TUCKER: LARVAL DEVELOPMENT OF CITHARICHTHYS AND ETROPUS 



Citharichthys gymnorhinus 

 (Figs. 1, 6, 7) 



Identification 



Larvae approaching transformation had com- 

 plete complements of countable characters. 

 Those specimens were identified by comparing 

 the following larval counts with known adult 

 counts. Number of specimens is given in paren- 

 theses. 



Caudal fin formula = 4-5-4-4 (15) 



Caudal vertebrae = 23(3)-24(18) 



Gill rakers (lower limb, first left) = ~12 (1) 



Left pelvic rays = 5 (12) 



Anal rays = 55-59 (11) 



Dorsal rays = 70-75 (11) 



Of the potential species listed in Table 1, only C. 

 gymnorhinus has counts that agree with these (it 

 is unique in having only five left pelvic rays). In 

 addition, larvae were captured over the outer 

 shelf, but not as far offshore as C. cornutus (Fig. 

 1). This is consistent with bathymetric distribu- 

 tion of adults. 



Distinguishing Characters 



Citharichthys gymnorhinus larvae have no 

 pectoral melanophore, and notochordal pigment 

 is restricted to the caudal region. Three elongate 

 dorsal rays are present from preflexion (4.6 mm) 



through postflexion (probably through transfor- 

 mation). Caudal vertebrae (23-24) can be counted 

 by early flexion (6 mm). Lateral pigment is rela- 

 tively sparse except for the caudal band. Flexion 

 is complete at 7-8 mm SL. Morphology is similar 

 to that of C. cornutus. However, the left pelvic fin 

 of C. gymnorhinus has a full complement of only 

 five rays, and in larvae the first ray is much re- 

 duced in size compared with that of C. cornutus. 

 Length of C. gymnorhinus at transformation is 

 probably about 18 mm. Larvae may appear in 

 collections year-round. 



Pigmentation 



Pigmentation of C. gymnorhinus larvae is 

 moderate. Gas bladder and caudal band pigment 

 are the most striking. 



By 4.6 mm and throughout larval develop- 

 ment, the dorsal one-third of the left side of the 

 gas bladder is fairly heavily pigmented, usually 

 with distinct melanophores. With growth, the 

 number of melanophores increases. There are 

 usually more of them than in C. cornutus larvae. 

 The maximum number in a preflexion specimen 

 was about 15 (4.6 mm, Fig. 6A). The right side of 

 the gas bladder is either unpigmented or has 

 only one or two melanophores. 



By 4.6 mm (Fig. 6A) a caudal band of melano- 

 phores is present on the dorsal and ventral fin- 

 folds and sides and margins of the body about 

 halfway from the anus to the notochord tip. This 

 band is more distinct and regular than in other 



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