narrow portion of the distal region of the fin becomes 

 clear in mid- and late-stage larvae. 



Other pigmentation is not substantially different from 

 that of S. guttata and other known Scorpaena larvae. A 

 melanistic blotch appears just anterior to the junction of 

 the cleithra at about 3.0-mm length and remains 

 throughout the larval period. Melanophores form pos- 

 teriorly on the brain when the larvae are about 4.0 mm 

 long. At about 5.5 mm, one or two melanophores appear 

 above the olfactory lobes. In 7-mm larvae additional 

 melanophores form above the optic lobes and at 8.0 mm 

 the brain is covered. At 4.0-mm length an embedded 

 melanophore forms at the nape and remains throughout 

 the larval period. Myoseptal pigment is present in the 

 epaxial musculature above the pectoral fin in the 8.0-mm 

 larva. 



that station the mean number of larvae for the other 25 

 stations in the Gulf was 12. The species that produces 

 larvae of Scorpaena Type A is a summer spawner since 

 no larvae were taken on the December, February, or 

 April cruises in the Gulf during 1956 and 1957. 



Larvae of Scorpaena Type A occurred at two stations 

 of the EASTROPAC expedition in the vicinity of Panama 

 Bay and at two stations of the Scripps Tuna Ocean- 

 ography Cruise 58-1, one near Panama Bay and one off 

 the Tres Marias Islands (lat. 21°30'N, long. 106°30'W). 

 The low incidence of these larvae on these wide-ranging 

 expeditions probably reflects the near-shore nature of 

 spawning in the species producing the larvae. 



Pontinus Poey 



Distribution. — Most of our larvae of Scorpaena Type 

 A were collected on the CalCOFI cruise in the Gulf of 

 California during June 1957. They occurred at 24 stations 

 distributed throughout the entire Gulf (Fig. 34). They oc- 

 curred at two stations of the CalCOFI cruise during 

 August 1957, however, only a small portion of the plank- 

 ton from that cruise was sorted and the larvae may have 

 occurred more extensively on that cruise. Except for one 

 station, where the standardized number of larvae was 

 143, the larvae occurred in small numbers. Eliminating 



Figure 34.— Stations at which lar- 

 vae of Scorpaena Type A were 

 taken on CalCOFI cruises in the 

 Gulf of California during 1956 and 

 1957. 



Literature. — The literature contains no descriptions 

 or illustrations of the developmental stages of Pontinus. 



The taxonomy of Pontinus in the eastern Pacific is 

 poorly known. At present there are five recognized and 

 six nominal species, however, unpublished information 

 of W. Eschmeyer (Calif. Acad. Sci.) indicates that the 

 species complement of eastern Pacific Pontinus is more 

 than double the presently recognized number. In fact, a 

 previously undescribed but abundant species was dis- 

 covered while examining museum specimens during the 

 present study. Unfortunately, the characters that 

 separate this host of species are mostly not the kind that 

 may be traced backward into larval series. 



Distinguishing features. — Larvae of Pontinus can be 

 separated from those of other eastern Pacific genera by a 

 combination of characters. As in larvae of Scorpaenodes 

 and Ectreposebastes. Pontinus larvae lack the melanis- 

 tic shield that covers the dorsolateral surfaces of the gut 

 in Sebastes, Sebastolobus, and Scorpaena. In place of 

 this, larvae of Pontinus, Scorpaenodes, and Ec- 

 treposebastes have a deeply embedded medial blotch 

 just dorsal to the axilla. This blotch later enlarges to 

 cover the dorsal surface of the gas bladder. Pontinus lar- 

 vae differ from Scorpaenodes in several characters. In 

 Pontinus, a single elongate spine develops at the ter- 

 minus of each parietal ridge. In midstage larvae a small 

 subjacent nuchal spine develops posterior to each 

 parietal spine and remains inconspicuous throughout the 

 larval period. This contrasts greatly with the bifurcate 

 terminus of the parietal ridge in Scorpaenodes. The pec- 

 toral fins of the two genera differ in shape, relative 

 length, and pigment pattern. They are aliform in Pon- 

 tinus and fan -shaped in Scorpaenodes. The pectorals are 

 shorter in Pontinus; pectoral fin length averages 31% of 

 the body length in postflexion larvae of Type A and 27% 

 in Pontinus Type B; mean length was 39% in postflexion 

 larvae of S. xyris. The pectoral fin base is also narrower 

 in Pontinus; the depth of the fin base averages 14% of the 

 body length in postflexion larvae of Type A and 16% in 

 Pontinus Type B. Fin base depth averaged 18% in post- 

 flexion S. xyris larvae. Pigmentation of the pectoral fins 

 is limited to the distal margin of the pectoral fin in Scor- 



60 



