Ditty and Shaw: Larval development and distribution of Lobotes sunnamensis 



35 



eye diameter/head length ratio. We consider noto- 

 chord length in preflexion and flexion larvae synony- 

 mous with SL in postflexion larvae and report all 

 lengths as SL unless otherwise noted. Specimens 

 were fixed in 10% formalin and later transferred to 

 70% ethyl alcohol. Representative specimens were 

 illustrated with the aid of a camera lucida. Because 

 of the paucity of material, only two specimens were 

 cleared with trypsin and stained with alizarin to 

 examine head spines. We examined the surface of 

 the occipital and frontal bones with a scanning elec- 

 tron microscope (SEM) after the epithelium was par- 

 tially digested with trypsin. Soft rays of the dorsal and 

 anal fins were counted when their pterygiophores were 

 visible, and spines were counted when present. 



Results 



Larval morphometries and pigmentation 



Ninety-eight larval or juvenile tripletail were exam- 

 ined during this study (Appendix Table 2): 7 were 

 preflexion or flexion (<5.0 mm), 34 were postflexion 

 (5.1 to 9.5 mm), and 57 were transforming or juve- 

 nile (>9.5 mm). Body depth increased rapidly dur- 

 ing preflexion and flexion with depth >50% SL by 

 5.0 mm. The gut was straight. Larvae had 24 

 myomeres which became obscured by pigment in 

 postflexion larvae. Preanal length was 60-65% SL 

 in preflexion larvae and increased to 70-75% SL in 

 larvae >5.0 mm. Head length averaged 29% SL dur- 

 ing preflexion and increased to about 40% SL in 

 juveniles. The head became increasingly steep, and 

 the upper profile of the forehead was concave by 20.0 

 mm. The eye was large and had an orbit diameter 

 usually from 35 to 40% head length ( 12.5 to 15.0% 

 SL) by 4.0 mm. The upper jaw reached about mid- 

 eye. Pelvic fins were precocious, heavily pigmented, 

 and inserted behind the pectoral fins near mid-body, 



usually about 40-50% SL (Table 1). The pelvic fins 

 extended past the anus by 4.0 mm. 



Early preflexion larvae of 2.2-2.4 mm were 

 sparsely pigmented; pigment was primarily re- 

 stricted to the head and abdomen. On the head, 

 external pigment was present on the posterior sur- 

 face of the midbrain, posteriorly at the base of the 

 supraoccipital crest, on the nape, and immediately 

 anterior to the cleithral symphysis (Fig. 1). By early 

 flexion (4.0 mm), pigment was added between the 

 fore- and mid-brain and on the preopercle above the 

 dorsal-most preopercular spine (Fig. 1). Pigment 

 occurred at the tip of the upper and lower jaws and 

 at the angle of the preopercle near the base of the 

 angle spine by 5.0 mm. The head became heavily 

 pigmented during postflexion. By 10.0 mm, a band 

 of pigment extended diagonally across the head from 

 the nape to the orbit and from below the orbit to the 

 angle of the preopercle (Fig. 1). The eye was at the 

 apex of this chevron-shaped band of pigment. Two 

 parallel stripes of pigment were present between the 

 orbits by 14.0-15.0 mm, extending from the nares 

 to the anterior margin of the supraoccipital crest. 

 These pigment stripes became better formed as lar- 

 vae developed. On the abdomen, melanophores were 

 distributed dorsally over the air bladder, and dor- 

 sally and ventrally along the visceral mass and 

 hindgut of early larvae (Fig. 1). By early flexion, 

 pigment also was present on the pectoral axilla, 

 posteriorly over the visceral mass and hindgut, and 

 was scattered laterally over the body above the vis- 

 ceral mass. Body pigmentation increased rapidly 

 during early postflexion and extended posteriorly to 

 the caudal peduncle by 6.0 mm (Fig. 1). Blotches or 

 mottled areas of pigment formed over the body by 

 8.0-9.0 mm, becoming more evident as larvae devel- 

 oped (Fig. 1). 



Pigment along the ventral midline between the 

 anus and notochord tip was restricted to four to five 



