Ditty and Shaw. Larval development and distribution of Lobotes surinamensis 



41 



nathids, lethrinids, priacanthids, and Hap- 

 alogenys sp. These taxa generally have a 

 median supraoccipital crest, an elongate 

 spine at the preopercular angle, and about 

 24 myomeres (except cepolids which have 

 28+ myomeres). In addition, cepolids are 

 lightly to moderately pigmented and have 

 fewer dorsal spines and more soft dorsal- 

 fin rays than tripletail (Leis and Trnski, 

 1989). Species of other families may have 

 a median supraoccipital crest during devel- 

 opment, but most have pelvic fins inserted 

 anterior to pectorals. Also, larvae of other 

 percoid families are usually not as deep- 

 bodied and as heavily pigmented as triple- 

 tail by early postflexion, and few possess 

 an elongate preopercular spine and low 

 myomere count. Of the aforementioned 

 taxa, only caproids, carangids, ephippids, 

 and priacanthids occur in the Gulf of 

 Mexico. Larvae of the caproid genus 

 Antigonia are most similar to tripletail but 

 have a serrate frontal crest and lower jaw, 

 a very long and serrate preopercular angle 

 spine, and more than 39 dorsal and 26 anal 

 elements (Tighe and Keene, 1984; Leis and 

 Trnski, 1989). In carangids, the two ante- 

 rior-most anal spines are separated from 

 the third by a distinct gap and most spe- 

 cies have a low, median supraoccipital crest 

 with dorsal serrations; other carangids lack 

 a supraoccipital crest entirely. Some car- 

 angids also have a precocious dorsal fin 

 with elongate anterior spines or rays, or a 

 serrated preopercular angle spine. 

 Drepaneids have pigment on the pectoral 

 fins and multiple barbels along the lower 

 jaw. Both larval drepaneids and ephippids 

 are rotund and have pelvic fins inserted 

 anterior to the pectorals. In addition, the 

 Gulf ephippid Chaetodipterus faber has a 

 supraoccipital crest with a single spine 

 dorsally rather than the vaulted, serrate 

 supraoccipital crest found in tripletail. Atlantic spa- 

 defish also have more anal fin elements (tripletail: 

 A. Ill, 11-12; Atlantic spadefish: A. Ill, 17-18). Lar- 

 val leiognathids and lethrinids have a supraoccipital 

 crest that originates above the anterior margin of 

 the eye and both taxa are lightly pigmented (Leis 

 and Trnski, 1989). Also, lethrinids have higher anal 

 fin counts and serrations along the lower jaw (Leis 

 and Rennis, 1983), and leiognathids have a distinc- 

 tive pattern of pigment ventrally on the tail (Leis 

 and Trnski, 1989). Priacanthids have serrate dorsal, 

 anal, and pelvic spines and other serrate ridges and 



DEPTH ZONE 



LENGTH (SL) 

 <5 LZZI 5-50 KX] 



51-180 rV^ 



Figure 5 



Distribution of larval tripletail iLobotes surinamensis) in the 

 northern Gulf of Mexico with respect to station depth (m). 

 Length classes are combined as follows: 2 mm = 1.0-2.9 mm, 

 4 mm = 3.0-4.9 mm, 6 mm = 5.0-6.9 mm, etc. All measurements 

 are standard length (SL). Numbers above bars are number of 

 larvae in each length category. 



spines on the head that tripletail lack (Johnson, 

 1984). Hapalogenys sp. larvae are extremely simi- 

 lar to tripletail but Hapalogenys sp. apparently lack 

 pigmented pelvic fins, have a serrate supraorbital 

 ridge, have a lacrimal spine, and have pterotic 

 spines or a ridge (Johnson, 1984). 



Collections of early larvae (this study) and gravid 

 females (Baughman, 1941; Merriner and Foster, 

 1974) suggest that tripletail spawn primarily dur- 

 ing summer along both the U. S. Gulf and Atlantic 

 coasts. In the Gulf, spawning begins in May, based 

 on the collection of a 7.0-mm larva, and extends 

 through September with peak spawning during July 



