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Marine Planktonic Copepods
Tortanus (Eutortanus) derjugini  Smirnov, 1935   (F,M)
Taxonomy
Order Calanoida
Superfamily Diaptomoidea
Family Tortanidae
Sub-Genus Eutortanus

References

Brodsky, 1950 (1967) (p.431, figs.F); Chen & Zhang, 1965 (p.117, 130, figs.F,M); Bowman, 1971 b (p.521); Kos, 1976 (Vol. II, figs.F,M); 1984 (1985) (p.246, figs.F,M, Rem.); Zheng Zhong & al., 1984 (1989) (p.260, Rem., figs.F,M); Ohtsuka, 1992 a (p. 264); Ohtsuka & al., 1992 (p.119, fig.M); Ohtsuka & al., 1995 (p.147, Redescr., figs.F,M, Rem: p.154, comparison between specimens from Japanese, Korean and Chinese waters); Chihara & Omori, 1997 (p.925, Pl.185: F,M); Ohtsuka & Reid, 1998 (p.788, 796: figs.M); Soh & al., 2001 (p.1158, figs. F,M, juv.)

Figures

Plate 1 issued from: Q.-c Chen & S.-z. Zhang in Studia Marina Sinica, 1965, 7. [Pl.53, 2-5].
Female (from E China Sea): 2, habitus (dorsal); 3, P5 (anterior).

Male: 4, habitus (dorsal); 5, P5 (posterior).
Plate 2 issued from : S. Ohtsuka, Y.H. Yoon & Y. Endo in The J. Oceanol. Soc. Korea, 1992, 27 (2). [p.119, Fig.5 C].
Male: C, exopod segments of right P5 (anterior).
Plate 3 issued from : S. Ohtsuka & J.W. Reid in J. Crustacean Biol., 1998, 18 (4). [p.796, Fig.11].
Male: B, P5.
Plate 4 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.149, Fig.1].
Female (from Ariake Sea): A, habitus (dorsal); B, idem (lateral left side); C, prosomal end and urosome (dorsal); D, idem (lateral left side); E, idem (lateral right side); F-K, variability of prosomal end (dorsal); L-O, variability of prosomal end (lateral left side); P-S, variability of prosomal end (lateral right side); T, posterior margin of genital operculum.
W : width; L: length; R: length of right caudal ramus.
Scales in mm.
Nota: Prosome 2.4 times as long as urosome. Cephalosome and 1st pedigerous somite separate, 4th and 5th fused dorsally but separate laterally. Posterior end of last prosomal somite slightly asymmetrical. Urosome 3-segmented, anal somite incompletely coalesced with caudal rami (suture clearly visible in some specimens but not in other ones. Genital double-somite almost as wide as long, genital operculum concave posteromedially; 1st abdominal somite bearing minute dorsal prominence posteriorly; anal somite longest, having low dorsal projection (fig.1C, arrowed). Caudal rami asymmetical, right slightly longer than left.
Plate 5 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.150, Fig.2].
Female: A, A1; B, A2; C, Md (cutting edge); D-G, variability of central and dorsal teeth on mandibular cutting edge; H, Md (mandibular palp); I, Md (exopod, setae omitted); J, Mx1.
Scales in mm.
Nota: 1st central tooth on mandibular cutting edge variable in shape, tri- or bicusped at tip; five exopodsegments of Md almost coalescent, with 3 rows of minute spinules.
Plate 6 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.151, Fig.3].
Female: A, Mx2; B, Mxp.
Scales in mm.
Plate 7 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.152, Fig.4].
Female (from Ariake Sea): A, P1 (anterior); B, P2 (anterior); C, endopod of P2 (setae omitted); D, P3 (anterior); E, P4 (anterior); F, P5 (anterior); G-H, variability of right exopod of P5. R: length of right ramus; L: length of left ramus.
Scales in mm.
Plate 8 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.153, Fig.5].
Male (from Ariake Sea): A, habitus (dorsal); B, prosomal end and 1st and 2nd urosomel somites (lateral left side); C, idem (lateral right side); D, urosome (ventral); E, right A1; F, P5 (anterior); G, terminal exopod segment of left P5.
Scales in mm.
Plate 9 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.154, Fig.6].
Male (from Ariake Sea): A, B, right exopod of P5; C, D, terminal exopod segment of left P5.
Scales in mm.
Plate 10 issued from : S. Ohtsuka, H. Ueda & G.-S. Lian in Bull Plankton Soc. Japan, 1995, 42 (2). [p.155, Fig.7].
Female: A, : from Ariake Sea; B, from Xiamen; C-E, from Gwang Yang Bay.
A-C: urosome (dorsal; low prominence on anal somite arrowed); D, urosome with spermatophore on genital double-somite (lateralright side); E, idem (dorsal).
Scales in mm.
Plate 11 Issued from : K.A. Brodskii in Calanoida of the Far Eastern Seas and Polar Basin of the USSR. Opred. Fauna SSSR, 1950, 35 (Israel Program for Scientific Translations, Jerusalem, 1967) [p.432, Fig.305].
Female (from Sea of Japan): habitus (dorsal and lateral left side); S5, P5.
Nota: A comparison of specimens from the Sea of Japan with those from the Sea of Okhotsk reveals a difference in size and in the absence of denticles from the posterior margin of the genital segment in specimens from the Sea of Japan.

