TUCKER: LARVAL DEVELOPMENT OF CITHAKICHTHYS AND ETROPUS 



transformation and is obscured by body muscu- 

 lature in most specimens longer than 10 mm. A 

 caudal band does not appear until the myoseptal 

 pigment pattern of early juveniles is established 

 (9-10 mm, Fig. 9B). By the end of transforma- 

 tion, myoseptal pigment is well developed, 

 mostly adjacent to dorsal and anal pigment clus- 

 ters; it often forms additional vertical bands 

 across the body. In older juveniles (16 mm, Fig. 

 9C), the dorsal and anal clusters and myoseptal 

 pigment become less distinct and partially blend 

 in with the increasing brownish ground color. 



Morphology (Figs. 8, 9; Tables 3, 7) 



General morphological features are similar to 

 those of C. cornutus, with the qualification that 

 the smallest C. spilopterus specimen examined 

 was 3.7 mm NL. Adult morphometries given in 

 the following discussion were derived from 

 Gutherz (1967) and Dawson (1969). 



During flexion and postflexion, the mouth is 

 relatively small and is similar in size to that of E. 

 crossotus. The adult mouth is also small for the 

 genus. Upper jaw length/BL decreases greatly 

 from 9.9% (preflexion) to 6.7% (postflexion) and 

 then increases greatly to 9.0% (midjuvenile). 

 Adult upper jaw length/BL is 10.5%. Upper jaw 

 length/HL decreases greatly from 36% (preflex- 

 ion) to 27-29% (flexion to early juvenile) and then 

 increases greatly to 36% (midjuvenile). Adult 

 upper jaw length/HL is about 37%, range 31-40%. 

 Lower jaw length/BL decreases greatly from 

 12.1% (preflexion) to 9.1% (postflexion) and then 

 increases greatly to 13.1% (midjuvenile). Adult 

 lower jaw length/BL is 12.4%. Lower jaw length/ 

 HL decreases greatly from 43% (preflexion) to 

 38% (flexion and postflexion) and then increases 

 greatly to 53% (midjuvenile). Adult lower jaw 

 length/HL is 44%, range 41-47%. 



The larval snout is relatively long but blunt. 

 The adult snout is relatively pointed. Snout 

 length/BL decreases from 7.5-7.6% (preflexion 

 and flexion) to 6.4% (postflexion) and 5.0% (mid- 

 juvenile). Adult snout length/BL is 5.6%. Snout 

 length/HL is fairly constant at 27-29% from pre- 

 flexion through postflexion and then decreases to 

 20% (midjuvenile). Adult snout length/HL is 

 20%, range 18-22%. 



The eye is moderate in larvae and small in 

 adults. Eye diameter/BL decreases greatly from 

 9.7% (preflexion) to 6.5% (postflexion) and then 

 increases slightly to 7.0% (midjuvenile). Postflex- 

 ion eye diameter/BL is similar to those of E. cros- 



sotus and E. microstomus. Adult orbit diameter/ 

 BL is 5.6%. The large decrease in larval eye 

 diameter/BL is exceptional among known west- 

 ern North Atlantic Citharichthys and Etropus 

 larvae. Eye diameter/HL decreases greatly from 

 35% (preflexion) to 27-28% (postflexion to mid- 

 juvenile). Adult orbit diameter/HL is 20%, range 

 13-25%. 



The head is very blunt, with a nearly vertical 

 anterior profile, prior to transformation. It is 

 relatively long during preflexion, moderate dur- 

 ing flexion, short during postflexion, and moder- 

 ate in adults. Head length/BL decreases greatly 

 from 28% (preflexion) to 24% (postflexion) and 

 then increases to 25% (early and midjuvenile). 

 Adult head length/BL is 28%, range 26-31%. The 

 decrease in relative larval head length is excep- 

 tional among known western North Atlantic 

 Citharichthys and Etropus larvae. The head is 

 relatively deep during preflexion and flexion, 

 and shallow during postflexion. Head depth/BL 

 increases from 37% (preflexion) to 39% (flexion), 

 then decreases greatly to 33% (postflexion) and 

 31% (midjuvenile). Postflexion head depth/BL is 

 similar to those of C. gymnorhinus and E. cros- 

 sotus. 



Snout to anus length is relatively short. Snout 

 to anus length/BL decreases greatly from 39-40% 

 (preflexion and flexion) to 31-32% (postflexion to 

 midjuvenile). 



The body is deep throughout the larval stages, 

 except that the abdomen becomes only moder- 

 ately deep by postflexion. During postflexion, 

 the dorsal and ventral profiles are not as convex 

 as in other known western North Atlantic Cith- 

 arichthys and Etropus larvae. Adult body depth 

 is moderate. Body depth at pelvic fin/BL in- 

 creases from 40% (preflexion) to 47% (flexion) 

 and then decreases to 39% (postflexion) and 35% 

 (midjuvenile). Body depth at anus/BL increases 

 from 39% (preflexion) to 51% (flexion) and then 

 decreases to 43% (postflexion) and 39% (midjuve- 

 nile). Body depth at third hemal spine/BL in- 

 creases from 23% (preflexion) to 41% (flexion), 

 decreases to 37% (early juvenile), and then in- 

 creases to 40% (midjuvenile). Adult body depth/ 

 BL is 46%, range 40-51%. Caudal peduncle depth/ 

 BL decreases from 14.4% (preflexion) to 13.5% 

 (postflexion) and 11.4% (midjuvenile). Adult 

 caudal peduncle depth/BL is 12.8%, range 11.0- 

 13.9%. The decrease in relative larval caudal 

 peduncle depth is exceptional among known 

 western North Atlantic Citharichthys and 

 Etropus larvae. 



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