738 



Abstract.— The lai-val development of 

 Symphurus williamsi Jordan and Cul- 

 ver, 1895 (Cynoglossidae: Pleuronecti- 

 formes I is described from 69 specimens 

 from the Gulf of California, Me.xico. Di- 

 agnostic characteristics used to identify 

 larvae of this species are 3-5 pigment 

 spots situated on the dorsal region of 

 the body of the base of the pterygio- 

 phore of the dorsal fin and 3-4 pigment 

 spots on the ventral region of the body 

 an the base of the pterygiophore of the 

 anal fin. In early stages, a pigment is 

 present on the base of each anal-fin ray. 

 These pigments also appear at the 

 bases of the dorsal-fin rays in the pos- 

 terior third of ^he dorsal fin. The first 

 three dorsal-fin rays are elongated in 

 lan'ae less than 11.2 mm body length. 



Larval development of Symphurus williamsi 

 (Cynoglossidae: Pleuronectiformes) from the 

 Gulf of California 



Gerardo Aceves-Medina 



Departamento de Plancton y Ecologia Manna 



Centre Interdisciplinano de Ciencias Marinas 



Apdo. Postal 592. La Paz, Baia California Sur, Mexico, C P 23000 



E-mail address gacevesiffivmredipn ipn mx 



Enrique A. Gonzalez 



Departamento de Biologia Marina 



Universidad Autonoma de Baia California Sur 



Apdo Postal 19-B La Paz, Baia California Sur, Mexico, C R 23080 



Ricardo J. Saldierna 



Departamento de Plancton y Ecologia Manna 

 Centro Interdisciplinano de Ciencias Mannas 

 Apdo, Postal 592 La Paz, Baia California Sur, Mexico, CP 23000 



Manuscript accepted 25 Septemlicr 199fS, 

 Fish. Bull. 97:738-745 ( 1999i. 



Symphurus is a world-wide genus 

 distributed predominantly in tem- 

 perate and tropical seas and oceans. 

 The genus has 71 recognized spe- 

 cies, 17 of which are found in the 

 American region of the Pacific 

 Ocean (Munroe, 19921. Thirteen 

 species have been found in the Gulf 

 of California: S. atramentatus, S. atri- 

 caudus, S. callopterus, S. chaban- 

 audi, S. eloiigatus, S. fasciolaris, S. 

 gorgonae, S. leei, S. melanuru.s. S. 

 rnelasniatotheca , S. oligomerus, S. 

 prolatinaris, and S. williamsi 

 (Munroe and Mahadeva, 1989; 

 Munroe, 1990; Munroe and Nizin- 

 ski, 1990; Mahadeva and Munroe, 

 1990; Munroe et al., 1991; Munroe 

 et al., 1995). Specimens of Sym- 

 phurus are usually captured in large 

 quantities by shrimp trawls in some 

 tropical regions, but they are not 

 exploited commercially because of 

 their relatively small size (Perez 

 and Findley, 1985; Van der Heiden, 

 1985; Van der Heiden et al., 1986). 

 The taxonomy of the eastern Pa- 

 cific species was poorly defined un- 

 til the recent study of Munroe 

 (19921, who concluded that it was 

 possible to identify each of these 



species by a combination of the dor- 

 sal-, anal-, and caudal-fin ray counts 

 and by the interdigitation patterns 

 of dorsal proximal pterigyophores 

 and neural spines (ID pattern). 



Symphurus williamsi Jordan and 

 Culver, 1895, can be found from the 

 southern region of the Gulf of Cali- 

 fornia, Mexico, to Panama in shal- 

 low waters with sandy bottoms 

 (Munroe et al., 1995 1. Larvae occur 

 throughout the Gulf of California. 

 Large numbers were found during 

 the summer in collections made 

 south of Islas Tiburon and Angel de 

 la Guarda (Aceves, 1992). 



Of all species found in the Ameri- 

 can region of the Pacific, only the lar- 

 vae of S. atricaudus (the only species 

 of this genus distributed north as far 

 as California) and S. elongatus have 

 been described (Moser, 1981; Ahl- 

 strom et al., 1984; Matarese et al., 

 1989; Charter and Moser, 1996). In 

 this study, we offer a description of 

 the larval stages of S. williamsi from 

 preflexion through prejuvenile 

 stages. Obsei'vations made on the lar- 

 val development of S. williamsi are 

 compared with those made previously 

 on S. atricaudus and S. elongatus. 



