vae of Pontinus and Scorpaenodes have only oc- 

 casionally been taken off Baja California and as far north 

 as the vicinity of Cedros Island. The larvae of four genera 

 may cooccur in the Gulf of California — Scorpaena, Scor- 

 paenodes, Pontinus, and Sebastes. Larvae of Sebastes 

 and Scorpaena are taken commonly in the upper and 

 middle Gulf, whereas larvae of Pontinus and Scor- 

 paenodes are taken in the middle and lower Gulf; 

 however, there is a broad area of overlap of the four 

 genera in the Gulf. 



Larvae of scorpaenids are commonly taken at con- 

 siderable distance from shore. In the CalCOFI area, lar- 

 vae are taken as far offshore as 500 km, and on EAS- 

 TROPAC cruises even further offshore. Scorpaenid larvae 

 that are taken at considerable distances offshore often 

 belong to species that have an extended pelagic juvenile 

 stage. A prime example is Sebastolobus altivelis, which 

 spend about 20 mo in the pelagic environment from 

 spawning to settling and attain a length of up to 56 mm 

 as pelagic juveniles (Moser 1974). Another example is 

 Pontinus Type A, the common form in the EAS- 

 TROPAC area. The larvae grow to about 15 mm before 

 transforming to pelagic juveniles, which then attain 

 lengths up to 27.4 mm. There apparently is a large size 

 range over which juveniles of Pontinus Type A become 

 demersal, since bottom-caught specimens as small as 

 17.2 mm are present in collections. This may be related 

 to the extensive offshore distribution observed for this 

 scorpaenid, with nearshore individuals settling out first. 



KEYS TO LARVAE OF EASTERN PACIFIC 

 SCORPAENID GENERA 



The most obvious feature of the larval period of marine 

 fishes is change. Changes in form and pigmentation from 

 hatching to transformation into the juvenile stage range 

 from substantial to spectacular. Because of this it is im- 

 possible to write a dichotomous key that would allow 

 identification of a species or genus of scorpaenid during 

 all phases of its early life history. To overcome this we 

 have constructed two keys, one for larvae which have not 

 undergone notochord flexion and have not formed me- 

 dian fins and the other for larvae which have completed 

 notochord flexion. The characters used in these keys are 

 summarized in the preceding section and discussed in 

 detail in the generic and species accounts. Since larvae of 

 the eastern Pacific species of Helicolenus and Trachy- 

 scorpia were not available to us we have omitted these 

 genera from the keys. 



Key to Early Preflexion Larvae of 

 Eastern Pacific Scorpaenid Genera' 



dorsal and ventral margins, sometimes ex- 

 panded to a solid band Sebastolobus 



lb. Melanophores on tail along ventral mid- 

 line only, or along dorsal and ventral mid- 

 line, but each series contains a number of 

 discrete melanophores 2 



2a. Series of both dorsal and ventral margin 

 melanophores developed on tail .... 

 Sebastes (some spp.) 



2b. Only ventral margin melanophores series 



on tail 3 



3a. Melanistic shield of pigment covering dor- 

 solateral surface of gut 4 



3b. No melanistic shield covering dorsolateral 

 surface of gut; pigment restricted to deeply 

 embedded blotch 5 



4a. Larvae 2.0 to 3.0 mm at hatching, 24 myo- 

 meres, voluminous finfold Scorpaena 



4b. Larvae 4.0 to 6.0 mm at hatching, 26 or 27 



myomeres, moderate finfold . . .Sebastes (some spp.) 



5a. Melanophores on pectoral fins restricted to 



distal margin of fin Scorpaenodes 



5b. Melanophores on pectoral fins distributed 



over entire blade of fin 6 



6a. Depth of pectoral fin base 18 to 22% of 



body length Ectreposebastes 



6b. Depth of pectoral fin base 15 to 16% of 



body length Pontinus 



Key to Postflexion Larvae of 

 Eastern Pacific Scorpaenid Genera' 



la. Parietal ridge bifurcate posteriorly, with 



posterior (nuchal) spine large 2 



lb. Parietal ridge ending in single spine (pari- 

 etal) or if two spines are present the second 

 (nuchal) is small and positioned basally ... 3 



2a. Myomeres, 29-31; dorsal spines, XTV- 



XVn Sebastolobus 



2b. Myomeres, 24 or 25; dorsal spines, XIII 



Scorpaenodes 



3a. Myomeres, 26 or 27; dorsal spines XHI . . . Sebastes 



3b. Myomeres, 24; dorsal spines, XII 4 



4a. Depth of pectoral fin base, 19 to 22% of 



body length Ectreposebastes 



4b. Depth of pectoral fin base 8 to 18% of body 



length 5 



5a. Pectoral fins wing-shaped Pontinus 



5b. Pectoral fins with rounded posterior mar- 

 gin Scorpaena 



DESCRIPTION OF LIFE HISTORY SERIES 



la. Melanophores on tail portion of body re- 

 stricted to two large opposing blotches on 



'Not included is Helicolenus from the southeastern Pacific which prob- 

 ably would key to couplet 4a based on the Atlantic species and Trachy- 

 scorpia which might key to la. 



Of the 19 life history series included in this guide, 11 

 have not appeared previously in the literature or have 

 appeared as fragmentary accounts. These are Sebastes 

 jordani, S. levis, S. cortezi. S. sp. (Gulf of California, 



'Trachyscorpia probably would key to couplet la and Helicolenus to 5b. 



