POWELL and GORDY: EGG AND LARVAL DEVELOPMENT OF THE SPOT 



Table l. — Meristic data from cleared and stained larval and juvenile Leiostomus xanthurus. Standard lengths suffixed with W 



indicate wild-caught specimens. All others are laboratory reared. 



' LF designates larval fin. 

 ^ Upper - lower. 

 ^Damaged. 



spines at 6.9 mm SL. All specimens &8.2 mm SL 

 had a completely developed anal fin. 



The pelvic fin appeared as a bud at 5.1 mm SL. 

 All specimens 2=10.8 mm SL had a completely de- 

 veloped pelvic fin. The fin formula 1,5 is typical 

 among sciaenids. 



The pectoral, the last fin to develop a full com- 

 plement of rays, persisted as a rayless blade for a 

 relatively long period. Rays began to appear at 8.0 

 mm SL at the dorsal position of the blade and then 

 developed ventrally. All specimens ^16.0 mm SL 

 had a complete pectoral fin. 



Fin development, relative to body length of lar- 

 vae, collected from the South Atlantic Bight 

 (Powles and Stender 1978) was similar to fin de- 

 velopment of laboratory-reared larvae, but spot 

 larvae collected from the Gulf of Mexico (Fruge 

 and Truesdale 1978) began and completed fin de- 

 velopment at a much smaller size (Table 2). Rate of 

 fin development could be influenced by tempera- 



TabLE 2. — The size (mm SL) when fins and associated struc- 

 tures begin and complete development for laboratory-reared spot 

 (this study), spot collected from the South Atlantic Bight ( Powles 

 and Stender 1978) and spot collected from the Gulf of Mexico 

 (Fruge and Truesdale 1978). 



Fin or associated 

 structure 



Begins formation 



Powles Fruge 



and and 



Stender Truesdale This 



(1978) (1978) study 



Completes formation 



Powles 



and 



Stender 



(1978) 



Fruge 

 and 

 Truesdale This 

 (1978) study 



Notochord flexion 

 Caudal fin: 



Principal rays 



Secondary rays 

 Anal fin 



pterygiophores 

 Anal fin 

 Dorsal fin: 



Pterygiophores 



Second 



First 

 Pelvic fin bud 

 Pelvic fin 

 Pectoral fin 



4.4 



4.5 

 6.2 



4.4 

 7.2 



4.4 

 7.2 

 7.2 

 5.2 



8.0 

 10.7 



4-5 



3 

 5 



5 



7 



5-6 



6 



7 



3.8 



4.6 

 63 



5.5 

 6.3 



5.1 

 6.7 

 8.0 

 5.1 

 8.2 

 8.0 



4.7 



7.2 



15.5 



6.2 



9.3 



9.3 



14.1 



10.7 

 16.8 



4-5 



5 

 >10.7 



8 

 9 



7-9 

 >10.7 



5.3 



6.3 

 14.4 



6.3 

 8.2 



7.3 



8.8 



10.8 



10.8 

 16.0 



ture. Size at hatching, at least, has been show^n to 

 be influenced by incubation temperature (Laur- 

 ence and Rogers 1976). 



707 



