Cercyon (Cercyon) whuljensis Suzumura, 2019

Suzumura, Alyssa Lee, Kobayashi, Norio & Ôhara, Masahiro, 2019, Revision of the Beach-Dwelling Species of Cercyon Leach (Coleoptera: Hydrophilidae) of the West Coast of North America, The Coleopterists Bulletin 73 (3), pp. 473-493 : 477-492

publication ID	https://doi.org/ 10.1649/0010-065X-73.3.473
publication LSID	urn:lsid:zoobank.org:pub:234159CD-885B-4D4B-8ECF-8C2D1A930ADE
persistent identifier	https://treatment.plazi.org/id/486BCAD2-AF82-46EF-AA92-838B183B1353
taxon LSID	lsid:zoobank.org:act:486BCAD2-AF82-46EF-AA92-838B183B1353
treatment provided by	Valdenar
scientific name	Cercyon (Cercyon) whuljensis Suzumura
status	sp. nov.

Treatment

Cercyon (Cercyon) whuljensis Suzumura View in CoL , new species

Zoobank.org/ urn:lsid:zoobank.org:act:486BCAD2-AF82-46EF-AA92-838B183B1353 ( Figs. 1A, B View Fig , 2A View Fig , 4C View Fig , 5 View Fig , 6 View Fig , 7A–C View Fig )

Cercyon luniger: Smetana 1978: 150 View in CoL (partim).

Description. Body length = 2.1–4.2 mm, width = 1.7–2.9 mm; body oval, convex though dorsoventrally compressed ( Figs. 1A, B View Fig , 5A View Fig ), body outline continuous between pronotum and elytra. Surface shiny anteriorly, becoming matte, rugose on posterior half of elytra; head piceous; pronotum and elytra irregularly piceous to testaceous with lateral and posterior margins pale, variegated; base of elytra often with pale spots, elytral suture often dark. Ventrally piceous with white pubescence; femora testaceous or fulvous. Head covered with dense punctures separated by a little more than their diameter except a narrow space around epicranial suture; interspaces with dense, granulate microsculpture except along median line and posterolateral to epicranial sutures, clypeus anteriorly truncate with marginal stria, anterior margins rounded ( Fig. 5B View Fig ). Eyes separated by about 9X their width dorsally. Mentum trapezoidal (length:width index = 0.46); anterior margin carinate; surface slightly convex; covered in uniform, dense granulate microsculpture and setae on posterior half and around to anterolateral margins. Maxillary palpi a little longer than half width of head; second palpomere swollen apically, about 2X as long as wide; apical palpomere fusiform, a little longer than penultimate. Male with adhesion disks on maxillae, diameter a little over 1/5 width of mentum ( Fig. 5C View Fig ). Antenna about 0.85X width of head; pedicel about 1/5 length of scape; club compact, about 2X as long as wide. Pronotum widest at base, lateral margins evenly rounded; surface covered with dense punctures separated by about their diameter; very sparse, minute microsculpture only visible at high magnification ( Fig. 5A, D View Fig ). Elytra with sides regularly curved, widest at about the middle; with 10 relatively superficial striae, becoming less impressed posteriorly and laterally. Intervals flat, with dense punctures separated by about their diameter, interspaces with dense granulate microsculpture and sparse microrugae, though absent on anteromedial disk of elytra. Prosternum weakly tectiform, with or without complete carina medially, with grooves for reception of antennal club, pubescent, not reaching lateral margin. Mesoventral tablet extremely narrow, almost linear (length:width index = 7.3–13.0); surface flat, shiny, with fine punctures ( Fig. 5E, F View Fig ). Metaventrite with raised pentagonal plate, convex, shiny, punctate, punctures separated by about 2–3X their diameter, interspaces in anteromedial area sometimes with weak granulate microsculpture, projecting anteriorly between mesocoxae and contacting mesoventral tablet at a single point; lateral portions densely pubescent, lacking punctures or femoral lines ( Fig. 5E View Fig ). Femora punctate, punctures separated by 2–3X their diameter; interspaces with indistinct to dense granulate microsculpture. Tibia with dense granulate microsculpture. Aedeagus as in Fig. 7A–C View Fig ; median lobe roundly narrowed to apex, apical third with short, dense setae, parameres narrow (genital ratio = 1.01).

Type Material. Holotype male: CANADA: British Columbia, Big Beach, Ucluelet , 48.93500°N, 125.55250°W, M. Ôhara, 2014.VII.1, BC14MO-025, pinned, with genitalia preserved in Canada balsam GoogleMaps . Paratypes: Canada, British Columbia, Vancouver Isle: Otter Point , Sooke , 48.39667°N, 123.86694°W, M. Ôhara, 2014.VI.26, BC14MO-007 (1 sex undetermined); Sombrio Beach, Juan de Fuca , 48.49810°N, 124.30000°W, M. Ôhara, 2014.VI.27, BC14MO-010 (2 males) GoogleMaps ; Little Beach, Ucluelet , 48.93389°N, 125.54056°W, M. Ôhara, 2014.VII.1, BC14MO-023a (1 male) GoogleMaps ; Big Beach, Ucluelet , 8.93500°N, 125.55250°W, M. Ôhara, 2014.VII.1, BC14MO-025 (5 males, 2 females) GoogleMaps ; “Bowser, B.C./VI.8: -55/W. J. Brown// C. luniger Mannerheim / Det. M. Hatch ” OSAC _ 0000186121 – OSAC _186126 (4 males, 1 sex undetermined); USA: Washington. Whisky Creek Beach, Port Angeles , Clallam Co., 48.15557°N, 123.780673°W, A. Suzumura, 2018.VIII.22, WA18AS-008 (9 males, 9 females) GoogleMaps ; Chito Beach Resort, Sekiu , Clallam Co., 48.305656°N, 124.428559°W, A. Suzumura, 2018.VIII.22, WA18AS-009 (6 sex undetermined); unnamed beach, Sekiu , Clallam Co. , 48.345279°N, 124.17207°W, A. Suzumura, 2018.VIII.22, WA18AS-010 (4 males, 1 female) GoogleMaps ; Hobuck Beach, Neah Bay , Makah Reservation , 48.336265°N, 124.663221°W, A. Suzumura, 2018.VIII.22, WA18AS-011 (1 sex undetermined); Derelict Conveyor , Ferndale , Whatcom Co., 48.855832°N, 122.72963°W, A. Suzumura, 2018.VIII.28, WA18AS-015 (1 male, 1 female) GoogleMaps .

