Watson et at: Early larvae of Sebastes ensifer identified by molecular methods 
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The pectoral fins are pigmented in nearly all larvae, 
most densely at the margin and progressively more 
lightly toward the fin base. Early in the preflexion stage, 
melanophores occur on the distal -50-60% of the pec- 
toral fin but they become more concentrated near the 
margin with development and are only on the distal 10— 
20% of the fin during the postflexion stage. The pectoral 
fin base is unpigmented before 4.5 mm; afterward, me- 
lanophores form on its inner surface and densely cover 
it during the postflexion stage. Melanophores form on 
the distal -25% of the pelvic fins during the postflexion 
stage, and pigmentation is densest at the margin be- 
tween rays 1-2, sparser between rays 3-4, and little or 
none at ray 5. No other fin pigmentation was observed, 
except that the 8.4-mm specimen had one small melano- 
phore each at the bases of anal-fin rays 2 and 3. 
Discussion 
Identification of larvae 
It has only relatively recently become possible to iden- 
tify to species all the Sebastes larvae that are collected 
during plankton surveys conducted in the vicinity of 
the California Current during peak parturition season 
(e.g., Chen, 1971; Wyllie Echeverria, 1987). Among the 
larval S. ensifer sequenced for this study, divergence 
from reference haplotypes (0.0000 to 0.0080) was well 
below the divergence between Sebastomus species 
(0.0102-0.0204 [Hyde and Vetter, 2007]). Haplotype 
diversity within Sebastomus species has a mean dis- 
tance of 0.0046 (ranging from 0.000 in S. oculatus and 
S. spinorbis to 0.0115 in S. rosaceus [Hyde and Vetter, 
2007]), comparable to the values found in this study 
for S. ensifer. 
Distribution 
Sebastes ensifer ranges along the Pacific coast from the 
central Baja California Peninsula, Mexico, to central 
California; the highest abundance occurs off Southern 
California and northern Baja California (Love et ah, 
2002). Within the current CalCOFI domain (e.g., Mc- 
Clatchie, 2014), larval S. ensifer is the second most 
abundant rockfish species, accounting for about one- 
fifth of the total rockfish larvae collected in 1999 and 
2002. Larval S. ensifer were collected primarily in the 
vicinity of the Southern California Eddy (SCE) (Taylor 
et al., 2004), a persistent feature in the Southern Cali- 
fornia Bight northwest of San Clemente Island. 
Comparisons 
Larval Sebastomus are more or less readily identifiable 
as a group on the basis of several shared characters, 
including a relatively robust body, with large parietal 
and preopercular spines present by about mid-preflex- 
ion stage and with melanophores usually present on 
the lower jaw, always present on the pectoral fins and 
ventral margin of the tail, absent on the upper jaw and 
snout, and absent dorsally and laterally on the trunk 
and tail until the latter part of the postflexion stage 
when a bar begins to form on the caudal peduncle. A 
dorsal saddle may form on the trunk as well, late dur- 
ing the postflexion stage or during transformation to 
the pelagic juvenile stage (e.g., Rocha-Olivares et al., 
1999). On the basis of these characters, larval Sebasto- 
mus can be distinguished from larvae of most, but not 
all, Sebastes species described to date. 
Within Sebastomus in the North Pacific, early-pre- 
flexion-stage larvae of all 6 species for which larvae are 
known share the pattern of melanophores dorsally and 
ventrally on the gut, on the ventral margin of much of 
the tail (but none dorsally on the trunk or tail), and 
melanophores present at birth or soon thereafter on 
the pectoral fins. Pectoral-fin melanophores are exclu- 
sively or most concentrated near the margin, but are 
more evenly distributed in the honeycomb rockfish ( Se- 
bastes umbrosus) (Moser et al., 1977; Moser, 1996b). All 
but the rosy rockfish (S. rosaceus) have pigment at the 
tip of the lower jaw (Moser et al., 1977; Matarese et 
al., 1989; Moser, 1996b). On the basis of morphological 
features and pigmentation early during the preflexion 
stage, larval S. ensifer are essentially indistinguishable 
from the other Sebastomus larvae, except perhaps Se- 
bastes rosaceus and S. umbrosus. 
Larvae older than the early preflexion stage are 
known for only 3 Sebastomus species in the North Pa- 
cific: the starry rockfish ( Sebastes constellatus), known 
to the mid-flexion stage (Moser et al., 1977; Moser and 
Butler, 1987; Moser, 1996b) and the late postflexion to 
pelagic juvenile stages (Rocha-Olivares et al., 2000); 
the rosethorn rockfish (S. helvomaculatus ), known from 
the late flexion to pelagic juvenile stages (Richardson 
and Laroche, 1979); and S. ensifer, illustrated at extru- 
sion stage by Moser (1967) and described here through 
the early postflexion stage and by Rocha-Olivares et 
al. (2000) from the late postflexion to pelagic juvenile 
stages. 
During the preflexion stage, S. constellatus and S. 
ensifer are nearly indistinguishable, although the pec- 
toral fins may become more heavily pigmented in S. 
constellatus and S. ensifer may be somewhat deeper- 
bodied than S. constellatus (mean: 21% BL, range: 
15-24% BL in S. ensifer versus mean: 16% BL, range: 
15-17% BL in S. constellatus ). Note that, although this 
comparison is between ethanol-preserved S. ensifer and 
formalin-preserved S. constellatus, shrinkage does not 
differ greatly between the 2 preservatives (typically 
about 3-6% in 80-95% ethanol and about 2-10% in 5% 
formalin solution). 
By the late preflexion stage, S. constellatus has dis- 
tinctly more evenly and heavily pigmented pectoral fins 
than S. ensifer, and it has melanophores on the snout 
and upper jaw, on the isthmus, and on the hypural 
margin, which are all lacking in S. ensifer. It should 
be noted that these comparisons are between field- 
collected S. ensifer and laboratory-reared S. constella- 
tus-, it is yet to be determined whether the differences 
