Pelamichthys Giglioli 1880:25 (type-species 

 Scomber unicolor Geoffroy St. Hilaire by 

 original designation). 



Comparative Diagnosis.-The monotypic genera 

 Orcynapsis and Cybiosarda share several impor- 

 tant characters that distinguish them from Sarda 

 and Gymnosarda: low and poorly developed bony 

 caudal keels versus well-developed caudal keels' 

 divided into anterior and posterior sections; right 

 lobe of liver longest versus right and left lobes 

 much longer than the middle lobe; spleen small and 

 not visible in ventral view versus large and 

 prominent in ventral view. Both genera have high 

 first dorsal fins (Figure la, b) and are relatively 

 more compressed (almost like Scomberomorus) 

 than fusiform. Orcynopsis, Cybiosarda, and Gym- 

 nosarda have two patches of tongue teeth, but the 

 patches are attached to the glossohyal bone in Or- 

 cynopsis and Cybiosarda and are on separate 

 plates that fit over the glossohyal in Gymnosarda. 



FISHERY BULLETIN: VOL. 73, NO. 3 



Orcynopsis differs from Cybiosarda most ob- 

 viously in lacking the bold pattern of stripes and 

 blotches on the body of the latter. Orcynopsis has 

 lower counts than does Cybiosarda: vertebrae 

 37-39 vs. 47-48; dorsal spines 12-14 vs. 16-18; second 

 dorsal rays 12-15 vs. 17-19; pleural ribs 16 vs. 20; 

 and intermuscular bones 19-20 vs. 24-25. 



Orcynopsis unicolor is a short-bodied and 

 short-headed species (Table 15). It has a shorter 

 snout-anal and snout-second dorsal distance than 

 do other bonitos. The snout-first dorsal and snout- 

 pelvic fin origin distances are shorter than in other 

 bonitos except Gymnosarda unicolor and Sarda 

 australis. The snout-pectoral fin origin, pelvic fin 

 insertion-vent, and pelvic fin tip-vent distances 

 are all shorter than in other bonitos except Gym- 

 nosarda. The fins are high compared to fork 

 length, the second dorsal and anal fins are higher 

 than in other bonitos except for the second dorsal 

 in Cybiosarda. The bases of the second dorsal and 



Table 15.-Coinparison of morphometric characters of three populations of 

 Orcynopsis unicolor. First set of numbers are measurements expressed as 

 thousandths of fork length, second set as thousandths of head length. 



592 



