FISHERY BULLETIN: VOL. 69, NO. I 



Benthosema panatnense (Taning) ( 7 occurrences, 

 1,027 larvae) 



The relatively large number of larvae taken 

 in a fewf hauls probably results from the adults 

 of this species occurring in more compact ag- 

 gregations than other myctophids (Alverson, 

 1961) . All occurrences were within a few hun- 

 dred miles of the coast, mostly off Mexico and 

 Costa Rica. Distribution of larvae of B. pana- 

 tnense in the eastern tropical Pacific was illus- 

 trated in Moser and Ahlstrom (1970). 



Centrobranchus spp. (3 occurrences, 4 larvae) 



The larvae assigned to Centrobranchus rep- 

 resent two kinds; one of these is identical to 

 the larvae described as C. choerocephalus (Mo- 

 ser and Ahlstrom, 1970). The other is pos- 

 sibly C. andrae. 



Ceratoscopelus townsendi-complex (117 

 occurrences, 1,020 larvae) 



Until recently, only two species of Ceratosco- 

 pelus were recognized: C. townseyidi (Eigen- 

 mann and Eigenmann) and C. maderensis 

 (Lowe). The larvae of these two species are 

 distinctively different, especially in pigmenta- 

 tion. Nafpaktitis and Nafpaktitis (1969) con- 

 cluded that C. warmingi (Lutken) was distinct 

 from C. townsendi and was the more wddely 

 distributed species. They indicated that C. 

 to^vyisendi probably was restricted in its distri- 

 bution to the eastern North Pacific. The major 

 difference between the two species is the pres- 

 ence on C. townseyidi of a large patch of luminous 

 tissue along the dorsal rim of the orbit on speci- 

 mens larger than ca. 21 mm SL; otherwise, 

 the two species are almost identical in meristic 

 characters, arrangement of photophores, and 

 the placement of most luminous patches. 



Subsequent to the publication of the paper 

 by Nafpaktitis and Nafpaktitis (1969), my col- 

 league, H. G. Moser, and I studied developmen- 

 tal series of Ceratoscopelus larvae previously 

 assigned to C. townseyidi. Moser (unpublished) 

 studied eastern North Pacific material (Cal- 

 COFI and NORPAC) and material from the 

 eastern South Pacific obtained on EASTROPAC 



I; I had the opportunity to examine a number 

 of collections of Ceratoscopelus larvae collected 

 by the Meteor in the Indian Ocean (through 

 the generosity of W. Nellen of the Institut fiir 

 Meereskunde, University of Kiel, Germany). 

 Based on criteria of Nafpaktitis and Nafpaktitis, 

 adults from both the Indian Ocean and southern 

 portion of the EASTROPAC area were refer- 

 able to C. ivarmingl, those from CalCOFI and 

 NORPAC to C. totunsendi. Larvae from the 

 three regions were strikingly similar in appear- 

 ance. Observed differences were mostly in rate 

 of development, particularly in the sizes at which 

 fin formation took place and at which photo- 

 phores developed. Even so, somewhat greater 

 differences were observed between Ceratosco- 

 pelus larvae from the Indian Ocean and those 

 from the EASTROPAC area, than between 

 larvae from the two eastern Pacific regions. For 

 the present, I choose to call attention to the 

 complexity of this problem by referring EAS- 

 TROPAC material to the C. townsendi-complex. 

 Distribution of C. townsendi-complex larvae 

 on EASTROPAC I is illustrated in Figure 8. 

 Most occurrences were in offshore waters be- 

 tween lat 5° and 20° S, i.e., in the South Pacific 

 central water mass. Ceratoscopelus larvae are 

 known to have a complementary distribution in 

 the eastern North Pacific. On the NORPAC 

 Expedition Ceratoscopelus larvae were the dom- 

 inant myctophid in the North Pacific central 

 water mass between ca. lat 20° and 40° N. The 

 occurrences of Ceratoscopelus larvae in the Argo 

 pattern between lat 17° and 20° N are a frag- 

 ment of this northern population. The few 

 occurrences of Ceratoscopelus larvae in waters 

 of the equatorial current system were small 

 individuals. A few adults also were collected 

 in this region, hence tropical waters may not 

 be a barrier to the interchange of fish between 

 the populations in the North and South Pacific. 



Diaphus spp. (251 occurrences, 2,873 larvae) 



Diaphus, the genus of myctophids with the 

 largest number of species, is represented in 

 the tropical eastern Pacific by a number of 

 larval forms whose specific identities have been 

 worked out only partially. 



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