averages 26% and 32%, respectively. The pectoral fin 

 base is slightly deeper in Pontinus Type B compared 

 with Pontinus Type A and like the latter becomes rela- 

 tively shallower as development proceeds. The fin base 

 averages 17% of the body length in Pontinus Type B lar- 

 vae undergoing notochord flexion, 16% in postflexion lar- 

 vae, and 14% in pelagic juveniles. In comparable stages 

 of Pontinus Type A, the averages are 15%, 14%, and 13%. 

 The shape of the fin in Pontinus Type B is aliform as it is 

 in Pontinus Type A. The sequence of ossification of fin 

 elements and rays could not be determined because of 

 calcium leaching in the small larvae during preservation 

 and storage. In six larger larvae and pelagic juveniles 

 which were stained, all had 18 pectoral rays. The dorsal, 

 anal, and pelvic fins were well formed in the smallest lar- 

 vae available. The counts of the stained specimens were 

 D. XII, 9; A. Ill, 5; P. I, 5. Three superior and two in- 

 ferior hypural elements develop in the caudal fin; there 

 are 8 -(- 7 principal and 5-7 -I- 5-7 procurrent rays. All 

 stained larvae had 24 vertebrae. Gill rakers of the stained 

 pelagic juveniles ranged from 5 to 6 on the upper limb 

 and 9 to 11 on the lower limb of the first arch. There were 

 7 branchiostegal rays. 



The absence of specimens of Pontinus Type B smaller 

 than 5.0 mm precludes knowledge of the pigment pat- 

 tern of early larval stages. Pigmentation of larvae larger 

 than this and pelagic juveniles is similar to that in lar- 

 vae and pelagic juveniles of Pontinus Type A, but there 

 are distinctive differences that allow separation of the 

 two forms. 



Several melanophores are present at the ventral mid- 

 line posterior to the developing anal fin. These remnants 

 of the ventral midline series are not found in larvae larger 

 than 8.7 mm. Another component of the original pig- 

 ment pattern, the melanistic shield covering the gas 

 bladder, is already masked by trunk musculature in the 

 5.0-mm larva and becomes further embedded with con- 

 tinued development. 



The pattern on the pectoral fins is markedly different 

 from that on the fins of Pontinus Type A larvae. On the 

 5.0-mm specimen a pigment streak extends obliquely 

 ventrad from the dorsal tip of the fin blade to the mid- 

 region of the fin. Also, a small blotch is present along the 

 base of the six most ventral rays and one is present on the 

 medial surface of the fin base in this region. The medial 

 blotch is not present in larvae larger than 6.0 mm; 

 however, the ventral blotch at the base of the fin blade 

 extends dorsad with further development and ul- 

 timately connects with the dorsal streak to produce a 

 complete bar in larvae longer than 10.0 mm. This ob- 

 lique bar remains a prominent feature throughout the 

 larval and pelagic juvenile stages. Other fin pigment pres- 

 ent in the 5.0-mm larva is a patch of melanophores at 

 the base of each pelvic fin. It remains in larger larvae and 

 in pelagic juveniles. 



Pigment is also present in 5-mm larvae on the spinous 

 dorsal fin. The blotch on the spinous dorsal membrane 

 extends from the 3rd or 4th spine to the 6th, 7th, or 8th 

 spine and remains throughout later developmental 

 stages. It enlarges slightly with development and covers 



the membrane from the Ist to 10th rays in the 23.1-mm 

 pelagic juvenile. A portion of this blotch from the 6th to 

 10th ray is darker than the background and stands out as 

 a black spot. This same pattern is present on the spinous 

 dorsal fin of a 39.0-mm benthic juvenile of P. sierra. 



The dorsal pigment saddles appear much earlier than 

 in larvae of Pontinus Type A and are distinctly different 

 in form. In 5-mm larvae of Pontinus Type B, small 

 blotches are present on either side of the dorsal midline 

 at the anterior end of the spinous dorsal fin and at the 

 posterior region of the fin. In 8-mm larvae the anterior 

 saddle has enlarged to occupy the region along the an- 

 terior one-third of the spinous dorsal and has enlarged 

 ventrad to the head and forward over the nape. A narrow 

 space separates the anterior saddle from the posterior 

 saddle which now extends along the posterior two-thirds 

 of the spinous dorsal and ventrad about halfway to the 

 lateral line. A third pigment saddle is beginning to form 

 on either side of the soft dorsal fin. In 10-mm larvae the 

 posterior saddle of the spinous dorsal fin extends to the 

 lateral line and the one at the soft dorsal extends to the 

 horizontal septum. In 14-mm larvae the latter saddle ex- 

 tends ventrad to the anal fin where it meets a blotch of 

 pigment on the membrane of the soft anal rays. Anterior 

 to this bar three distinctive blotches lie along the 

 horizontal septum. At about 17 mm a blotch forms on 

 each side of the caudal peduncle, and in the largest 

 pelagic juvenile (23.1 mm) it has connected with dorsal 

 midline pigment to form a saddle. Also, in this largest 

 specimen a blotch is present over each side of the hy- 

 pural region. The pattern of pigment saddles and 

 blotches in the largest pelagic juveniles matches closely 

 the pattern found in a 39.0-mm benthic juvenile of P. 

 sierra. 



Head pigment first appears in 8-mm larvae on the dor- 

 sal and lateral surfaces of the brain and remains 

 throughout the larval period. In 10-mm larvae, pigment 

 appears along the basal region of the branchiostegal rays 

 and on the posterior region of the opercle. Also, a blotch 

 of pigment is present on the cheek ventroposterior to the 

 eye. In the largest pelagic juvenile additional pigment 

 appears anterior to the eye. 



Distribution. — Pontinus sierra is known to range from 

 the Gulf of California to Peru. Pelagic juveniles of Ponti- 

 nus Type B were taken on two midwater trawl stations in 

 the southern Gulf of California and on a single midwater 

 trawl station on the outer coast between Magdalena Bay 

 and Cape San Lucas (Fig. 38). A wide latitudinal gap 

 separates these occurrences from the remainder of the 

 pelagic juveniles and larvae which were taken off the 

 Central and South American coasts, as far south as the 

 equator. They appear to be more restricted to coastal 

 waters than are larvae and pelagic juveniles of Pontinus 

 Type A and there were no occurrences at the Galapagos 

 Islands. 



Larvae and pelagic juveniles of Pontinus Type B are 

 rare compared to catches of Pontinus Type A. Of the 23 

 total positive hauls, 17 contained a single specimen and 6 

 contained two specimens. 



66 



