COPEPODS FROM EQUATORIAL WATERS OF PACIFIC OCEAN 



201 



al., 1955; Chiba, 1956; Honjo et al., 1957; Tanaka, 

 1958; Yamazi, 1958a. 



Vessel: Station Occurrence 



Hugh M. Smith __ 132 1 female, 2.50 mm. 



Do 63 1 female, 2.52 mm. 



Stranger 34 3 females, 2.24-2.38 



mm. ; 2 males, 



2.21, 2.35 mm. 

 Horizon 32 1 female, 2.55 mm.; 



3 males, 2.31-2.44 



mm. 

 Satsuma 32 2 females, 2.38, 2.40 



mm.; 1 male, 2.31 



mm. 



Remarks: The female is distinguished by 

 the long genital segment, the right posterior 

 margin of which is produced into a rounded 

 knob (fig. 2). The relative lengths of the 

 outer-edge spines on the second and third exo- 

 podal segments of the second feet (fig. 4) are 

 also diagnostic (cf. E. vmnna, plate 13, fig. 1). 

 The male is identified by the structure of the 

 terminal part of the left fifth foot (fig. 9). 



Euchaeta media Giesbrecht, 1888 



(Plate 13, figs. 10-14) 



Pacific records: Vervoort, 1957. Also, Johnson, 

 1942; Brodsky, 1950; Tsuruta and Chiba, 19.54b; Chiba, 

 Tsuruta, and Maeda, 1955; Nagaya et al., 1955; Hein- 

 rich, 1957b; Honjo et al., 1957; Tanaka, 1958. 



Vessel : Station Occurrence 



Hugh M. Smith __ 63 1 female, 3.52 mm. 



Remarks : The female of E. media is recog- 

 nized by the characteristic swelling on the left 

 side and the knob-like protrusion on the right 

 side of the genital segment (figs. 10, 11). The 

 middle spine on the outer edge of the third 

 exopodal segment of the second pair of feet is 

 elongate and the spine on the second exopodal 

 segment reaches beyond the base of the proxi- 

 mal spine on the third segment (fig. 14). 



Euchaeta tenuis Esterly, 1906 



(Plate 13, figs. 15-20) 



Pacific records: Esterly, 1906; Scott, 1909; Brodsky, 

 19.50. As E. solida, Esterly, 1911. 



Vessel : Statioyi Occurrence 



Hugh M. Smith — 29 4 females, 5.60-5.98 



mm. ; 3 males, 

 5.03-5.22 mm. 



Vessel : 



Do 



Do 



Station Occurrence 



-- 63 1 female, 5.13 mm.; 



1 male, 4.75 mm. 

 __ 32 present. 



Remarks: The large and asymmetrical ven- 

 tral protrusions (figs. 16, 17) of the female 

 genital segment will identify this species. The 

 outer-edge spines of the second pair of feet 

 (fig. 18) are also diagnostic. In the male the 

 structure of the second segment of the left fifth 

 foot (figs. 19, 20) is characteristic. It is di- 

 lated and coarsely serrate. 



Euchaeta concinna Dana, 1849 

 (Plate 14, figs. 1-13) 



Synonymy : 



Euchaeta consimilis Farran, 1936, Great Barrier 

 Reef Exped. 1928-29. Sci. Kept. 5(3): 90. 



Pacific records: Scott, 1909; Farran, 1936; Mori, 

 1937; Dakin and Colefax, 1940; Wilson, 1950; Tanaka, 

 1953; Rose, 1955; Honjo et al., 1957; Heinrich, 1958b; 

 Tanaka, 1958. As E. consimilis; Farran, 1936; Rose, 

 1955. 



Vessel : 



Satsuma 



Station 

 ._ 32 _.. 



Occurrence 

 3 females, 2.52-2.55 

 mm.; 1 male, 2.24 

 mm. 



Remarks: Farran (1936) described E. con- 

 similis from 4 female specimens collected near 

 the Great Barrier Reef. He also found E. con- 

 cinna in his collections, but this species was 

 observed only inside the reef where it was one 

 of the most characteristic of the copepods. Ac- 

 cording to Farran, consimilis differs, morpho- 

 logically, from concinna in the form of the pro- 

 trusion on the right side of the genital segment 

 in the female (see Farran's fig. 6) and in size. 

 As Farran pointed out, Sewell (1929) observed 

 "a considerable degree of variation" in the form 

 of the genital protrusion in concinna collected 

 in the Indian Ocean. The latter author sug- 

 gested that this variation may be correlated 

 with egg laying which causes the protrusion to 

 increase in size. 



The size of specimens, as recorded in the 

 literature is also variable. 



Source: Female 



Mori, 1937 (Japan) 3.0 mm. 



Tanaka, 1958 (Japan) 2.87-3.25 



mm. 



Male, 



