Saldierna-Martinez et al.: Larval development of Symphurus oligomerus 
51 
B 
Figure 2 
Spotfin tonguefish ( Symphurus oligomerus)'. (A) postflexion larva (18.0 mm body length [ BL] ) 
showing two internal cartilaginous struts (ICS); and (B) juvenile (18.2 mm BL). 
to the notochord (Fig. 1C). These bands begin on the 
dorsal and ventral margins of the body and extend to- 
ward the body midline (Fig. 1C). The pigment pattern 
consists of two incomplete and one complete band on the 
left side of the body, located approximately equidistant 
from each other. The most anterior band overlies the 
bases of dorsal-fin pterygiophores 11-19 and extends 
to midway between the dorsal margin and the body 
midline; the second incomplete band overlies the bases 
of dorsal-fin pterygiophores 29-35 and extends to the 
body midline; the third band is complete and overlies 
the bases of dorsal-fin pterygiophores 53-63. Two or 
three star-shaped melanophores overlie the notochord 
below the second dorsal band and three or four other 
similar melanophores overlie the notochord below the 
third dorsal band. The first ventral band is located on 
the bases of the anal-fin pterygiophores 19-27 and the 
second ventral band is located on the bases of the anal- 
fin pterygiophores 39-48. Two discontinuous series of 
dashed pigments are located on the anal fin; one lies 
over the bases of pterygiophores 9-70; the second series 
occurs on the bases of the anal-fin rays 1 to 45 and cov- 
ers almost two-thirds the length of the postabdominal 
region (Fig. 1C). 
Head pigment is first present in flexion-stage larvae. 
Two to four star-shaped melanophores are located on 
the dorsal margin of the brain; all are equidistant from 
each other and located between the first and fourth 
dorsal-fin rays (Fig. 1C). A comparison of specimens 
preserved in formalin and ethyl alcohol revealed that 
the first and fourth melanophores fade in specimens in 
the formalin solution. Two internal melanophores are 
present in the posterior head region; one is located in 
the middle of the cleithrum near the base of the pec- 
toral bud and the second is located on the base of the 
brain near the cleithrum. The left side of the head also 
has three series of small star-shaped melanophores. The 
first series (visible in specimens preserved with forma- 
lin and ethyl alcohol) extends along the ventral head 
margin from the lower jaw tip to the pelvic fin base. The 
second series (visible only in specimens preserved with 
ethyl alcohol) forms ‘V’ located along the ventroposte- 
rior margin of the jaw to the ventroposterior margin 
of the eye. The third series (visible only in specimens 
preserved with ethyl alcohol) begins at the bases of the 
first branchiostegal rays and extends posteriorly to the 
cleithrum. One prominent pigment blotch is present 
between the fourth and fifth branchiostegal rays. Both 
upper and lower jaws have four to five star-shaped me- 
lanophores at the posterior region. 
Several small, star-shaped melanophores are present 
on the pectoral fins of flexion larvae: two or more oc- 
cur on the base, three or more on the external margin 
of the surrounding membrane, and two or more in the 
