742 



Fishery Bulletin 97(4), 1999 



Formation of scales begins at 7.7 mm BL over the 

 cephalic region, and by about 10.3 mm BL, scales 

 are evident over the entire body. 



Pigmentation Early preflexion larvae typically have 

 three melanophores along the middorsal line and two 

 or three on the dorsal-fm fold. Three other melano- 

 phores are present along the midventral line, and one 

 or two similar spots are found on the anal-fin fold. A 

 illelanophore is located over the coiled intestine in 

 anterior and posterior positions. The ventral surface 

 of the coiled intestine shows numerous smaller and 

 dispersed melanophores. Two other melanophores ap- 

 pear in the anterior region: one on the cleithrum near 

 the base of the pectoral bud; the other on the ventral 

 margin of the preopercle. The dorsal surface of the 

 swimbladder is also pigmented (Fig. lA). 



With fmfold disappearance (late preflexion larvae), 

 the characteristic pigmentation pattern is estab- 

 lished: five spots located along the middorsal line at 

 the bases of the dorsal-fm pterygiophores and two or 

 three spots on the bases of dorsal-fin rays. Three or 

 four spots appear along the midventral line at the 



bases of the anal-fm pterygiophores, and one or two 

 spots are present on the bases of anal-fin rays. 



When formation of the dorsal- and anal-fin rays is 

 complete, a pigment spot appears on the base of each 

 anal ray. Similar pigments are found on the bases of 

 the fin rays in the posterior third of the dorsal fin. 

 On the head, an inner melanophore appears over the 

 forebrain and another over the otic region. Finally, a 

 melanophore is present on the distal margin of the 

 peduncle of the pectoral fin (Fig. IB). 



During the flexion stage, the pigmentation pattern 

 of preflexion lai^vae remains, but the spots on the 

 bases of anal- and dorsal-fin rays sometimes disap- 

 pear. The pigment over the otic region, that on the 

 opercle margin, and the melanophore on the poste- 

 rior part of the intestine also disappear. In this stage 

 there are additional pigments that appear. A series 

 of dots are found over the ventral margin of the head, 

 and a melanophore appears over the inferior portion 

 of the base of the ventral fin. Flexion larvae are simi- 

 lar to those of postflexion larvae (Fig. 2A). 



At the postflexion stage, three melanophores appears 

 on the bases of the caudal-fin rays, and at 11.2 mm BL, 

 the cephalic and opercular pigments 

 may disappear (Fig. 2A). 



In early juveniles, four spots ap- 

 pear on the midline of the body. Their 

 positions with respect to the melano- 

 phores already present on the dorsal 

 margin are one between second and 

 third spots, one between third and 

 fourth, one directly ventral to the 

 fourth spot, and one posterior to the 

 fourth spot. There is now pigment on 

 the base of every dorsal-fin ray 

 throughout the entire fin. A series of 

 small spots also develop on the rays 

 on the anterior part of the anal fin 

 (Fig. 2B). 



Fin formation 



Unpaired fin development Incipient 

 dorsal-fin rays are present in the an- 

 terior dorsal finfold at 2.8 mm BL. At 

 4.0 mm BL, about one half of the dor- 

 sal and anal rays are formed in a pos- 

 terior direction. Complete formation 

 of these fins occurs at about 6.8 mm 

 BL. The 3 elongated dorsal-fm rays, 

 present since this fin originated, dis- 

 appear at 11.4 mm BL. 



Figure 1 



Symphurus williamsi: (A) 2.2-mm preflexion larva; (B) 6.3-mm flexion larva. 



Paired fin development Pectoral-fin 

 buds are present in the smallest lar- 



I 



