 23: scutellum of P. nigrovittatum; 24: anterior leg of P. nigrovittatum; 25: abdomen of P. nigrovitattum.

FIGURES 26 – 28. Characters of male genitalia of possible phylogenetic significance (a: detail of apex, b: detail of basal struts). 26: median lobe of P. haemorrhoum; 27: median lobe of P. kubani; 28: apical portion of the aedeagus of P. nigrovittatum. Abbreviations: lr: lateral rim.

FIGURES 29 – 32. Male genitalia of Asian Pachysternum (a: tegmen, b: median lobe, c: apical portionof median lobe, d: sternite 9). 29: P. c a rd o n i, 30: P. coomani, 31: P. haemorrhoum; 32: P. nigrovitattum.

FIGURES 39 – 50. Anterior tibia of Asian Pachysternum species. 39: P. apicatum (a: lectotype, b: specimen from Borneo, Sabah); 40: P. c u r v a t u m, 41: P. sandacanum; 42: P. c a rd o n i; 43: P. coomani, 44: P. haemorrhoum, 45: P. kubani, 46: P. nigrovittatum, 47: P. rugosum, 48: P. stevensi, 49: P. s u l a w e s i c u m.