COLLETTE and RUSSO: SPANISH MACKERELS 



second dorsal fin rays 19-21, usually 

 20 or more; distance from 2D origin to 

 caudal base 51.8-57.5% FL, x 54.8% . . 

 S. plurilineatus Fourmanoir 



16a. Sides with bars or large spots, larger 



than the diameter of the eye 17 



16b. Sides with small round spots, about the 

 diameter of the eye, orange colored 

 in life 19 



17a. Sides with large spots or blotches; total 

 gill rakers on first arch 3-9, usually 7 

 or fewer S. queenslandicus Munro 



17b. Sides plain or with bars; total gill rakers 



of first arch 6-15, usually 9 or more . . 18 



18a. First dorsal fin spines 13-15; second dor- 

 sal fin rays 19-22, usually 20 or more; 

 total gill rakers on first arch 6-13, 

 usually 11 or fewer; total vertebrae 

 44-46, usually 45; base first dorsal fin 



17.0-23.6% FL 



S. semifasciatus (Macleay) 



18b. First dorsal fin spines 15-18, usually 16 

 or more; second dorsal fin rays 16-19, 

 usually 17; total gill rakers on first 

 arch 12-15; total vertebrae 46-47, usu- 

 ally 46; base first dorsal fin 23.8- 

 30.4% FL S. tritor (Cuvier) 



19a. Total vertebrae 51-53; second dorsal fin 



rays 17-20, usually 18 or more 



S. maculatus (Mitchill) 



19b. Total vertebrae 46-49; second dorsal fin 



rays 15-19, usually 18 or fewer 20 



20a. Pectoral fin rays 21-24, usually 22 or 

 more; pelvic fin short, 2.9-5.9% FL, x 

 4.5% . . . . S. brasiliensis Collette, Russo, 



and Zavalla-Camin 



20b. Pectoral fin rays 20-24, usually 21 or 

 fewer; pelvic fin longer, 3.2-6.4% FL, 

 x 5.3% S. sierra Jordan and Starks 



COMPARATIVE MORPHOLOGY 



The morphological characters useful for distin- 

 guishing the species of Scomberomorus and for 

 evaluating their phylogenetic relationships are 

 divided into six categories: lateral line, nasal 

 denticles, morphometry, meristics, soft anatomy, 

 and osteology. 



Lateral Line 



In most species of Scomberomorus, the lateral 

 line runs posteriorly above the pectoral fin and 

 then gradually descends to the middle of the body 

 at about the level of the second dorsal fin. Gram- 

 matorcynus differs from Scomberomorus, Acan- 

 thocybium , and all other members of the family 

 by having a second lateral line that joins the 

 upper lateral line at a right angle behind the 

 pectoral fin base and then courses ventrally and 

 posteriorly along the ventral surface of the body 

 to join the dorsal lateral line on the caudal 

 peduncle. In Acanthocybium and three species of 

 Scomberomorus, the lateral line moves abruptly 

 downward under the first or second dorsal fin. 

 The abrupt downward curve is under the first 

 dorsal fin in Acanthocybium and S. sinensis 

 (see Figure 68); it is under the second dorsal in 

 S. cavalla and S. commerson (see Figures 50 

 and 52). 



Scomberomorus guttatus and S. koreanus dif- 

 fer from other members of the genus in having 

 many fine branches from the anterior part of the 

 lateral line, both dorsally and ventrally (see 

 Figures 54 and 56). Acanthocybium and S. ni- 

 phonius (see Figure 62) may have branches from 

 the lateral line but they are not as numerous or 

 distinct. 



Nasal Denticles 



Nasal denticles (Fig. la, b) are small general- 

 ized teeth found within the olfactory chamber 

 on the medial surface surrounding the posterior 

 nares and on the skin covering the anterior 

 surface of the lateral ethmoid. Nasal denticles 

 are similar to the small villiform teeth present 

 within the mouth cavity and adjoining regions of 

 stomadeal origin and on the skin covering the 

 cleithrum (Fig. lc, d) and on the isthmus where 

 they are contacted by the opercular membrane. 

 These teeth typically fit into sockets in pads of 

 fine spongelike bone. They point posteriorly and 

 are aligned with presumed flow of water from the 

 anterior naris through the olfactory chamber and 

 out the posterior naris. Nasal denticles were 

 found only in the six species of the Scomberom- 

 orus regalis species-group {brasiliensis, concolor, 

 maculatus, regalis, sierra, and tritor). Nasal 

 denticles are not present in Acanthocybium or 

 Grammatorcynus. We do not know their function 

 and are not aware of such structures in other 

 fishes. 



549 



