INTRODUCTION 



This account of the taxonomy and distribution of the lanternfishes (family Myctophidae) is 

 intended to include species that are known, or may reasonably be expected, to occur in the 

 eastern Pacific Ocean, the Polar regions, and eastward of 16(]f longitude. This westward limit 

 was imposed because of the paucity of collections from west of the Hawaiian Islands and also to 

 avoid the high probability of encountering the poorly understood myctophid fauna of the 

 Indo-Pacific region. Indeed, some species of that fauna were found in both the central and 

 eastern Pacific sectors. 



Even in this restricted area, a total of 31 genera (all those currently recognized in the 

 family) and nearly 150 species are recognized as occurring. Some questionable species in the 

 genera Diaphus and Symbolophorus may later be described as new. Such action is withheld at 

 this time because knowledge of these fishes in the eastern and central Pacific area is incom- 

 plete. Also, several of the questionable species appear to be related to forms from the South 

 Atlantic and Indian Oceans. Further comparative studies will be necessary before firm conclu- 

 sions are warranted. 



Prior to this work, few keys to myctophid fishes of the eastern Pacific have encompassed 

 wide ranges of genera or species, and most have been constructed for use in rather restricted 

 areas. This is the first attempt at a key for the entii e area and for so many genera and species. 

 A task of this magnitude could not be accomplished without substantial reliance on existing 

 literature. I have drawn heavily from Andriashe v's ( 1962 ) work on Antarctic myctophids for 

 information on poorly known southern forms of the genera Gymnoscopelus and Protomyc- 

 tophum, and on Becker's ( 1963) study of the latter genus, because of a lack of available study 

 material. Also, as the genus Lampadena is poorly represented in the eastern Pacific, and in 

 available study material, I have used keys, illustrations, and data from Nafpaktitis and Pax- 

 ton (1968). I have used illustrations of other authors when I felt that redrawing would yield no 

 significant improvement or when inadequate material left me no choice. I have restricted my 

 investigation to adults and subadults, because during the earlier part of the study information 

 on larval stages of myctophid fishes of the eastern Pacific was scant. For such information I 

 refer the reader to the recent works of Moser and Ahlstrom ( 1970, 1972, and 1974). These 

 authors are now completing a study on larval forms of lampanyctid species. 



At present, the myctophid fauna from far southern waters of the eastern Pacific are poorly 

 understood, and until very recently the central Pacific area was inadequately collected. Much 

 of the early literature is inadequate or incorrect, particularly that regarding far southern 

 fauna of the Electronini and the genus Gymnoscopelus . Most problems with these genera stem 

 from a lack of specimens. In the near future, some of these difficulties may be resolved by study 

 of collections gathered by cruises of the USNS Eltanin in far southern waters and now under 

 investigation. 



Although almost all species treated here are known to occur in the eastern Pacific Ocean, 

 a few from other oceans are included, either because of questionable identification or because 

 they are essential to a discussion of species that do occur in the western Pacific. This is 

 particularly true of the genus Loweina; understanding the total problem requires extended 

 discussion of early systematics and the designation and detailed description of lectotypes for 

 two species known mainly from the Atlantic and Indian Oceans, L. rara and L. interrupta. A 

 similar situation involves the species Myctophum selenoides from the Atlantic Ocean; type 

 material of the Atlantic form is not discussed in detail. 



