PUERTO RICAN COPEPODS — GONZALEZ AND BOWMAN 271 



Al is a little longer, reaching the middle of the posterior margin of 

 PedSeg 4 ; and Re3 of Pi has only 2 instead of 3 outer spines. Lindberg 

 gives no indication as to the source of his information on the caudal 

 setae of 0. hebes. Pesta (1921) and Rose (1933) repeated Giesbrecht's 

 illustrations and diagnosis without adding any details; hence, Lind- 

 berg's information on the caudal setae of 0. hebes was not taken from 

 any literature known to us. 



At our request, Dr. Peter Dohrn kindly searched for Oithona hebes 

 in the Giesbrecht collection at the Naples Zoological Station and 

 reported (in litt., May 4, 1963) that it is not present. Fortunately, 

 through the kindness of Dr. Harold Loesch, Institute Nacional de 

 Pesca del Ecuador, we obtained several plankton samples from 

 Guayaquil, Ecuador, the type locality of 0. hebes. Some of these 

 samples contained specimens of 0. hebes agreeing closely with the 

 descriptions of Giesbrecht and of Kiefer. As shown in figure 206, the 

 caudal ramus is twice as long as wide, and the medial apical seta is 

 about twice as long as the lateral apical seta, contrary to the state- 

 ment in Lindberg's key. 



The identity of Oithona hebes is clarified by these findings, but there 

 remains the problem of how to treat the Puerto Rican form, which 

 differs only in the proportions of the caudal ramus. Should it be 

 considered a distinct species, a subspecies of 0. hebes, or included 

 under 0. hebes without further nominal status? We are arbitrarily 

 following the last course here but wish to emphasize that a decision 

 cannot be made until reasonably complete information is available 

 on the distribution of the 2 forms and the presence or absence of 

 intergrades. 



0. ovalis Herbst, from Canan^ia, Brazil, appears to be very close to, 

 if not identical with, 0. hebes. Other species that resemble 0. hebes 

 in having 2 thick setae on B2 of Md are 0. minuta T. Scott (1894) 

 and 0. brevicornis Giesbrecht (1891). 0. minuta, from the Gulf of 

 Guinea, differs in that P5 has 2 terminal setae (placing it in Dioithona 

 Kiefer, 1935) ; the genital segment has lateral spinulose areas, and the 

 lateral apical setae of the caudal rami are very long. 0. brevicornis, 

 originally described from Hong Kong, differs in having a well- 

 developed rostrum. A species of Oithona identified as 0. brevicornis 

 by Wilson (1932a, 1932b) and Grice (1960a, 1960b) occurs along the 

 east and Gulf of Mexico coasts of the United States. Wilson reported 

 it from Chesapeake Bay (1932a) and Penzance Pond, Woods Hole, 

 Mass. (1932b), and Grice found it to be abundant in nearshore and 

 estuarine waters along the west coast of Florida. 



One of us (Bowman) has identified this species from off Jacksonville, 

 Fla., and from Laguna Madre of Texas. The identity of the United 

 States species with the Hong Kong species is questionable since in 



