Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Euchaetidae ( Family )
            Euchaeta ( Genus )
Euchaeta plana  Mori, 1937   (F,M)
Syn.: Euchaeta murrayi Sewell, 1947 (p.117, figs.F); 1948 (p.429); Gaudy, 1963 b (p.13); Silas, 1972 (p.646); Hernandez-Trujillo & Esqueda-Escarcega, 2002 (in Appendix) ; Kazmi, 2004 (p.229);
Paraeuchaeta plana : Bradford & al.,1983 (p.23); Chihara & Murano, 1997 (p.801, Pl.107,111: F,M); Shimode & Shirayama, 2004 (tab.2); Choi & al., 2005 (p.710: Tab.III); Ohtsuka & al., 2008 (p.115, Table 5)
Ref.:
Mori, 1937 (1964) (p.46, figs.F,M); Chiba, 1953 a (p.615, figs.M); Chiba & al., 1957 (p.308); 1957 a (p.11); Tanaka, 1958 (p.329, figs.F,M); Chen & Zhang, 1965 (p.55, figs.F,M); Furuhashi, 1966 a (p.295, vertical distribution in Kuroshio region, Table 10) ; Tanaka & Omori, 1968 (p.221, figs.F); Kos, 1972 (Vol. I, figs.F,M, Rem.); Tanaka, 1973 (p.137, Rem.); Chen & Shen, 1974 (p.125, 127, figs.M); Park, 1995 (p.21, Redescr. F,M, figs.F,M); Mulyadi, 2004 (p.74, figs.F, Rem.); Jeong & al., 2011 (p.117, 125, figs.F,M, Rem.: genital aperture); Soh & al., 2013 (p;27, figs.F,M); Ohtsuka & al., 2015 (p.123, Table 2).
Species Euchaeta plana - Plate 1 of morphological figuresissued from : T. Park in Bull. Scripps Inst. Oceanogr. Univ. California, San Diego, 1995, 29. [p.121, Fig.11].
Female: a, forehead (left side); b, urosome (left); c, d, e, f, genital somite (left, dorsal, right, ventral, respectively); g, idem (ventral, tilted counterclockwise); h, P1 (anterior); i, P2 (anterior).
laterally, dorsal margin of forehead only slightly arched. Frontal eminence highly pronounced, conical. Rostrum elongate, slightly curved backward pointing in an anteroventral direction.
Dorsally, genital somite asymmetrical, with a rounded swelling just anterior to middle on left side and with a low angular ridge at middle of right side. Ventrally, genital field strongly asymmetrical with 2 genital flanges appearing very different from each other and right side of genital field deeply emarginate. When the somite is tilted counterclockwise, however, 2 genital flanges look quite similar. Laterally, 2 genital flanges also appear similar with rounded margin. Genital prominence very characteristic with a long, gradually sloping anterior margin and a short posterior margin which is perpendicular to ventral wall of somite.
All cephalosomal appendages similar to those of E. concinna except that 1st inner lobe of Mx1 with 1+9+1 setae (as in E. marina).
Swimming legs similar to those of E. concinna. 2nd outer spine of P2 exopod, however, short of reaching distal end of following outer spine.

Male: j, forehead (left); k, last pedigerous and genital somites (left); l, exopod of left 5th leg (medial); m, idem (anterior, tilted clockwise); n, serrated lamella (lateral).


Species Euchaeta plana - Plate 2 of morphological figuresissued from : O. Tanaka & M. Omori in Publs Seto Mar. Biol. Lab., 1968, XVI (4). [p.222, Fig.1].
Female (small form): A, forehead (lateral); B, last thoracic segment and urosome (lateral left side); C, last thoracic segment and genital somite (lateral right side); D, genital somite (ventral); E, Mx1; F, inner lobe 1 of Mx1; G, Mx2; H, Mxp; I, exopod of P2; J, endopod of P2; K, P1.
Nota: The urosome segments and furca are in the proportional lengths as 47:21:15:4:13 = 100.


