COLLETTE and RUSSO: SPANISH MACKERELS 



margin being about equal (95-103% ) to the dis- 

 tance to the tip of the process. In the other species 

 of Scomberomorus, the distance to the anterior 

 margin is less than (76-96%) the distance to the 

 tip of the process. This percent is low in S. 

 lineolatus (167c), indicative of a long process, but 

 the figures for S. commerson (80-83%) and S. 

 sinensis (83-85% ) are not much lower than those 

 for many other species with shorter processes. 

 The lowest figures are for Acanthocybium (72- 

 80%) and Grammatorcynus (65-71%), indicative 

 of the long process in these two genera. 



Hyoid complex. — This complex includes the 

 two hypohyals (= basihyal of Mago Leccia 1958), 

 ceratohyal, epihyal, and interhyal bones, and the 

 seven branchiostegal rays (Fig. 29). The hypo- 

 hyals, ceratohyal, and epihyal are closely asso- 

 ciated and form a functional unit. 



Hypohyals. — The hypohyals are composed of 

 separate dorsal and ventral elements joined lon- 

 gitudinally. In lateral view, the ventral hypohyal 

 is clearly larger than the dorsal hypohyal in all 

 species of Scomberomorus and in Grammator- 

 cynus (Fig. 29a, c). The ventral hypohyal is about 

 three times larger than the dorsal in Acanthocyb- 

 ium (Fig. 29b). Devaraj (1977:29) stated that the 

 dorsal and ventral hypohyals were of equal size 

 in S. commerson, but we find the ventral larger 

 in lateral view, as in the other species of the 

 genus. In mesial view, the dorsal and ventral 

 hypohyals in S. commerson and the other 17 

 species are about equal in size. The ventral hypo- 

 hyal is perhaps a little larger than the dorsal in 

 mesial view in S. multiradiatus and S. queens- 

 landicus. Laterally, the suture between the dor- 

 sal and ventral hypohals runs almost horizontal- 

 ly in Acanthocybium but curves ventrally at 

 various angles in Scomberomorus and Gramma- 

 torcynus. Devaraj (1977) stated that it formed "an 

 upward curve anteriorly in S. koreanus, S. lineo- 

 latus, S. regalis, and S. niphonius and runs 

 nearly straight in the other species including A. 

 solandri." The specimen of S. commerson that he 

 illustrated (figure 12D) does show a straight 

 suture, but in our material a downward curve 

 usually is present. Mesially, a pointed lateral 

 process at the anterodorsal end of the dorsal 

 hypohyal forms a symphysis with the glossohyal, 

 urohyal, basibranchial, and the process of the 

 hypohyal from the opposite side in Scomberomo- 

 rus and Grammatorcynus. Acanthocybium also 

 has a pointed lateral process but it appears to be 



further posterior due to also having an anterior 

 pointed end to the hypohyals at the junction of 

 the dorsal and ventral hypohyals. In addition, 

 Acanthocybium has a prominent anterolateral 

 process on the ventral hypohyal. The groove for 

 the hyoidean artery runs along the outer surface 

 of the epihyal, ceratohyal, and ventral portion of 

 the dorsal hypohyal. The groove extends anteri- 

 orly 29-54% of the length of the dorsal hypo- 

 hyal before becoming a covered tunnel in Scom- 

 beromorus and Grammatorcynus or a foramen in 

 Acanthocybium leading to the inner side of the 

 dorsal hypohyal. The opening on the inner side 

 appears as a small to moderate pit usually lo- 

 cated in the ventral portion of the dorsal hypo- 

 hyal in Scomberomorus and Grammatorcynus. 

 The pit lies astride the junction of the dorsal and 

 ventral hypohyals in S. brasiliensis and extends 

 slightly into the ventral hypohyal in S. macula- 

 tus and S. sierra. The pit also is larger in these 

 species. 



Ceratohyal. — The ceratohyal is a long flat 

 bone, broadest at the posterior end and with an 

 anteroventral projection that articulates with the 

 posteroventral notch of the ventral hypohyal. It is 

 the largest bone of the hyoid complex. Posterior- 

 ly, the middle part of the ceratohyal interlocks 

 with the epihyal by means of odontoid processes 

 issuing from both elements (ceratohyal-epihyal 

 suture of McAllister 1968), while the upper and 

 lower portions are joined by cartilage. Four acin- 

 aciform branchiostegal rays are attached to the 

 respective articular surfaces along the concave 

 middle portion of the ventral margin. In Scom- 

 beromorus (Fig. 29a) the fifth branchiostegal ray 

 usually is attached to the most posterior part of 

 the ceratohyal or on the space between the cera- 

 tohyal and epihyal, not on the anterior part of the 

 epihyal as stated by Devaraj (1977) and Mago 

 Leccia (1958:pl. 4). In Acanthocybium and Gram- 

 matorcynus, the fifth ray is on the anterior part of 

 the epihyal (Fig. 29b, c). The hyoidean groove 

 runs the length of the ceratohyal on its lateral 

 surface. The groove is so deep in some specimens 

 of some species that it forms a thin slit through 

 the bone, the ceratohyal window or beryciform 

 foramen. Slits are common in 10 species of Scom- 

 beromorus: brasiliensis, commerson, concolor, 

 multiradiatus, munroi, niphonius, queensland- 

 icus, semifasciatus , sierra, and tritor; rare in 

 four, cavalla, plurilineatus , maculatus, and si- 

 nensis plus Acanthocybium and Grammator- 

 cynus; and occasional in the other four species: 



585 



