Feeney Post-yolksac development of two southern California sculpins 



461 



(preanal length 31.5-44.8% SL in preflexion larvae), 

 and 4 preopercular spines in late-flexion and postflex- 

 ion larvae. Postflexion larvae and juveniles have an 

 anus advanced from the anal fin. Juveniles develop 

 rows of spiny scales between the dorsal fin and lateral 

 line. 



Morphology Orthonopias triads larvae hatch at 

 2. 9-3. 8mm (Bolin 1941); field-collected larvae are as 

 small as 2.6mm (after preservation). At 4.3 mm, the 

 caudal fin anlage is forming (Fig. 5B). Flexion occurs 

 in larvae between 4.2 and 7.2 mm (Table 3). 



In preflexion larvae, the preanal length averages 

 39% SL (Table 1). During flexion the preanal length in- 

 creases to an average of 42% SL. Postflexion preanal 

 length averages 43.5% SL. Small juveniles (13.2 mm, 

 LACM W67-153, not illustrated) also have an average 

 preanal distance of 43.5% SL. 



In postflexion larvae, the anus starts to advance 

 anteriorly from the developing anal fin. In larger post- 

 flexion larvae (Fig. 6C), a cirrus forms on the orbit. 

 Small juveniles (13.2mm, LACM W67-153, not illus- 

 trated) have a cirrus on the orbit and one in the inter- 

 orbital space; they also have lateral line scales and scale 

 bands under the dorsal fin. 



Larger juveniles (Fig. 6D) have numerous cirri and 

 spines on the head; a smaller cirrus forms on the max- 

 illary and cirri develop between the preopercular 

 spines. The anus is located about halfway to pelvic 

 origin. 



Fin development In postflexion larvae, complete 

 rays are formed by 7.2mm in all fins except the pelvics, 

 which are present as buds (Table 3). 



Spination Preopercular spines start to form in 

 Orthonopias triads during flexion at 4.2-5.8 mm 

 (Fig. 5C, Table 3). Postflexion larvae typically have 

 4 preopercular spines of about equal size and equally 

 spaced (Fig. 6B). Sometimes an accessory preoper- 

 cular spine is present; a 7.3 mm larva possesses a 

 smaller spine adjacent to the 2 large spine from the 

 top. 



Small juveniles (13.2mm, LACM W67-153, not illus- 

 trated) still retain the 4 preopercular spines (Table 3). 

 In larger juveniles (Fig. 6D, Table 3), preopercular 

 spines are reduced to 3 and a bump where the ventral- 

 most one used to be; the dorsalmost spine becomes 

 bifurcate. 



In large postflexion larvae (Fig. 6C), nasal spines are 

 present. Three post-temporal/supracleithral spines 

 appear above the opercular flap near the point where 

 the lateral line will start to form. A small foramen is 

 present on the parietals where a sensory canal forms. 



Pigmentation Yolksac Orthonopias triads have 

 pigmented eyes at hatching, a cap of dense pigment 

 on the dorsoposterior gut, and about 35 PAVM that 

 start on the 3d or 4th postanal myomere. One or a pair 

 of head melanophores is sometimes present (Bolin 

 1941). 



The dorsoposterior gut pigment in field-collected 

 larvae is composed of ~80-90 melanophores in a cir- 

 cular pattern (Fig. 5 A). Small larvae (<4mm) have 

 32-55 PAVM (Fig. 7); preflexion larvae >4mm have 

 26-43 PAVM. One or two head melanophores over the 

 midbrain occur in about 33% of preflexion larvae. Nape 

 pigment is usually absent; one punctate melanophore 

 occurs at the nape in about 25% of preflexion larvae. 



Flexion larvae have similar pigment as above (Fig. 

 5D, 6A). The first few PAVM are formed as dashes of 

 pigment at the start of the anal fin base (Fig. 6A). A 

 7.0mm specimen (Washington et al. 1984) has at least 

 3 head melanophores and 1 nape melanophore, and 

 seems to be just completing flexion. A 5.8 mm specimen 

 (that may have shrunk to a greater extent because it 

 was ETOH-preserved) completing flexion has 12 head 

 melanophores and 2 nape melanophores (LACM 009- 

 80-36-BB-Ol). 



