36 



Fishery Bulletin 90(1). 1992 



The neural prezygapophyses on the first vertebra are 

 modified to articulate with the exoccipital where the 

 vertebral axis is firmly articulated with the skull. 

 Neural postzygapophyses arise posterodorsally from 

 the centrum and overlap prezygapophyses posterior- 

 ly. The postzygapophyses progressively merge into the 

 neural spine in the peduncular region to disappear by 

 the last 5-6 vertebrae. The basic structure and ele- 

 ments of the neural arches and neurapophyses are 

 similar to those of other scombrids (Kishinouye 1923, 

 Conrad 1938, Mago Leccia 1958, Nakamura 1965, 

 Gibbs and Collette 1967, Collette and Chao 1975, 

 Potthoff 1975, Collette and Russo 1985b). 



Variable characters are found on the haemal arches 

 and haemapophyses. Laterally directed parapophyses, 

 arising from the middle of the centrum, appear on the 

 4th-6th vertebrae where the intermuscular bones and 

 pleural ribs are encountered (see section on Ribs and 

 Intermuscular Bones). The parapophyses become 

 broader and longer posteriorly and gradually shift to 

 the anteroventral portion of the centra. In lateral view, 

 the first ventrally visible parapophyses are found on 

 the 6th-7th vertebra in Grammatorcynus, the 7th-9th 

 in Scomberomorus (usually the 8th), and on the 

 14th- 15th in Acanthocybium. 



Posteriorly, the distal ends of the paired para- 

 pophyses meet, forming the first closed haemal arch. 

 The first closed haemal arch is on the 8th vertebra in 

 Grammatorcymis, 10th-16th vertebra in Scomberomo- 

 rus, and 25th-28th vertebra in Acanthocybium. This 

 location is correlated with the total number of verte- 

 brae. The haemal spines become elongate and point 

 posteriorly until they abruptly become more elongate 

 on the first caudal vertebra. The paired pleural ribs (see 

 section on Ribs and Intermuscular Bones) attach to the 

 distal ends of the parapophyses and arches and extend 

 posteriorly to the last precaudal vertebra. The haemal 

 arches and spines bend posteriorly at the caudal pedun- 

 cle and then merge into the caudal complex sym- 

 metrically with the neural arches and spines on the 

 caudal vertebrae. 



Haemapophyses include pre- and postzygapophyses, 

 but their relative positions are different from those of 

 the neurapophyses, and they do not overlap. The first 

 haemal postzygapophyses arise posteroventrally from 

 the 6th-7th centrum in Grammatorcynus, the 6th-8th 

 in Scomberomorus, and the 9th-10th in Acantho- 

 cybium. They reach their maximum length at about the 

 junction of the precaudal and caudal vertebrae. The 

 haemal postzygapophyses fuse with the haemal spine 

 or disappear in the caudal peduncle region. The haemal 

 prezygapophyses arise from the anterior base of the 

 haemal arches on the 8th- 11th vertebra in Gramma- 

 torcynus, the 10th-22nd in Scomberomorus, and the 

 23rd-25th in Acanthocybium. 



Struts between the haemal arch and the centrum 

 form the inferior foramina. Foramina are present from 

 the 17th-19th to the 25th-28th vertebra in Gram- 

 matorcynus, the 21st-33rd to the 35th-52nd in Scom- 

 beromorus, and the 49th-51st to the 56th-57th in 

 Acanthocybium. 



Ribs and intermuscular bones Pleural ribs are 

 present from the second or third vertebra posterior to 

 the 12th-31st vertebra in the three genera. Inter- 

 muscular bones start on the back of the skull or the 

 first vertebra and extend to the 10th-30th vertebra. 



Correlated with its low number of vertebrae. Gram- 

 matorcynus has the fewest pleural ribs (10 pairs). 

 Acanthocybium has the most pleural ribs (30 pairs) in 

 agreement with its many vertebrae. Species of Scom- 

 beromorus are intermediate in number of vertebrae and 

 also in number of pleural ribs (15-21). The first pleural 

 rib articulates with the centrum of the third vertebra 

 in Grammatorcynus and most species of Scombero- 

 morus, and articulates with the centrum of the second 

 vertebra in Acanthocybium., as noted by Devaraj 

 (1977:44), and in at least one specimen each of S. com- 

 m£rson, S. maculatus, and S. sinensis. Pleural ribs 

 usually extend posteriorly to about the last precaudal 

 vertebra: 12 in Grammatorcynus, 17-23 in Scombero- 

 morus, and 31 in Acanthocybium. 



Intermuscular bones start on the first vertebra in 

 Grammatorcynus, Acanthocybium, and some species 

 of Scomberomorus. In some specimens of at least 13 

 species of Scomberoynonis, the first intermuscular bone 

 is attached to the exoccipital on the skull, and in S. con- 

 color, S. koreanus (also noted by Devaraj 1977), and 

 S. sierra, it appears to be the usual condition. Gram- 

 matorcynus has 19-21 pairs of intermuscular bones, 

 many more than Acanthocybium (only 10 pairs, which 

 seems odd given its high number of vertebrae and 

 pleural ribs), but fewer than most species oi Scombero- 

 morus (20-30 pairs). 



Caudal complex Three preural centra support the 

 caudal fin in Grammatorcynus. In Scomberomorus four 

 or five preural centra support the caudal fin, and in 

 Acanthocybium there are five. The urostyle represents 

 a fusion of preural centrum 1 and the ural centrum 

 (Potthoff 1975). The urostyle is fused with the trian- 

 gular hypural plate posteriorly and articulates with the 

 uroneural dorsally. In Grammatorcynus there is very 

 little compression of the preural centra. Preural cen- 

 trum 4 is not shortened at all, preural centrum 3 is 

 shortened slightly, and preural centrum 2 is shortened 

 slightly more (Collette and Russo 1985b: fig. 39). In 

 Acanthocybium and Scomberomorus, preural centra 

 2-4 are compressed more than any of the preural 

 centra in Graynmatorcynus, but still not as much as the 

 centra in the bonitos and tunas (Collette and Chao 



