38 



Fishery Bulletin 93(1), 1995 



below the otic capsule. Melanophores are irregularly 

 present ventrally on the gular membrane. Additional 

 pigment on the head does not develop until after 

 settlement. Melanophores then develop immediately 

 anterior to and above the eye as well as on the snout 

 and lower jaw. Larger specimens quickly develop a 

 cap of melanophores over the mid and hindbrain. 



Pigment on the dorsal surface of the gut consists 

 of 2-7 approximately evenly spaced melanophores 

 in preflexion larvae. This reduces to 2 or 3 just prior 

 to flexion. In postflexion larvae, internal pigment 

 over the gut is restricted to above the gas bladder. 

 Ventral pigment on the gut consists of a midline se- 

 ries of 8-14 melanophores extending from just ante- 

 rior to the cleithral symphysis to the anus in both 

 preflexion and flexion larvae. One to two additional 

 melanophores are usually present either side of this 

 series below the level of the pectoral fin base (76% of 

 larvae, random subsample «=25), forming a diamond 

 pattern when viewed ventrally (Fig. 5). 



Preflexion larvae have 10-18 discrete, evenly 

 placed melanophores that extend in a dorsal linear 

 series on the trunk and tail to within 1-3 myomeres 

 of the notochord tip. The dorsal surface of the noto- 

 chord tip remains unpigmented throughout devel- 

 opment. The dorsal series of melanophores gradu- 

 ally disappears during flexion (4.9—6.5 mm). 

 Postflexion larvae have 0-3 melanophores (most com- 

 monly 0) below the bases of the second dorsal fin. 

 Dorsal pigment redevelops after settlement as a se- 

 ries of discrete bands each comprising 3-6 pairs of 

 stellate melanophores. The first of these bands de- 

 velops immediately below the posterior-most second 

 dorsal fin rays, 5 or 6 additional bands subsequently 



Figure 5 



Ventral pigment on the gut: (A) Sillaginodes punctata, 4.7 mm; 

 Sillago schomburgkii, 4.4 mm; (C) Sillago bassensis, 4.1 mm. 



(B) 



develop anteriorly, and a single band developes pos- 

 teriorly on the caudal peduncle by 20.0 mm. Lateral 

 midline pigment on the tail does not form until after 

 settlement, although some internal pigment may be 

 present over vertebrae between myomeres 25-30 

 after 11.0 mm. 



A single row of 14—19 melanophores is present 

 along the ventral midline of the tail in preflexion lar- 

 vae. This ventral row is gradually obscured by over- 

 lying musculature during flexion. Paired external 

 melanophores subsequently develop ventrally on the 

 tail in postflexion larvae, approximately one pair per 

 myomere. After settlement, this ventral series forms 

 a regular pattern of expanded and contracted mel- 

 anophores producing a similar banding pattern to 

 the dorsal series. One to two (most commonly 2) mel- 

 anophores are present ventrally on the notochord tip 

 in preflexion larvae. These are retained in postflexion 

 larvae and, with additional melanophores, form a band 

 of pigment over the caudal-fin ray bases. 



Yellow fin whiting [Sillago schomburgkii Peters 

 1865), Figure 6 



Material examined — 16 specimens, 2.7-18.7 mm 

 BL. 



Larval development — The smallest S. schomburg- 

 kii examined was 2.7 mm. At this size the mouth and 

 gut are functional, the eyes are pigmented, a gas blad- 

 der is present, and yolk absorption is complete. 



Larvae are elongate (BDp= 14-18% BL) and have 

 36-38 myomeres (15-17+20-22). Body depth at anus 

 increases from 8 to 16% BL during development. 

 Other body proportions remain relatively constant 

 (Table 4). The gut forms a convoluted tube in the 

 smallest specimen and is already differenti- 

 ated into fore, mid and hindgut regions. The 

 midgut becomes rugose by 4.4 mm and re- 

 mains so, although overlying musculature 

 obscures this feature prior to settlement. The 

 gut has not begun coiling in the largest flex- 

 ion-stage larva available (5.1 mm). Coiling 

 of the midgut has begun in the 10.1-mm larva 

 and is well developed in all postsettlement 

 larvae. Insufficient specimens were available 

 to further document the timing of gut coil- 

 ing. Coiling of the gut proceeds without mi- 

 gration of the anus and is achieved by elon- 

 gation and anterior looping of the midgut. 

 Consequently, body proportions do not show 

 a significant change in preanal length which 

 remains at 51-53% BL. The gas bladder has 

 its origin at myomeres 1-8 in preflexion lar- 

 vae and is inflated and prominent in all larvae 

 collected during night tows. The gas bladder is 

 inconspicuous in larvae caught during the day. 



