FISHERY BULLETIN: VOL. 80, NO. 3 



Table 4.— Summary of measurements (in millimeters) of Genyonemus lineatus larvae. The mean ( x), sample size (n), and standard 

 deviation (SD) are given for each distance measured. Notochord flexion takes place in the size range demarked by dashed lines. 



the sciaenids Seriphus politus and Roncador 

 stearnsii (Moser and Butler 5 ), the haemulid Ani- 

 sotremus davidsonii, and the scombrid Scomber 

 japonicus. Genyonemus lineatus is principally a 

 winter spawner while the other species are prin- 

 cipally summer spawners, but some overlap 

 occurs in spring and fall. 



Scomber japonicus is distinct in having 30-31 

 myomeres versus 25-26 for the other species. 

 Yolk-sac larvae of A. davidsonii are undescribed; 

 however, yolk-sac larvae of the Atlantic haemu- 

 lids Haemulon plumierii (Saksena and Richards 

 1975) and Orthopristis chrysoptera (Hildebrand 

 and Cable 1930) have an anterior oil droplet in 

 contrast with the posterior oil droplet typical of 



5 H. G. Moser, and J. L. Butler. Description of the early life 

 history stages of croakers (Family Sciaenidae) occurring off 

 California. Manuscr. in prep. Southwest Fisheries Center 

 La Jolla Laboratory, National Marine Fisheries Service, 

 NOAA, La Jolla, CA 92038. Pers. commun. February 1981. 



sciaenids. Seriphus politus yolk-sac larvae lack 

 the dorsal pigmentation and banded pattern 

 typical of G. lineatus (Moser and Butler footnote 

 5). Roncador stearnsii closely resemble G. linea- 

 tus until late in the yolk-sac stage (Moser and 

 Butler footnote 5) when G. lineatus may be dis- 

 tinguished by a single (rarely two) large dendrit- 

 ic nape melanophore extending into the finfold 

 rather than two or more smaller nape melano- 

 phores not extending into the finfold. Roncador 

 stearnsii, typically has heavier anterior gut pig- 

 ment than G. lineatus. 



Characters useful for separating G. lineatus 

 from similar larvae are summarized in Table 5. 

 The nape melanophore separates G. lineatus lar- 

 vae from A. davidsonii and S. politus for as long 

 as it remains visible. Anisotremus davidsonii 

 may be distinguished from G. lineatus to at least 

 as small as 2.6 mm by ventral pigmentation, and 

 by dorsal fin ray counts in older specimens 



414 



