FISHERY BULLETIN VOL 77. NO 1 



44° 



40° 



35° 



30° 



10° 



106° 



FU'.URE 8. — Distribution of eggs and larvae of Pleuronichthys 

 coenosus examined in this study, iTriangles represent eggs, 

 open circles larvae, and closed circles eggs and larvae.) 



Pleiirouichthys verticalis Jordan and 



Gilbert (hornxhead turbot) 



Figures 9, 10 



Literature. — The eggs and two early larvae (3.16 

 and 3.35 mm) were de.scribed and illustrated by 

 Budd ( 1940). Four illustrations of larvae, between 

 4.4 and 8.7 mm SL. are contained in CalCOFI 

 Atlas No. 23 lAhlstrom and Moser 1975). 



Distinguishing characters. — Preflexion and early 

 flexion larvae of this species are recognizable by 

 the triangular patches of pigment, one each on the 

 dorsal and ventral finfold posterior to the anus; 

 these form late in the yolk-sac stage and persist 

 through the notochord flexion stage. No other 

 species of Pleuronichthys develops this distinctive 

 pigmentation character. 



Late flexion and postflexion larvae are distin- 

 guished by size (i.e., larger than H. guttulata, P. 

 ritteri. and P. ocellatus, but smaller than P. 

 coenosus and P. decurrens ), and by sparse pigment 

 on the head and on the dorsal and anal fin 

 pterygiophores. This is in sharp contrast to the 

 heavy pigment in these areas for the other species 

 discussed. 



Newly transformed specimens are difficult to 

 distinguish from comparable stages of P. ritteri. 

 However, pigment on the body tends to be mottled 

 on P. verticalis rather than evenly distributed as 

 on P. ritteri at this stage. Small juveniles are eas- 

 ily separable from P. ritteri because P. verticalis 

 lacks the anterior prolongation of the supratem- 

 poral branch of the lateral line found on P. ritteri 

 juveniles. 



Pigmentation . — Pigment on yolk-sac and older 

 preflexion larvae of P. verticalis is heavy on the 

 head, trunk, and tail and ends anterior to the last 

 three to five myomeres (Figure 9A, B). As the last 

 remnant of yolk is absorbed, scattered finfold pig- 

 ment differentiates into triangular-shaped clus- 

 ters posterior to the anus, the dorsal patch being 

 situated slightly anterior of the ventral patch. The 

 head region below and on each side of the eye is 

 only sparsely pigmented which is typical of most 

 early preflexion larvae of several species of 

 Pleuronichthys. The top of the head to the shoulder 

 region is unpigmented, a character shared with 

 preflexion larvae of P. ritteri. Small pigment spots 

 dot the margin of the tip of the tail, but do not 

 persist beyond the flexion stage (Figure 9C, D). 



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