STEVENS ET AL.: LARVAE AND JUVENILES OF THREE KYPHOSID FISHES 



creasingly dense and spreads posteriorly; at the 

 end of flexion the last three myomeres are usu- 

 ally unpigmented but acquire pigment by the 

 end of the larval stage. 



Midbrain pigment increases in concert with 

 the dorsal trunk and tail pigment, covering the 

 area over the midbrain and spreading anteriorly 

 to the snout and posteriorly over the hindbrain. 

 Thus, by the beginning of flexion, larvae are 

 nearly completely pigmented along the upper 

 surface (Fig. IH). Snout and nape pigment are 

 usually lighter than the remaining dorsal pig- 

 ment. 



Preflexion larvae have a single melanophore at 

 the roof of the mouth; during flexion more mela- 

 nophores may be added in this area. A mela- 

 nophore first appears below the otic capsule in 

 the preflexion stage (by 2.6 mm) and one devel- 

 ops under the anterior midbrain by 3.1 mm. 

 Melanophores proHferate in these areas to give 

 the appearance of a stripe through the head by, 

 or during, flexion. 



Pigment first appears on the dorsal surface of 

 the hindbrain by 2.8 mm (one melanophore), and 

 rapidly increases to essentially cover the dorsal 

 surface of the hindbrain by early flexion (ca. 4.8 

 mm). This pigment subsequently extends pos- 

 teriorly as a series of melanophores over the 

 vertebral column. 



One or two melanophores first appear at the 

 tip(s) of the upper and/or lower jaw(s) between 

 2.8 and 3.1 mm. Melanophores spread along the 

 upper jaw beginning late in preflexion or early 

 in flexion, and along the lower jaw beginning 

 midway or later through flexion. At ca. 2.8 mm a 

 single melanophore appears on the gular mem- 

 brane; by the beginning of flexion 3-4 additional 

 melanophores form a longitudinal series evenly 

 spaced along the membrane (Fig. IG). 



A single melanophore appears on the opercle 

 late in preflexion or early in flexion (by 4.4 mm). 

 Melanophores proliferate here to form a large 

 pigment patch midway through flexion, and sub- 

 sequently extend dorsally, ventrally, and ante- 

 riorly to cover the entire opercular area, usually 

 by the end of flexion or early in postflexion. 



The smallest specimens examined had a con- 

 tinuous double row of melanophores, which ex- 

 tended over the dorsal surface of the gut and 

 swimbladder, and posteriorly as a single row 

 nearly to the end of the hindgut. These speci- 

 mens also had 1-6 melanophores evenly spread 

 along the ventral midline of the gut from the 

 anterior midgut to the anterior hindgut. The 

 dorsal gut pigment increases, extending as far as 



halfway down the front and sides of the gut by 

 the beginning of flexion, and completely covers 

 the sides of the gut by the end of flexion. This 

 pigment continues to spread ventrally, from 

 anterior to posterior, meeting the midline series 

 in postflexion larvae (between 8.6 and 9.6 mm). 

 The series of melanophores along the ventral 

 midline of the gut changes little during larval 

 development. Modal numbers of melanophores 

 in the series were 3-4 (range of IS) for pre- 

 flexion larvae and 4 (range of 2-6) for flexion 

 larvae. 



Initially, ventral midline pigment on the tail 

 consists of a single row of 7-10 large mela- 

 nophores between the first and the 13th postanal 

 myomeres. Usually 2 or 3 (1-4) small mela- 

 nophores lie under the notochord tip; later these 

 become located along the hypural margin (Fig. 

 6B, 6C). Occasionally, the first one or two post- 

 anal myomeres are unpigmented in preflexion 

 larvae (14% of the preflexion specimens lacked 

 pigment here), but thereafter the first postanal 

 myomeres are always pigmented. The ventral 

 melanophores enlarge and may increase in num- 

 ber during preflexion, so that by ca. 3.5 mm a 

 melanistic band extends along the tail to ca. 

 myomere 20 or 21. 



A series of 1-3 small melanophores appears on 

 the lateral midline of the tail at the 14th-20th 

 myomeres late in preflexion or early in flexion 

 (ca. 3.7-4.3 mm). Melanophores proliferate to 

 form a band as do the ones along the dorsal and 

 ventral midlines. Further enlargement of the 

 ventral, lateral, and dorsal bands results in a 

 nearly continuous tail bar during mid to late 

 flexion. Subsequent proliferation of mela- 

 nophores in this region and over the gut and 

 trunk results in complete body pigmentation, 

 except for the last 3-5 myomeres, by ca. midway 

 through postflexion. Pigmentation is complete 

 by transformation. 



The dorsal and ventral midline pigment be- 

 gins to spread onto the bases of the middle and 

 posterior dorsal and anal soft rays during 

 flexion at ca. 5.4 mm. By late flexion or early 

 postflexion the membranes between dorsal rays 

 5 or 6 to 10 or 11 and between anal rays 5, 6 or 

 7 to 9 or 10 are pigmented. During postflexion, 

 the base of the entire dorsal fin becomes heavily 

 pigmented and near the end of the larval stage 

 the membranes between the dorsal spines be- 

 come pigmented (by ca. 9.6 mm). Pigmentation 

 does not develop on the membranes between 

 dorsal soft rays 1-5 during the larval period, 

 and is very sparse there in juveniles. The base 



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