FISHERY BULLETIN: VOL. 70. NO. 3 



FxGtTRE 9. — Developmental stage of Bolinichthys sp. — A, 10.6-nim larva, R.R.S. Discovery Station 702; B, 10.6-mm 



larva, dorsal view. 



we would enlarge the tribe Gjntnnoscopelini to 

 include Ceratoscopelus, Lepidophanes, Bolinich- 

 thys, Lampadena, and Taaningichthys as well as 

 the six genera assigned to the tribe by Paxton. 

 We would restrict the tribe Lampanyctini to 

 Lampanyctus, Stenobrachius, and Triphoturus, 

 three genera with distinctive larvae that devel- 

 op only the Br2 photophores, and are character- 

 ized by an abrupt transformation from larva to 

 juvenile. Our suggested modification of Pax- 

 ton's scheme is shown in Figure 15. 



Even though we propose a different distribu- 

 tion of genera in the tribes Gymnoscopelini and 

 Lampanyctini, there is a striking concordance 

 between our groupings of related genera and 

 Paxton's, derived from quite different criteria. 

 For example, both methods suggest a close re- 

 lationship for Scopelopsis, Lampichthys, and 

 Notoscopelns as well as for Ceratoscopelus, Lep- 

 idophanes, and Bolinichthys. 



It should be noted that the heaviest develop- 

 ment of accessory luminous tissue occurs in the 

 genera we place in the tribe Gymnoscopelini and 

 that such luminous tissue is best developed on 



Ceratoscopelus, Bolinichthys, Lepidophanes, 

 Lampichthys, and Hintonia. On Ceratoscopelus 

 townsendi and various species of Bolinichthys, 

 conspicuous patches of luminous tissue form on 

 the head between the orbits, especially in adult 

 males. In these genera there may be a direct 

 relation between the absence of the Dn photo- 

 phores and the presence of accessory luminous 

 tissue on the head. 



A PROPOSED THEORY FOR THE 



EVOLUTION OF PHOTOPHORE 



PATTERN IN MYCTOPHIDAE 



Perhaps the most intriguing result of our 

 studies of larvae of the tribe Gymnoscopelini 

 is a theory for the evolution of photophore pat- 

 tern in lanternfishes. The only previous theory 

 was proposed by Bolin (1939) and fully devel- 

 oped by Fraser-Brunner (1949). Fraser-Brun- 

 ner (1949) postulated an hypothetical ancestral 

 myctophid with a pair of continuous photophore 

 rows on the ventral margin, beginning with the 



556 



