Morphological development of Pellona flavipinnis post-yolk-sac larvae and juveniles (Clupeiformes: Pristigasteridae)

Pristigasterids are predominantly coastal marine sardines of tropical and subtropical seas, with some species being found in fresh water. Two species of the genus Pellona, P. castelnaeana Valenciennes, 1847 and P. flavipinnis ( Valenciennes, 1837), inhabit fresh waters of the neotropical region, with the latter occurring in the Pantanal of Mato Grosso, in the Paraguay River basin of central Brazil. The development of P. flavipinnis larvae and early juveniles was characterized from an ontogenic series of 27 specimens (6.3-35 mm SL), based on morphological and meristic characters. The larval and juvenile development of this freshwater sardine are typical of most clupeiforms. Exact hatching size is unknown, but it is less than 6 mm standard length ( SL) and the yolk is absorbed under 10 mm. Transformation to the flexion stage occurs at about 11 mm, to the postflexion stage between 16 and 19 mm, and to the juvenile stage after 26 mm. The ventral scutes begin to form between 25 and 31 mm, with the full complement of scutes ( 32 to 37) formed between 32 and 35 mm. Total myomere count averages 42. As the dorsal fin and origin of the anal fin and vent migrate anteriorly, the preanal myomere count ranges from 29 in the flexion larvae to 24 in early juveniles up to 35 mm. Corresponding preanal lengths range from 85 to 61%, respectively.