Table 4. — Cojnparison of diagnostic characters of the species of Thunnus 



Character 



Cutaneous artery orginates at 



vertebra number 



Cutaneous artery passes 



between ribs number 



Cutaneous artery divides between 



intermuscular bones number 

 Number of arteriolar rows from 



cutaneous artery 



Post-cardinal vein 



Liver striations and vascular 



cones 



Liver lobes 



Swimbladder 



Spleen position 



First haemal arch on vertebra 



number 



First ventrally directed 



parapophysis on vertebra 



Anterior haemal prezygapophysis 



position 



Anterior haemal postzygapophysis 



length 



Ventrolateral foramina size 



Number of precauda! vertebrae... 



Posterior parasphenoid margin 



Pectoral length. 



Gill raker number 



T. alalunga 



3-4 



3-4 



4-5 



1 

 absent 



present 



subequal 



present 



right 



10 



9 



on centrum 



short 

 small 



18 

 angulate 

 long 



25-31 



T. thynnus 



3-4 



3^ 



4-5 



2 

 absent 



present 



subequal 



present 



left 



10(11) 



g 



near centrum 



short 

 small 



18 

 angulate 

 short 



34^3 



T. maccoj/ii 



3-4 



3-1, 2-3 



4-5, 3-4 



2 

 absent 



present 



subequal 



present 



left 



near centrum 



short 

 small 



18 

 angulate 

 short 



31-40 



T. obesus 



&-8 



5-6 



6-7 



2 

 present 



present 



subequal 



present 



11(10) 



near centrum 



short 

 small 



18 

 angulate 

 long to medium 

 23-31 



T. albacares 



6-8 



5-6 



fi-7 



1 

 present 



absent 

 right long 

 present 



left 



11(10, 12) 



well ventrad 



long 

 large 



18 

 non-angulate 

 medium 

 26-34 



T. atlantkus 



6-8 



5-6 



6-7 



1 

 present 



absent 

 right long 

 present 



left 



11(10) 



well ventrad 



long 

 large 



19 

 non-angulate 

 medium 

 19-25 



T. tonggot 



6-8 



5-6 



6-7 



1 

 present 



absent 

 right long 

 absent or 

 rudimentary 

 left 



11(12) 



10 



well ventrad 



long 

 large 



18 

 non-angulate 

 medium to short 

 19-28 



and in the flattened haemal spine of its firet caudal 

 vertebra. 



Not only is the subdivision of Thunnus into genera 

 or subgenera an arbitrary matter, but such subdivi- 

 sion obscures the close relationship among the species. 

 In this concept we agree with such workers as Rivas 

 (1951, but not 1961), de Sylva (1955), and Iwai, 

 Nakamura, and Matsubara (1965). Thunnus can 

 be divided into as many as six groups, but these are 

 essentially species, not subgenera or genera (table 4). 

 However, based on the 18 characters in table 4 (ex- 

 cluding pectoral fin length), there do appear to be 

 two groups of species. T. alalunga, T. thynnus, and 

 T. maccoyii are similar to each other in 14-16 char- 

 acters; T. albacares, T. atlanticus, and T. tonggol are 

 similar to each other in 15-16 characters; and T. 

 obesus is in between the two groups, sharing 12 

 characters with T. maccoyii and 10 with T. albacares. 

 This agrees with the intra-generic relationships pre- 

 sented by Iwai et al. (1965) and Xakamura (1965). 

 It disagrees with Watson's (1964) groups where she 

 placed T. obcstis in the first group. T. obesus is 

 similar to the first group in several liver and verte- 

 bral characters but fits with the second group in 

 position of the cutaneous artery, presence of the post- 

 cardinal vein, and position of the first haemal arch. 



The synonymy of each species includes all the 

 combinations of names we have found, together with 

 selected references containing information on anato- 

 my, morphometry, and distribution. Readers wish- 

 ing more references should consult tuna bibliog- 

 raphies such as Corwin (1930), Shimada (1951), and 



volume 4 of the "Proceedings of the World Scinetific 

 Meeting on the Biology of the Tunas and Related 

 Species" (Bernabei, 1964). 



THUNNUS ALALUNGA (Bonnaterre, 1788) 

 ALBACORE 



Scomber pinnis pectoralibus longissimis Cetti, 1777: 

 191-193 (Sardinia, alalunga in vernacular). 



Scomber alalunga Bonnaterre, 1788: 139 (original 

 description based on Cetti). Walbaum, 1792: 

 222. Risso, 1810: 169-170. 



Scomber alalunga Gmelin, 1789: 1330 (original de- 

 scription based on Cetti; "alalunga" a misprint 

 for "alalunga" ; date of publication according to 

 Cat. Books British Mus. is 1789, not 1788). 

 Lacepede, 1800: 599 and 1802: 21-22. 



Scomber gcrmo Lacepede, 1800: 598 (original descrip- 

 tion in table of species of Scomber; misspelled S. 

 germon). Lacepede, 1802: 1-8 (description: S. Pa- 

 cific Ocean, 17° S., 103° W. ; based on Commerson's 

 manuscript). 



Orcynus germon, Cuvier, 1817: 314. 



Orcynus alalonga, Risso, 1826: 419-420 (Mediter- 

 ranean). 



Thynnus alalonga, Cuvier in Cuvier and Valencien- 

 nes, 1831 : 87-95 (Atlantic), fig. 215. Lowe, 1839: 

 78 and 1849: 2 (Madeira). Gtinther, 1860: 366. 

 Cunningham, 1910: 109-110 (synonymy, descrip- 

 tion; St. Helena), fig. 3. 



Thynnus pacificus Cuvier in Cuvier and Valenciennes, 

 1831: 96-97 (substitute name for Scoynbcr germo 

 Lacepede, 1800). 



AN.\TOMV AND SYSTEM.\TICS OF TUNAS 



99 



