Eogammarus kygi ( Derzhavin, 1923 )

Tomikawa, Ko, Morino, Hiroshi, Toft, Jason & Mawatari, Shunsuke F., 2006, A revision of Eogammarus Birstein, 1933 (Crustacea, Amphipoda, Anisogammaridae), with a description of a new species, Journal of Natural History (J. Nat. Hist.) 40 (17 - 18), pp. 1083-1148 : 1085-1095

publication ID	https://doi.org/ 10.1080/00222930600828859
publication LSID	lsid:zoobank.org:pub:41F5583D-BD6D-4FFF-961F-39AA6A6ECCE8
persistent identifier	https://treatment.plazi.org/id/BF741C1D-B216-5736-FE39-870DFD4CABDB
treatment provided by	Felipe
scientific name	Eogammarus kygi ( Derzhavin, 1923 )
status

Treatment

Eogammarus kygi ( Derzhavin, 1923) View in CoL

[Japanese name: Togeo yokoebi]

( Figures 1–4 View Figure 1 View Figure 2 View Figure 3 View Figure 4 )

Gammarus kygi Derzhavin 1923, p 185 –187, Plate 1; Derzhavin 1927, p 2 –3; Derzhavin 1930, p 91 –92; Uéno 1935, p 91 –92, Figure 3 View Figure 3 ; Uéno 1936a, p 244; Uéno 1936b, p 250. Gammarus (Marinogammarus) kygi: Gurjanova 1951, p 768 –769, Figure 534.

Anisogammarus kygi: Kurenkov and Mednikov 1959, p 84 View in CoL , Figure 4 View Figure 4 .

Anisogammarus (Eogammarus) kygi: Schellenberg 1937, p 274 View in CoL ; Stephensen 1944, p 51 –52, Figure 12 View Figure 12 ; Tzvetkova 1972, p 214; Tzvetkova 1975, p 118 –121, Figure 45.

Eogammarus kygi: Bousfield 1979, p 314 View in CoL .

