Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Aetideidae ( Family )
            Chiridius ( Genus )
Chiridius gracilis  Farran, 1908   (F,M)
Syn.: Chiridius poppei : Farran, 1905 (p.35);
no C. gracilis : Farran, 1929 (p.229, fig.F, Rem.); Bradford, 1970 a (p.353, figs.M)
? Chiridius gracilis : Tanaka, 1937 (p.255, fig.F, Rem.)
Farran, 1908 b (p.30, Descr.F, figs.F); A. Scott, 1909 (p.42, figs.F, Rem.); With, 1915 (p.85, figs.F); ? Farran, 1926 (p.248: juv.); Sewell, 1929 (p.100); Farran, 1936 a (p.87); Vervoort, 1952 c (n°44, p.3, figs.F); 1957 (p.6, 55, Rem.); Tanaka, 1957 a (p.48, figs.M, Rem.F); Grice, 1963 a (p.495); Bradford, 1969 a (p.97); Tanaka & Omori, 1970 (p.117); Bradford, 1972 (p.38, figs.F, Rem.); Shih & al., 1971 (p.143); Maclellan & Shih, 1974 (p.1337, figs. juv., F,M); Park, 1975 b (p.283, figs.F,M); 1978 (p.122, figs.F); Björnberg & al., 1981 (p.604, 632, fig.F); Gardner & Szabo, 1982 (p.212, figs.F,M); Mazzocchi & al., 1995 (p.138, figs.F,M, Rem.); Markhaseva, 1996 (p.111, figs.F,M); Chihara & Murano, 1997 (p.683, Pl.34: F,M); Bradford-Grieve & al., 1999 (p.879, 920, figs.F,M); G. Harding, 2004 (p.54, figs.F); Mulyadi, 2004 (p.56, figs.M, Rem.); Yamaguchi & al., 2005 (p.835, Tabl. VIII); Vives & Shmeleva, 2007 (p.553, figs.F,M, Rem.)
Species Chiridius gracilis - Plate 1 of morphological figuresissued from : T. Park in Antarctic Res. Ser. Washington, 1978, 27. [p.123, Fig.13].
Female: A, habitus (dorsal view); B, idem (lateral view); C, urosome (dorsal view); D, idem (left lateral view); E, Mx1; F, P1; G, P2; H, P3. Legs 1-3: anterior view.

Species Chiridius gracilis - Plate 2 of morphological figuresissued from : E.L. Markhaseva in Trudy Zool. Inst. RAN, St. Petersburg, 1996, 268. [p.112, Fig.83].
Female. figures from specimens from different stations. Gn: genital field (ventral); Gntb Md: gnathobase of Md (partial).

Species Chiridius gracilis - Plate 3 of morphological figuresissued from : E.L. Markhaseva in Trudy Zool. Inst. RAN, St. Petersburg, 1996, 268. [p.113, Fig.84].
Male (from different specimens, SE Pacif.). P.md: mandibular palp..

Species Chiridius gracilis - Plate 4 of morphological figuresissued from : T. Park in Bull. Mar. Sci., 1975, 25 (2). [p.283, Fig.7]
Female (from Gulf of Mexico): a, urosome (dorsal); b, posterior part of metasome and urosome (right side, lateral); c, exopod of P1 (anterior); d, P2 (anterior); e, lateral portion of third exopodal segment of P2 (anterior). P1-2: legs.

Species Chiridius gracilis - Plate 5 of morphological figuresissued from : T. Park in Bull. Mar. Sci., 1975, 25 (2). [p.284, Fig.8].
Male (from Gulf of Mexico): a, b, habitus (dorsal, lateral, respectively); c, forehead (lateral); d, A2; e, distal part of Mxp; f, P1 (anterior); g, P2 (anterior); h, third exopodal segment of P2 (anterior); i, P3 (anterior); j, fifth pair of legs (posterior). P1-3: legs.

