Venerus et al.: Early life history of Pseudoperas semifasciata 



201 



and Prolatilus jugularis (Velez et al., 2003). Larval 

 abundance and distribution have been studied for 

 a few species of Parapercis (Houde et al., 1986; 

 Gaughan et al., 1990; Neira et al., 1992) and, 

 more recently, for Prolatilus jugularis (Velez et al., 

 2003); no information is available for posttransi- 

 tion pinguipedid juveniles. 



Larvae of P. semifasciata resembled the larvae 

 of other pinguipedids in their gut size, meristics, 

 and general pattern of pigmentation. They differed 

 from Parapercis spp. and P. jugularis larvae in 

 some relevant features: 



• The head had no spines and was less rotund, 

 rather moderate instead of large (HL ranged from 

 0.17 to 0.30 BL; mean HL/BL = 0.22 [±0.02]); 



• The body was rather elongate instead of mod- 

 erate (BD ranged from 0.12 to 0.26 BL; mean 

 BD/BL = 0.16 [±0.03]); 



• The notochord flexion occurred between 6.2 

 and 8.7 mm BL, at a relatively large size range 

 compared to that for Parapercis spp. (3.7-4.8 

 mm BL) and to P. jugularis (5.7-6.9 mm BL). 

 Pseudopercis semifasciata is a larger and more 

 rotund species; 



• The finfold was still present in preflexion and 

 flexion larvae. 



De Cabo 3 described some osteological, meristic, 

 and morphological characteristics of Argentine Sea 

 pinguipedid larvae. Like De Cabo 3 we found that 

 the first cranial bones that appeared during larval 

 development in P. semifasciata were the premax- 

 illa, the dentary and the cleithrum. These struc- 

 tures were already ossified in 3.4 mm BL preflexion 

 larvae. From the adult osteological descriptions by 

 Herrera and Cousseau (1996) and Gosztonyi and 

 Kuba, 2 we determined that the larvae studied were 

 P. semifasciata. The only other sympatric species 

 of Pinguipedidae in the Argentine shelf is the 

 Brazilian sandperch (Pinguipes brasilianus), which 

 shares several similarities in meristic counts with 

 P. semifasciata (Rosa and Rosa, 1987; Herrera 

 and Cousseau, 1996). However, some osteological 

 features from the neuro- and branchiocranium are 

 of great value for identification of larval stages 

 of P. semifasciata. The two species could be dis- 

 tinguished by the placement of the first process 

 of the premaxilla, which is perpendicular to the 

 premaxilla in the Argentine sandperch, and back- 

 inclined in the Brazilian sandperch, drawing an 

 acute angle with the premaxilla (Herrera and 

 Cousseau, 1996). The dentary in P. semifasciata 

 has a quadrangulate anterior end and a margin 

 almost straight, whereas the margin of the dentary 

 in P. brasilianus is oblique (Herrera and Cousseau, 

 1996). In addition, the head and the teeth patch 

 of the vomer are quadrangulate in Pinguipes and 

 triangular in Pseudopercis (Herrera and Cous- 

 seau, 1996). 



35°S 



70°W 



35°S 



70°W 



Figure 5 



Distribution of ichthyoplankton stations (upper) and Pseu- 

 dopercis semifasciata larvae (lower) in the Argentine Sea in 

 the period 1978-2001. Dot diameter, classified into four cat- 

 egories, is proportional to larval abundance at each station 

 (expressed as larvae/10 m 2 of sea surface). 



