COLLETTE and CHAO: SYSTEMATICS AND MORPHOLOGY OF THE BONITOS (SARDINI) 



Figure 34.-Left angulars and retroarticulars of six species of Sardini, external view. Line 

 indicates position of retroarticular. a. Cybiosarda elegans, New South Wales, 355 mm FL. b. 

 Orcynopsis unicolor, Tunisia, 645 mm FL. c. Sarda australis, New South Wales, 407 mm 

 FL. d. Sarda sarda, Tunisia, 504 mm FL. e. Gymnosarda unicolor, Truk Islands, 772 mm 

 FL. f. Allothunnus fallal, California, 680 mm FL. 



Allothunnus as in Thunnus. There is also an 

 anterodorsally projecting spine on the dorsal edge 

 of the angular. This spine has a sharp point in the 

 bonitos, except in Gymnosarda where the spine is 

 heavier and blunt as in Scomberomorus. The re- 

 troarticular bone (frequently called angular) is 

 rhomboid and attached firmly to the posteroven- 

 tral margin of the angular. No differences were 

 found among the retroarticulars of the bonitos. 



PALATINE ARCH. -The palatine arch consists 

 of four pairs of bones in the roof of the mouth: 

 palatine, ectopterygoid, entopterygoid, and me- 

 tapterygoid. 



Palatine.-For illustration (Figure 35), the pala- 

 tine bones were placed flat with the external side 

 up and tipped so that when viewed from above the 

 palatine teeth and part of the anterior end of dor- 

 sal ridge were exposed. A longer ventral ridge and 

 a shorter dorsal ridge are present as in Thunnus. 

 Cybiosarda, Orcynopsis, Gymnosarda, and 



Figure 33.-Left dentaries, external view, of six species of Sar- 

 dini. a. Cybiosarda elegans. New South Wales, 355 mm FL. b. 

 Orcynopsis unicolor, Tunisia, 645 mm FL. c. Sarda australis. 

 New South Wales, 495 mm FL. d. Sarda orientalis, Tokyo, 500 

 mm FL. e. Gymnosarda unicolor, Truk Islands, 775 mm FL. f. 

 Allothunnus fallai, Tasmania, 775 mm FL. 



Allothunnus have slightly elongated dorsal ridges 

 compared to Sarda (Figure 35c, d). The anterior 

 process of the dorsal ridge is hooked in all bonitos 

 except Allothunnus in which the distance between 

 the process and the front of the ventral ridge is 

 greater (Figure 35f ). 



Teeth are located along the inferior margin of 

 the ventral ridge. Palatine teeth vary from a rela- 

 tively few, large, conical teeth curved posteriorly 

 and arranged in a single row to a broad roughened 

 patch of tiny villif orm teeth. Species of Sarda have 

 one row of small conical teeth, the number of teeth 

 varying from 7 to 22, usually 10-18. Sarda chilien- 

 sis has the most palatine teeth (9-22, x 15.2) but it 

 broadly overlaps with the other three species: S. 

 sarda (8-21, x 12.3), S. orientalis (8-19, x 11.9), and 

 S. australis (7-14, x 10.7). Cybiosarda has about 50 

 small teeth in two or three rows; Orcynopsis about 

 75 tiny teeth in a patch one or two rows wide 

 posteriorly and about five rows anteriorly; and 

 Gymnosarda has an elongate oval tooth patch with 

 hundreds of tiny teeth. There are even more and 

 smaller teeth in Allothunnus, so small that 

 Nakamura and Mori (1966) thought they were ab- 

 sent. 



Ectopterygoid. -All bonitos have a slender T- 

 shaped ectopterygoid (Figure 36). The ventral 



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