SUMIDA ET AL EARLY DEVELOPMENT OF SEVEN FLATFISHES 



character in H. stomata because other species of 

 Hippoglossina possess this bone. 



The dorsal fin of//, stomata develops quite dif- 

 ferently than in Pleuronichthys. An anterior 

 group of about five dorsal rays is the first to form in 

 H. stomata; these become more elongated than the 

 other rays. The anlage of these is evident on a 

 6.4-mm NL preflexion specimen and four rays are 

 formed on a 9.3-mm NL early flexion larva. A 

 similar pattern of early forming dorsal fin rays is 

 found in the closely related genera Paralichthys 

 (Okiyama 1967; Smith and Fahay 1970; Ahlstrom 

 and Moser 1975) and Pseudorhombus (Devi 1969). 

 Although the anterior dorsal rays form early, the 

 pelvic fins do not develop elongated rays, such as 

 in the bothid genera Syacium (Aboussouan 1968) 

 and Cyclopsetta (Gutherz 1970). The dorsal fin 

 rays differentiate posteriad but most rays form 

 simultaneously and the full complement is de- 

 veloped on a late flexion specimen. The base of the 

 anal fin is evident during early caudal formation, 

 rays are forming on midflexion specimens, and the 

 total number is formed on a late flexion specimen. 

 Pelvic fin buds are evident on early flexion speci- 

 mens, but rays can be distinguished only on post- 

 flexion larvae. 



Distribution. — This species ranges from Monterey 

 Bay, Calif., to the Gulf of California, including 

 Guadalupe Island (Miller and Lea 1972). Larvae 

 occurred over a wide band of inshore and offshore 

 stations (Figure 24). The southern limit of H. 

 stomata overlaps the northern range of H. tet- 

 rophthalmus which has different fin counts 

 (Ginsburg 1952). To date, larvae of H. tet- 

 rophthalmus are not known. 



SUMMARY 



We used a combination of larval morphology, 

 meristics, and pigmentation to distinguish seven 

 known eastern North Pacific species of flatfishes 

 with heavily pigmented larvae. Table 20 sum- 

 marizes many pertinent characters for identifying 

 eggs and larvae of these species. Information is 

 given for three characters of eggs; size, ornamen- 

 tation of the chorion, and presence or absence of an 

 oil globule. 



In most instances, the size of a newly hatched 

 larva is directly related to the size of the egg from 

 which it hatched, and such is the case with 

 Pleuronichthys. Pleuronichthys decurrens. with 

 the largest egg, has the largest larva, with a suc- 



40' 



35' 



30' 



25' 



20' 



129° 

 "7 



125° 



"7 — r 



CAPE 



MENDOCINO 



^MONTEREY 

 BAY 



POINT 

 'CONCEPTION 



O rJ SAN 



DIEGO 



\ 



440 



40° 



35° 



30° 



25° 



115° 



)06° 



FiGL'RE 24. — Distribution of eggs and larvae o^ Hippoglossina 

 stomata examined in this study. (Triangles represent eggs, 

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



cessive decrease in larval size of the other species 

 corresponding to their smaller sized eggs. This 

 also applies to the yolk-sac larvae of Hypsopsetta 

 guttulata and Hippoglossina stomata. Pleuron- 



141 