Species Euchaeta plana - Plate 3 of morphological figuresissued from : O. Tanaka & M. Omori in Publs Seto Mar. Biol. Lab., 1968, XVI (4). [p.223, Fig.2].
Female (large form): A, forehead (lateral); B, last thoracic segment and genital somite (lateral right side); C, last thoracic segment and urosome (lateral left side); D, genital somite (ventral).
Nota: The urosome segments and furca are in the proportional lengths as 45:21:18:4:12 = 100.


Species Euchaeta plana - Plate 4 of morphological figuresIssued from : O. Tanaka in Publs Seto mar. Biol. Lab., 1958, VI (3). [p.329, Fig.62].
Female: a, habitus (dorsal); b, forehead (lateral); c, last thoracic segment and genital segment (lateral left side); d, idem (dorsal); e, outer margin of exopod of P2 .
Male: f, forehead (lateral); g, 2nd segment of exopod of left P5.


Species Euchaeta plana - Plate 5 of morphological figuresissued from: Q.-c Chen & S.-z. Zhang in Studia Marina Sinica, 1965, 7. [Pl.16, 1-7].
Female (from E China Sea): 1, habitus (dorsal); 2, forehead (lateral); 3, genital segment (lateral right side); 4, shape of genital complex (ventral); 5, outer marginal spines of 2nd and 3rd exopodal segments of left P2 (posterior).

Male: 6, habitus (dorsal); 7, 2nd exopodal segment of left P5 (posterior).


Species Euchaeta plana - Plate 6 of morphological figuresissued from : R.B.S. Sewell in The John Murray Expedition, 1933-34, Scientific Reports, VIII (1), 1947. [p.118, Fig.26]. As Euchaeta murrayi.
Female (from N Arabian Sea): A, habitus (dorsal); B, genital segment (lateral left side); C, idem (another aspect); D, idem (ventral); E, Mx1; F, Mx2; G, basal segment of Mxp; H, P1; I, P2.
Nota: The proportional lengths of the cephalothorax and abdomen as 71 to 29. The proportional lengths of the various segments of the body (cephalon to caudal rami) as 330:135:59:56:59:140:77:77:21:46 = 1000. Genital segment rather sparsely covered with short hairs on the dorsal aspect, and the dorsal part of the posterior margin is fringed with a row of small spinules; the genital aperture is bounded by, on the left side, a prominent rounded lamella, that commences at about the middle of the segment and is continued backwards and across the segment behind the vulva; on the right side is a smaller lappet. 2nd and 3rd urosomal segments covered both dorsally and ventrally with numerous short hairs, and a few longer hairs on the ventral aspect of the 3rd segment. Caudal rami with a number on short hairs on the ventral aspect. A1 23-segmented (segments 8-9 and 24-25 fused, 12-13 partly fused) reaches back to about the middle of the abdomen. In A2 the basal 1st segment is provided with a row of hairs on the inner aspect, the two rami approximately equal length; the terminal endopodal segment with 6 and 7 setae on the two lobes. In Mx1 the vaious lobes bear: outer lobe 1 (5 setae), inner lobe (10), inner lobe 2 (or 3) (1 ); basipodal segment 2 (1 long and 2 short setae; endopod 1 (no seta), endopod 2-3 (1 + 3 setae. In Mx2 one of the spines, out of six, arising from the terminal lobe, presents the characteristic lateral spinules.


Species Euchaeta plana - Plate 7 of morphological figuresissued from : Q.-c Chen & C.-j. Shen in Studia Marina Sinica, 1974, 9. [p.128, Figs.9-12].
Male: 9, last thoracic segments and urosome (dorsal); 10, forehead (lateral); 11, P5; 12, exopod of left P5 (medial).


Species Euchaeta plana - Plate 8 of morphological figuresissued from : T. Mori in The pelagic Copepoda from the neighbouring waters of Japan, 1937 (2nd edit., 1964). [Pl.21, Figs.1-8].
Female: 1, 8, habitus (lateral and dorsal, respectively); 2, P2; 7, genital area.

