460 
Fishery Bulletin 113(4) 
Illustrations of stages of eggs of Acanthistius patachonicus : 
(A) early stage with blastodermal cup, 12 h after fertiliza- 
tion, and (B) late stage with embryo surrounding the yolk 
(approximately 270°), 60 h after fertilization. The diameter 
of the eggs is 1.1 mm. 
4. 2-8. 4 mm; it was 34% in the posttransition juvenile 
and reached 39% in adults (reference values for adults 
from Nakamura et al., 1986) (Fig. 4A). Body depth 
was moderate, with means of 22—26% BL in larvae 
<4.2 mm and of 27-33% in larvae 4. 2-8. 4 mm; it was 
35% in the posttransition juvenile and 28% in adults 
(Fig. 4B). The preanal length was moderate in larvae 
<4.2 mm (44-46% BL) and long in larger larvae (54- 
62%), posttransition juveniles (62%), and adults (57%) 
(Fig. 40. 
In the head, SnL increased between 30% and 40% 
and remained rather stable in larger larvae and in the 
posttransition juvenile (Fig. 5A), and ED decreased 
markedly (between 41% and 24% [Fig. 5B]). The mouth 
size increased slightly with development. By -6 mm, 
the larvae had conic teeth in the upper jaw. 
The posttransition juvenile stage was identified by 
its morphological similarities with the morphological 
features of adults (Fig. 3G). The snout was short and 
rounded. The mouth was terminal and reached the an- 
terior edge of the eye. Both jaws showed only canini- 
form teeth. 
Development of meristic characters Most of the meris- 
tic features of larvae of A. patachonicus developed be- 
tween ~6 and 8.4 mm (flexion and postflexion stages) 
(Table 2). Larvae had 23-26 myomeres (mode: 25 myo- 
meres), 7-12 preanal and 13-18 postanal; the myomere 
formula did not change with development. Preflexion 
larvae had only an undifferentiated finfold and paired 
pectoral-fin buds (Fig. 3, B-D). Fin-ray formation 
started with the development of dorsal, pectoral, cau- 
dal, and pelvic fins during flexion and was completed 
between 8.4 and 13.1 mm; fin elements reached their 
full complement in the posttransition juvenile. All fin 
spines were smooth. 
Three branchiostegal rays were present at 4.4 mm; 
by 6.8 mm, 6 rays were formed, and, by 7.7 mm, the 
full complement of 7 rays was present (Table 2). 
Fin formation The finfold in yolk-sac and preflex- 
ion larvae was symmetrical around the tip of the 
notochord (Fig. 3, A-C). By 5.5 mm, the first ray 
ventral to the notochord appeared, and in larg- 
er larvae the number of rays were added nearly 
symmetrically in the upper and lower lobes (Fig. 
3D). In postflexion larvae, the caudal fin had a 
rounded, homocercal outline with about 8 rays 
in each of the upper and lower lobes. The adult 
complement of 9 branched rays in the upper lobe 
and 8 branched rays in the lower lobe developed 
by 13.1 mm (Table 2; Fig. 3G). 
Pectoral fin buds were present in the smallest 
preflexion larvae (Fig. 3B). By ~6 mm the upper 
2-5 pectoral-fin rays, 1 pelvic-fin spine, and 3 
pelvic-fin rays were present (Fig. 3E). Rays in the 
pectoral fin developed ventrally (Fig. 3F). 
The undifferentiated dorsal finfold extended 
from the nape to the caudal region in larvae <6.1 
mm. The dorsal-fin spines and rays started to ap- 
pear during flexion and were added in an anterior 
to posterior sequence. Between 6. 1-6.9 mm, 2 spines 
had already formed, and between 7. 0-7. 6 mm the 3 
first rays had formed. Anal-fin rays were not yet devel- 
oped in larvae <8.4 mm (Table 2; Fig. 3F). 
Nearly full complements of fin spines and rays were 
present as early as the posttransition juvenile stage: 
the pelvic fin had 1 spine and 4 rays; the pectoral fin 
had 17 rays; the dorsal fin had 12 spines and 16 rays; 
and the anal fin had 2 spines and 9 rays (Table 2; Fig. 
3G). The first and second dorsal spines were shorter 
than the third and fourth spines. The first 2 dorsal 
interneurals were separate and supported the first 2 
spines. The first anal spine was shorter than the sec- 
ond spine (Fig. 3G). The spines in the anal fin were 
supported by 2 separate interhaemals. 
Axial skeleton Ossification of the vertebral column pro- 
ceeded posteriorly from the first vertebra. This process 
began at 6.1 mm; by 7.0 mm, 11 vertebrae were ossified, 
and by 7.7 mm all except for the last 8 vertebrae and 
the urostyle were ossified. Each neural spine and arch 
ossified first, followed by the centrum and then by the 
haemal arch and spine. Ossification of the pleural ribs 
was not evident in the posttransition juvenile studied. 
The caudal complex in the posttransition juvenile 
was the typical perciform type (Fig. 6). The caudal 
skeleton had 3 epurals, the urostyle, a small uroneural 
dorsal to the urostyle, 4 hypurals, and 2 autogenous 
haemal arches on the antepenultimate and penultimate 
vertebrae. There were 15 branched, segmented rays sup- 
ported by the hypurals: 6 ventrally on hypurals 1 and 
2 and 9 dorsally on hypurals 3 and 4. Four dorsal and 
7 ventral raylets were adjacent to the segmented rays. 
Head spination and opercular complex development The 
number and location of head spines in A. patachonicus 
were of great taxonomic value and helpful in the con- 
struction of the larval developmental series. All head 
spines were smooth. 