Male: habitus (dorsal); S5, P5.
Plate 12 H.Y. Soh, H.-L Suh, S. Ohtsuka, Y.O. Yoon & S.D. Choi in J. Plankton Res., 2001, 23 (10). [p.1158, Fig.1].
Female (from Mankyung & Dongjin Rivers, W Korea): A, habitus (dorsal); B, idem (lateral left side); E, P5.
Plate 13 H.Y. Soh, H.-L Suh, S. Ohtsuka, Y.O. Yoon & S.D. Choi in J. Plankton Res., 2001, 23 (10). [p.1159, Fig.2].
Male: A, habitus (dorsal); B, C, left side and right side respectively; F, P5; G, distal exopodal segment of left P5 [l = left leg; r = right leg; S 1-3 = lateral spines 1-3; Si 1-3 = inner setae 1-3; St = terminal spine.
Plate 14 Issued from : M.S. Kos in Issled. Fauny Morei, 1984 (1985), 30 (38). [p.250, Fig.15].
Male (from South Sakhalin Islands): 1, habitus (dorsal); 2, A1; 3, abdomen (dorsal); 4, P5.
Plate 15 Issued from : M.S. Kos in Issled. Fauny Morei, 1984 (1985), 30 (38). [p.249, Fig.14].
Female (from South Sakhalin Islands): 1, habitus (dorsal); 2, abdomen (dorsal); 3, Mxp; 4, P1; 5, P2; 6, P4; 7, P3; 8, P5.

Complementary References

Chen Q., 1983 (p.133); Dai & al., 1991 (tab.1); Myung & al., 1994 (tab.1); Shih & Young, 1995 (p.74); Ohtsuka & al., 1995 (p.159); Marcus, 1996 (p.144, as derjugunii); Mauchline, 1998 (tab.40); Bragina, 1999 (p.196); Choi & al., 2005 (p.710: Tab.III); Ohtsuka & al., 2008 (p.115, Table 6); Sakaguchi & al., 2011 (p.18, Table 1, 2, occurrences); Suzuki, K.W. & al., 2013 (p.15, Table 2, 3, 4, estuaries, annual occurrence);

Distribution

NZ: 3

Distribution map of Tortanus (Eutortanus) derjugini by geographical zones


Additional Maps & Charts

Map 3 issued from : S. Ohtsuka, Y.H. Yoon & Y. Endo in The J. Oceanol. Soc. Korea, 1992, 27 (2). [p.120, Fig.6].
Schematic illustration of distribution patterns of five sepecies of the subgenus Eutortanus.
Map 4 issued from : H. Itoh, S. Ohtsuka & T. Sato in Plankton Biol. Ecol., 2001, 48 (1); [p.66, Fig.6].
horizontal distribution of species of the subgenus Tortanus (Eutortanus) around the Japan Sea, redrawn after Ohtsuka (1999); current system modified from Uda (1934).
In T. terminalis and T. komachi symbol indicates collected site, whereas in others the distributions are schematically exhibited.
The speciation of the six known species might have occured in the ancient East China Sea Gulf with low salinity water during the Middle Miocene to the Pleistocene, and relatively recently members of the subgenus may have secondarily expanded their distributions in the neighboring waters of the East China Sea.
Map 5 Issued from : K.W. Suzuki, K. Nakayama & M. Tanaka in J. Oceanogr., 2011, 69. [p.23, Fig.5].
Bubble plots of densities of the semi-endemic calanoid Tortanus derjugini in relation to temperature, salinity, and turbidity observed in the Chikugo River estuary (south Japan) in 2005 and 2006.

Localisations

China Seas (Bohai Sea, Yellow Sea, East China Sea, South China Sea, Xiamen Harbour), Korea, Ariake Sea, Asan Bay, Japan (south estuaries: Chikugo, Midori & Kuma Rivers), Japan Sea, Okhotsk Sea, S Kuril Is.

Quotations

N: 22

Dimensions (mm)

(22) F: 1,93-1,71; 2,26-2,03; M: 1,65-1,4; 1,97-1,81; (290) F: 2-2,3; M: 1,8-2; (640) F: 2,36; 2,35; 2,16; 2,06-1,94; M: 2,09; 1,98; 2,04; 1,71; (643) F: 1,82; (831) F: 1,85-1,73; M: 1,69-1,4; (1221) M: 1,70-1,82; {F: 1,71-2,36; M: 1,40-2,09}

Remarks

coastal, estuary.
Observed in ballast waters of ships in San Francisco.
See remarks in T. dextrilobatus.
Last update : 09/04/2020

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