WATSON: DEVELOPMENT OF EGGS AND LARVAE OF WHITE CROAKER 



size may retain a midlateral melanophore in the 

 myomere 16-18 region. The ventral midline me- 

 lanophore series increases quickly from 8 to 10 

 late in the yolk-sac stage to 15-21 by ca. 2.6 mm. 

 The melanophores at myomeres 9-10 and 16-18 

 remain largest. 



The dorsal notochord tip melanophores and 

 those at myomeres 6-8 are lost by ca. 2.8 mm 

 (Fig. 4b). The melanophore at myomeres 16-18 

 often persists to 5 mm, and may continue until 6 

 mm in some specimens. The nape melanophore 

 migrates internally and is obscured by the over- 

 lying tissue as early as ca. 2.5 mm or as late as ca. 

 6.1 mm, but most often between 4.8 and 5.6 mm. 

 Following the internal migration of the nape me- 

 lanophore the trunk remains unpigmented dor- 

 sally and laterally through the larval and transi- 

 tional periods. Early in the juvenile stage a 

 barred pattern develops (Fig. 5). At 17.2 mm a 

 short bar crosses the nape and may extend later- 

 ally to the level of the supracleithral spine. A sec- 

 ond bar extends to the midlateral line from dor- 

 sal spines VII-X, a third and fourth from dorsal 

 rays 5-10 and 16-21, and a fifth crosses the pe- 

 duncle. Six to nine bars ultimately develop in the 

 juvenile stage, counting the snout and cranial 

 bars. Trunk melanophores in these bars are prin- 

 cipally myoseptal. 



The midventral trunk melanophores number 

 between 15 and 21 at the beginning of the larval 

 stage. They begin coalescing immediately, but 

 from 7 to 19 remain through 4.5 mm. By the be- 

 ginning of caudal flexion (ca. 5.5 mm) they de- 

 cline to between 2 and 12, and thereafter number 

 between 2 and 6. The melanophore between myo- 



meres 16 and 18 is always largest and persists 

 through the larval stage (Fig. 4e). This melano- 

 phore lies at the posterior end of the anal fin in 

 older larvae. The second largest midventral me- 

 lanophore, which initially lies between myo- 

 meres 9 and 10, shifts one to three myomeres 

 posteriorly and migrates internally by the time 

 of anal fin anlage formation (Fig. 4c, d). It often 

 persists through the larval stage, lying near the 

 anal fin origin in older specimens. One to three 

 small melanophores may also remain in the ven- 

 tral midline between myomeres 20 and 25 

 through the larval period. One small melano- 

 phore usually persists near the end of the noto- 

 chord, becoming located at the central distal 

 margin of the developing hypural complex dur- 

 ing flexion. As the caudal fin rays ossify, one to a 

 few melanophores develop along the central and 

 lower fin ray bases. During transition internal 

 melanophores begin to appear along the urostyle 

 and lower hypurals, and a band of pigment de- 

 velops along the distal one-third of the caudal 

 rays. 



Soon after anal fin completion melanophores 

 develop at the anal fin ray bases. These occur 

 first on either side between anal soft rays 1 and 4, 

 and proceed both anteriorly and posteriorly. The 

 number of melanophores is variable— usually 

 three or fewer in larvae <9 mm and five or fewer 

 in larger specimens. 



The gut region is moderately pigmented at the 

 beginning of the larval period: a single external 

 melanophore normally lies on each side just be- 

 hind the upper pectoral insertion; one to three 

 pairs of melanophores occur on top of the swim 



Figure h.—Genyonemus lineatus early juvenile, 19.20 mm. 



409 