Male: 3, forehead (lateral); 4, distal portion exopodite of left P5: 5, habitus (dorsal); 6, P5.


Species Euchaeta plana - Plate 9 of morphological figuresissued from : M.-K. Jeong, H.-L. Suh & H.Y. Soh in Ocean Sci., 2011, 46 (2). [p.126, Fig.6].
Female (E Korea): A-B, habitus (dorsal and lateral, respectively); C, genital double-somite; D, A1.

Male: E-F, habitus (dorsal and lateral, respectively); G, P5; H, 2nd exopodal segment of left P5; I, A1.

Scale bars in micrometers.


Species Euchaeta plana - Plate 10 of morphological figuresissued from : O. Tanaka in I O B C Handbook, 1973, IV. [p.148, Fig.9: 7].
Female: 7, 2nd outer marginal spine of exopod of P2.

Nota: This 2nd marginal spine short.


Species Euchaeta plana - Plate 11 of morphological figuresissued from : Mulyadi in Published by Res. Center Biol., Indonesia Inst. Sci. Bogor, 2004. [p.74, Fig.42].
Female (from 07°29'S, 121°05'E): a, habitus (dorsal); b, forehead (lateral); c, posterior part of last thoracic segment and genital complex (lateral right side); d, P1; e, P2.


Species Euchaeta plana - Plate 12 of morphological figuresEuchaeta plana Female:
1 - See Key to concinna species Group.
2 - Dorsally, genital somite nearly symmetrical (Fig.11-d).


Species Euchaeta plana - Plate 13 of morphological figuresIssued from : H.Y. Soh, S.Y. Moon & J.H. Wi in Invertebrate Fauna of Korea (eds) Incheon: NIBR, 2013, 21 (28). [p.28, Fig.12].
Female (from Korean waters): A-B, habitus (dorsal and lateral, respectively); C, A1.
Scale bars: 500 µm.


Species Euchaeta plana - Plate 14 of morphological figuresIssued from : H.Y. Soh, S.Y. Moon & J.H. Wi in Invertebrate Fauna of Korea (eds) Incheon: NIBR, 2013, 21 (28). [p.29, Fig.13].
Female: A, P1; B, P2; C, last thoracic segment and genital segment (dorsal); D-E, genital segment and part of 2nd urosomal segment (right and left sides, respectively).
Scale bars: 200 µm.


Species Euchaeta plana - Plate 15 of morphological figuresIssued from : H.Y. Soh, S.Y. Moon & J.H. Wi in Invertebrate Fauna of Korea (eds) Incheon: NIBR, 2013, 21 (28). [p.30, Fig.14].
Male: A-B, habitus (dorsal and lateral, respectively); C, A1.
Scale bars: A-B = 500 µm; C = 200 µm.


Species Euchaeta plana - Plate 16 of morphological figuresIssued from : H.Y. Soh, S.Y. Moon & J.H. Wi in Invertebrate Fauna of Korea (eds) Incheon: NIBR, 2013, 21 (28). [p.31, Fig.15].
Male: A, P1; B, P2; C, forhead (lateral); D, last thoracic segment and genital segment (lateral); E, P5; F, distal segments of left P5.
Scale bars: 200 µm.

