46 
Fishery Bulletin 108(1) 
Table 1 
Sampling methods, locations, depths, and preservation methods for larval Symphurus oligomerus collected in the Gulf of Califor- 
nia in 2005. 
B= bongo net, M: 
=multilevel net, BL=body length. 
Net 
Coordinates 
Number of specimens (BL, mm) 
N 
W 
Catch depth (m) 
Ethyl alcohol 
Formalin 
B 
28°30'38" 
113°6'39" 
0-21 
1(18.0) 
B 
28°12' 
112°17' 
0-195 
1(15.8) 
B 
27°28'46" 
112°16'27" 
0-214 
1 (18.2) 
B 
27°14'24" 
111°14'24" 
0-211 
1(14.6) 
B 
26°54'30" 
111°46'16" 
0-71 
2 (3. 0-3. 4) 
B 
26°36'1.5" 
110°32'1.5" 
0-209 
1 (8.8) 
3 (3.8-18.0) 
B 
26°11T9" 
11P18'31" 
0-182 
3 (1.6-2. 6) 
B 
25°24'40" 
109°16'28" 
0-45 
5(6.8-10.4) 
B 
24°52'26" 
109°48'19" 
0-97 
1 (12.0) 
M 
24°42'8" 
110°17'28" 
0-50 
1 (10.0) 
M 
24°42'8" 
110°17'28" 
50-100 
2(11.3-12.3: 
M 
24°42'8" 
110°17'28" 
100-150 
2 (7.8-10.4) 
50-0 m with simple conical nets with a mouth diameter 
of 75 cm and net mesh of 333 pm (Table 1). Samples 
obtained with the 333 -pm mesh bongo net and the multi- 
level tows were fixed in ethyl alcohol (96%), and samples 
from the 505-pm mesh bongo net were fixed with 10% 
formalin solution buffered with sodium borate. 
Among the fish larvae taken in this collection, twen- 
ty-four specimens of larval and juvenile Symphurus 
(1.6-18.2 mm body length [BL] ) were grouped because 
they shared the same meristic counts and pigmentation 
patterns. Comparison of this group of larvae with pub- 
lished descriptions of the early life stages of tonguefish 
from the eastern Pacific (Evseenko, 1990; Charter and 
Moser, 1996; Aceves et al., 1999; Evseenko and Shtaut, 
2000; and Saldierna-Martinez et al., 2005) indicated 
that these specimens belonged to a species whose lar- 
val development had not been described. Seven larvae 
and one juvenile from this group of specimens were 
cleared and stained (Potthoff, 1984) and identified as 
Symphurus oligomerus on the basis of meristic char- 
acters (dorsal-fin rays, anal-fin rays, caudal-fin rays, 
total vertebrae, and hypural bones) and interdigita- 
tion of dorsal-fin pterygiophores and neural spines (ID 
pattern), which was 1-3-2-2-2 (Mahadeva and Munroe, 
1990; Munroe, 1992; Munroe et al., 1995). Subsequently 
a developmental series of larvae was assembled by us- 
ing similar pigmentation pattern (oblique band on the 
body) as well as meristic and morphometric features 
(total dorsal and anal-fin rays and conical appendix). 
Measurements to the nearest 0.1 mm were taken on 
the left side of the body as illustrated in Figure 1C and 
Table 2 by using a stereomicroscope (Stemi 2000-C, 
Zeiss) fitted with an ocular micrometer. 
All larvae and juveniles were deposited in the Colec- 
cion cientifica de huevos y larvas de peces del Paci- 
fico Mexicano (ICTIOPLANCTON) registered with the 
Secretaria del Medio Ambiente y Recursos Naturales 
(B.C.S.-INV196-06-07) and located at the Departamento 
de Plancton y Ecologla Marina, Centro Interdisciplin- 
ary de Ciencias Marinas-Instituto Politecnico Nacional 
(CICIMAR-IPN). Catalogue numbers for specimens of S. 
oligomerus deposited in this collection are L108-L126. 
Illustrations of larval and juvenile stages of S. oligo- 
merus were drawn with a camera lucida (Stereomi- 
croscope Stemi SV8, Zeiss). Descriptions of larval and 
juvenile stages were based on 24 specimens from 1.6 to 
18.2 mm BL. None of the specimens were in the yolksac 
stage, indicating that hatching takes place at sizes <1.6 
mm notochord length (NL). Preflexion, flexion, post- 
flexion, and juvenile stages accord with the larval fish 
developmental stages described by Ahlstrom (1976). 
Results 
Identification 
Twenty-four specimens sharing similar morphomet- 
ric and meristic characteristics were identified among 
the material examined. Seven larvae and one juve- 
nile tonguefish from 7.8-18.2 mm BL were cleared and 
stained. These cleared specimens had the following 
ID patterns: 1-3-2-2-2 (n-1) and 2-3-2-2-2 (rc = l). We 
observed differences in the number of hypural elements 
in the cleared and stained specimens; these differences 
were associated with the development stage, as well as 
with the degree of ossification of the hypural elements. 
Five hypural bones were observed in one postflexion 
larva and one juvenile (18.0 and 18.2 mm BL); four 
cartilaginous hypurals were present in four larvae (10.4 
to 12.0 mm BL), and three cartilaginous hypurals were 
present in two larvae (7.8 and 10.0 mm BL). From these 