Species Chiridius gracilis - Plate 6 of morphological figuresIssued from: M.G. Mazzocchi, G. Zagami, A. Ianora, L. Guglielmo & J. Hure in Atlas of Marine Zooplankton Straits of Magellan. Copepods. L. Guglielmo & A. Ianora (Eds.), 1995. [p.139, Fig.3.23.1].
Female: A, habitus (dorsal); B, P2.
Nota: Proportional lengths of urosomites and furca 37:22:19:8:14 = 100. Exopod 3 of P2 with outer margins between spines, moderately bulged in the middle (as compared to C. molestus).

Male: C, habitus (dorsal).
Nota: Proportional lengths of urosomites and furca 17:27:22:19:2:13 = 100. Mxp with last endopod segment bearing strong seta ornated with two rows of small teeth.

Species Chiridius gracilis - Plate 7 of morphological figuresIssued from: M.G. Mazzocchi, G. Zagami, A. Ianora, L. Guglielmo & J. Hure in Atlas of Marine Zooplankton Straits of Magellan. Copepods. L. Guglielmo & A. Ianora (Eds.), 1995. [p.140, Fig.3.23.2].
Female (SEM preparation): A, habitus (dorsal); B, forehead (ventral); C, urosome (ventral); D, P2; E, last exopod segment of P2.
Bars: A 0.500 mm; B-D 0.100 mm; E 0.050 mm.

Species Chiridius gracilis - Plate 8 of morphological figuresissued from : O. Tanaka in Publ. Seto Mar. Biol. Lab., 1957, VI (1). [p.49, Fig.30].
Male: a, habitus (dorsal); b, forehead (anterior view); c, last thoracic segment (lateral); d, P5; e, detail of the characteristic setae of 5th segment of endopod of Mxp.
Nota: Head and 1st thoracic segment fused, 4th and 5th fused. Rostrum represented by a thin triangular plate. Proportional lengths of urosomites and furca 18:26:25:17:2:12 = 100. 2nd to 4th urosomal segments are fringed with fine teeth on the distal margin. A1 (23-segmented) extends to distal margin of last thoracic segment. mx1: 5 setae on outer lobe, 9 setae on exopod, 9 setae on endopod, 1st inner lobe with aesthetask-like filaments.

Species Chiridius gracilis - Plate 9 of morphological figuresissued from : A. Scott in Siboga-Expedition, 1909, XIX a. [Plate XI, Figs.1-9]. With doubt.
Female (from Indonesia-Malaysia): 1, habitus (dorsal); 2, forehead (lateral); 3, last thoracic and genital segments (left side); 4, A1; 5, Md; 6, Mxp; 7, P1; 8, P2; 9, P4.
Nota: The spines of the last thoracic segment are produced distinctly beyond the middle of the genital segment. Terminal spine of the seopodite of P4 with 22 teeth.

Species Chiridius gracilis - Plate 10 of morphological figuresissued from : J.M. Bradford in Mem. N. Z. Oceonogr. Inst., 1972, 54. [p.39, Fig.7, (1-2)].
Female (from Kaikoura, New Zealand): 1, habitus (dorsal); 2, P2.
Scale bars: 1 mm (1): 0.1 mm (2).

Species Chiridius gracilis - Plate 11 of morphological figuresissued from : G.P. Farran in Fish. Ire. Sci. Invest., 1906, II [1908]. [Pl. II, Figs.1-3].
Female (from 52°6N, 12°0'W): 1-2, habitus (dorsal and lateral, respectively); 3, P2.

Species Chiridius gracilis - Plate 12 of morphological figuresissued from : A.G. Lewis, S. Allen & G. Martens in Crustaceana, 2006, 79 (4). [p.505, Fig.3];
Male (from off British Columbia coast): lateral view of the median intersomitic ridge (MIR) with right 1st pereiopod (P-1) removed.
P-1 = left 1st periopod; rc= ridge crest; TR = transverse ridge.; IcS = intercoxal sclerite.

Species Chiridius gracilis - Plate 13 of morphological figuresissued from : Mulyadi in Published by Res. Center Biol., Indonesia Inst. Sci. Bogor, 2004. [p.57, Fig.31].
Male (from Flores Sea): a, habitus (dorsal); b, forehead (lateral); c, posterior end of last thoracic segment and genital somite; d, P1; e, P2; f, P3 (exopodite segments 2 and 3 missing); g, P5.

