PUERTO RICAN COPEPODS — GONZALEZ AND BOWMAN 273 



Distribution. — Widespread in temperate and tropical coastal 

 waters. In the Puerto Rican collections it was common both in the 

 bays and on the shelf. 



Oithona oculata Farran 



Figures 20h-i, 2la-e 



Oithona oculata Farran, 1913, pp. 188-189, pi. 30, figs. 8, 9; pi. 31, figs. 2-9.— 

 Rosendorn, 1917, pp. 37-39.— Kiefer, 1929, p. 10.— Sewell, 1947, pp. 254- 

 255.— Tanaka, 1960, pp. 60-61, pi. 26, figs. 5-10.— Bjornberg, 1963, p. 76.— 

 Vervoort, 1964, pp. 25-26. 



Dioithona oculata (Farran). — Kiefer, 1935, p. 322. 



Female. — Length 0.65-0.70 mm. Prosome:urosome = about 1.5. 

 Head rounded anteriorly. Rostrum absent, but head is slightly pro- 

 duced in front of and between Al (fig. 20A). Genital segment with 

 sclerotized transverse dorsal ridge m middle. Last 3 urosome seg- 

 ments and caudal ramus subequal. Caudal ramus about 2.8 times as 

 long as wide; lateral marginal seta inserted sUghtly proximal to 

 middle of margin, half as long as lateral apical seta; relative lengths of 

 apical seta (lateral apical = 1) 1:3.4:4.1:1.9; dorsal seta = 1.1. 

 Head with pair of lenses surrounded by blue pigment. Al reaches 

 middle of PedSeg 2. B2 of Md with 2 slender plumose setae; Ri with 

 5 setae. Re of P1-P4 armed as follows: 



Outer setae: 1-1-3, 1-1-3, 1-1-3, 1-1-2. 

 Inner setae: 1-1-4, 1-1-5, 1-1-5, 1-1-5. 



Terminal seta of P4 slightly longer than Re. P5 consists of short 

 broad basal segment with long outer seta and narrow distal segment 

 bearing 2 apical setae reaching posterior margin of genital segment. 

 Egg sacs each with 8 eggs. 



Male. — Length about 0.60 mm, Prosome: urosome = about 1.4. 

 Terminal segment of Al drawn out into point distal to insertion of 

 setae and aesthetascs. Seta of P6 reaches beyond middle of urosome 

 segment 3. 



Remarks. — The conspicuous ocular lenses, the transverse ridge on 

 the genital segment, and the 2 terminal setae on P5 separate 0. 

 oculata from other Puerto Rican species of Oithona. The ridge on the 

 genital segment is not mentioned by Farran and not shown in his 

 illustrations. We have not seen material from the type locality 

 (Christmas Island, Indian Ocean), but we have examined specimens 

 from Ifaluk Atoll, Caroline Islands, also studied by Vervoort (1964) 

 and identified by him as Oithona oculata. The Ifaluk specmiens 

 closely resemble the Puerto Rican specimens and have the dorsal 

 transverse ridge on the genital segment. The only difference we have 

 noted is that the caudal ramus is slightly shorter in relation to its 

 width in the Ifaluk specimens (cf. figs. 21c, 2ld). 