Compl. Ref.:
Yamazi, 1958 (p.149, Rem.); Delalo, 1968 (p.137); Uye S-i., 1982 (p.149, relation length-weight-C-N); Madhupratap & Haridas, 1986 (p.105, tab.1); Hernandez-Trujillo, 1989 a (tab.1); Cervantes-Duarte & Hernandez-Trujillo, 1989 (tab.3); Yoo, 1991 (tab.1); Dai & al., 1991 (tab.1); Hirakawa & al., 1995 (tab.2); Shih & Young, 1995 (p.70); Park & Choi, 1997 (Appendix); Hsieh & Chiu, 1998 (tab.2); Padmavati & al., 1998 (p.349); Palomares Garcia & Vera, 1995 (tab.1); Suarez-Morales & Gasca, 1998 a (p.109); Noda & al., 1998 (p.55, Table 3, occurrence); Mauchline, 1998 (tab.33, 35, 36); Hsieh & al., 2004 (p.397, tab.1); Lan & al., 2004 (p.332, tab.1); Wang & Zuo, 2004 (p.1, Table 2, dominance, origin); Prusova & Smith, 2005 (p.77); Zuo & al., 2006 (p.162: tab.1, 3, abundance, fig.8: stations group); Hwang & al., 2006 (p.943, tabl. I); Dur & al., 2007 (p.197, Table IV); Fernandes, 2008 (p.465, Tabl.2); Ayon & al., 2008 (p.238, Table 4: Peruvian samples); Lan Y.C. & al., 2008 (p.61, Table 1, % vs stations); Tseng L.-C. & al., 2008 (p.153, Table 2, fig.5, occurrence vs geographic distribution, indicator species); Sun & al., 2010 (p.1006, Table 2); W.-B. Chang & al., 2010 (p.735, Table 2, abundance); Maiphae & Sa-ardrit, 2011 (p.641, Table 2); Zhaoli & al., 2011 (p.84, abundance %); Chen H; & al., 2011 (p.84, spatial & temporal variations); Tseng & al., 2012 (p.621, Table 3: abundance); Jang M.-C & al., 2012 (p.37, abundance and seasonal distribution); Huo & al., 2012 (p.1, Table 1: dominance); in CalCOFI regional list (MDO, Nov. 2013; M. Ohman, comm. pers.); Tachibana & al., 2013 (p.545, Table 1, seasonal change 2006-2008); Hwang & al., 2014 (p.43, Appendix A: seasonal abundance)
NZ: 8

Distribution map of Euchaeta plana by geographical zones
Loc:
Red Sea, G. of Oman, Arabian Sea, Indian (equatorial), Bay of Bengal, Indonesia-Malaysia, Flores Sea, China Seas (Yellow Sea, East China Sea, Changjiang River estuary, South China Sea, Xiamen Harbour), Taiwan (S, SW, E, NW, NE), S & E Korea, Korea Strait, Japan Sea, Tsushima Straits, Japan (Kuchinoerabu Is., Inland Sea, Izu, Tokyo Bay, Tanabe Bay), Bikini Is., W Baja California, Peru
N: 56
Lg.:
(3) F: 3,3-3,1; M: 3,16-2,84; (11) F: 2,78-2,58; (63) F: 2,95-2,85 and 3,45-3,19; (91) F: 3,1-3; (98) F: 2,77-2,69; M: 2,9-2,75; (99) F: 3,38-2,87; M: 2,95-2,75; (290) F: 3,25-3,5; M: 2,9-3,05; (1106) F: 2,90-3,18; M: 2,51-2,63; (1122) F: 3,1; (1174) F: 2,9-3,18; M: 2,51-2,63; {F: 2,58-3,50; M: 2,51-3,16}

The mean female size is 3.049 mm (n = 19; SD = 0.2611), and the mean male size is 2.844 mm (n = 10; SD = 0.1929). The size ratio (male : female) is 0.922 (n = 5; SD = 0.0719), or ± 92 %. In samples, the sex ratio is 2.2.
Rem.: mesopelagic.
For Park (1995, p.18) the species belongs to ''concinna'' Group.
According to Yamazi (1958, p.149) the species is very rare in Tanabe Bay (Japan).
After Park (1995, p.22) this species was originally described from the East China Sea and has since been recorded from the Izu region (Japan) and the Arabian Sea (Tanaka, 1973). E. murrayi Sewell (1947), described from the Arabian Sea and the Gulf of Oman, was considered by Tanaka and Omori (1968) to be a junior synonym of E. plana. Park (1995, p.22) found this species in the Malay Archipelago and off southern and central Japan between 3°N and 35°N.
The presence of this species in Southern California needs confirmation.
Observed in ballasts of ships in San Francisco.
Last update : 09/12/2020
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