DEVELOPMENT OF CYCLOPSETTA 

 FIMBRIATA LARVAE 



No information is available on the fertilized eggs 

 or the yolk sac larvae of C. fimbriata; however, I 

 do have certain observations on the larger larvae, 

 including their identification, patterns of general 

 growth, formation of fins, spination, pigmenta- 

 tion, migi-ation of eyes, and sequence of 

 ossification. 



IDENTIFICATION OF LARVAE 



Larvae of O. fi7n'briata are identifiable at very 

 small sizes. The smallest larva in my sample (1.72 

 mm. SL) has a large head with a well-developed 

 mouth. Hatching size is probably about 1.50 mm. 

 SL or slightly smaller. Larvae of this species have 

 two prominent transitory features (they may be 

 generic) that are readily seen on the smallest lar- 

 vae (fig. 3) : a small, single spine on the sphenotic 

 region of the cranium and several small single 

 spines on the preopercle {Syacium has larger 

 sphenotic and preopercular spines) . These spines 

 persist throughout the larval stages (figs. 3-7) 

 and are still evident during metamorphosis (that 

 period when the eye is migrating) . No fin rays are 

 discernible in the finfold of the smallest larva 

 (1.72 mm. SL). At about 2.10 mm. SL the first 

 three elongate dorsal fin rays appear. Elongate 

 dorsal fin rays (8-11 in the large larvae) persist 

 throughout the larval stages (figs. 4-7). At about 

 3.00 to 3.30 mm. SL one to three elongate pelvic 

 fin rays appear (fig. 4) and persist throughout the 

 larval stages (figs. 4-7). 



The right side eye is migrating in the largest 

 larva in my sample (14.51 mm. SL). The dorsal 



edge of the migrating eye is above the middorsal 

 ridge of the cranium. During metamorphosis the 

 eye moves under the dorsal fin which is attached 

 anteriorly to the ethmoid region of the cranium. 

 The migrating eye had not yet begun to turn onto 

 the left side, but it appeared about ready to move 

 under the dorsal fin. Elongate dorsal and pelvic 

 fin rays and head and preopercular spination per- 

 sist (fig. 7). 



Four transitory larval features help differenti- 

 ate C. fimbriata and Syacium larvae from all other 

 bothid larvae found along the southeastern coast 

 of the United States: (1) a single spine in sphen- 

 otic region of the cranium, (2) several single pre- 

 opercular spines, (3) relatively high numbers of 

 elongate anterior dorsal fin rays, and (4) three 

 elongate pelvic fin rays (figs. 3-7). Compared to 

 Cyclopsetta, Syacium has larger and heavier 

 spines, fewer elongate dorsal fin rays, and rela- 

 tively shorter elongate pelvic fin rays. The sphen- 

 otic spine is surrounded by concentric rings on 

 large Cyclopsetta larvae but by a crenulated cap on 

 Syacium larvae. The origins of the pelvic fin bases 

 in relation to each other and to the cleithrum and 

 the transitory larval characters provide the 

 generic identity of Cyclopsetta larvae. 



Three species of Cyclopsetta occur in the west- 

 ern North Atlantic Ocean (Gutherz, 1967). C. fim- 

 hriata is the only species known from the Atlantic 

 coast of the United States, C. decu^ata is known 

 only from the type, and C. chittendeni is found 

 along the coast of the United States only in the 

 Gulf of Mexico. The distribution of these species 

 excludes all known species of Cyclopsetta except 

 fimbiiata from consideration for my larvae. 



FiouBE 3.— Larva of Cyclopsetta fimbriata, 1.8» mm. SL. Note sphenotic and preopercular spinaUon. Pectoral fin is 



omitted to show swim bladder and gut. 



268 



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