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Fishery Bulletin 103(1) 



then remained constant (Fig. 2, A and B). The gut was 

 initially straight but began to constrict at 4 mm BL and 

 was loosely constricted throughout development (Fig. 3, 

 A-C). It was moderate to long and extended to near 

 the midpoint of the body, resulting in a relative preanal 

 length of 0.45 to 0.62 BL. 



Body pigmentation Argentine sandperch larvae were 

 lightly pigmented during all stages of development 

 (Fig. 3; A-C). The pigmentation on the ventral body 

 surface, between the isthmus and the anus, consisted of 

 small stellate melanophores. Several small melanophores 

 were scattered on the lateral surface of the anterior part 

 of the gut. A double row of minute melanophores along 

 the ventral surface ended in a single melanophore at the 

 constriction of the gut. Pigmentation along the lateral 

 midline of the tail consisted of four to seven stellate 

 melanophores. 



In preflexion larvae (Fig. 3A), small spots were evi- 

 dent along the lower jaw and the ventral part of the 

 head. Several small stellate melanophores were present 

 on the dorsal surface of the gut. A few melanophores 

 were scattered at the base of the pectoral fin bud. 



Preflexion and flexion larvae (Fig. 3, A and B) showed 

 a distinct pattern of 12 to 23 small postanal melano- 

 phores serially arranged, about one per myomere, along 

 the ventral midline. A total of 11 to 18 melanophores, 

 about one melanophore per anal fin pterygiophore, was 

 observed in postflexion larvae (Fig. 3C). As flexion pro- 

 gressed (Fig. 3, B and C), the number of melanophores on 

 the ventral part of the head and over the gut diminished. 



Fins and meristic features Modes of preanal and post- 

 anal myomeres were 14 and 23, respectively. All speci- 

 mens examined had 33-40 total myomeres (mode:36-38 

 myomeres). Vertebral column ossification started anteri- 

 orly. A total of 38-39 vertebrae were recorded in 10-12 

 mm BL postflexion larvae (n = 2). 



In yolksac larvae, finfold and pectoral buds were the 

 first fin development distinguished. In preflexion and 

 flexion larvae, the finfold was present and it was gradu- 

 ally lost as the true fins developed. The sequence of 

 fin-ray formation, characterized by initial development 

 of fin elements, was caudal (7-8 mm BL), then pectoral 



