Zuniga and Acuiia- Development of Pcsra/zc/if/iys spp larvae 



619 



is not present in P. adspersus or 

 P. microps. Reared and field- 

 caught specimens of P. adsper- 

 sus lack pigmentation in the dor- 

 sal finfold during the first half 

 of their larval development, a 

 unique feature among described 

 paralichthyid larvae. 



In flounders, the main change 

 in body shape occurs during flex- 

 ion, wfith an increase in body 

 depth and head length. This 

 stage is characterized by devel- 

 opment of skeletal structures 

 and by a change in swimming 

 and feeding (Balart 1984). After 

 flexion, the rate of growth of the 

 head, snout, and jaws is compar- 

 atively greater in P. microps, while the rate of increase 

 in body depth is greater in P. adspersus. 



Preflexion larvae of P. adspersus and P. microps are 

 statistically indistinguishable using morphometries. 

 After flexion and loss of the elongated dorsal-fin rays, 

 separation is based mostly on morphometric character- 

 istics, especially SnL/HL and HL/SL. After metamor- 

 phosis, during the juvenile stage when all fin rays are 

 already developed, the adult range of meristic counts 

 can be used (Table 7). 



Acknowledgments 



The authors are deeply indebted to Mr. Alfonso Silva 

 for allowing them to use reared larvae which were part 

 of a culturing experiment and to Mr. Alejandro Aron 

 for providing field-collected larvae. Also, comments and 

 editorial recommendations of two anonymous 

 reviewers are greatly appreciated. This research was 

 financed by D.G.L Universidad Catolica del Norte. 



