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Fishery Bulletin 89(2), 1991 



ally collected near the coast at 22-38°N, off the west 

 coast of California and Baja California (but mainly 

 28-33°N). Samples of S. abei were also collected near 

 the coast at 28-38°N, with one individual from 4°N, 

 142°W. 



Most specimens were initially preserved in formal- 

 dehyde and later transferred to 70% isopropanol. 

 Length measurements of small specimens were taken 

 with an ocular micrometer of a dissecting microscope 

 and by dividers for larger measurements. All S. abei 

 and H. latifrons examined had a flexed notochord. 

 Since the notochord extended more than 1 mm beyond 



the hypurals in the earlier stages, the standard length 

 (SL) measurements of the larvae were taken from the 

 snout to posterior tip of notochord, or to the most 

 posterior extension of the hypurals, whichever was 

 greater. 



Head length (HL) measurements were taken from 

 the tip of the snout to the posterior margin of opercle. 

 In individuals with torn or curled gill covers, the 

 anterior base of pectoral fin was substituted as the 

 posterior reference point for HL. 



Photophore nomenclature follows Parr (1960) as 

 modified in Matsui and Rosenblatt (1971). 



Key to young platytroctids off California 



la Photophores (or melanophores in the shape of photophores) in gular region (G0 2 ; Figs. 1, 2) from 



yolksac through later juvenile stages 2 



lb Neither photophores nor patch of melanophores in gular region 3 



2a Photophores and silvery reflector present on anterior dorsal margin of eye (00) and on subopercle 

 (SBO) from yolksac stage; intraventral photophore (IVO) present from yolksac stage; opercular open- 

 ing extending dorsally to about mideye; body coloration generally whitish blue Sagamichthys abei 



2b 00 and SBO photophores absent; IVO appearing near end of yolksac stage; opercular opening ex- 

 tending dorsally to top of eye; epidermal layer lightly pigmented from yolksac stage, becoming dark- 

 brown in juvenile Holtbynia latifrons 



3a Broad edentulous space between innermost tooth of each premaxilla; small photophore between bases 

 of pelvic fins (IVO) present after yolk is resorbed; gill opening extending dorsally to a level with 

 top of eye Maulisia argipalla 



3b Only narrow edentulous space between innermost tooth of each premaxilla; photophores absent; 



gill opening on a level with mideye 4 



4a Nasal sac nearly bordering maxilla; premaxilla not meeting medially with part extending laterally 



Pellisolus eubranchus 



4b Nasal sac midlength of snout; premaxilla meeting medially, with none along lateral margin of mouth 



Mirorictus taningi 



Description 



Holtbyrnia latifrons (Fig. 1 J 



Pigmentation The least developed individual exam- 

 ined has pigmented eyes, pigmentation on the shoulder 

 organ and at the site of the posterior gular organ 

 (G0 2 ); the posterior margin of opercle and the dorsal 

 portion of yolksac are lightly pigmented (Fig. 1A). This 

 is the only specimen examined that is considered a lar- 

 va; the remaining yolksac stages are already beginning 

 to form the juvenile pigment pattern, and are termed 

 transitional individuals. The most prominent pigmen- 

 tation in these is the black tissue lining the digestive 

 tract from the mouth and branchial chamber to the 



anus. Melanophores are concentrated at the dorsal and 

 ventral margins, and on the fins and fin bases. Pigmen- 

 tation increases with size, and in late juveniles the en- 

 tire body as well as the head (except for the translu- 

 cent top of skull) is nearly black in color. 



Morphometries The larva (Fig. 1A) has a small head 

 and mouth and an oblong eye that is nearly twice as 

 long horizontally as vertically. The transitional speci- 

 men (Fig. IB) is much more adult-like with the head 

 and eyes nearly doubling in size, and the eyes almost 

 round. 



Much of the growth in transition stages is in the head 

 region, and although the body length of 12-17 mm 



