TUCKER: LARVAL DEVELOPMENT OF CITHARICHTHYS AND ETROPUS 



Fin and Axial Skeleton Formation 



Caudal skeleton development is similar to that 

 of C. cornutus. Size ranges of available speci- 

 mens in each stage are as follows: Early caudal 

 formation, 4.6 mm NL; early flexion, 4.9-5.4 mm 

 NL; midflexion, 5.4-6.0 mm NL; late flexion, 6. 1- 

 9.5 mm NL; postflexion, 9.3-10.8 mm SL. Caudal 

 rays become calcified between early flexion (4.9 

 mm NL) and late flexion (about 6.5 mm NL). 



All precaudal neural spines stain with alizarin 

 at 4.6 mm NL. Some caudal neural spines and 

 hemal spines stain with alizarin at 4.6 mm NL, 

 and all do by 5.6 mm NL. All precaudal and cau- 

 dal centra stain with alizarin at about 6.0 mm NL. 

 The urostyle stains with alizarin at 6.2 mm NL. 

 The smallest specimen in which caudal centra 

 could be counted was 5.4 mm NL (midflexion). 



The second and third dorsal rays are elongate 

 and moderately separated at the bases from pre- 

 flexion (4.6 mm NL) through transformation 

 (about 11 mm SL). During early flexion (4.9 mm 

 NL), rays near the middle of the fin begin to cal- 

 cify. Calcification proceeds anteriorly and pos- 

 teriorly. Adult counts are present from late flex- 

 ion (about 8.0 mm NL) onward. The first ray and 

 most posterior rays are calcified prior to trans- 

 formation (by about 9.6 mm SL). 



During early flexion (4.9 mm NL), anal rays 

 near the middle of the fin begin to calcify. Calci- 

 fication proceeds anteriorly and posteriorly. 

 Adult counts are present from late flexion (about 

 8.0 mm NL) onward. The most posterior rays are 

 calcified during late flexion (about 9.3 mm NL). 



Development of the left pelvic fin precedes that 

 of the right. The left pelvic fin bud appears dur- 

 ing preflexion (before 4.6 mm NL). Rays develop 

 between early caudal formation (4.6 mm NL) 

 and late flexion (8.5 mm NL). The second ray is 

 the first to appear; it is elongate. The first ray 

 appears soon after the second; it may be slightly 

 elongate. The right pelvic fin bud appears dur- 

 ing midflexion (5.5 mm NL). Rays develop 

 between midflexion (5.8 mm NL) and late flexion 

 (8.5 mm NL). Each complete fin has six rays. 



Rayless, fanlike, larval pectoral fins are 

 present on the smallest available specimen (4.6 

 mm NL). Calcification of rays in the left fin oc- 

 curs during late transformation (10-11 mm SL). 



Fig. 10A). With development (Fig. 10B), addi- 

 tional spines appear until maximum numbers of 

 about 24 on the left (range 18-29) and 22 on the 

 right (range 16-27) are reached during midflex- 

 ion (5.4-6.0 mm NL). Thereafter, spines are lost 

 until none or only a few remain at transforma- 

 tion (Fig. 11B). 



Most specimens had three or four relatively 

 inconspicuous frontal-sphenotic spines on each 

 side, including one or two that were noticeably 

 stronger. 



Larval Teeth (Table 5) 



The early caudal formation specimen (4.6 mm 

 NL, Fig. 10A) had three upper and five lower 

 teeth on each side. Early flexion larvae (4.9-5.4 

 mm NL) have three upper and five or six lower 

 teeth on each side. During midflexion (5.4-6.0 

 mm NL), there are three to five upper and five to 

 seven lower teeth on each side. During late flex- 

 ion (6.1-9.5 mm NL), larvae usually have four 

 upper and seven lower teeth on each side. During 

 postflexion (9.3-10.8 mm SL), there are usually 

 four or five upper and seven lower teeth on each 

 side. The nearly transformed specimen ( 10.3 mm 

 SL, Fig. 11B) had seven upper and more than 

 nine lower teeth on each side. 



Transformation 



Migration of the right eye may begin as early 

 as late flexion (7.4 mm NL) or as late as postflex- 

 ion (10.8 mm SL). The right eye moves from the 

 right side of the head around the dorsal fin origin 

 (Fig. 11 A) as in C. arctifrons and E. microstomas 

 (Richardson and Joseph 1973). The right eye 

 reaches its final position on the left side of the 

 head at about 10-12 mm SL. 



Occurrence 



Larvae were collected in the Cape Fear River 

 Estuary during May (pers. obs.) and in the Gulf 

 of Mexico off Louisiana west of the Mississippi 

 River Delta during July and August (Walker 7 ). 

 Moe and Martin (1965) suggested a spawning 

 season from March to at least June for the east- 

 ern Gulf of Mexico off Florida (based on ripe 



Cephalic Spination 



Preopercular spines (Table 4) were present in 

 the smallest preflexion specimen (4.6 mm NL, 



7 H. J. Walker, Research Technician, North Carolina State 

 University, Cape Fear Estuarine Laboratory, P.O. Box 486, 

 Southport, NC 28461, pers. commun. July 1977. 



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