COLLETTE and RUSSO: SPANISH MACKERELS 



tatus and niphonius), and slightly concave in 

 most (commerson, maculatus, regalis, and caval- 

 la). We find similar tendencies, but there is 

 extensive variation even in small samples. Six 

 species tend to have the dorsal margin convex: 

 guttatus, koreanus, lineolatus, multiradiatus, 

 plurilineatus , and semifasciatus; seven species 

 tend to have the dorsal margin concave: cavalla, 

 commerson, maculatus, munroi, queenslandicus , 

 regalis, and sinensis; and five usually have the 

 dorsal margin nearly straight: brasiliensis , con- 

 color, niphonius, sierra, and tritor. 



Epihyal. — The epihyal is a triangular bone 

 which interlocks anteriorly with the ceratohyal. 

 It has a posterior process which articulates with 

 the interhyal. In Scomberomorus , two branchios- 

 tegal rays are seated on the ventral portion of 

 the epihyal, not three as stated by Devaraj (1977) 

 or shown by Mago Leccia (1958). Three branchios- 

 tegal rays do articulate with the epihyal in 

 Acanthocybium and Grammatorcynus. The depth 

 of the epihyal is least in Acanthocybium, 58-62% 

 of the length from the smooth anterior margin of 

 the bone to the tip of the posterior process. Two 

 species of Scomberomorus (commerson and cav- 

 alla) have relatively low epihyals, 68-71% of 

 length. Grammatorcynus also has a relatively 

 low epihyal, 66-77% of length. The deepest epi- 

 hyals are in four species of Scomberomorus: ko- 

 reanus (90-98%), concolor (86-94%), plurilineatus 

 (87-91%), and guttatus (87-90%). 



Interhyal. — The interhyal is a small flattened 

 bone that is attached to the epihyal dorsal to 

 the posterior process. The interhyal is directed 

 obliquely upward and links the hyoid complex to 

 the hyomandibula and symplectic. No differences 

 were noted among interhyals. 



Glossohyal. — The glossohyal (basihyal) (Fig. 

 30) is a median bone that supports the tongue and 

 overlies the first basibranchial bone at the ante- 

 rior end of the branchial arch. In Scomberomo- 

 rus, the glossohyal is roughly rod-shaped or coni- 

 cal in most species. Its width is 35-54% of its 

 length. It generally has a flat or narrowed ante- 

 rior end and broadens posteriorly, but terminates 

 in a small posterior cone or flattened projection. 

 The glossohyal protrudes ventrally adjacent to 

 the posterior articulation. The glossohyal of 

 Acanthocybium is flattened and spatulate with a 

 broad anterior end, a narrow posterior end, and 

 no ventral protrusion (Fig. 30c). Grammator- 



a 



i 



\ 



FIGURE 30. — Glossohyals in dorsal view. a. Scomberomorus 

 plurilineatus, Natal, 910 mm FL, 4x. b. Scomberomorus 

 munroi. New Guinea, 512 mm FL, 5x. c. Acanthocybium 

 solandri, Indian Ocean, 1,088 mm FL, 2 x . d. Grammatorcynus 

 bilineatus, Queensland, 521 mm FL, 4x . 



cynus differs in having a quadrangular to oval 

 tooth plate fused to and covering the dorsal 

 surface of the bone (Fig. 30d). Two bonitos, Cyb- 

 iosarda and Orcynopsis, have a similar condition 

 but there are two separate oval tooth patches in 

 these genera (Collette and Chao 1975:fig. 43a, b). 

 Another bonito, Gymnosarda, has what appears 

 to be a single tooth plate on the glossohyal, but 

 this plate is actually composed of left and right 

 portions that fit over the bone rather than being 

 fused to it (Collette and Chao 1975:fig. 430. The 

 glossohyal is a little wider in Grammatorcynus 

 than in Acanthocybium or most species of Scom- 

 beromorus, 47-55% of length. 



The size of the ventral protrusion varies among 

 the species of Scomberomorus. It is greatest in S. 

 sinensis, commerson, and cavalla. The glossohyal 

 is narrowest in S. multiradiatus and plurilinea- 

 tus (Fig. 30a), 35-36% of width. It is widest in 

 S. sierra and munroi (Fig. 30b), 52-54%. The 

 anterior end is widest in S. niphonius and sinen- 



587 