Holotype deposited in BBM with six paratypes (BC14MO-007, 1 specimen; BC14MO-010, 1 specimen; BC14MO-023a, 1 specimen; BC14MO- 025, 3 specimens). Six paratypes will be deposited in MCZ ( WA18 About MCZ AS-008, 6 specimens) and five in OSAC ( OSAC _0000186121– OSAC _0000186126, 5 specimens).The remaining paratypes will be deposited in SEHU ( BC14 MO-010, 1 specimen; BC14MO-25, 3 specimens, WA18AS-008, 12 specimens; WA18AS- 010, 5 specimens; WA18AS-011, 1 specimen; WA18AS-015, 2 specimens).

Distribution. British Columbia and Washington State.

Etymology. “whulj” from the Lushootseed language means “salt water” and is the original name for the Salish Sea, a complex network of waterways extending from southwestern British Columbia through northwestern Washington State and the type locality for this species.

Remarks. Cercyon whuljensis is similar to C. luniger and often found living with it ( Smetana 1978) but differs in the vastly different shape of the male parameres, absence of a small area of microsculpture on the apical angles of the pronotum, and darker, more mottled coloration. Due to close external similarities, several specimens of C. whuljensis were previously identified by M. H. Hatch (OSAC_00000186121-00000186126) as C. luniger , but examination of the lectotype (GAC. 28090) and one paralectotype (MCZ- ENT00007930) of C. luniger revealed that the specimens Hatch identified are in fact a previously undescribed species. The genitalia illustrated as belonging to C. luniger in Smetana (1988) corresponds to C. whuljensis , whereas the genitalia of C. spathifer in Smetana (1978) corresponds to the true C. luniger .

Cercyon (Cercyon) dux Sharp, 1873 ( Figs. 1C, D View Fig , 2B View Fig , 4A, C View Fig , 7D–F View Fig , 8 View Fig )

Cercyon dux Sharp 1873: 65 View in CoL [ Japan, Kyushu]. Cercyon (Cyceron) dux: Shatrovskiy 1992: 366 View in CoL . Cercyon (Cercyon) dux: Shatrovskiy 1989: 281 View in CoL

[southern Kurils?]; Hansen 1999: 278; Ohara and

Jia 2006: 2.

Redescription. Body length = 3.5–5.0 mm, width = 2.1–2.8 mm; body oval, outline slightly interrupted between pronotum and elytra, convex ( Figs. 1C, D View Fig , 8A View Fig ); shiny with dense punctation, no microsculpture dorsally. Color patterns as follows: 1) head piceous, pronotum and elytra piceous to testaceous, fulvous along lateral area, though often not reaching margin, often paler along elytral suture and striae ( Fig. 1C, D View Fig ); 2) head, pronotum, and scutellum piceous, lateral margins of pronotum often paler, elytra testaceous. Ventrally piceoustestaceous with white pubescence, legs testaceous. Head covered with dense punctures separated by a little less than their diameter except a narrow area around epicranial sutures; clypeus truncate with marginal striae ( Fig. 8B View Fig ). Eyes large, separated by about 6X their width dorsally. Mentum trapezoidal (length:width index = 1.79), anterior margin carinate, deeply impressed anteromedially, male mentum evenly covered with a dense patch of seate ( Fig. 8C View Fig ), female mentum punctate, interspaces filled with granulate microsculpture. Length of maxillary palpi about 0.5X width of head; 2 nd palpomere swollen apically, about 2.5X as long as wide; apical palpomere fusiform, about as long as penultimate. Male with large adhesion disks on maxillae, diameter about half width of mentum ( Fig. 8C View Fig ). Length of antenna a little less than width of head, pedicel about 1/3 length of scape, club compact, a little less than 2X as long as wide. Pronotum widest about 1/3 before base; lateral margins strongly convex, evenly rounded; surface covered with very dense punctures separated by a little less than their diameter. Elytra with sides regularly curved, widest at about middle; with 10 striae, deeply impressed posteriorly, 10 th stria superficial, pigmented but not impressed; intervals convex with dense punctures separated by less than their diameter ( Fig. 8D View Fig ); without pubescence. Pseudepipleura almost horizontal; epipleura densely pubescent. Prosternum tectiform, carinate medially; with welldefined grooves for reception of antennal club; pubescent. Mesoventral tablet narrowly triangular, widest posteriorly and narrowed anteriorly (length: width index = 5.3–8.0), surface shiny, densely punctate, flat though anterior 1/7 depressed ( Fig. 8E, F View Fig ). Metaventrite with raised pentagonal plate, convex, shiny, and densely punctate; projecting anteriorly between mesocoxae and almost contacting posterior margin of mesoventral plate, lateral portions densely pubescent, lacking punctures or femoral lines ( Fig. 8E View Fig ). Metepisterna rectangular, parallel, about 5X as long as wide. Femora densely punctate with punctures separated by about 2–3X their diameter, interspaces on meso- and metafemora with indistinct to dense granulate microsculpture. Tibiae with fine rugose microsculpture. Aedaegus as in Fig. 7D–F View Fig , median lobe wide, with opening at about 1/3 from apex, rounded and with dense setae from opening to tip; parameres wide, diagonally weakly tapered to diagonally truncate apices (genital ratio = 0.92).

