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



nophores. Gradually the fin membrane becomes 

 covered with melanophores as does the basal half 

 of the soft dorsal fin. Anal fin pigment is limited 

 to a few anterior melanophores, and the caudal 

 and the paired fins remain unpigmented. 



Medialuna californiensis 

 Figures 1, 4, 5 



General Morphology 



The smallest yolk-sac larva in our collection is 

 2.6 mm long; it has a large oval yolk sac, a single 

 posteriorly located oil globule (0.20 mm diam- 

 eter), unpigmented eyes, and lacks a mouth 

 (Fig. 4A). Larvae are ca. 3.0 mm long at the 

 completion of yolk absorption; development is 

 gradual with no abrupt changes in body form 

 (Tables 2, 4). 



The first head spines appear during flexion on 

 the posterior preopercular margin near the 

 angle. A 6.1 mm larva has 2 spines. The number 

 of spines increases up to 6 in preflexion larvae 

 and to 10-13 spines in juveniles up to 21.5 mm. 

 In larger juveniles the spines are blunt and the 

 posterior preopercular margin is smooth in a 

 33.7 mm juvenile. A single spine is present on 

 the anterior preopercular ridge in a 6.5 mm 

 larva. This spine is variously present or absent 

 in flexion and postflexion larvae, and is absent in 

 juveniles larger than 13.8 mm in our collections. 



A single spine is present at the edge of the sub- 

 opercle in larvae as small as 7. 1 mm and is found 

 on all postflexion larvae and juveniles up to a 

 length of 21.5 mm. An interopercular spine is 

 present in all postflexion larvae and in juveniles 

 up to 18.2 mm. A supracleithral spine appears 

 late in the postflexion stage (at 10.1 mm) and a 

 posttemporal spine appears at 12.8 mm. Both 

 spines are present in juveniles up to 21.5 mm but 

 are absent in larger specimens. An opercular 

 spine is present in juveniles between 12.8 and 

 21.5 mm. A cleithral spine is present on a single 

 18.2 mm juvenile. 



Notochord flexion begins at ca. 5.8 mm and is 

 completed at ca. 8.6 mm (Table 5). Transforma- 

 tion into the pelagic juvenile occurs at ca. 12 mm 

 (Fig. 5). 



Fin Formation and Meristics 



The first rays to form are the principal caudal 

 rays early in flexion (Table 5). The full comple- 

 ment of 9-1-8 rays is present at midflexion, when 

 the procurrent rays begin to develop. The full 

 complement of 11-13 -I- 10-11 procurrent rays is 

 present in early juveniles. 



Dorsal, anal, and pectoral rays begin to calcify 

 during midflexion in the manner described for G. 

 nigricans. Full complements of dorsal (IX-X, 

 22-27) and anal (III, 17-21) rays form in early 

 postflexion larvae (Table 5). The full complement 



Table 5. — Meristics of cleared and stained specimens of Medialuna californiensis. Broken lines enclose specimens 

 undergoing notocfiord flexion and specimens below solid line are pelagic juveniles. 



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