208 



ONTOGENY AND SYSTEMATICS OF FISHES-AHLSTROM SYMPOSIUM 



Table 57. Selected Meristic Characters of Myctophiform Genera. 



• For the details, see relevant section. 



head profile; short fins; anus far fiDrward with wide preanai 

 interspace; anteriorly placed dorsal and pelvic fins. A size series 

 of A. japonicus reveals the gradual and direct development, with 

 scant pigmentation throughout the pelagic stages; melanophores 

 are restricted to the eyes and the caudal and postanal regions, 

 other than the peritoneal section which increases in size in older 

 larvae. Sequence of fin formation is C-D-A-P,-?,. Full ray com- 

 plements are visible at about 13.3 mm, but vertebral ossification 

 is delayed until about 20 mm, the smallest bottom specimen 

 available in my collection. Ontogeny of the upper jaw bones is 

 remarkable in possessing maxillary teeth (1-3) in larvae smaller 

 than 1 1 mm. Two supramaxillaries, peculiar to this family, are 

 ossifying in metamorphosed juveniles. 



Myctophidae (see Moser, Ahlstrom. Paxton, this volume). 



Neoscopelidae (Fig. 709C-D^. — Systematics of this deep-sea pe- 

 lagic and benthopelagic family are well understood (Butler and 



Ahlstrom, 1976; Nafpaktitis, 1977), except for 5o/;vc)Wfr which 

 is restricted to the tropical Western Pacific. The remaining two 

 genera are known from the world oceans. Developing eggs are 

 unknown. Mature ovarian eggs of Neoscopelus macrolepidotus 

 (0.83-0.98 mm in diameter) contain a large single oil globule 

 of 0.39-0.61 mm (Maruyama, 1970). Advanced larval stages 

 have been described and illustrated for Neoscopelus sp. (Oki- 

 yama, 1974b) and two species of Scopelengys (Butler and Ahl- 

 strom, 1976). They are characterized by large fan-shaped pec- 

 toral fins, large head with blunt snout tip, small round eyes, 

 laterally compressed deep body, and an oval patch of melano- 

 phores in the peritoneum, distinct from the solid peritoneal 

 pigment sections of most other myctophiforms. All fins differ- 

 entiate rapidly with the possible sequence as P,-D-A-C-P,, full 

 counts being attained at a small size (less than 10 mm). Pig- 

 mentation is clearly difl^erent between the two genera. Scope- 

 lengys lacks the pigment patch lying along the dorsum of the 

 rectum in Neoscopelus. Scopelengys uniquely develops a hori- 



