439 



equal to the length of the head. The oral sinus occupies nearly half the 

 height of the head. 



The length of the 2nd segment of pereopods V is slightly more than 

 twice its width; the 5th segment is approximately the same length as 



356 the 2nd segment; the proximal denticle on the anterior margin is large; 

 the length of the larger denticles is approximately 1/3 the width of the 

 segment and that of the smaller denticles approximately half the width 

 of the 6th segment; the 6th segment is weakly curved. The length of the 

 2nd segment of pereopods VI is twice its width, and the anterior margin 

 is uniformly bulged; the posterior margin of the 6th segment has very 

 fine spinules, noticeable only under high magnification, the 2nd segment 

 of pereopods VII is approximately the same length as the rest of the 

 segments together. 



The tip of uropods III is less sharply stretched than in P. macropa. 



Distribution: Warm-water and temperate regions of the Pacific 

 Ocean. Also found in the southeastern part of the Gulf of Guinea. 

 Apparently lives in warmer waters than P. macropa but unlike 

 P. latreillei, is not confined to tropical and subtropical waters and even 

 enters temperate zones. 



3. Primno latreillei Stebbing, 1888 (Fig. 191) 



Stebbing, 1888: 1445.— johnsoni Bowman, 1978: 15. 



Length up to 9 mm. 



The body is well proportioned. The rostrum is short and pointed. 

 The pereon is 3.5 times longer than the head and approximately the same 

 length as the pleon. Antennae I in females are almost 1/3 the length of 

 the head. The oral sinus occupies nearly half the height of the head. 



The length of the 2nd segment of pereopods V is slightly less than 

 3 times its width; the 5th segment is approximately the same length as 



357 the 2nd segment; the proximal denticles on the anterior margin are large, 

 the length of the largest denticles of the anterior margin almost equal 

 to the width of the segment, the length of the smaller denticles equal to 

 the width of the 6th segment; the 6th segment is almost straight. The 

 2nd segment of pereopods VII in females is longer than the rest of the 

 segments together; in males it is roughly equal to them. 



Uropods III are the same shape as in P. brevidens and the tip less 

 stretched than in P. macropa. 



Notes: Primno macropa and P. latreillei differ in: 1) size — P. macro- 

 pa reaches 21 mm; 2) sequence of smaller and larger denticles on the 5th 

 segment of pereopods V; and 3) geographic distribution — P. latreillei 

 inhabits tropical and subtropical waters while P. macropa replaces it 

 in temperate and subpolar regions. The remaining differences are less 

 significant. In such a situation it would appear that P. macropa and 

 P. latreillei are cold- and warm-water subspecies of the same species. 