Specimens Examined. CANADA: British Columbia. Vancouver Isle: Cowichan Bay, near Dancan , 48.740556°N, 123.941667°W, M. Ôhara, 2014.VI.28, BC14MO-012 (1 sex undetermined); Connox Bay , Royston , 49.64917°N, 125.94417°W, M. Ôhara, 2014.VII.2, BC14MO-027 (1 male, 4 females) GoogleMaps ; Arbutus Grove Provincial Park, Nanoose Bay, 49.26194°N, 124.18889°W, M. Ôhara, 2014.VII.3, BC14MO-030 (3 males, genitalia illustrated); Qualicum Beach , Nanaimo , 49.35664°N, 124.48334°W, M. Ôhara, 2016.VIII.4, BC16MO- 032 (17 males, 6 females) GoogleMaps ; Qualicum Beach, Nanaimo , 49.86327°N, 125.11438°W, M. Ôhara, 2016.VIII.5, BC16MO-033 (1 female) GoogleMaps ; Campbell River , 50.00677°N, 125.23288°W, M. Ôhara, 2016.VIII.7, BC16MO-040 (7 males, 6 females) GoogleMaps . USA: Washington. Neptune Beach, Lummi Reservation, Ferndale , 48.79467°N, 122.71103°W, B. Oxborrow, 2016.X.25, WA16AS-015 (4 males) GoogleMaps ; Derelict Conveyor, Ferndale , Whatcom Co., 48.855832°N, 122.72963°W, A. Suzumura, 2018.VIII.26, WA18AS-015 (3 males, 3 females) GoogleMaps . JAPAN: Hokkaido. “ Tachimachi-misaki / Hakodate, Hokkaido / Japan , 8-IX-1995 / M. Ôhara [under seaweed]” (1 male: SEHU0000027966 ); “ Tachimachi-misaki / Hakodate , Hokkaido / Japan , 8-IX-1995 / M. Ôhara [under seaweed]” (1 male: SEHU0000027860 ); “ Hokkaido: JAPAN/ Aikage , Teuri-to ,/ Off Haboro / TE-08-MO-007/ 44°25’07”N, 141°19’16”E / 15.VI.2008, M. Ôhara / Under sea weed” (2 males: SEHU0000027838 , SEHU0000027839 ); “ Hokkaido: JAPAN/ Tomisato, Okushiri-to/ Off Setana/OK-08-MO-015/ 42°04’18”N, 139°28’17”E / 12.VII.2008, M. Ôhara / under sea weed” (2 males: SEHU0000027901 , SEHU0000027900 ); “Tokachi: Hokkaido: Japan/ Oshirabetsu, Hiroo/HK-09-MO-007/cobble beach/ 42°07’40”N, 143°19’03”E / 5.VI.2009, M. Ôhara / Under seaweed” (1 male: SEHU0000028026 ); “Nemuro: Hokkaido: JAPAN/ Shoji riv., Rausu,/ 44°07’09”N, 145°15’12”E / 13-IX-2009, M. Ôhara,/ H. Yamamoto and M. Furuta /under seaweeds ( Laminaria )/[HK-09-MO097/CO]” (1 male: SEHU0000027994 ); Motoineppu, Oumu, Monbetsu, 44.624293°N, 142.931578°E, A. Suzumura leg., 2018.VI.26, HK18AS-027 (3 males) GoogleMaps . Honshu. “Japan: Shimane /Izumo-shi Takicho Kumura/Tamura beach/ 5.Oct.2008 / T. Hayama leg.” (1 male: SEHU0000028111 ). Ryukyu Islands . “Onna, Onnason/ Okinawa-ken, Japan/ 26°29’34”N, 127°50’34”E / [seashore], 25.vii.2015 / Takuma Yoshida leg.” GoogleMaps

Distribution. Palearctic: Russian Federation (Far East), Japan, Korea; Nearctic: British Columbia, northern Washington ( Fig. 4A, C View Fig ).

Remarks. Cercyon dux is easily distinguished from other littoral Cercyon by its large size, lack of dorsal microsculpture, and presence of an oily, feltlike patch of setae covering the mentum in males. This is the first Nearctic record of this species, and it has so far only been collected from a few localities in the Strait of Georgia region of the Salish Sea ( Fig. 4C View Fig ). Only individuals of the second, darker coloration have been found in North American populations. The absence of records of this distinctively large species in the region prior to 2014 suggests a recent introduction. One possibility is that it may have been directly introduced from Asia via debris generated by the 2011 Tohoku Earthquake Tsunami Disaster, though more physiological and phylogenetic studies are needed to better support or refute this hypothesis.

Cercyon (Cercyon) fimbriatus Mannerheim 1852 ( Figs. 1E, F View Fig , 2C View Fig , 4B View Fig , 7G–I View Fig , 9 View Fig )

Cercyon fimbriatum Mannerheim 1852: 344 [ USA, Alaska, Mt. Edgecumbe]; Smetana 1978: 105.

Cercyon (Cyceron) fimbriatus: Shatrovskiy 1992: 326 View in CoL

Cercyon (Cercyon) fimbriatus: Horn 1890: 293 View in CoL .

