42 



Fishery Bulletin 90(1). 1992 



Diagnosis Grammatorcynus differs from all other 

 scombrid genera in having a second ventral lateral line, 

 and it differs from all other scombrids and billfishes 

 in lacking a triangular bony stay on the fourth pharyn- 

 geal toothplate (Johnson 1986). Like the Scombrini, it 

 has a low number of vertebrae (31) and the caudal fin 

 rays are supported by only the last three vertebrae. 

 Like the Scomberomorini, it has a well-developed 

 median keel on the caudal peduncle, but it lacks the 

 bony support for the keel that is present in bonitos and 

 higher tunas. Grammatorcynus differs from Scom- 

 beromorus in having a pineal window, a single inter- 

 pelvic process, and large scales. 



Collette and Russo (1985b: 612) reported that Gram- 

 matorcynus bilineatus differed from Scomberomorus 

 and Acanthocybium in 16 osteological characters. 

 Grammatorcynus bicarinatus also differs in 15 of those 

 16 characters: (1) supracleithrum wide, 72-89% of 

 length (narrow, 42-62% in Scomberomorus and Acan- 

 thocybium); (2) pores absent along dorsal branch of 

 supratemporal (present); (3) nasal bones protrude far 

 beyond ethmoid region (do not protrude far beyond); 

 (4) posterior end of urohyal tripartite (forked); (5) 

 glossohyal with large tooth patch fused to dorsal sur- 

 face of bone (no fused tooth patch); (6) hyomandibula 

 narrow, 34-39% of length (wide, 39-52%); (7) angle 

 of lateral and medial arms of fourth epibranchial more 

 acute (less acute); (8) anterior process of second epi- 

 branchial elongate (shorter); (9) three vertebrae sup- 

 port caudal fin rays (four or five vertebrae); (10) 

 distinct anterior process on second postcleithrum (no 

 such process); (11) anterior end of first postcleithrum 

 notched (pointed); (12) first two pectoral radials attach 



to scapula (upper one-third of third radial also attaches 

 to scapula); (13) jaw teeth conical (compressed and 

 triangular); (14) shaft of parasphenoid narrow and con- 

 cave or flat (wider and convex); and (16) posterior edge 

 of ectopterygoid long, 63-72% of ventral distance 

 (short, 41-63%). Unlike G. bilineatus, G. bicarinatus 

 resembles Scomberomorus and Acanthocybium in hav- 

 ing the upper margin of the dentary longer than the 

 lower margin (15). 



Relationsiiips Larval characters of Grammatorcynus 

 bilineatus (as described by Wade 1951 from eight 

 specimens 8.5-17.5 mm FL) were used by Okiyama and 

 Ueyanagi (1977, 1978) and Ueyanagi and Okiyama 

 (1979) to construct an "index of primitiveness" that 

 divided the Scombrinae into four groups: mackerels, 

 Grammatorcynus, tunas, and Spanish mackerels and 

 bonitos. Nishikawa (1979) expanded the description of 

 larvae based on 62 specimens, 4.75-56.9 mm SL, from 

 Papua New Guinea. Nishikawa (1979) and Jenkins 

 (1989) noted that Grammatorcynus larvae have pre- 

 opercular spines characteristic of higher scombrids but 

 absent in Scomber and Rastrelliger. 



Lewis (1981) examined Australian scombrids elec- 

 trophoretically and found that the two Gramma- 

 torcynus species showed fixed differences at 6 (23%) 

 of 26 loci (GPD, ADA, ADH, GDA, FKg, and PGMi). 

 Fixed differences were also observed at several other 

 loci not used in his study, namely AD2 and XO. He 

 analyzed the electrophoretic data phenetically and 

 cladistically. The two most parsimonious Wagner net- 

 works involved 308 steps. The species of Gramma- 

 torcynus were always paired and well-separated from 



Figure 26 



One of two equally parsimonious Wagner 

 networks for 23 Australian species of 

 Scombridae expressed in dendrogram form 

 (from Lewis 1981: fig. 6.4). (1) Scomber 

 autitralasinis, (2) Rastrelliger kanagurta, 

 (3) Grammatorcynus bicarinatus, (A) G. 

 bilineatus, (5) Scomberomonis commerson, 

 (6) S. queenslandicus, (7) S. midtiradiatus, 

 (8) S. semifasciatus, (9) S. munroi, (10) 

 Acanthocybium solandri, (11) Sarda aus- 

 trali.'i, (12) S. orientalis, (13) Cybiosarda 

 elegans, (14) Gymnosarda unicolor, (15) 

 Auxi^ sp., (16) Eulhynnus affinis. (17) Kat- 

 suivonus pelamis, (18) Thunnus albacares, 

 (19) T. tonggol, (20) T. obesus, (21) T. ala- 

 hmga, (22) T. maccoyii, (23) T. thynnus 

 orientalis. 



