COLLETTE and RUSSO: SPANISH MACKERELS 



and S. concolor (26th-38th). They extend posteri- 

 orly only to the 35th-36th vertebra in S. cavalla. 



Ribs and Intermuscular Bones 



Pleural ribs are present from the 2d or 3d 

 vertebra posterior to the 12th-31st vertebra, de- 

 pending on the species. Intermuscular bones start 

 on the back of the skull or the first vertebra and 

 extend to the 10th-30th vertebra. 



Correlated with its high number of vertebrae, 

 Acanthocybium has the most pleural ribs (30 

 pairs) of the three genera. Similarly, Gramma- 

 torcynus has the fewest pleural ribs (10 pairs) in 

 agreement with its low number of vertebrae. 

 Species of Scomberomorus are intermediate in 

 number of vertebrae and pleural ribs (15-21 

 pairs). The first pleural rib articulates with the 

 centrum of the third vertebra in Grammator- 

 cynus and most specimens of Scomberomorus. 

 The first rib articulates with the centrum of the 

 second vertebra in Acanthocybium, as noted by 

 Devaraj (1977:44), and in one or two specimens of 

 at least three species of Scomberomorus: com- 

 merson (1 of 5), maculatus (2 of 10), and sinensis 

 (our only specimen). Pleural ribs extend posteri- 

 orly usually to about the last precaudal vertebra. 

 They extend to the 31st vertebra in Acantho- 

 cybium, to the 17th-23d in Scomberomorus, and 

 only to the 12th in Grammatorcynus. Of the 

 species of Scomberomorus , the most ribs are 

 found in S. munroi (20-21 pairs), S. guttatus (20), 

 S. brasiliensis (18-20), and S. maculatus (18-20). 

 The fewest are in S. cavalla (15 pairs), S. semi- 

 fasciatus (15-17), and S. concolor (16-18). Ribs 

 extend back furthest in the same four species 

 with the most pleural ribs, S. munroi (to the 22d- 

 23d), S. guttatus (20th-22d), S. brasiliensis (20th- 

 22d), and S. maculatus (17th-22d). They extend 

 back the shortest distance in S. cavalla (to the 

 17th) and.S. semifasciatus (17th-19th). As Dev- 

 araj (1977:44) noted, the anterior ribs in Acan- 

 thocybium are very broad compared with those in 

 Scomberomorus. 



Intermuscular bones start on the first vertebra 

 in Acanthocybium, Grammatorcynus, and some 

 species of Scomberomorus. In some specimens of 

 at least 13 species of Scomberomorus, the first 

 intermuscular bone is attached to the exoccipital 

 on the skull. This appears to be the usual condi- 

 tion in three species, S. concolor, S. koreanus 

 (also noted by Devaraj 1977), and S. sierra. At 

 least three other species usually appear to have 

 the first intermuscular bone attached to the first 



vertebra: S. guttatus, S. munroi, and S. niphon- 

 ius. The condition in the remaining 12 species 

 either varies or is based on only a single speci- 

 men. The greatest number of intermuscular 

 bones are found in S. guttatus, 26-30 pairs. 

 Counts as high as 27 are found in S. koreanus, S. 

 maculatus, and S. multiradiatus. Except for S. 

 koreanus, the other three species with high num- 

 bers of intermuscular bones also have high verte- 

 bral counts. The fewest intermuscular bones in 

 Scomberomorus are found in S. cavalla and S. 

 sinensis, 20 pairs, and S. lineolatus, S. niphonius, 

 and iS. semifasciatus, 20-23 pairs each. Gramma- 

 torcynus has relatively few intermuscular bones 

 (19-21 pairs) and Acanthocybium, unexpectedly, 

 has the fewest (10 pairs) among the genera under 

 discussion. This seems odd in view of its high 

 number of vertebrae and pleural ribs. Intermus- 

 cular bones extend back furthest in the four 

 species with the highest number, S. guttatus (to 

 the 25th-29th), S. koreanus (24th-29th), S. macu- 

 latus (22d-27th), and S. multiradiatus (26th). 

 They extend back the shortest distance in S. 

 cavalla (to the 19th), the species with the fewest 

 intermuscular bones. Correlated with their low 

 number in Grammatorcynus and Acanthocybium, 

 the bones extend back to the 19th-21st and to the 

 10th vertebra respectively. 



Caudal Complex 



The supporting bones of the caudal fin (Fig. 39) 

 consist of four or five preural centra in Scomber- 

 omorus. Having four preural centra supporting 

 the caudal fin is not a diagnostic character of the 

 family as stated by Potthoff (1975). Only three 

 preural centra support the caudal fin in Gram- 

 matorcynus, Scomber, and Rastrelliger. Five cen- 

 tra support the caudal fin in Acanthocybium. In 

 Scomberomorus and Acanthocybium, preural 

 centra 4 and 3 bear stout haemal and neural 

 spines. Preural centrum 2 has an epural. Preural 

 centra 2 and 3 each have autogenous haemal 

 spines. The urostyle represents a fusion of preural 

 centrum 1 and the ural centrum (Potthoff 1975). 

 The urostyle is fused with the triangular hypural 

 plate posteriorly and articulates with the uro- 

 neural dorsally. Dorsally, the urostyle bears an 

 autogenous epural and ventral ly, the autogenous 

 parhypural. Preural centra 2-4 are compressed in 

 Scomberomorus and Acanthocybium but not so 

 much as in the bonitos and tunas (Collette and 

 Chao 1975; Gibbs and Collette 1967). Preural 

 centrum 4 is not at all shortened in Grammator- 



599 