Material examined

Japan. „, 17.0 mm, ♀, 12.5 mm, Naibetsu River (42 ° 489420N, 141 ° 359560E), Rankoshi, Chitose City, Hokkaido, 11 May 2002, collected by K. Tomikawa. 2 „, 13.5 mm, 15.2 mm, 6♀, 8.0–11.0 mm, Chitose River (42 ° 499590N, 141 ° 359560E), Hanazono, Chitose City , Hokkaido, 25 August 2002, collected by K. Tomikawa. 7 „, 13.2–17.3 mm, 7♀, 11.7– 13.5 mm, Mamachi River (42 ° 519130N, 141 ° 409330E), Mamachi, Chitose City, Hokkaido, 27 August 2002, collected by N. Matsumoto. 9 „, 13.7–16.9 mm, 3♀, 10.0– 13.9 mm, Lake Shirarutoro (43 ° 119180N, 144 ° 309320E), Shibecha Town , Kawakami County, Hokkaido, 23 August 1987, collected by N. Hikita. 9 „, 16.2–16.8 mm, 3♀, 10.0– 13.9 mm, Daikokujima Island (42 ° 569350N, 144 ° 529360E), Akkeshi Town , Akkeshi County, Hokkaido, 23 May 1989, collected by K. Kuribayashi. „, 19.6 mm, ♀, 15.0 mm, Kiritappu Bog (43 ° 059080N, 145 ° 039560E), Hamanaka Town, Akkeshi County, Hokkaido, 13 June 2002, collected by K. Tomikawa. 2 „, 15.1 mm, 18.1 mm, Poro-numa Pond (45 ° 169520N, 142 ° 109570E), Sarufutsu Village, Sohya County , Hokkaido, 13 June 2002, collected by K. Wada. ♀, 10.0 mm, Lake Kuccharo (45 ° 079460N, 142 ° 199150E), Hamatonbetsu Town , Esashi County, Hokkaido, 12 July 2002, collected by K. Wada. 4 „, 16.8–21.0 mm, 2♀, 16.0 mm, 16.1 mm, Lake Akkeshi (43 ° 029240N, 144 ° 539570E), Akkeshi Town , Akkeshi County, Hokkaido, 16 May 2002, collected by K. Wada. Twenty-three juveniles, 4.5– 9.6 mm, Bekanbeushi River (43 ° 079560N, 144 ° 519170E), Akkeshi Town , Akkeshi County, Hokkaido, 12 June 2002, collected by K. Tomikawa. 7 „, 9.0– 16.8 mm, 17♀, 8.0– 11.9 mm, Lake Takkobu (43 ° 069330N, 144 ° 299180E), Kushiro Town, Kushiro County, Hokkaido, 18 June 2002, collected by K. Tomikawa. 27 „, 10.8–14.8 mm, 36♀, 6.5–16.0 mm, Lake Tohro (43 ° 089480N, 144 ° 319230E), Shibecha Town , Kawakami County , Hokkaido, 18 June 2002, collected by K. Tomikawa. 9 „, 10.6–14.1 mm, 13♀, 8.9–10.2 mm, Kushiro River (43 ° 299300N, 144 ° 269440E), Teshikutsu Town , Kawakami County, Hokkaido, 30 August 2002, collected by N. Matsumoto. „, 12.5 mm, 3♀, 9.9–11.3 mm, Kushiro Bog (43 ° 109040N, 144 ° 199340E), Tsurui Village, Akan County, Hokkaido, 7 October 2002, collected by N. Matsumoto. 8 „, 13.8–19.4 mm, 2♀, 17.9 mm, 19.6 mm, Oshokomanai River (44 ° 029430N, 144 ° 579130E), Shari Town , Shari County , Hokkaido, 16 June 2002, collected by K. Tomikawa. 6 „, 15.0– 19.7 mm, 5♀, 16.9–17.2 mm, Oshinkoshin Fall (44 ° 029140N, 144 ° 569050E), Shari Town , Shari County, Hokkaido, 17 June 2002, collected by K. Tomikawa. 10 „, 14.2–19.3 mm, Rausu (44 ° 089220N, 145 ° 159510E), Rausu Town, Menashi County, Hokkaido, 16 June 2002, collected by K. Tomikawa. 2 „, 17.5 mm, 18.5 mm, ♀, 12.8 mm, ovigerous, Lake Odanai-numa (40 ° 449030N, 141 ° 229110E), Misawa City , Aomori Prefecture, 22 November 2001, collected by K. Tomikawa. 2 „, 15.6 mm, 16.8 mm, 5♀, 9.5–13.8 mm, Lake Towada (40 ° 269130N, 140 ° 519070E), Towadako Town , Kamikita County, Aomori Prefecture, June 1996 (day unknown) , collected by R. Ueno . Russia. „, 13.0 mm, CMNC 1980-0429 , Rakyma Southern Sakhalin Island, W coast, 29 July 1946, collected by E. F. Gurjanova. 4 „, 11.9– 12.9 mm, Lake Tunaicha (46 ° 479330N, 143 ° 15970E), east of Okhotskoye Town , Sakhalin Island, 17 July 2002, collected by J. Toft. 7♀, 7.9–10.0 mm, Lake Svobodinskoye (46 ° 489320N, 143 ° 15970E), east of Okhotskoye Town, Sakhalin Island , 17 July 2002, collected by J. Toft. 2 „, 14.1 mm, 16.1 mm, five juveniles, 5.5–8.9 mm, Lake Hvalisekoye (46 ° 479270N, 143 ° 309210E), east of Okhotskoye Town, Sakhalin Island , 17 July 2002, collected by J. Toft. Five juveniles, 5.6–8.8 mm, Lake Vavaskoye (46 ° 379500N, 143 ° 189320E), north of Aniva Bay, east of Korsakov , Sakhalin Island , 18 July 2002, collected by J. Toft. 4 „, 14.9–19.1 mm, 6♀, 8.8–9.9 mm, Uryum River (46 ° 289140N, 142 ° 199200E), west of Aniva Bay, Sakhalin Island, 21 July 2002, collected by J. Toft. 4 „, 12.9–25.0 mm, 2♀, 11.0 mm, 17.8 mm, Uryum River (46 ° 279370N, 142 ° 209590E), west of Aniva Bay, Sakhalin Island , 21 July 2002, collected by J. Toft. 3♀, 15.1–15.5 mm, ovigerous, Val River (52 ° 219200N, 143 ° 069590E), east of Chayvo Bay, Sakhalin Island , 28 July 2002, collected by J. Toft. 2 „, 10.0 mm, 14.0 mm, 2♀, 10.2 mm, 10.8 mm, Mereya River (46 ° 379410N, 142 ° 539390E), east of Korsakov, Sakhalin Island , 7 August 2002, collected by J. Toft. 2 „, 16.9 mm, 17.0 mm, Illinka River (47 ° 589370N, 142 ° 199170E), Sakhalin Island, 9 August 2002, collected by J. Toft. 2 „, 16.0 mm, 19.5 mm, 2♀, 13.8 mm, 14.5 mm, Manuy River (47 ° 589370N, 142 ° 199170E), northwest of Vzmorye, Sakhalin Island , 9 August 2002, collected by J. Toft. 3♀, 16.2–17.5 mm, four juveniles, 11.0– 16.0 mm, Paramushir Island (50 ° 229420N, 155 ° 369280E), Kuril Islands , 13 August 1997 , collected by T. Ritchie. Five juveniles, 11.0– 16.5 mm, Paramushir Island (50 ° 039570N, 155 ° 139290E), Kuril Islands , 15 August 1997, collected by N. Minakawa. „, 21.2 mm, Shumshu Island (50 ° 409120N, 156 ° 239580E), Kuril Islands , 10 August 1997, collected by Y. Kuwahara.