Redescription. Body length = 2.8–3.5 mm, width = 1.6–2.1 mm; body oval, convex though dorsoventrally compressed ( Figs. 1E–F View Fig , 9A View Fig ), body outline interrupted between pronotum and elytra; glabrous with dense punctation. Surface shiny on head and pronotum, elytra matte, color patterns ( Fig. 1E, F View Fig ) as follows: 1) piceous with lateral margins and apex of elytra paler, fulvous; 2) head and disc of pronotum piceous, lateral margins of pronotum paler, fulvous, elytra yellow to light brown, opaque, often with dark crescentic spot on apical third, scutellum and elytral suture darkened. Ventrally piceous with white pubescence; femora fulvous to piceous; maxillary palpi and antennal club testaceous; scape, pedicel, and flagellum testaceous to fulvous. Head covered with punctures separated by about 2X their diameter except a narrow space around epicranial sutures; clypeus truncate, anterior margin emarginate, with marginal stria ( Fig. 9B View Fig ). Eyes separated by about 10X their width dorsally. Mentum trapezoidal, convex, widened to apical 2/5 and narrowed anteriorly, anterior margin truncate, carinate, depressed behind; with sparse punctures separated by about 3–5X their diameter, denser posteriorly; interspaces filled with dense, rugose microsculpture (length:width index = 0.44). Maxillary palpi about 0.6X width of head, 2 nd palpomere swollen apically, about 2X as long as wide, apical palpomere fusiform, slightly longer than penultimate. Male with adhesion disks on maxillae, their diameter a little over 1/3 width of mentum. Antenna about 0.70X width of head; pedicel about 0.27X as long as scape; club compact, about 2X as long as wide. Pronotum widest at base, lateral margins evenly rounded; surface covered with dense punctures separated by a little more than their diameter; without microsculpture. Elytra with sides regularly curved, widest at about half length; with 9 deeply impressed striae, 1 st 2 curved towards each other, often seemingly joined at base ( Fig. 9D View Fig ). Prosternum weakly tectiform, almost flat except for median carina, with well-defined grooves for reception of antennal club; pubescent, not reaching lateral margin. Mesoventral tablet variably shaped, fusiform, widest at about half length, acute anteriorly, rounded posteriorly (length:width index = 3.3–4.7) ( Fig. 9E, F View Fig ); surface flat, shiny, densely punctate. Metaventrite with raised pentagonal plate, convex, projecting anteriorly between mesocoxae and almost contacting posterior margin of mesoventral plate; shiny, densely punctate, punctures separated by about their diameter; lateral portions densely pubescent, lacking punctures or femoral lines. Femora punctate, punctures separated by about 2X their diameter; interspaces with dense granulate microsculpture. Tibiae with dense granulate microsculpture. Aedeagus as in Fig. 7G–I View Fig ; median lobe with apical 1/5, tapered to a truncate apex, bearing short setae; parameres apically rounded with a membranous protrusion on inner apical margin (genital ratio = 0.71).

