| Similar to Triphoturus mexicanus but gut slightly shorter, eye wider, more postanal melanophores (19-22 vs. 11-14), and Br2 photophores form early (about 6.8 mm); Diaphus theta have <17 pigment at >4.4 mm; Vn, PO1, PO5 form in late larvae; Op and Br1 form early in transformation; distinguished from other myctophids with round eyes by: three spots in preflexion larvae (pectoral fin base, midgut, anus); with development spots are retained, although their position shifts posteriorly; series of postanal ventral melanophores (>15) in preflexion larvae (Ref. 265).
Pigmentation:
Preflexion: postanal ventral midline series with 19-22; lateral pairs on gut at terminal section, at midgut, and just posterior to pectoral fin base; embedded above gas bladder at about 6.0 mm; at end of stage, anterior gut pair migrates anteroventrad and coalesces in the midline below the pectoral fin base and postanal series begins to coalesce.
Flexion: postanal series coalesces to 1-3 at end of stage, the one at anal fin insertion not embedded; 1 at midline of hindbrain and 1-2 at nape.
Postflexion: 1 (minute) embedded in otic region by 8.0 mm; in some larvae arrangement, 1 or more at dorsal fin insertion, adipose fin origin and insertion, and a series on lateral midline anterior to dorsal fin.
Transformation: paired series on dorsum and lateral midline augmented.
Sequence of fin development: caudal, anal and dorsal, pectorals, pelvics. |
