DISCUSSION OF GENERA AND SPECIES 



Protomyctophum Fraser-Brunner, 1949 



PLC before and nearly touching PVO,, the two on about the same level and usually below 

 level of PVOj, the latter lying at bases of lower pectoral rays. Lateral line pores not visible. AG 

 series undivided, no Pol. SAO series in a straight or slightly angulate line. Interorbital width 

 as great or greater than width of expanded distal portion of upper jaw. 



A subgenus, Hierops Fraser-Brunner- (1949), is separable, in part, in that the interorbital 

 width is seldom more than half (usually less) the expanded portion of upper jaw. 



In the eastern Pacific Ocean most species of Protomyctophum occur in Antarctic waters 

 and northward along the coast of Chile to about 30° S. Only three species (all of the subgenus 

 Hierops) occur north of the equator; one of these, P. (H.J beckeri, is a tropical species which 

 may occur on either side of the equator. 



Since the circumglobal waters of the Antarctic are still poorly collected, it is not possible to 

 give exact ranges for the species of this genus; it is assumed that all may be circumglobal in 

 distribution. When known, an eastern Pacific range is given. 



As a result of participation in several trans-Pacific cruises of the USNS Eltanin in antarc- 

 tic and subantarctic waters, personnel of the University of Southern California obtained large 

 collections of fishes of the tribe Electronini Wisner (1963b). These collections, now being 

 studied, should further the understanding of these fishes. 



The following species accounts and figures for Protomyctophum are taken largely from 

 Andriashev (1962) and Becker (1963a), whose studies were the result of several cruises of 

 Soviet vessels into far southern waters. 



Key to species o{ Protomyctophum 



la. Interorbital width as great or greater (rarely slightly less) than greatest width of distal 

 portion of upper jaw, the upper orbital margins converging anteriorly (subgenus Pro- 

 tomyctophum ) 2 



lb. Least interorbital width seldom more than half (usually less) than greatest width of 



distal portion of upper jaw, the upper orbital margins parallel (subgenus Hierops) 6 



2a. Two SAO (rarely 3), the series very low on body and lying between verticals from VO4 



and AOi. The 2 Pre separated by about half a photophore diameter P. (P.) anderssoni 



2b. Three SAO (rarely 4); SAO, about over VO;i 3 



3a. SAO series distinctly angulate; SAO.j interspace greater than that of SAO^-ii 4 



3b. SAO series in a straight line, evenly spaced 5 



4a. SAO, slightly behind a vertical from VO). AO 17-19; 4 AO behind end of anal 



base P. (P.) tenisoni 



4b. SAO, over VO:,. AO 15-17; 3 AO behind end of anal base P. (P.) normani 



5a. SAO series in a flatly oblique line. AO 17-19 4 AO behind end of anal base. Gill rakers 

 5-1- 1-H5-16, total 21-22. The Pre separated by 1.0 to 1.5 photophore 



diameters P. (P.) bolini 



5b. SAO in a steeply oblique line. AO 16-17; 3 AG behind end of anal base. Gill rakers 

 4-1- H- 14, total 19. Pre very close together P. (P.) andriashevi 



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