45 
Abstract — Larval and early juvenile 
stages of Symphurus oligomerus are 
described from 24 specimens from the 
Gulf of California. Meristic features 
were 48-49 total vertebrae, 87-94 
dorsal-fin rays, 73-77 anal-fin rays, 
12 caudal-fin rays, and five hypural 
bones. Seven larvae and one juvenile 
were cleared and stained to obtain 
the pterygiophore formula (1-3-2-2- 
2) that confirmed the identification 
of S. oligomerus. The pigment pat- 
tern from preflexion to juvenile stage 
consists of three bands on the dorsal 
margin and two bands on the ventral 
margin formed by star-shaped mela- 
nophores on the left side of the body. 
The intestine in preflexion to post- 
flexion larvae forms an abdominal 
projection that ends in a short conical 
appendix. The intestine is supported 
by three cartilaginous struts; larvae 
with these physical attributes are 
called exterilium larvae. Preflexion 
larvae have two elongated dorsal-fin 
rays, and in flexion to postflexion 
larvae the second to the fourth dorsal- 
fin rays are elongate. We found an 
apparent connection between the size 
at metamorphosis of the species of 
Symphurus and the depth distribu- 
tion range of adults such that the 
fish species that metamorphose at a 
larger size have a deeper distribution 
as adults and exterilium larvae seem 
to correspond to species that have 
deeper distributions. 
Manuscript submitted 15 October 2008. 
Manuscript accepted 20 October 2009. 
Fish. Bull. 108:45-55 (2010). 
The views and opinions expressed 
or implied in this article are those 
of the author (or authors) and do not 
necessarily reflect the position of the 
National Marine Fisheries Service, 
NOAA. 
Larval development of the spotfin tonguefish 
(Symphurus oligomerus Mahadeva and 
Munroe, 1990) (Pleuronectiformes: Cynoglossidae) 
from the Gulf of California, Mexico 
Ricardo J. Saldierna-Martmez (contact author ) 1 
Gerardo Aceves-Medina 1 
Enrique A. Gonzalez-Navarro 2 
Email address for contact author: rsaldier@ipn.mx 
1 Departamento de Plancton y Ecologia Marina 
Centro Interdisciplinario de Ciencias Marinas 
Av. Instituto Politecnico Nacional S/N 
Colonia Playa Palo de Santa Rita 
Apdo Postal 592 
La Paz, Baia California Sur 23000, Mexico 
2 Departamento de Biologia Marina 
Universidad Autonoma de Baja California Sur 
Apdo. Postal 19-B 
La Paz, Baja California Sur. 23080, Mexico 
The Cynoglossidae family in the east- 
ern Pacific Ocean is represented by a 
single subfamily (Symphurinae) and 
a single genus ( Symphurus ; tongue- 
fish). This genus has a world-wide 
distribution, including the eastern 
Pacific Ocean where it is represented 
by 18 species, inhabiting temperate 
and tropical waters on the continental 
shelf and slope (Munroe et al., 1995; 
Munroe and Robertson, 2005). Previ- 
ous studies have demonstrated the 
diagnostic value of the pterygiophore 
interdigitation pattern (ID pattern) 
which, combined with other meris- 
tics, can be used to identify symphu- 
rine tonguefish all over the world 
(Munroe, 1992; Munroe et al., 1995). 
Species with the 1-3-2 and 1-3-3 ID 
patterns are found in both the Atlan- 
tic Ocean and in the tropical eastern 
Pacific Ocean from the Gulf of Cali- 
fornia to northern Peru. Species with 
the 1-3-4, 1-4-2, 1-4-3 and 1-5-3 ID 
patterns are found only in the New 
World. Currently, the early life history 
stages of seven species of symphurine 
tonguefishes occurring in the eastern 
Pacific can be distinguished from each 
other by their melanistic pigmenta- 
tion patterns. Symphurus eallopterus 
has an accumulation of pigment in 
the form of two oblique, incomplete 
and two complete bands on the caudal 
section of the body (Evseenko, 1990), 
whereas S. williamsi (Aceves et al., 
1999) , S. elongatus (Charter and 
Moser, 1996), S. chabanaudi, and S. 
prolatinaris (Evseenko and Shtaut, 
2000) have blotches or spots or both on 
the dorsal and ventral margins of the 
body; and both S. atricaudus (Charter 
and Moser, 1996) and S. atramenta- 
tus (Saldierna-Martmez et al., 2005) 
have a series of dash-like spots on 
the dorsal and ventral margins of the 
body. Although S. oligomerus (spotfin 
tonguefish) is a species with wide dis- 
tribution from the Gulf of California 
to Panama (Mahadeva and Munroe, 
1990; Munroe et al., 1995), its larvae 
are still undescribed. This study pro- 
vides the first description of the larval 
development of S. oligomerus from the 
preflexion to the juvenile stage. 
Materials and methods 
Plankton samples were collected in 
November 2005 in the Gulf of Califor- 
nia. Twenty-four oblique zooplankton 
tows were made with bongo nets with 
a mouth diameter of 60 cm and net 
mesh of 505 and 333 pm as detailed in 
Kramer et al. (1972). Three additional 
samples were obtained from multilevel 
oblique tows at 150-100, 100-50, and 