Description of male (17.0 mm from Naibetsu River)

Antenna 1 ( Figure 1A View Figure 1 ): peduncular articles 1:2: 3 in ratio of 1.0:0.8:0.3, article 1 with robust seta posterodistally, article 1 posterior margin with two pairs of setae and a single seta; article 2 posterior margin with three pairs of setae; article 3 posterior margin with cluster of setae; accessory flagellum four-articulate; primary flagellum 26-articulate, each article with one short aesthetasc ( Figure 1B View Figure 1 ). Antenna 2 ( Figure 1C View Figure 1 ): peduncular article 1 with slender apical setae; articles 4 and 5 about equal in length, posterior margin of article 4 with three clusters of setae and seven minute setae, posterior margin of article 5 with four clusters of setae; flagellum 13-articulate, with cup-calceoli ( Figure 1D View Figure 1 ).

Pleon: smooth.

Mandible ( Figure 1G, H View Figure 1 ): palp article 2 with 11 marginal and 15 submarginal setae; article 3 length 0.8× article 2 length, with three clusters of A-setae and a B-seta. Maxilla 1 ( Figure 1I View Figure 1 ): inner plate with 25 plumose setae medially; palp article 1 with two setae on outer margin; article 2 with five setae on outer margin and six stout and eight slender setae apically. Maxilla 2 ( Figure 1J View Figure 1 ): inner plate with 22 facial setae.

Gnathopod 1 ( Figure 1N View Figure 1 ): anterior margin of propodus with one pair and two clusters of setae, palmar margin ( Figure 1P View Figure 1 ) lined with 14 inner and four outer robust striated peg setae. Gnathopod 2 ( Figure 1Q View Figure 1 ): anterior margin of propodus with two clusters of setae, palmar margin ( Figure 1S View Figure 1 ) lined with nine inner and seven outer robust, striated peg setae and two inner pectinate stiff setae.

Pereopod 3 ( Figure 2A View Figure 2 ): merus, carpus and propodus in ratio of 1.0:0.9:0.7. Pereopod 4 ( Figure 2B View Figure 2 ): merus, carpus and propodus in ratio of 1.0:0.7:0.8. Pereopod 6 ( Figure 2D View Figure 2 ): longest posteromarginal seta of basis 0.7× width of ischium. Pereopod 7 ( Figure 2E View Figure 2 ): longest posteromarginal seta of basis 0.9× width of ischium.

Pleopods ( Figure 2F View Figure 2 ): retinacula paired ( Figure 2G View Figure 2 ). Epimera 1–3 ( Figure 2H–J View Figure 2 ): with setose anteroventral margins.

