paenodes whereas in Pontinus the pattern of pigmen- 

 tation is more complex and develops through sequential 

 stages. Larvae of Ectreposebastes are highly distinctive 

 and may be separated from those of Pontinus on the 

 basis of body depth and pectoral fin length. Body depth 

 averages 46% of body length for postflexion larvae of Ec- 

 treposebastes and 39^'c for postflexion larvae of Pontinus 

 Type A. The pectoral fin extends to the base of the 

 caudal fin in Ectreposebastes and extends only to the 

 midregion of the anal fin in Pontinus. Also, pigmen- 

 tation of the pectoral fin is markedly different as evident 

 in the illustrations of larvae of the two genera. 



Despite the large species complement of Pontinus, we 

 can distinguish only three larval forms in our collection. 

 We have a complete larval series of the abundant form, 

 here called Pontinus Type A. It ties in with the juveniles 

 of a common but undescribed species of Pontinus dis- 

 covered in this study. A second, much less abundant 

 form, called Pontinus Type B, is distinguishable down to 

 a length of about 5.0 mm. Its largest pelagic juveniles 

 have a pigment pattern similar to the smallest known 

 benthic juveniles of Pontinus sierra (Gilbert) and it is 

 likely that Pontinus Type B is P. sierra. A third form, 

 here called Pontinus Type C, is known from a few small 

 larvae and is presently not identifiable. 



Since larvae of Pontinus have not been previously de- 

 scribed, a detailed description of Pontinus Type A is 

 given below along with a brief description of Type B. 



Pontinus Type A, Figure 35 

 Literature. — None . 



Distinguishing features. — The smallest larva 

 available to us is a specimen 2.3 mm long that has no 

 yolk sac. When the larvae reach about 15 mm, pigment 

 saddles begin to form dorsally on the trunk. Although 

 there is no associated abrupt morphological change we 

 have designated this as the beginning of the pelagic 

 juvenile stage. This stage is protracted in Pontinus Type 

 A, our largest pelagic specimen being 27.4 mm long. Ap- 

 parently, there is a large size range over which Pontinus 

 Type A pelagic juveniles may become demersal since 

 bottom-caught specimens as small as 17.2 mm are pres- 

 ent in our collections. 



Larvae of Pontinus Type A are deep-bodied. Body 

 depth increases from a minimum of 25% of the body 

 length in the smallest larva to 33% at notochord flexion 

 (Table 36). Body depth averages 39% in postflexion lar- 

 vae and pelagic juveniles. In small benthic juveniles, 

 average body depth is reduced slightly to 36% of the body 

 length. 



The gut is compact in small larvae of Pontinus Type A 

 and undergoes a relative lengthening throughout the lar- 

 val period. Snout-anus distance averages 48% of the body 

 length before notochord flexion, 54% during flexion, and 

 6Kt following flexion. In pelagic and small benthic 

 juveniles, snout-anus length averages 64% of the body 

 length. 



Table 35. Measurements (im) of larvae of Pontinus Type A. (Spectmens between dashed lines 

 are undergoing notochord flexion.) 



•Pelagic juvenile. 

 •■Benthic juveni te. 



The head is large in Pontinus Type A larvae. Head 

 length increases from a mean of 30% of the body length in 

 preflexion larvae to 32% in larvae undergoing notochord 

 flexion, and averages 40% in postflexion larvae and in 

 pelagic and small benthic juveniles. The moderately 

 small eyes undergo a relative diminution during the lar- 

 val period. Eye diameter averages 32% of head length 

 before and during notochord flexion and is reduced to a 

 mean of 27% in postflexion larvae and pelagic juveniles. 

 Eye diameter increases slightly to a mean of 28.5% of 

 head length in newly transformed benthic juveniles. 

 Snout length increases from a mean of 32% of head 

 length in preflexion larvae to a mean of 41% in larvae 

 undergoing flexion. Thereafter the mean decreases to 

 33% in postflexion larvae and to 29% in pelagic juve- 

 niles. 



The pectoral fins are prominent in the smallest larvae 

 in our collection. At this stage they have a slight aliform 

 shape; however, during later larval stages they become 

 distinctly aliform. Fin length increases from an average 

 of 20% of the body length in preflexion larvae to 26% in 

 larvae undergoing notochord flexion, and to 32% in post- 

 flexion larvae and pelagic and small benthic juveniles. 

 The depth of the pectoral fin base is not as great as in 

 other eastern Pacific scorpaenine genera but is greater 

 than in sebastine genera. It decreases from an average of 

 16% of the body length before and during notochord flex- 

 ion, to 14% in postflexion larvae and 13% in pelagic and 

 early benthic juveniles. Sequence of ossification of fin 

 elements was not analyzed because only a few larger lar- 

 vae could be properly stained. Apparently calcium in the 

 larvae leached out in preservative. Pectoral ray counts 

 for nine stained specimens ranged from 17 to 19. 



The dorsal, anal, and pelvic fins begin to develop in 

 larvae about 4.0 mm long. The counts for the nine stain- 

 ed specimens were D. XII, 9; A. Ill, 5; P. I, 5. Hypural an- 

 lagen of the caudal fin are visible in the smallest larvae; 



61 



