RICHARDSON and JOSEPH: LARVAE AND YOUNG OF BOTHIDS 



C. iirctifrous - Abdominal Region 



A heavy concentration of pigment occurs 

 over the gas bladder in larvae of 2.5 mm (Figure 

 2B) and persist until metamorphosis. Additional 

 melanophores appear over the dorsal surface 

 of the hindgut beginning at about 4 mm (Figure 

 5B). Scattered melanophores occur along the 

 ventral body margin from the cleithrum to the 

 hindgut. When the pelvic fin forms (5-7 mmi), 

 this pigment becomes less concentrated at its 

 base. The concentration of pigment over the 

 ventral part of the gut cavity increases with 

 age (Figure 5C, D), and several diffuse melano- 

 phores appear near the end of the hindgut by 

 8-10 mm (Figures 5D; 6A, B). Pigment be- 

 comes noticeable on the tip of the pelvic fin by 

 about 5-6 mm (Figure 5C, D). As the larva 

 approaches metamorphosis, one to three prom- 

 inent pigment spots appear along the proximal 

 margin of the interneural musculature (Figure 

 6B, C). After these spots appear, a general in- 

 crease in pigmentation occurs along the myo- 

 septa of the body (Figure 6B, C) on the eyed 

 side. 



Pigmentation over the gut cavity increases 

 greatly after metamorphosis (Figure 7B) and 

 the pectoral and pelvic fins become dotted with 

 melanophores. The amount of pigment lining 

 myosepta tends to decrease on the body and 

 increase in the interneural and interhemal 

 regions. 



C. arctifrous - Tail Region 



Larvae of 2-3 mm may have a postanal band 

 of pigment, which becomes a dorsal and anal 

 bar of pigment (Figures 2B, 5A), on the body 

 margins about two-thirds the distance from the 

 anus to the notochord tip. A distinct horizontal 

 pigment bar appears intermediate to the dorsal 

 and anal bars by 4-5 mm (Figure 5C). The 

 three postanal pigment bars remain until meta- 

 morphosis (Figure 6C). 



Melanophores appear scattered along the 

 ventral body margin from the hindgut to the 

 tail tip at 2-3 mm (Figures 2B, 5A). This pig- 

 mentation shifts to the distal margin of the 

 interhemal musculature as development pro- 

 ceeds (Figure 5D). By about 10-11 mm, two 



clusters of melanophores develop along the 

 proximal margin of the interhemal musculature 

 between the hindgut and the ventral horizontal 

 pigment bar (Figure 6A, B). These clusters 

 increase in prominence until metamorphosis 

 (Figure 6C). 



Internal pigment spots appear along the dor- 

 sal surface of the notochord immediately above 

 the intermediate postanal pigment bar by about 

 5 mm (Figure 5C). These internal spots remain 

 apparent until metamorphosis. 



Along the proximal margin of the interneural 

 musculature, several (usually three) clusters of 

 pigment become prominent by 12-13 mm, two 

 between the abdominal region and the dorsal 

 postanal pigment bar and one posterior to the 

 dorsal bar (Figure 6B, C). After the appearance 

 of the dorsal and anal pigment clusters, as meta- 

 morphosis proceeds, pigmentation increases 

 along the myosepta of the body on the eyed 

 side (Figure 6C). 



Scattered pigment may occur on the finfold 

 from 2 to 4 mm, but in no set pattern (Figures 

 2B; 5 A, B). Melanophores begin to delineate 

 the base of the caudal fin by about 10 mm (Fig- 

 ure 6 A) and later appear scattered over the fin 

 (Figure 6C). Pigmentation appears on the dor- 

 sal and anal fins, first in clusters (Figure 6C) 

 and then scattered throughout, as the larva 

 nears the completion of metamorphosis at 

 around 14 mm. 



After metamorphosis, pigmentation becomes 

 less pronounced along the body myomeres but 

 increases along the septa of the interneural and 

 interhemal musculature (Figure 7B). Pigmen- 

 tation appears along the lateral line on both 

 eyed and blind sides. In females, pigmentation 

 increases over the ovarian cavity. In adults, the 

 most prominent pigmentation is that of the 

 scale pockets which results in a general dark- 

 ening of the eyed side (Figure 8B). 



Comparative Morphological Changes 



Nonmorphometric changes are described for 

 both species together as they are quite similar. 

 Differences are noted. 



Body shape of the earliest stage larvae of 

 both species is characteristic of flatfishes. The 

 head and abdominal region are deep and later- 



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