PAXTON ET AL.: MYCTOPHIDAE 



241 



Lampanyctini 



Diaphini 



Triphoturus 



Parvilux 



Lampanyctus 



Stenobrachius 



Lampadena 



Taaningichthys 



Bolinichthys 



Ceratoscopelus 



Lepidophanes 



Idiolychnus 



Lobianchia 



Diaphus 



Notoscopelus 



Lampichthys 



Scopelopsis 



Gymnoscopelus 



Hintonia 



Lampanyctodes 



Notolychnus 



Fig. 125. Phylogenetic diagram of the Myctophidae, subfamily Lam- 

 panyctinae. Numbers refer to the apomorphic characters described in 

 Table 63. Numbers in the middle of vertical lines (e.g., 4, 6) refer to 

 characters for which the apomorphic state is unknown. Underlined 

 numbers refer to apomorphic states unique to all members of a given 

 lineage; bracketed numbers (e.g., 59) refer to apomorphic states that 

 have secondanly reversed in at least one member of the lineage; non- 

 bracketed, non-underlined numbers refer to character states found in 

 all members of a given lineage but also by convergence in at least one 

 other taxon in the family. 



parison. All previous workers have considered the Myctophidae 

 and Neoscopelidae as sister groups; we have taken the character 

 state in the Neoscopelidae to be the plesiomorphic condition 

 for the Myctophidae. Paxton (1972:57) described the parallel 

 evolutionary trends in the neoscopelids and myctophids, with 

 SoliYonier similar to the Lampanyctinae and Neoscopelus sim- 

 ilar to the Myctophinae. We have largely limited our analysis 

 to those characters which display only one state in the Neosco- 

 pelidae. Where variation occurs within the family, the character 

 is discussed individually below. (2) Linear photophores. We 

 have considered a photophore elevated out of linear series to 

 be apomorphic. One line of support for this decision occurs in 

 the ontogeny of those myctophid species with a larval PLO 

 photophore, which develops on the pectoral base (where it pre- 

 sumably has a different function from that of the adult) and 

 moves dorsally during development (Ahlstrom et al., 1 976:Fig. 

 4). Also the photophores of Neoscopelus. the only luminous 

 neoscopelid genus, are largely linear. However there is some 

 question of the homology of Neoscopelus and myctophid pho- 

 tophores. O'Day (1972:71) described the ultrastructure of myc- 

 tophid photophores and ". . . confirm(s) Brauer's ( 1 908) original 

 recognition of the close resemblance of photogenic tissue in the 

 Neoscopelidae to that found in the Myctophidae." However 

 Herring and Morin (1978:318) considered photophores of Neo- 

 scopelus and the myctophids to be very different, on the basis 



Myctophini 



Gonichthyini 



41,42,43 



Notolychnus 



Krefftichthys 

 Protomyctophum 

 Electrona 

 Metelectrona 



Symbolophorus 



Myctophum 

 Benthosema 

 s^ Diogenichthys 

 Hygophum 



Loweina 



Tarletonbeania 



Gonichthys 



Centrobranchus 



48,49 



Fig. 126. PhylogeneticdiagramoftheMyctophidae, subfamily Myc- 

 tophinae. Numbers are defined as in Fig. 125. 



of Kuwabara's (1954) description of Neoscopelus compared to 

 that of Brauer (1908). As ventral photophores have evolved 

 independently at least one other time in the stomiiform fishes 

 (Fink and Weitzman 1982:71), the potential for such evolution 

 in deeper water fishes is high enough that one cannot consider 

 their mere existence a case for homology. A study of the ultra- 

 structure of Neoscopelus photophores would be of value. (3) 

 Generalized larvae. The larvae of neoscopelids are highly spe- 

 cialized with a robust body, a large head and jaws with prom- 

 inent teeth, a long gut that may be coiled and large pectoral fins. 

 We do not think these features were present in the ancestors of 

 the two families, and where they are present in the myctophids, 

 consider they have evolved independently. We have used only 

 one such feature, large pectoral fins (40, Table 63) in our anal- 

 ysis. We consider the generalized larva of the myctophid ances- 

 tor had the following characters, based on the distribution of 

 larval features in myctophids and other teleosts: body moder- 

 ately slender, gut slightly S-shaped, extending to about midbody, 

 head moderate in size, eyes round or nearly so, without stalks 

 or choroid tissue, small or moderate finfold and fins and Br, 

 the only larval photophores present. 



We have used a total of 59 characters, far fewer than the total 

 described in the previous studies. For many we were unable to 

 determine a derived state, as they displayed two or more states 

 or were absent in the neoscopelids. In the osteological descrip- 

 tions small shape differences or classifications of a continuum 

 were often found in both families and were not included. A 

 number of the characters utilized require comment or expla- 

 nation: (I) Jaws are long in Solhomer and short in Neoscopelus, 

 and following our ground rules should not be utilized. However, 

 they appear to be of such fundamental importance, affecting 

 many correlated characters and appearing to represent a major 

 subfamilial difference (Paxton, 1972), that they are included 

 here. Paxton (1972:58) considered short jaws to be primitive, 

 primarily because they occurred in Protomyctophum, thought 



