CRESSEY ET AL.: COPEPODS AND SCOMBRID FISHES 



Figure 7. — Numbers of copepod species on Scomberomorus commerson in different areas of its distribution 

 (large numbers represent number of copepod species; small numbers represent number of hosts examin- 

 ed). 



orientalis, S. australis) with infestations of 8-12%. 



Acanthocybium Gill 



This monotypic genus appears to be a specialized 

 offshoot of Scomberomorus and does not merit place- 

 ment in its own subfamily or tribe as has been ad- 

 vocated by some previous authors (e.g., Starks 1910). 

 It is closest to the Cyhium group of Scomberomorus 

 (S. cavalla andS. commerson), according to Conrad 

 (1938) and MagoLeccia (1958). The wahoo, A. solan- 

 dri (Cuvier), is a large species (reaching over 1,500 

 mm SL) and has a well-developed swim bladder. It is 

 a high-seas epipelagic species found round the world 

 in tropical and subtropical waters. Copepod fauna: 6 

 species in 5 genera. A canthocybium is similar to the 

 other Scomberomorini in being parasitized by Shi- 

 inoa and Tuxophorus, but the rate of infestation is 

 very low. The most common two copepods are the eu- 

 ryphorid Gloiopotes hygomianus (infestation rate of 

 42% of our 64 specimens, 54% of the 100 fish from 

 the Line Islands examined by Iverson and Yoshida 

 1957) and the lerneopodid Brachiella thynni (61% of 

 our specimens, 98% of those examined by Iverson 



and Yoshida). The other four species of Gloiopotes 

 are parasites of billfishes (Istiophoridae). 



Some workers in the past (e.g., Liitken 1880) and 

 the present (G. David Johnson, pers. commun. 4 ) be- 

 lieve that Acanthocybium is closely related to the 

 billfishes. We feel that the parasite data are best in- 

 terpreted as evidence of ecological similarity between 

 the groups (fast swimming, high-seas species) rather 

 than as evidence of phylogenetic relationships. Bra- 

 chiella thynni was also found on three species of 

 Thunnus (T. obesus, T. albacares, and T. thynnus) 

 and two of Scomberomorus (S. regalis and S.plurilin- 

 eatus). This species has been reported from a variety 

 of hosts, usually attached in the axil of the pectoral 

 fin. A second species of Brachiella is known only from 

 two western Pacific species of Scomberomorus . There 

 seems little ecological or phylogenetic information 

 that can be drawn from parasitism by Brachiella. 



Parasitic copepods of the genera Tuxophorus and 

 Gloiopotes suggest relationships between Scomber- 

 omorus and Acanthocybium of the Scomberomorini 



4 G. David Johnson, South Carolina Wildlife and Marine Re- 

 sources Department, Charleston, SC 29412. 



239 