Specimens Examined. Paratype: “Sitkha // MCZ- ENT00007932 ” (1 sex undetermined). CANADA: British Columbia. Vancouver Isle: Alberthead Regional Park, Metchosin, 48.39583°N, 123.48833°W, M. Ôhara, 2014.VI.26, BC14MO- 005 (1 male); French Beach, Juan de Fuca, 48.39583°N, 123.94528°W, M. Ôhara, 2014.VI.26, BC14MO-006 (1 sex undetermined); Otter Point, Sooke, 48.39667°N, 123.86694°W, M. Ôhara, 2014.VI.26, BC14MO-007 (2 sex undetermined); Wickaninnish Beach, Ucluelet, 49.01611°N, 125.67417°W, M. Ôhara, 2014.VI.29, BC14MO-015 (9 sex undetermined); Half Moon Bay, Ucluelet, 48.94444°N, 125.61278°W, M. Ôhara, 2014.VI.30, BC14MO-017a (3 sex undetermined); Florencia Bay , Ucluelet, 49.98111°N, 125.61111°W, M. Ôhara, 2014.VI.30, BC14MO- 018 (4 sex undetermined); Long Beach, Ucluelet, 49.07028°N, 125.75583°W, M. Ôhara, 2014.VI.30, BC14MO-019 (1 sex undetermined); Esowista, Long Beach, Ucluelet, 49.06861°N, 125.78417°W, M. Ôhara, 2014.VI.30, BC14MO-020 (3 sex undetermined); Little Beach, Ucluelet, 48.93389°N, 125.54056°W, M. Ôhara, 2014.VII.1, BC14MO- 023a (2 males); Terrace Beach, Ucluelet, 48.92861°N, 125.54722°W, M. Ôhara, 2014.VII.1, BC14MO-024 (3 sex undetermined); Arbutus Grove Provincial Park, Nanoose Bay , 49.26194°N, 124.18889°W, M. Ôhara, 2014.VII.3, BC14MO- 030 (6 sex undetermined); Qualicum Beach, Nanaimo, 49.35664°N, 124.48334°W, M. Ôhara and N. Kobayashi, 2016.VIII.4, BC16MO-032 (1 sex undetermined); Qualicum Beach, Nanaimo, 49.86327°N, 125.11438°W, M. Ôhara and N. Kobayashi, 2016.VIII.5, BC16MO-033 (2 male); Fort Rupert , near Port Hadley , 50.69515°N, 127.41035°W, M. Ôhara and N. Kobayashi, 2016.VIII.6, BC16MO-036 (1 sex undetermined); Sayward, 50.39783°N, 125.96224°W, M. Ôhara and N. Kobayashi, 2016.VIII.7, BC16MO- 039 (1 sex undetermined); Perimeter Park, Metchosin, Colwood, 48.47530°N, 123.47365°W, M. Ôhara, 2016.VIII.8, BC16MO-044 (3 sex undetermined) GoogleMaps . USA: Alaska. Unalaska, Amaknak Island , 53.88491°N, 166.55671°W, M. Ôhara, 2015.VIII.12-13, UN15MO-019 (5 sex undetermined); Land End , Homer , Kenai Peninsula , 59.600849°N, 151.412078°W, M. Ôhara, 2015.VIII.17, AL15MO-022 (28 sex undetermined); Anchor Point , Homer , Kenai , Alaska, 59.77291°N, 151.87000°W, M. Ôhara, 2015.VIII.18, AL15MO-023 (21 sex undetermined); Nash Road , Seward Peninsula , 60.08330°N, 149.35199°W, M. Ôhara, 2015.VIII.19, AL15MO-029 (55 sex undetermined). Washington. Roosevelt Ocean Beach Access , Copalis Crossing , 47.17639°N, 124.19694°W, M. Ôhara, 2013.VI.21, WA13MO- 039 (1 sex undetermined); Glenwood Creek , Snohomish Co., 47.959751°N, 122.248971°W, A. Suzumura, 2016.VI.6, WA16AS-006 (1 sex undetermined); Neptune Beach , Lummi Reservation , Ferndale , 48.79467°N, 122.71103°W, B. Oxborrow, 2016.X.25, WA16AS-015 (8 sex undetermined); Howarth Park , Snohomish Co. , 47.96440°N, 122.24050°W, A. Suzumura, 2017.VI.5, WA17AS-001 (2 sex undetermined); Meadowdale , Snohomish Co. , 47.85948°N, 122.33526°W, A. Suzumura, 2017.VI.9, WA17AS- 004 (7 males); North of Battery Van Horne , Whidbey Island , 48.16159°N, 122.68286°W, A. Suzumura, 2017.VI.24, WA17AS-005 (2 males); Port Williams County Park , Sequim , Clallam Co. , 48.097421°N, 123.046779°W, A. Suzumura, 2018.VIII.14, WA18AS-004 (1 sex undetermined); Dungeness Landing County Park , Sequim , Clallam Co. , 48.151984°N, 123.143518°W, A. Suzumura, 2018.VIII.21, WA18AS-005 (1 sex undetermined); Cline Spit County Park , Sequim , Clallam Co. , 48.151984°N, 123.152187°W, A. Suzumura, 2018.VIII.21, WA18AS-006 (1 sex undetermined); Port Angeles waterfront, Clallam Co. , 48.119615°N, 123.428617°W, A. Suzumura, 2018.VIII.21, WA18AS-007 (1 sex undetermined); Chito Beach Resort , Sekiu , Clallam Co. , 48.305656°N, 124.428559°W, A. Suzumura, 2018.VIII.22, WA18AS-009 (1 sex undetermined); unnamed beach, Sekiu , Clallam Co. , 48.345279°N, 124.172070°W, A. Suzumura, 2018.VIII.22, WA18AS-010(1 male); Hobuck Beach , Neah Bay , Makah Reservation , 48.336265°N, 124.663221°W, A. Suzumura, 2018.VIII.22, WA18AS-011 (1 sex undetermined); Clallem Bay Spit , Clallam Bay , Clallam Co. , 48.255792°N, 124.26017°W, A. Suzumura, 2018.VIII.23, WA18AS-013 (1 sex undetermined); Washington Park Boat Landing , Anacortes , Skagit Co. , 48.500156°N, 122.693686°W, A. Suzumura, 2018.VIII.26, WA18AS-016 (1 sex undetermined); Libbey Beach Park , Coupeville , Whidbey Island , 48.232156°N, 122.701029°W, A. Suzumura, 2018.VIII.26, WA18AS-017 (1 male). Oregon. OSAC _00000206873; OSAC _00000206879; OSAC _00000206882; OSAC _00000206894 GoogleMaps .

Distribution: Pacific Coast of North America, Alaska through Mexico ( Fig. 4B View Fig )

Remarks: The most common species of beachdwelling Cercyon in the region, C. fimbriatus can be easily distinguished by the deeply impressed, often connecting bases of the first and second striae ( Fig. 9D View Fig ). Body size and coloration are highly variable within this species.

Cercyon (Cercyon) luniger Mannerheim, 1853 ( Figs. 1G, H View Fig , 2D View Fig , 4B View Fig , 7J–L View Fig , 10 View Fig )

Cercyon lunigerum Mannerheim 1853: 168 View in CoL [type locality: Kodiak, AK].

Heteryon luniger: Winters 1944: 94 .

Cercyon (Cercyon) spathifer: Smetana 1978: 149 [ San Pedro, CA].

Cercyon (Cyceron) luniger: Smetana 1988: 161 View in CoL ; Shatrovskiy 1992: 362.

Cercyon (Cyceron) spathifer: Smetana 1978: 150 ; Shatrovskiy 1992: 362.