Uropod 1 ( Figure 3A View Figure 3 ): inner and outer rami length 0.6× peduncle length, latter with robust marginal setae and basofacial seta; inner ramus with robust inner marginal seta; outer ramus with two inner and one outer marginal setae, all robust. Uropod 2 ( Figure 3B View Figure 3 ): inner ramus length 0.8×, outer ramus length 0.6× peduncle length, latter with robust marginal setae; inner ramus with robust inner marginal seta; outer ramus marginally bare. Uropod 3 ( Figure 3C View Figure 3 ): inner ramus length 0.3× outer ramus length; outer margin of outer ramus with three clusters of robust setae, a few simple and plumose setae, inner margin with two clusters of robust setae, a few simple and numerous plumose setae; terminal article length 0.1× proximal article length. Telson ( Figure 3G View Figure 3 ): length 0.9× width, with robust apical and distolateral setae, slender and penicillate apical and distolateral setae, apical robust setae shorter than slender setae; cleft 71%.

Description of female (12.5 mm from Naibetsu River)

Antenna 1 ( Figure 4A View Figure 4 ): peduncular articles 1:2: 3 in ratio of 1.0:0.7:0.3; article 1 posterior margin with pair of setae and two single setae; article 2 posterior margin with two clusters of setae; article 3 posterior margin with seta; accessory flagellum four-articulate; primary flagellum 19-articulate, each article with one aesthetasc. Antenna 2 ( Figure 4B View Figure 4 ): peduncular articles 4: 5 in ratio of 1.0:0.9; posterior margin of article 4 with one pair and two clusters of setae and minute setae; posterior margin of article 5 with two clusters of setae and seta; flagellum 13-articulate, with cup-calceoli.

Gnathopod 1 ( Figure 4C View Figure 4 ): inner and outer distal part of palmar margin of propodus ( Figure 4E View Figure 4 ) with 10 and two robust simple setae, respectively. Gnathopod 2 ( Figure 4F View Figure 4 ): palmar margin of propodus ( Figure 4H View Figure 4 ) with three simple and four robust pectinate setae on inner distal part, two simple and four robust pectinate setae on outer distal part.

Pereopod 6 ( Figure 4J View Figure 4 ): longest posteromarginal seta of basis 0.7× width of ischium. Pereopod 7 ( Figure 4K View Figure 4 ): posterodistal margin of basis with robust seta, longest posteromarginal seta 1.1× width of ischium.

Uropod 3 ( Figure 4M View Figure 4 ): inner ramus length 0.3× outer ramus length; outer margin of outer ramus with three clusters of robust setae and a few simple setae; inner margin with two clusters of robust setae, a few simple and numerous plumose setae; terminal article of outer ramus length 0.2× proximal article length.

Variation

The number of clusters of setae on peduncular articles of both antennae 1 and 2 varies from one to six, depending on the locality. Specimens from three localities on the Shiretoko Peninsula, Hokkaido, Japan (Oshokomanai River, Oshinkoshin Fall and Rausu) have shorter posteromarginal setae on the basis of pereopod 7, up to 70% of the width of the ischium at maximum, and robust setae on the ventral margins of epimera 2–3. The number of clusters of robust setae on the outer margin of the outer ramus of uropod 3 varies from three to four. The telson is as long as the width in some specimens.

Remarks

Eogammarus kygi is similar to E. barbatus , but is distinguished from the latter by the following characters ( E. barbatus in parentheses): (1) in male pereopod 7, the longest posteromarginal seta on the basis is shorter than the width of the ischium (longer) and (2) the robust apical setae on the telson are shorter than the slender setae (longer) (see Table I).

Eogammarus kygi is also similar to E. confervicolus , but is distinguished from the latter by the following characters ( E. confervicolus in parentheses): (1) aesthetasc on the flagellum of antenna 1 is shorter than the surrounding normal setae (about equal); (2) spiniform setae are absent on the peduncular article 1 of antenna 2 (present); and (3) marginal setae are present on palp article 1 of maxilla 1 (absent) (see Table I).

Distribution

North Honshu, Hokkaido, Vladivostok, Udskaya Gulf (Sea of Okhotsk coast of Russia), Anadyrskiy Bay (Bering Sea coast of Russia), Kamchatka, Sakhalin, Kuril Islands.

Habitat

Rivers, river mouths, brackish lakes, and estuaries.