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



Figure 8.-01factory rosettes (left) of eight species of Sardini. a. 

 Cybiosarda ekgans, New South Wales, 365 mm FL. b. Orcynopsis 

 unicolar, Tunisia, 645 mm FL. c. Sarda australis, New South 

 Wales, USNM 59881, 332 mm FL. d. Sarda chiliensis, Santa 

 Barbara, Calif., USNM 31104, 335 mm FL. e. Sarda chiliensis, 

 Callao, Peru, 571 mm FL. f. Sarda orientalis, Pearl Island, 

 Panama, USNM 128644, 505 mm FL. g. Sarda sarda, Portuguese 

 Guinea, 361 mm FL. h. Sarda sarda, Chesapeake Bay, 436 mm 

 FL. i. Gymnosarda unicolor, Bikini, USNM 140980. j. Allothun- 

 nusfallai, New Zealand, DM 2472, 740 mm FL. 



broad as in the most advanced scombrid 

 genersi—Thunnus, Euthynnus, Katsuwonus, and 

 Auxis (Kishinouye 1923; de Sylva 1955; Gibbs and 

 Collette 1967), but are broader than in the more 

 primitive genera— Scomber, Rastrelliger, Gram- 

 matorcynus, Scomberomorus, and Acanthocybium 

 (Allis 1903; Kishinouye 1923; Conrad 1938; Mago 

 Leccia 1958; Gnanamuttu 1971), except in Gym- 

 nosarda which has a broad and short skull (Figure 

 10; Kishinouye 1923, fig. 38). Allothunnus has a 

 more elongate and narrov^^ skull (Figure 11) than 

 do other bonitos. Bonitos lack the prominent 

 frontoparietal foramen (Gibbs and Collette 1967) 

 which is present on each side of the dorsal surface 



of the skull at (or near) the junction of the frontal, 

 parietal, and supraoccipital bones of the three 

 most advanced genera of Scombridae: Euthynnus, 

 Katsuwonus, and Thunnus. The corresponding 

 junction in bonitos does have a small hole and/or 

 an area of very thin dermal bone (see Figure 12 of 

 Sarda sarda). Two prominent dorsolateral crests 

 are present on each side of the neurocranium 

 (Figures 10-14). The inner crest arises at the 

 anterolateral edge of the frontal bone, extends 

 along the frontal and parietal bones, and ter- 

 minates at the posterolateral corner of the epiotic 

 bone. This crest is a thin bony process in all bonitos 

 except Allothunnus, in which it arises from the 

 posterior half of the frontal bones and has a much 

 thicker and wider anterior half than do the other 

 scombrid genera mentioned above. The primitive 

 scombrid Grammatorcynus resembles Allothun- 

 nus in this character. The outer crest (Figure 11), 

 which constitutes the posterolateral margins of 

 the neurocranial roof, is formed by the edges of 

 the frontal and pterotic bones. It originates at the 

 posterolateral region of the frontal bones and ex- 

 tends posteriorly as a flat pterotic spine. The 



SUPRAOCCIPITAL CREST 



BASISPHENOID 

 PTEROSPHENOID 



HYOMANDIBULAR 



LACHRYMAL 



FRONTAL 



NASAL 



PREMAXILIA 



FIRST NEURAL SPINE 



OPERCLE 



MAXILLA 



GLOSSOHYAL 

 TEETH 



PREOPERCLE 



SUBOPERCLE 



— INTEROPERCLE 



DENTARY 



ANGULAR 



MAXILLA 



METAPTERYGOID 



SUPRAMAXILLA 



QUADRATE 



ECTOPTERYGOID SYMPLECTIC 



Figure 9.-Lateral view of head of Gymnosarda unicolor, Bikini, Marshall Islands, USNM 11478, 750 mm FL. 



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