Redescription. Body length = 3.1–3.9 mm, width = 1.8–2.1 mm. Body oval, convex though dorsoventrally compressed ( Figs. 1G, H View Fig , 10A View Fig ); body outline continuous between pronotum and elytra. Surface shiny anteriorly, though becoming matte, rugose on posterior half of elytra. Head, pronotum, and scutellum piceous, lateral margins of pronotum often paler, testaceous; elytra fulvoustestaceous, often with crescentic oblique spot in apical third ( Fig. 1G, H View Fig ). Ventrally piceous with pale pubescence, legs and maxillary palpi testaceous to fulvous. Head covered with dense punctures separated by a little more than their diameter except a narrow space around epicranial suture; interspaces with dense, granulate microsculpture except along median line and posterolaterally to epicranial sutures; clypeus anteriorly truncate with marginal stria, anterior corners rounded ( Fig. 10B View Fig ). Eyes separated by about 9X their width dorsally. Mentum trapezoidal to almost rectangular (length:width index = 0.52), anterior margin carinate, depressed behind; surface with uniform, dense granulate microsculpture and long setae around lateral and posterior margins. Maxillary palpi a little longer than half width of head; 2 nd palpomere swollen apically, a little over 2X as long as wide; apical palpomere fusiform, slightly longer than penultimate. Male with adhesion discs on maxillae, diameter about 1/4 width of mentum ( Fig. 10C View Fig ). Antenna about 0.90X width of head; pedicel about 1/5 length of scape; club compact, about 2X as long as wide. Pronotum widest at base, lateral margins evenly rounded; surface covered with dense punctures separated by a little more than their diameter; without microsculpture except a small area behind anterolateral corners ( Fig. 10D View Fig ). Elytra with sides regularly curved; widest at about half length; with 10 relatively superficial striae, becoming less impressed posteriorly and laterally; 10 th stria almost completely unimpressed, only marked by dark pigmentation. Intervals flat with dense punctures separated by 1–2X their diameter; interspaces with sparse rugose microsculpture and dense granulate microsculpture. Prosternum weakly tectiform, with a weak or incomplete carina medially; with grooves for reception of antennal club; pubescent though not reaching lateral margin. Mesoventral tablet extremely narrow, almost linear (length:width index>10.0), surface flat, shiny, with fine punctures ( Fig. 10E, F View Fig ). Metaventrite with raised pentagonal plate, convex, projecting anteriorly between mesocoxae and almost contacting posterior margin of mesoventral plate; shiny, sparsely punctate, punctures separated 2–5X their diameter; lateral portions densely pubescent, lacking punctures or femoral lines ( Fig 10E View Fig ). Femora with punctures separated by about 2–3X their diameter, interspaces with dense to indistinct granulate microsculpture. Tibiae apically rounded, with dense granulate microsculpture. Aedaegus as in Fig. 7J–L View Fig , median lobe roundly narrowed to apex; with short, indistinct setae; parameres extremely wide, apical 2/5 almost triangular, apical margin flat (genital ratio = 0.71).

Specimens Examined. Lectotype: “Kadjak// Holmberg// Cercyon / lunigerum/ Mannerheim// Cercyon luniger / Mannh./ Smetana des 1974/ LECTOTYPE // Mus. Zool. H:fors/ Spec. typ. No 2379/ Cercyon lu-/ nigerum/ Mannh.// Mus.Zool. Helsinki/ Loan No./ CA 32// Photographed/ 2019/ Pekka Malinen// http://id.luomus.fi// GAC. 28090/ UNITED STATES Alaska/ Kodiak/ 57.47 N, 152.48 W / Holmberg leg.” ( LUOMUS) GoogleMaps . Paralectotype: “Type 7930 // C. lunigerum / Kadjak. Mann. // MCZ-ENT00007930” ( MCZ). CANADA: British Columbia, Vancouver Isle. Alberthead Regional Park, Metchosin, 48.39583°N, 123.48833°W, M. Ôhara, 2014.VI.26, BC14MO- 005 (1 sex undetermined); Otter Point, Sooke, 48.39667°N, 123.86694°W, M. Ôhara, 2014.VI.26, BC14MO-007 (1 male); Whiffin Spit Beach, Sooke, 48.35694°N, 123.86694°W, M. Ôhara, 2014.VI.27, BC14MO-008 (1 male); Sombrio Beach, Juan de Fuca, 48.4981°N, 124.30000°W, M. Ôhara, 2014.VI.27, BC14MO-010 (2 males); Nanaimo, Nanaimo, 49.17583°N, 123.94165°W, M. Ôhara, 2014.VI.28, BC14MO-013 (1 sex undetermined); Little Beach, Ucluelet, 48.93389°N, 125.54056°W, M. Ôhara, 2014.VII.1, BC14MO-023a (1 male); Big Beach, Ucluelet, 48.93500°N, 125.55250°W, M. Ôhara, 2014.VII.1, BC14MO-025 (6 males, 1 female); Connox Bay , Royston, 49.64917°N, 125.94417°W, M. Ôhara, 2014.VII.2, BC16MO- 027 (1 sex undetermined); Sayward, 50.39783°N, 125.96224°W, M. Ôhara and N. Kobayashi, 2016.VIII.7, BC16MO-039 (1 sex undetermined) GoogleMaps . USA: Washington. “Bowser, B.C./VI.8: -55/ W. J. Brown // C.luniger / det. M. Hatch ” OSAC _ 000184564, OSAC _000184565; just North of Battery Van Horne, Whidbey Island , 48.16159°N, 122.68286°W, A. Suzumura, 2017.VI.24, WA17AS- 005 (3 males, 1 female); Whisky Creek Beach , Port Angeles , Clallam Co., 48.15557°N, 123.780673°W, A. Suzumura, 2018.VIII.22, WA18AS-008 (13 sex undetermined); unnamed beach, Sekiu, Clallam Co. , 48.345279°N, 124.172070°W, A. Suzumura, 2018.VIII.22, WA18AS-010 (4 sex undetermined) GoogleMaps .

Distribution: Pacific Coast of North America, Alaska through Mexico ( Fig. 4B View Fig ).

Remarks: Cercyon luniger is similar to C. whuljensis and often found living with it ( Smetana 1978) but differs in the shape of the male parameres, the presence of a small area of microsculpture on the apical angles of the pronotum, and paler elytral coloration. Due to the close external similarities, specimens of C. whuljensis in OSAC were previously identified by Hatch (OSAC_0000186121 – OSAC_0000186126) and described within C. luniger in Smetana (1988), but examination of the genitalia revealed that what had previously been considered interspecific variation in coloration and microsculpture, corresponds, in fact, to two different species ( Suzumura 2019). The genitalia illustrated as belonging to C. spathifer in Smetana (1978) correspond to this species, whereas the genitalia illustrated as belonging to C. luniger in Smetana (1988) correspond to C. whuljensis .

Cercyon (Cercyon) setulosus Sharp, 1884 ( Figs. 1I, J View Fig , 2E View Fig , 4A View Fig , 7M–O View Fig , 12 View Fig , 13 View Fig )

Cercyon setulosus Sharp 1884: 48 View in CoL ; Kuwayama 1967: 134 [ Japan, Kuril Isles.: Kunashir].