Species Chiridius gracilis - Plate 14 of morphological figuresissued from : D.F. Arcos in Rev. Com. Perm. Pacifico Sur, 1976, 5. [Figs. 6, 8].
Male (from Magallanes region): 6, P2; 8, P5.
Scale bars: 200 µ.

Species Chiridius gracilis - Plate 15 of morphological figuresChiridius gracilis Female:
1 - Exopod of Mx1 with 8 setae. Points of last thoracic segment reaching the midlength of the genital segment, usually longer.
2 - Exopodal segment 3 of P2 without bulge and excavation between 2nd and 3rd external spines. Endopodal segment 2 of Md commonly with 9 setae.
3 - Exopodal segments 1 and 2 of P1 with external spines reaching or exceeding the base of next spine. Endopod of P2 2-segmented (sometimes separation obscure), mostly not reaching the border between exopodal segments 2-3.

Species Chiridius gracilis - Plate 16 of morphological figuresChiridius gracilis male:
1 - Points of last thoracic segment not longer than genital segment.
2 - Right P5 longer than left. Exopodal segments 1 and 2 of P1 with external spines reaching the midlength of the next segment or longer.
3 - Points of last thoracic segment reaching the posterior border of genital segment. Endopodal segment 1 of Mxp with 3 medial setae.
4 - Exopodal segment 1 of P1 not reaching the base of following spine.
5 - P5 longer than than half length of P4.
6 - Distal segment of left P5 3 times longer than wide.

Species Chiridius gracilis - Plate 17 of morphological figuresIssued from : O. Tanaka in Japanese J. Zool., 1937, VII, 13. [p.256, Fig.6].
Female (from coast of Heda, Japan): a, habitus (dorsal); b, abdomen (dorsal); c, last thoracic segment and abdomen (lateral), right side); d, spine of last thoracic segment; e, P1; f, P2.

Nota: Cephalothorax: 1.94 mm; abdomen: 0.66 mm.
Lateral spines on the last thoracic segment rather convergent and project to the middle of the genital segment; the distance between spines half the greatest width of the cephalothorax.
Combined length of the abdomen and caudal rami slightly longer than 1/3 of the cephalothorax.
Genital segment about as long as the 2nd and 3rd segment together.
2nd abdominal segment longer than the 3rd.
Anal segment equal to half the length of the 3rd segment.
Caudal rami longer than the anal segment and 1 1/3 as long as wide.
20th segment of A1 more than 4-times as long as wide.
Outer marginal spine of the 1st exopodal segment of P1 extends to the base of the 2nd segment.
In P2: Endopodite does not extend to the base of the 3rd segment of the exopodite [doubtful in the figure].
In P3: Endopodite shorter than that of Chiridius poppei.
Terminal spine on the exopodite of P2 to P4 with 24, 28 and 26 teeth respectively.

Species Chiridius gracilis - Plate 18 of morphological figuresIssued from : V.N. Andronov in Russian Acad. Sci. P.P. Shirshov Inst. Oceanol. Atlantic Branch, Kaliningrad, 2014. [p.85, Fig.22: 15]. after Markhaseva, 1996.
Male P5.

