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



26 



27 



28 



27 28 29 



Figure 53.-Inferior foramina on caudal vertebrae In six species 

 of Sardini, left lateral view. Vertebrae numbered from 

 anterior, a. Cybiosarda elegans, New South Wales, 365 mm 

 FL. b. Orcynopsis unicolor, Israel, 545 mm FL. c. Sarda aus- 

 tralis, New South Wales, 407 mm FL. d. Sarda sarda, Tunisia, 

 504 mm FL. e. Gymnosarda unicolor, Truk Islands, 772 mm 

 FL. f. Allothunnus fallai, California, 680 mm FL. 



the first closed haemal arch is at the 11th to 13th 

 vertebra in Orcynopsis, 13th in Cybiosarda, 13th to 

 15th in Sarda sarda, 12th to 14th in the other 

 species of Sarda, 11th in Gymnosarda, and 12th in 

 Allothunnus. This position is correlated with the 

 number of vertebrae (Table 9). The first closed 

 haemal arch is pointed anteriorly or posteriorly 

 (Figure 51). The haemal spines become elongate 

 and point posteriorly until they abruptly elongate 

 on the first caudal vertebra. The paired pleural ribs 

 (see section on ribs and intermuscular bones) at- 



tach to the distal end of the parapophyses and 

 arches and extend posteriorly to the last precaudal 

 vertebra. Symmetrically with the neural arches 

 and spines on the caudal vertebrae, the haemal 

 arches and spines bend posteriorly at the caudal 

 peduncle and then merge into the caudal complex. 



Haemapophyses include pre- and post- 

 zygapophyses but their relative positions are 

 different from those of the neurapophyses, and 

 they do not overlap in the bonitos. Haemal arches 

 and haemapophyses are best developed in 

 Allothunnus. The first haemal postzygapophyses 

 arise posteroventrally from the eighth or ninth 

 centrum, and they reach their maximum length at 

 about the junction of the precaudal and caudal 

 vertebrae (Figure 52). They begin at the fourth 

 vertebra in Thunnus (Gibbs and Collette 1967) and 

 the eighth vertebra in Scomberomorus and 

 Acanthocybium (Mago Leccia 1958; Conrad 1938). 

 The haemal postzygapophyses fuse with the 

 haemal spine in the caudal peduncle region. The 

 haemal prezygapophyses arise from the anterior 

 base of the haemal arches on the 14th to 23rd ver- 

 tebra, depending on the species. They begin at the 

 12th to 18th vertebra in "Thunninae" (Nakamura 

 1965; Gibbs and Collette 1967; Potthoff 1974) and 

 at the 16th in Acanthocybium (Conrad 1938). As do 

 their counterpart neural prezygapophyses, the 

 haemal prezygapophyses persist symmetrically 

 into the caudal complex. 



The relative position and contacts between pre- 

 and postzygapophyses of both neuro- and 

 haemapophyses, especially the latter, vary in 

 different regions of the vertebral column (Figures 

 51-53). Godsil (1954) compared haemal pre- and 

 postzygapophyses of eastern Pacific Sarda 

 chiliensis and S. orientalis. We believe that com- 

 parisons should be made within specific regions of 

 the vertebral column. The haemal post- 

 zygapophysis of the last precaudal vertebra and 

 the haemal prezygapophysis of the first caudal 

 vertebra (Figure 52) abut each other in Orcynop- 

 sis, Sarda orientalis, and Allothunnus. A space 

 between these two elements is present in other 

 bonitos. The haemal prezygapophysis is longer 

 than the postzygapophysis at the junction (Figure 

 52) of precaudal and caudal vertebrae in 

 Cybiosarda, Orcynopsis, S. chiliensis, and S. 

 orientalis. The opposite condition is found in S. 

 sarda, S. australis, and Allothunnus. 



Struts between the haemal arch and the cen- 

 trum form the inferior foramina. These are varia- 

 bly developed on 3 to 12 vertebrae anterior to the 



575 



