Larval Development of Macrobrachium Reyesi Pereira (Decapoda: Palaemonidae), With a Discussion on the Origin of Abbreviated Development in Palaemonids

Abbreviated development is a widespread characteristic in the life cycle of several species of palaemonid shrimps. This feature very probably arose early in the origin of the group in ancient estuaries or fresh-water habitats. There are at least 29 species of fresh-water palaemonids in South America with abbreviated development. Macrobrachium reyesi Pereira, 1986 (Decapoda, Palaemonidae), goes through 5 larval stages (molts) before reaching the juvenile morphology. Individuals start feeding after the second molt and the larval period lasts from 23-27 days. Descriptions and illustrations of all stages are given as well as comparison with larval stages of other strictly South American fresh-water Palaemoninae. A list of the palaemonid species with abbreviated development is included.