Cercyon (Cercyon) tolfino Hatch 1965: 41 ; Smetana 1978: 150; Shatrovskiy 1992: 367 (synonymy) [British Columbia, Washington].

Cercyon (Cyrceon) setulosus: Shatrovskiy 1992: 367 View in CoL [southern Kurils].

Cercyon (Cercyon) setulosus: Hansen 1999: 289 View in CoL ; Shatrovskiy 1989: 281 [southern Kurils]; Ohara and Jia 2006: 2 [Kurils].

Redescription. Body length = 2.0– 2.8 mm, width = 1.0– 1.4 mm; body oblong, convex though dorsoventrally compressed ( Figs. 1I, J View Fig , 12A View Fig ); surface matte, predominately covered with microsculpture. Body outline interrupted between pronotum and elytra, piceous, lateral margins of pronotum and elytra, apical portion of elytra, and elytral suture often paler ( Fig. 1I, J View Fig ). Ventrally piceous with pale pubescence, legs and maxillary palpi testaceous. Eyes separated by about 10X their width. Head covered with fine punctures, separated by a little more than their diameter except around epicranial sutures, interspace with dense granulate microsculpture; clypeus anteriorly truncate with marginal striae, anterior corners rounded ( Fig. 12B View Fig ). Mentum trapezoidal, anterior margin emarginate and carinate, sparsely punctate with interspaces filled with microsculpture consisting of short, horizontal wrinkles (length:width index = 2.44). Maxillary palpi a little less than 0.5X width of head, 2 nd palpomere swollen apically, apical palpomere fusiform and a little longer than penultimate. Male with small, indistinct adhesion disks on maxillae, their diameter about 1/4 width of mentum ( Fig. 12C View Fig ). Antenna about 0.70X width of head, pedicel about ¼ length of scape, club compact, about 2X as long as wide. Pronotum widest at base, about 2X as wide as long, lateral margins evenly rounded, surface covered with dense punctures separated by a little more than their diameter, interspaces with granulate microsculpture ( Fig. 12D View Fig ), densest laterally and reduced towards center. Elytra with sides regularly curved, widest at about middle, with 10 deeply impressed striae, sometimes transversely indented parallel to margin; intervals flat, with fine punctures separated by 2–3X their diameter, interspaces with fine microrugae and sparse, indistinct, decumbent pubescence laterally from 6 th stria and in posterior third ( Fig. 12G View Fig ). Prosternum tectiform, carinate medially, with well-defined grooves for reception of antennal club, pubescent. Mesoventral plate fusiform though variably shaped, widest at about middle, acute and often constricted anteriorly (length:width index = 2.0–3.0) ( Fig. 12E, F View Fig ), surface flat, shiny, sparsely punctate. Metaventrite with raised pentagonal plate, convex, shiny and irregularly punctate, projecting anteriorly between mesocoxae and contacting mesoventral tablet at a single point, lateral portions densely pubescent, lacking punctures or femoral lines ( Fig. 12E View Fig ). Femora with punctures separated by about 3X their diameter, interspaces with dense granulate microsculpture. Tibiae with indistinct granulate microsculpture. Aedaegus as in Fig. 7M–O View Fig ; median lobe evenly tapered to a point with long, sparse setae on apical fourth; parameres apically narrowed and diagonally truncate at tips (genital ratio = 0.92).

