506 



Fishery Bulletin 93(3), 1995 



developed in the caudal area. In the caudal area, 

 melanophores occurred in the dorsal- and anal-fin 

 folds, dorsal and ventral midlines, and sparsely on 

 the lateral surface (Fig. IB). Recently hatched P. 

 albigutta larvae ranged from 1.8 to 2.2 mm NL. The 

 oil globule was located in the posterior portion of the 

 yolk sac (Fig. 1C). 



Paralichthys lethostigma P. lethostigma eggs had a 

 mean diameter of 0.91 mm (range: 0.84-0.96 mm, 

 n=154), and the oil globule had a mean diameter of 

 0.18 mm (range: 0.16-0.20 mm, rc=154). Pigment on 

 embryos from middle-stage eggs (just after blasto- 

 pore closure) was less developed than that observed 

 for P. albigutta (Fig. 2A). Like P. albigutta, pigment 

 on P. lethostigma embryos was only observed in the 

 caudal area. Pigment on embryos from late-stage 

 eggs was less developed than that observed for P. 

 albigutta (Fig. 2B). Pigment was observed only in 

 the caudal area on P. lethostigma embryos. Recently 

 hatched P. lethostigma larvae were similar in size to 

 P. albigutta (range: 2.0-2.2 mm NL). Like P. 

 albigutta, the oil globule was located in the poste- 

 rior portion of the yolk sac (Fig. 2C). 



B 



Figure 2 



Laboratory-reared eggs and newly hatched larvae of south- 

 ern flounder, Paralichthys lethostigma: (A) middle stage: 

 left, anterior view; right, posterior view; (B) late stage: left, 

 anterior view; right, posterior view; and (C) 2.1-mm-NL 

 recently hatched yolk-sac larva. 



Fin development 



Paralichthys albigutta Fins began to develop in the 

 following sequence: dorsal and caudal, anal, pelvic, and 

 pectoral (Table 1). The adult complement of rays 

 (Gutherz, 1967; Woolcott et al., 1968; Fahay, 1983) was 

 attained in the following sequence: principal caudal rays 

 (10 upper + 8 lower), dorsal fin (71-85), anal fin (53-63) 

 and pelvic fin (6), and pectoral fin (10-12) (Table 1). 



The development of the caudal fin, indicated by a 

 thickening of tissue on the ventral side, began at 5.2 

 mm NL. Caudal-fin rays (2 upper + 2 lower) were 

 first observed at 5.5 mm NL, indicating the begin- 

 ning of the flexion stage. The rays began to form at 

 the middle of the fin and developed dorsally and ven- 

 trally almost simultaneously. The adult complement 

 of principal caudal rays ( 10 upper + 8 lower) was 

 attained at 6.9 mm SL. 



Dorsal rays were first observed during early flex- 

 ion (5.5 mm NL, Table 1). Dorsal rays first formed in 

 the head region anterior to the first neural spine. 

 They were accompanied by an extension of the dor- 

 sal-fin fold that appeared as a flap (Fig. 3B). Dorsal- 

 fin development proceeded slowly during the flexion 

 stage and more rapidly during postflexion (Table 1). 

 Development proceeded posteriorly; however, the 

 anteriormost ray was not observed until 6.1 mm SL. 

 The anterior rays in the head region, especially the 

 third ray, were elongated (Fig. 3D). The adult comple- 

 ment of dorsal-fin rays consistently was attained at 

 7.8 mm SL (Table 1). 



Anal-fin rays began to form on postflexion larvae 

 at approximately 6.1 mm SL (Table 1). Formation 

 began in the vicinity of the first haemal spine and 

 development proceeded anteriorly and posteriorly 

 simultaneously. Anal-fin-ray development was rapid, 

 and by 7.7 mm SL the adult complement of anal-fin 

 rays consistently was observed (Table 1). 



Pelvic-fin rays were first observed on postflexion 

 P. albigutta larvae at 6.9 mm SL (Table 1 ). All speci- 

 mens >8.5 mm SL had a completed pelvic fin. 



The pectoral fin persisted as a large rayless blade 

 throughout flexion and early postflexion (Table 1). 

 Rays began to form at 7.1 mm SL at the dorsal posi- 

 tion of the blade and developed ventrally (Fig. 4). All 

 specimens >8.5 mm SL had the adult complement 

 (10-12 rays) of pectoral fin rays (Table 1). 



Paralichthys lethostigma Fins began to develop in 

 the following sequence: dorsal, caudal, anal, pelvic and 

 pectoral (Table 2). The adult complement of rays 

 (Gutherz, 1967; Wolcott et al., 1968; Fahay, 1983) was 

 attained in the following sequence: caudal fin (10 up- 

 per + 8 lower), dorsal fin (80-95) and anal fin 

 (63-74), pelvic fin (6), and pectoral fin (11-13) (Table 2). 