Compl. Ref.:
Lysholm & Nordgaard, 1921 (p.12); Sewell, 1948 (p.347); C.B. Wilson, 1950 (p.189); Mazza, 1966 (p.70); Furuhashi, 1966 a (p.295, vertical distribution in Kuroshio region, Table 10) ;Park, 1970 (p.475); Björnberg, 1973 (p.323, 389); Arcos, 1976 (p.85, Rem.: p.93, Table II); Vives, 1982 (p.291); Brenning, 1983 (p.2, Rem.); Roe, 1984 (p.356); Tremblay & Anderson, 1984 (p.3); Brenning, 1985 a (p.28, Table 2); Mackas & Anderson, 1986 (p.115, Table 2); Wiebe & al., 1988 (tab.7); Shih & Marhue, 1991 (tab.2, 3); Errhif & al., 1997 (p.422); Suarez-Morales & Gasca, 1998 a (p107); Dolganova & al., 1999 (p.13, tab.1); Razouls & al., 2000 (p.343, Appendix); Holmes, 2001 (p.47); Sameoto & al., 2002 (p.12); Bradford-Grieve, 2004 (p.284); Hsiao & al., 2004 (p.325, tab.1); Park, W & al., 2004 (p.464, tab.1); Lo & al., 2004 (p.89, tab.1); Lewis & al., 2006 (p.501, Table I, fig.3); Kosobokova & al., 2007 (p.929: Tab.7); Gaard & al., 2008 (p.59, Table 1, N Mid-Atlantic Ridge); Darnis & al., 2008 (p.994, Table 1, figs.8, 9); Pepin & al., 2008 (p.1, 44, figs. 25 cont'd, 33, interannual variations); Galbraith, 2009 (pers. comm.); Park & Ferrari, 2009 (p.143, Table 4, Appendix 1, biogeography); Lewis & al., 2010 (p.695, Table I); Hidalgo & al., 2010 (p.2089, Table 2); Teuber & al., 2013 (p.1, Table 1, abundance vs oxygen minimum zone); Bonecker & a., 2014 (p.445, Table II: frequency, horizontal & vertical distributions)
NZ: 21

Distribution map of Chiridius gracilis by geographical zones
Antarct. (S Atlant., S & SE Pacif.), Magallones region, sub-Antarct. (Indian, S & SE Pacif.), South Africa, Angola, off Mauritania, Brazil, G. of Mexico, G. of St. Lawrence, off E Nova Scotia, Flemish Cape, S Iceland, off Ireland (S & W), N Scotland, Faroe Is., Norway Sea, Bay of Biscay, off W Cape Finisterre, Medit. (Tyrrhenian Sea, Lebanon), off S Laccadive Is., N Indian, S Indian (subtropical convergence), Indonesia-Malaysia, Flores Sea, Molucca Sea, Halmarea Sea, Philippines, China Seas (East China Sea, South China Sea), Taiwan (E, N: Mienhua Canyon), Japan Sea, Japan, Suruga Bay, SW Bösö, G. of Alaska (Icy Strait), NE Pacif. (Strait of Georgia, ? Reine Charlotte Is., British Columbia, Fjord system (Alice Arm & Hastings Arm), Portland Inlet, Saanich Inlet), Guaymas Basin, New Zealand (Kaikoura), Australia (Great Barrier), Chile (N-S), Straits of Magellan (Pacific and central area), Arct. (SE Beaufort Sea in Darnis & al., 2008 (p.994, Table 1)
N: 53
(5) F: 2,4; (7) F: 2,69; (24) F: 2,8-2,4; (25) F: 2,79; (29) F: 2,2; (34) F: 2,7; (35) F: 2,4-2,3; (36) F: 2,88-2,65; M: 2,43-2,29; (37) F: 2,8-2,45; M: 2,32-1,96; (39) F: 2,55; M: 2,32; (113) F: 2,87-2,4; M: 2,25-2,03; (116) F: 2,61; 2,54; (128) F: 2,64-2,57; (227) F: 3,1-2,68; M: 2,57-2,33; (231) M: 2,03; 2; (866) F: 2,2-2,87; M: 2,03-2,32; (1089) F: 2,6-3,1; M: 2,3-2,6; (1109) F; 2,5; (1122) M: 2,32; {F: 2,20-3,10; M: 1,96-2,60}
Rem.: Mesopelagic.
Sampling depth (Antarct., sub-Antarct.) : 0-1000 m
There are some disagreements on synonymies between the authors.
Found by Markhaseva (1996, p.111) in the southernmost from the Antarctic sector of the Pacific Ocean and for the first time in the north-eastern part the Indian Ocean.
Found in the Namibia-Angola region by Teuber & al., 2013 (Table 1) for the first time (epipelagic and mesopelagic)
Last update : 19/12/2016
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