PUERTO RICAN COPEPODS — GONZALEZ AND BOWMAN 255 



Family Acartiidae 



Body narrow; head and PedSeg 1 separated; PedSegs 4 and 5 fused. 

 Rostrum absent or consisting of 2 delicate filaments. Urosome 3-seg- 

 mented in female, 5-segmented in male. Upper lip large, prominent, 

 trilobed. Al long and slender; segments poorly defined and reduced 

 in number; setae generally plumose, some very long and arising from 

 swellings of the segments. Right Al of male prehensile, but not 

 greatly modified. Ri of A2 slender, much longer than Re. Mxp much 

 reduced, smaller than Mx2. P1-P4 slender; Ri 2-segmented, Re 

 3-segmented, outer spines reduced; inner setae long. Female P5 very 

 small, uniramous, 2-3-segmented. Male P5 uniramous, prehensile; 

 left P5 3-segmented; right P5 4-segmented. 



Genus Acartia Dana 



Prosome slender, usually widest posterior to middle, 2.5-4 times 

 as long as urosome. Genital segment not laterally expanded. Male 

 urosome segment 4 very small, sometimes partly fused with segment 5. 

 Female Al of 17-18 rather poorly defined segments. Mouthparts of 

 male and female alike. B2 of A2 fused with Ril, forming long 

 slender segment armed with 9 setae. Gnathal lobe of Md with large 

 gap between 2 anterior teeth; Re of palp much shorter than Ri. Mxl 

 with Ri apparently absent. Mx2 with long sparsely setose curved 

 setae reaching forward to mouth. Mxp with Bl apparently absent; 

 B2 broad; Ri much reduced. Female P5 3-segmented, segment 3 

 modified into long spine. Right male P5 larger than left, segment 3 

 with large inner lobe, segment 4 in form of cm-ved clasper. 



Remarks. — Steuer (1915, 1923) divided Acartia into 2 groups, 

 "Acartiae arostratae" and "Acartiae rostratae," according to whether 

 or not rostral filaments are present. He fm'ther divided the genus 

 into 8 subgenera, of which 2 were arostrate and 6 rostrate. Gurney 

 (1931) removed 1 arostrate subgenus (Acartiella) to the family Tortani- 

 dae and raised the rostrate subgenus Paracartia to its former full 

 generic rank, leaving 6 subgenera of Acartia. 



We beheve that a thorough study of the genus Acartia must be 

 carried out before the correctness of Steuer's action can be assessed, 

 and we therefore reserve judgment. 



Acartia lilljeborgii Giesbrecht 



Figures lOa-e, 11a 



Acartia lillgeborgn Giesbrecht, 1889, p. 25. 



Acartia lilljehorgii Giesbrecht.— Giesbrecht, 1892, pp. 508, 518-521, 523, pi. 30, 



figs. 8, 20, 30; pi. 43, figs. 1, 19.— Dahl, 1894, p. 23.— Breuer, 1962, p. 167. 

 Acartia (Odontacartia) lilljeborgi Giesbrecht. — Steuer, 1915, p. 397; 1923, pp. 



114-115, figs. 122-125. 



