FISHERY BULLETIN: VOL. 81, NO. 1 



erally on the caudal peduncle and pectoral fin 

 areas (footnote 5). Bathylagus ochotensis larvae 

 have eyes borne on moderately long stalks, lateral 

 body melanophores which increase in number 

 during ontogeny, as shown by Ahlstrom (1972), 

 and possess 46-48 myomeres. Bathylagus pacifi- 

 cus larvae have eyes carried on long stalks, pos- 

 sess 44-48 myomeres, and initially (at about 4 

 mm) only two lateral pigment bands — one near 

 the gut terminus and one near the notochord tip. 

 An additional lateral band of melanophores de- 

 velops at about 45-50% SL (approximately cover- 

 ing myomeres 14-17) in larvae 5-12 mm long. In 

 larvae larger than about 13 mm, the lateral pig- 

 ment increases to 3-5 patches over the lower body 

 wall and gut (pers. obs.). 



Because of the fragile nature of the eye stalks 

 in bathylagid larvae, specimens frequently have 

 their eyes missing or damaged by the collecting 

 gear. If the eyes of the specimen are missing, 

 then at certain sizes (about 5-13 mm), L. schmidti 

 could be confused with B. pacificus. In addition 

 to a lower myomere count, B. pacificus larvae in 

 this size range have lateral body melanophores 

 at about 40-48% and 64-69% SL, whereas L. 

 schmidti have such pigment patches located at 

 about 33-40% and 60-64% SL. Also, the pigment 

 on the notochord tip in B. pacificus is longer and 

 covers the lateral wall of the notochord, whereas 

 such pigment in L. schmidti is limited to the dor- 

 sal and ventral portions of the notochord tip. 



Larvae of L. schmidti in the northeastern Pa- 

 cific Ocean may be readily distinguished from 

 more southerly cooccurring argentinid larvae in 

 that the latter are characteristically much more 

 intensely pigmented at nearly all sizes as depict- 

 ed by Schmidt (1906, 1918), Sanzo (1931-33), and 

 Russell (1976). 



DEVELOPMENT OF 

 LEUROGLOSSUS SCHMIDTI 



(Figures 1, 2, 3) 

 Pigmentation 



Although pigmentation in L. schmidti varies 

 among similar size specimens and changes in 

 quantity and location with ontogeny, basic trends 

 persist that provide characters useful in identi- 

 fying the larvae. Descriptions of pigment pat- 

 terns are based primarily on 57 larvae (4.9-35.0 

 mm SL) and on 9 transformed juveniles (31.3- 



55.0 mm SL) preserved <3 yr, in which fading of 

 pigment therefore was minimal. 



Head Region 



Pigment in the head region is limited primarily 

 to the eyes, jaw, and opercle, develops gradually, 

 and is sparse until transformation. In small lar- 

 vae (about 5.0-6.5 mm), the head and eyes are un- 

 pigmented. The eyes are pigmented in 7 mm lar- 

 vae, and pigment is sometimes present on the tip 

 of the lower jaw. A pigment spot is present on the 

 posterior portion of the opercle in some larvae as 

 small as 16 mm; this pigment is not consistently 

 present until the larvae reach about 30 mm. At 

 this size, and until transformation (about 31-35 

 mm), the number and size of the opercle melano- 

 phores may vary from one or two large melano- 

 phores to three or four small pigment spots; the 

 tip of the lower jaw is sometimes pigmented. 

 After transformation, the head becomes heavily 

 pigmented and the opercle acquires dark mela- 

 nistic pigment. 



Preanal Region 



In larvae from about 5.0 to 6.5 mm, gut pig- 

 ment is limited to a single patch of pigment in the 

 middle portion of the gut. By 7 mm, pigment con- 

 sists of two lateral bands at about 37-40% SL and 

 60-64% SL. In larvae 11-12 mm, the anterior and 

 posterior pigment bands have begun to spread 

 laterally to form stellate melanophores. As the 

 larvae grow (about 16-24 mm), one or two pig- 

 ment spots are sometimes present on the ventral 

 gut below the larval pectoral fins; lateral body 

 pigment usually consists of two to eight stellate 

 melanophores or diagonal streaks of pigment. 

 Pigment near the anus consists of a series of 

 three to six melanophores. In larvae 24-34 mm in 

 length, gut pigment continues to be limited to 

 one or two pigment spots below the larval pec- 

 toral fins and a few (3-6) melanophores near the 

 anal tube. Lateral body pigment consists of gen- 

 erally three (range 3-5) stellate melanophores. 

 The pigment spots in the gut region persist in 

 various sizes and numbers until transformation, 

 when the juvenile acquires characteristic dark 

 melanistic pigment over the entire region. 



Postanal Region 



Preflexion larvae (about 5.0-13.0 mm) lack 

 postanal pigment except on the dorsal and ven- 



26 



