Cartwright: Description of early life stages of Icelinus borealis 
183 
Southeast Alaska and do not ex- 
tend farther north into the Gulf 
of Alaska or into the Bering Sea 
(Matarese et ah, 1989; Mecklen- 
burg et al., 2002). Larvae of 7. bur- 
chami and I. tenuis have not been 
identified, but there are subtle 
differences in meristic counts of 
juveniles and adults between these 
species and I. borealis (Table 4). 
Juvenile Icelinus may be distin- 
guished by using adult characters 
in any geographic location (e.g., by 
the presence of elongated, thread- 
like first two dorsal spines in I. 
filamentosus). 
Icelinus quadriseriatus is the on- 
ly species of Icelinus with current- 
ly identifiable and described early 
life history stages. Icelinus quad- 
riseriatus is distributed from So- 
noma County, California, south to 
Cabo San Lucas, Baja California, 
Mexico (Feeney, 1987). Although 7. 
borealis and 7. quadriseriatus are 
geographically separated and their 
distributions do not overlap, it is 
important to compare the larvae of 
these species. Larvae of 7. borealis 
and 7. quadriseriatus are similar- 
ly pigmented; however they differ 
primarily in number of PVMs and 
ventral gut pigment. Icelinus bo- 
realis PVMs number from three 
to 14 (vs. 25-63). Icelinus borealis 
may have a few, individual mela- 
nophores present on the ventral 
gut during preflexion, whereas 7. 
quadriseriatus has ventral gut pig- 
ment consisting of one to six rows 
of melanophores aligned antero- 
posteriorly in early development. 
Icelinus quadriseriatus retains 
ventral gut pigment throughout its 
larval development (Feeney, 1987). 
Icelinus borealis differs from 7. 
quadriseriatus by having an anal- 
fin ray count of 11-14 (vs. 10-15), 
and a vertebral count of 35-36 (vs. 
33-35) (Table 4). Icelinus borealis 
and 7. quadriseriatus also undergo 
flexion at different times (8.0-11.0 
mm vs. 5. 2-7. 6 mm, respectively) 
(Feeney, 1987). 
After examining all available 
putative larval specimens of Iceli- 
nus from the Bering Sea, it was 
found that the majority of larvae 
at AFSC were not 7. borealis but 
probably members of the closely 
