TUCKER: LARVAL DEVELOPMENT OF C ITH A RICHTHYS AND ETROPUS 



area from which other Etropus spp. have not 

 been reported. 



Distinguishing Characters 



Etropus crossotus larvae have a dashlike 

 melanophore at the base of each pectoral fin. In- 

 ternal pigment along the dorsal surface of the 

 notochord is extensive. Two elongate dorsal rays 

 are present from preflexion (4.6 mm) through 

 transformation. Caudal vertebrae (25-26, very 

 rarely 24) can be counted by midflexion (5.4 

 mm). Lateral pigment is relatively heavy. Flex- 

 ion is complete at 9-10 mm SL. The larval mouth 

 and eye are small. The left pelvic fin has a full 



complement of six rays. Length at transforma- 

 tion is 10-12 mm. Larvae usually appear in col- 

 lections from March through August. 



Pigmentation 



Pigmentation of E. crossotus larvae is rela- 

 tively heavy. Pigment on the gas bladder and on 

 the ventral and dorsal surfaces of the body is the 

 most striking. Most useful for identification is in- 

 ternal pigment along the dorsal surface of the 

 notochord and a melanophore at the base of the 

 pectoral fin. 



By about 4.6 mm (Fig. 10A) and throughout 

 larval development, the dorsal one-third of the 



Figure 10.— Larval stages of Etropus crossotus: A. Preflexion (early caudal formation), 4.6 mm; B. Midflexion, 6.0 mm. 



Scale = 1 mm. 



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