Specimens Examined. Paratypes: “Bowser, B.C./VI.8 -55/ W. J. Brown // PARATYPE / Cercyon (s. str)/ tolfino Hatch /1960// OSAC _0000063017- 0000063021” (5 sex undetermined). CANADA: British Columbia, Vancouver Isle.: Alberthead Regional Park, Metchosin , 48.39583°N, 123.48833°W GoogleMaps , M. Ôhara, 2014.VI.26, BC14MO- 005 (1 sex undetermined); French Beach, Juan de Fuca , 48.39583°N, 123.94528°W GoogleMaps , M. Ôhara, 2014.VI.26, BC14MO-006 (3 sex undetermined); Otter Point, Sooke , 48.39667°N, 123.86694°W GoogleMaps , M. Ôhara, 2014.VI.26, BC14MO-007 (2 males, 2 females); Whiffin Spit Beach, Sooke , 48.35694°N, 123.86694°W GoogleMaps , M. Ôhara, 2014.VI.27, BC14MO- 008 (3 males); Sombrio Beach, Juan de Fuca , 48.4981°N, 124.30000°W GoogleMaps , M. Ôhara, 2014.VI.27, BC14MO-010 (9 sex undetermined); Brown’ s Beach, Ucluelet , 49.93750°N, 125.55778°W GoogleMaps , M. Ôhara, 2014.VI.29, BC14MO-016a (2 sex undetermined); Florencia Bay, Ucluelet , 49.98111°N, 125.61111°W GoogleMaps , M. Ôhara, 2014.VI.30, BC14MO- 018 (1 sex undetermined); Chesterman Beach, Tolfino , 49.12250°N, 125.89694°W GoogleMaps , M. Ôhara, 2014.VI.30, BC14MO-022 (1 sex undetermined); Little Beach, Ucluelet , 48.93389°N, 125.54056°W GoogleMaps , M. Ôhara, 2014.VII.1, BC14MO-023a (1 male, 13 sex undetermined); Terrace Beach, Ucluelet , 48.92861°N, 125.54722°W GoogleMaps , M. Ôhara, 2014.VII.1, BC14MO-024 (20 sex undetermined); Big Beach, Ucluelet , 48.93500°N, 125.55250°W GoogleMaps , M. Ôhara, 2014.VII.1, BC14MO-025 (2 sex undetermined); Connox Bay, Royston , 49.64917°N, 125.94417°W GoogleMaps , M. Ôhara, 2014.VII.2, BC14MO-027 (7 sex undetermined); Arbutus Grove Provincial Park, Nanoose Bay , 49.26194°N, 124.18889°W GoogleMaps , M. Ôhara, 2014.VII.3, BC14MO-030 (4 males); Transfer Beach Park, Ladysmith , 49.26194°N, 124.18889°W GoogleMaps , M. Ôhara, 2014.VII.3, BC14MO- 031 (32 sex undetermined); Qualicum Beach, Nanaimo , 49.35664°N, 124.48334°W GoogleMaps , M. Ôhara and N. Kobayashi, 2016.VIII.4, BC16MO-032 (8 males, 2 female, 69 sex undetermined); Fort Rupert, near Port Hadley , 50.69515°N, 127.41035°W GoogleMaps , M. Ôhara and N. Kobayashi, 2016.VIII.6, BC16MO- 036 (7 males); Sayward , 50.39783°N, 125.96224°W GoogleMaps , M. Ôhara and N. Kobayashi, 2016.VIII.7, BC16MO-039 (1 sex undetermined); Campbell River , 50.00677°N, 125.23288°W GoogleMaps , M. Ôhara, 2016.VIII.7, BC16MO-040 (7 males); Otter Point, Muir Creek Beach, Sooke , 48.37970°N, 123.86755°W GoogleMaps , M. Ôhara and N. Kobayashi, 2016.VIII.8, BC16MO-042 (5 males); Whiffin Spit, Sooke , 48.37970°N, 123.86755°W GoogleMaps , M. Ôhara and N. Kobayashi, 2016.VIII.8, BC16MO-043 (2 sex undetermined); “ Bowser , BC/VI.8 -55/ W.J. Brown ” . USA: Alaska. Whitter, Kenai Peninsula , 60.78064°N, 148.71776°W GoogleMaps , M. Ôhara, 2015.VIII.17, AL15MO-021 (7 sex undetermined); Land End, Homer, Kenai Peninsula , 59.600849°N, 151.412078°W GoogleMaps , M. Ôhara, 2015.VIII.17, AL15MO-022 (19 sex undetermined); Lowel Point, Seward, Kenai Peninsula , 60.07127°N, 149.43613°W GoogleMaps , M. Ôhara, 2015.VIII.19, AL15MO- 028 (4 sex undetermined). Washington. Snohomish Co: Glenwood Creek , Snohomish Co., 47.959751°N, 122.248971°W GoogleMaps , A. Suzumura, 2016.VI.6, WA16AS- 006 (3 males, 2 females, 1 sex undetermined); Chito Beach Resort, Sekiu , Clallam Co., 48.305656°N, 124.428559°W GoogleMaps , A. Suzumura, 2018.VIII.22, WA18AS-009 (1 sex undetermined); unnamed beach, Sekiu , Clallam Co., 48.345279°N, 124.172070°W GoogleMaps , A. Suzumura, 2018.VIII.22, WA18AS-010 (1 sex undetermined); Derelict Conveyor, Ferndale , Whatcom Co., 48.855832°N, 122.729630°W GoogleMaps , A. Suzumura, 2018.VIII.26, WA18AS-015 (1 sex undetermined); Libbey Beach Park, Coupeville, Whidbey Island , 48.232156°N, 122.701029°W GoogleMaps , A. Suzumura, 2018.VIII.26, WA18AS-017 (1 sex undetermined). JAPAN: Hokkaido: “Daikoku-jima: Akkeshi: Hokkaido / 42°57’39”N, 144°52’11”E / 12.VII.2005, M. Ôhara”, DA05MO-005 (2 males: SEHU0000029423 , SEHU0000029424 ) GoogleMaps ; “ Hokkaido: Japan/ Yagishiri-to/ Off Haboro/ 44°26’02”N 141°25’41”E / 16.VI.2008, M. Ôhara / Under sea weed” YA08MO-010 (1 male: SEHU0000028193 ) GoogleMaps ; “Oshima: Hokkaido: Japan/ Osatsube, Minami-kayabe/ 41°53’37”N, 141°00’42”E / 15.VII.2009, M. Ôhara /under seaweeds ( Laminaria sp. )” HK09MO-041/SI (1 male: SEHU0000029596 ) GoogleMaps ; “Soya: Hokkaido: JAPAN/ Higashiura, Wakkanai/ 45°25’09”N 142°02’02”E / 23.VII.2008, M. Ôhara/ under seaweeds ( Laminaria ) and eel grass ( Zostera )” HK09MO-051/SI (1 male: SEHU0000029538 ; 2 females: SEHU0000029539 , SEHU0000029540 ) GoogleMaps ; Nosappu, Nemuro, 43.3855492°N,

145.81350176°E, A. Suzumura, 2018.VI.17, HK 18AS-017 (2 males, 3 females) .

Distribution. Palearctic: Kuril Islands, Japan, Russia Federation; Nearctic: Alaska through Washington ( Fig. 4A View Fig ).

Remarks. Cercyon setulosus is a very small, flat species characterized by the presence of dense microsculpture on most of the dorsal surface. Cercyon tolfino was placed in junior synonymy with C. setulosus by Shatrovskiy (1992), but the revision was either overlooked or not accepted as the two names have continued to be used. We are basing our understanding of this species on specimens examined by Shatrovskiy. This confirmed synonymy gives it a trans-Pacific distribution, ranging along the coastlines of the Northern Pacific Rim from northern Japan to Washington State.

OSAC	Oregon State Arthropod Collection
MCZ	Museum of Comparative Zoology

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Taxonomy

Kingdom	Animalia
Phylum	Arthropoda
Class	Insecta
Order	Coleoptera
Family	Hydrophilidae
Genus	Cercyon