COPEPODA FROM IFALUK ATOLL 265 



Genus Nitocra Boeck, 1864 



Nitocra affinis Gurney, 1927 



Figures 105c, 106fir, 107-109 



Nitocra affinis Gurney, 1927, pp. 545, 546, fig. 154.— Willey, 1930, p. 93.— Gurney, 

 1932, p. 54.— Lang, 1935, p. 6.— Chappuis, 1938, pp. 155, 159.— Sewell, 

 1940, pp. 359, 369.— Lang, 1948, p. 820, fig. 328 (no. 1).— Humes, 1953, p. 

 366.— Petkovski, 1954, pp. 106, 111, figs. 57-60.— Roe, 1958, pp. 230, 250, 

 figs. 131-136. 



Material. — Loc. 589, 1 ad. 9, damaged, not measured; 1 ad. d^, 

 0.42 mm. Loc. 590, 2 ad. 99, 0.43-0.45 mm.; 1 ad. cf , 0.42mm. Loc. 

 591, 5 ad. cTc^, 0.42-0.50 mm. (0.46 mm.). Loc. 592, 2 ad. 99, 0.47 

 and 0.56 mm. 



Description. — The following is based on a female specimen of 

 0.56 mm. length from locality 592 and a male of 0.42 mm. from 

 locaHty 591. 



Adult female (loc. 592), 0.56 mm.; greatest diameter 0.14 mm.; 

 length of longest furcal seta 0.39 mm. 



General shape of body slender, with greatest diameter at end of 

 cephalic somite, rounded anteriorly and very gradually narrowing 

 posteriorly. Cephalothorax and abdomen of nearly same length 

 (proportion 11:10), distinctly separated by ring-shaped constriction; 

 all thoracic and abdominal somites stand out fairly distinctly by 

 more shallow constrictions of same character (fig. 107a). Head and 

 1st thoracic somite fused to form cephalic somite, which is slightly 

 longer than combined lengths of thoracic somites 2 to 3. Back in 

 lateral aspect moderately curved, running into small, forwardly di- 

 rected rostrum (fig. 1076). Rostrum small, placed between two depres- 

 sions at insertion of antennules, conical, with rounded apex, half 

 length of 1st antennular segment. Sides of cephalic somites slightly 

 produced and broadly rounded to shield basal parts of oral append- 

 ages. Epimeral plates of 2nd and 3rd thoracic somites rounded; 

 of 4th somite, cut off squarely. 



5th thoracic somite very distinct in lateral and dorsal aspects, 

 with dorsolateral row of spinules on both sides. Genital somite 

 composed of two almost completely separated somites; separation 

 is marked further by almost completely closed row of spinules at 

 distal end of 1st abdominal somite (interrupted only ventraUy). 

 Such a row of spinules also occurs on 2nd to 4th abdominal somites. 

 The 1st to 4th abdominal somites have, on each side, an additional 

 oblique row of spinules, the position of which appears from figures 

 107a,6. Somites 1, 3, and 4 of nearly equal length, somite 2 slightly 

 longer. 



