COLLETTE ET AL.: SCOMBROIDEI 



617 



Table 161. Continued. 



" Data from Fnlzsche and Johnson ( 1 980) and G. D. Johnson, pers. comm. 



# Rtivelltis. Thyrmops and Tongaichthys have one predorsal bone. 



t Rexea has 2 spines, Nealolus ontogenelically has 3 spmcs but center spine fuses to basipterygium dunng development. 



Si Leptdocybiuw. Rexea and Gempyltts have a one-pan stay. 



•• Diplospinus ontogenelically has 3 epurals; poslenor 2 epurals are fused to one in adults, some Diplospinus develop only 2 epurals. 

 *•* Trichiunts has only 2 spines on the first anal pterygiophore. 



genera. Scomber, Rastrelliger. and Auxis, there is a separation 

 between the first and second dorsal fins similar to that in adult 

 Xiphias, except that in these scombrids the two fins are separate 

 initially even though the first and second dorsal fin pterygio- 

 phores are continuous (Kramer. 1960), 



Scombridae 



Hypural plate mostly covered by caudal fin rays; caudal fin 

 rays supported by 3 centra (Scombrini and Grammatorcynus) 

 or 4 to 5 centra (all other tribes) (urostyle and preural centra 

 2 to 4); premaxillae beak-like, free from the nasals which are 

 separated by the ethmoid; no canine teeth; pectoral fins placed 

 high on the body, with 19-36 rays; pelvic fins 1.5; vertebrae 31- 

 64 (Tables 154 and 155); 5-12 finlets follow the second dorsal 

 and anal fins. The family contains 1 5 genera and 49 species 

 (Collette, 1979, 1983). 



The family Scombridae can be divided into two subfamilies 

 (Fig. 324); the Gasterochismatinae, which contains only the 

 distinctive Gasterochisma nielampus, and the Scombrinae. There 

 are problems with the placement of Gasterochisma. To be in- 

 cluded in the Scombridae, it must have lost the extension of 

 the cartilaginous tip of the second epibranchial that extends over 

 the top of the third infrapharyngobranchial (Fig, 312, character 

 1; G, D, Johnson, pers, comm.), regain well developed predorsal 

 bones (character 2), and lose the pharyngeal tooth plate stay 

 characteristic of all other higher scombrids except Gasterochis- 

 ma and Grammatorcynus (G. D, Johnson, pers. comm.). How- 

 ever. Gasterochisma agrees with the billfishes and other scom- 

 brids in several caudal skeletal characters (Fig. 312. characters 

 8. 12, 14). 



The Scombrinae is composed of two groups of tribes. The 

 primitive mackerels (Scombnni— Scomber and Rastrelliger) and 

 Spanish mackerels (Scomberomorini — 5cow/)<'roworj<.s, Acan- 

 thocyhium, and Grammatorcynus) have a distinct notch in the 

 hypural plate, lack any bony support for the fleshy keels on the 

 caudal peduncle, and do not have preural centra two and three 

 greatly shortened. The more advanced bonitos (Sardini) and 

 tunas (Thunnini) form a monophyletic group showing: loss of 

 the notch between the fused lower and fused upper hypural 

 bones (Fig. 312, character 33), bony support for the medial 

 caudal peduncle keel (character 1 6), anterior corselet of enlarged 



scales (character 22) and have preural centra two and three 

 greatly shortened. The Scomberomorini. like the two more ad- 

 vanced tribes, have a median fleshy keel on the caudal peduncle 

 between the pair of small keels (character 1 1). However, there 

 is no bony support for this keel as there is in the bonitos and 

 tunas. Grammatorcynus shares this character state with the oth- 

 er two genera of Scomberomorini but has only three centra 

 supporting the caudal fin (reversal at character 8), as in the 

 Scombrini, rather than four or five as in the Scomberomorini, 

 Sardini and Thunnini. The Sardini (Orcynopsis, Cybtosarda, 

 Sarda, Gymnosarda, and Allothunnus: Collette and Chao. 1 975) 

 differ from the Thunnini (Auxis. Euthynnus, Katsuwonus. and 

 Thunnus) in lacking any trace of the subcutaneous vascular 

 system (Fig. 312. character 23) that permits the members of the 

 Thunnini to be warmer than the water around them. Instead of 

 being considered as a bonito. Allothunnus can better be inter- 

 preted as the most primitive member of the Thunnini. sharing 

 the presence of a prootic pit on the skull with the higher tunas 

 (character 26) but lacking their subcutaneous vascular system. 

 Allothunnus also has an autogenous second epibranchial carti- 

 lage as in the Thunnini (G, D, Johnson, pers. comm.) and shares 

 a common parasitic copepod, Elytrophora brachyptera. with six 

 of the seven species of Thunnus (Gibbs and Collette, 1967; 

 Cressey et al., 1983). 



The Scomberomorini is the most speciose group within the 

 Scombroidei and so merits further attention. After comparing 

 the 18 species of Scomberomorus with each other and with 

 Acanthocybium and Grammatorcynus (Collette and Russo, in 

 press), characters that differentiated among species or genera 

 were listed. Grammatorcynus clearly is more primitive than 

 Scomberomorus and. therefore, it was used as the outgroup for 

 comparison with Scomberomorus. Character polarities were de- 

 termined by considering the character stale present in Gram- 

 matorcynus to represent the plesiomorphous condition. Of the 

 72 characters that differentiated at least one taxon from the 

 others, 14 were autapomorphies oi .Acanthocybium. These can- 

 not contribute to an understanding of relationships within 

 Scomberomorus and were omitted from the analysis. The re- 

 maining 58 characters were employed to generate a cladogram 

 (Fig. 325) using a computer program (WAGNER 78) written 

 by J. S. Farris (following Farris, 1970 and Farris et al., 1970). 



