Species Card of Copepod
Calanoida ( Order )
    Diaptomoidea ( Superfamily )
        Acartiidae ( Family )
            Acartia ( Genus )
                Acanthacartia ( Sub-Genus )
Acartia (Acanthacartia) tsuensis  Ito, 1956   (F,M)
Ito, 1956 (p.470, figs.F,M); Greenwood, 1972 (p.317); Takahashi & Ohno, 1996 (p.125, figs. Nauplius, juv., F,M); Chihara & Murano, 1997 (p.671, Pl.20: F,M)
Species Acartia (Acanthacartia) tsuensis - Plate 1 of morphological figuresissued from : T. Ito in Pacif. Sc., 1956, 10 (4). [p.471, Fig.2].
Female (from brackish ponds, Kumozu and Heta regions, middle Japan): a, habitus (dorsal); b, last thoracic segment and urosome (dorsal); c, forehead (ventral); d-g, P1 to P4; h, P5.
Nota: Head and 1st thoracic segment separated, 4th and 5th fused.
A1 17-segmented, reaching to middle portion of genital segment.
Rostral filaments more slender than in A. iseana ( = A. sinjiensis).
Last two thoracic segments fused, lateral angle rounded with 6 spinules on either side.
Genital segment scarcely longer than other two abdominal segments combined ; first two abdominal segments each with 6 spinules along distal margins of dorsal surface.
Caudal rami rather shorter than that of A. iseana ( = A. sinjiensis), 1.5 times as long as wide.
P5 with basal segment longer than wide, outer seta rather slender and long ; exopodite unsegmented, proximal portion wider than distal spine, about 2 times as long as wide, bearing well-developeed, pointed process on outer edge ; terminal spine curved inwards midway, without spinules on either side

Male: i, P5.
Nota : P5 : Right leg with basal segment longer than wide (about 2 :1) ; lengths of basal segment and exopodite 1 and 2 (in micrometers) as 39 :42 :39 ; inner margin of exopodite 1 smooth ; inner lobe of exopodite 2 very prominent, about as long as wide, its top not bifurcate ; exopodite 3 very narrow at base, curved, without spines on outer margin, but with a spine on inner edge as in A. iseana ( = A. sinjiensis). Left leg : lengths of basal segment and exopodite 1 and 2 (in micrometers) as 46 :31 :26 ; basal segment rather slender, about 2 times as long as wide ; exopodite 1 very simple and smooth ; exopodite 2 consisting of 2 portions, proximal protuberance bearing a slender spine on inner margin and narrower distal portion with small spine on top and subapical small process.

Species Acartia (Acanthacartia) tsuensis - Plate 2 of morphological figuresissued from : T. Takahashi & A. Ohno in J. Oceanogr., 1996, 52 [p.128, 129, Figs.2, 3].
Female (from Momoshima station, coastal saltwater pond): A, P5; B, urosome (dorsal).
Nota: In the adult female of A. tsuensis, the terminal spine of the exopod of P5 is apparently more slender than in A. omorii.

Male: C, P5; D, urosome (dorsal).
The adult male of A. tsuensis possesses apparently curved setae on the caudal ramus , while they are nearly straight in A. omorii. In the adult male of A. omorii, the inner projection developed in the second segment of the right P5 exopod is bifurcated, while it is not bifurcated in A. tsuensis.

Compl. Ref.:
Uye S-i., 1982 (p.149, relation length-weight-C-N); Ohno & Okamura, 1988 (p.39); Ohtsuka & al., 1995 (p.159); Marcus, 1996 (p.143); Mauchline, 1998 (tab.33, 35, 36, 40, 47, 51); Lo & al., 2004 (p.468, tab.2); Kurihara & al., 2004 (p.721, CO2 effects); Kurihara & Ishimatsu, 2008 (p.1086, Rem: CO2 effects); Ohtsuka & al., 2008 (p.115, Table 5)
NZ: 2

Distribution map of Acartia (Acanthacartia) tsuensis by geographical zones
Japan: Inland Sea (bassin piscicole en eau saumâtre, Hiroshima), mers de Chine (East China Sea),Taiwan (Tapong Bay)
N: 7
(189) F: 0,992-0,893; M: 0,868-0,818; (866) F: 0,9-1; M: 0,8-0,9; {F: 0,893-1,00; M: 0,80-0,90}
Rem.: In brackish-water fish ponds (Mugil cephalus); Chlorinity: 6.696-7.768 p.1000.
The species resembles Acartia sinjiansis, but is distinguishable by the caudal ratio (1.5; exopodite of P5 in the female with a pointed process; inner prominence of right P5 in male rounded. (See table 1 from Greenwood, 1972, p.317).
For Takahashi & Ohno (1996) A. tsuensis seems to adapt to warm-water environment with an optimal water temperature of 25.0°C.
Last update : 11/02/2014
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[Accessed April 23, 2014]

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