Busby and Ambrose: Development of larval and juvenile Odontopyxis trispinosa and Xemeretmus latifrons 



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SL, increases to 56.7% SL during flexion, and decreases 

 to 47.4% SL during postflexion. 



Pigmentation Pigmentation in X. latifrons is consis- 

 tent among specimens and is a useful distinguishing 

 character (Fig. 7). Because pigmentation on the head 

 and gut regions of X. latifrons is so similar to that 

 described previously for O. trispinosa, discussion here 

 will be limited to areas of the lateral body and fins 

 that are diagnostically important. 



Lateral body The lateral surface of the body above 

 the gut in preflexion larvae is covered with melano- 

 phores, with the exception of an elongate, unpigmented 

 area along the dorsal midline above the pectoral fin. 

 Melanophores cover nearly the entire caudal region of 

 the body, with the exception of the notochord tip. Mel- 

 anophores extend along the dorsal and ventral mar- 

 gins of the unpigmented area around the notochord 

 tip (Fig. 7A). By early flexion, melanophores completely 

 cover the notochord tip (Fig. 7B). 



Three patches of melanophores appear along the dor- 

 sal midline near the notochord tip by about 10.5 mm 

 SL (Fig. 7C). The anterior patch forms the first band 

 which extends from the dorsal margin of the body, 

 posterior to the pectoral-fin base, to the anterior lat- 

 eral gut area. The second band extends dorsally to 

 connect with pigmentation seen on the first dorsal fin. 

 The third band transverses the body between the 

 posteriormost dorsal spine and the gut. Four or five 



distinct bands of pigmentation form between the ante- 

 rior edges of the second dorsal and anal fins and the 

 caudal fin. The first two bands transverse the body 

 between the anterior and posterior margins of the sec- 

 ond dorsal and anal fins. One or two bands are present 

 between the posteriormost dorsal- and anal-fin rays 

 and the hypural margin. The last band is the widest 

 and covers the hypural region, extending into the cau- 

 dal fin approximately 15-20% of its length (Fig. 7, C 

 andD). 



Fins Melanophores begin to appear on the ventral 

 margin of pectoral-fin base at about 5.0 mm. The pec- 

 toral-fin base is completely covered with pigment by 

 6.0 mm. Pigmentation is always absent from 

 the pectoral-fin blade, rays, and membrane (Fig. 7, A 

 and B). 



A small patch of melanophores appears in the dor- 

 sal finfold above the constriction of the gut at about 

 6.0mm (Fig. 7B). This pigmentation later expands and 

 is that seen on the spinous (first) dorsal fin in late 

 flexion and postflexion larvae (Fig. 7, C and D). Poste- 

 riorly, an additional patch of pigmentation begins about 

 one-third of the distance between the anus and noto- 

 chord tip and exhibits an irregular edge, appearing 

 somewhat serrated, below the dorsal margin. 



In preflexion larvae, a large patch of melanophores 

 covers most of the anal finfold beginning at approxi- 

 mately one-fourth of the distance between the anus and 

 notochord tip and continuing its entire length. The rela- 



