Brazil Crayfish Alex has started a nice website on South American Crayfish.
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The family Parastacidae, in South America, is represented by three genera: (1) Parastacus, (2) Samastacus and (3) Virilastacus. Six crayfish species occur in temperate regions of Brazil, more precisely in the southernmost States, Rio Grande do Sul and Santa Catarina, all of them belonging to the genus Parastacus. These species burrow in two types of habitat: swampy grounds and muddy banks of small lotic systems. They have a seasonal reproduction, that starts in the early spring and stops in the late summer. Intersexuality and hermaphroditism are common phenomena in Parastacus. All Brazilian species have male and female genital apertures. The bigger species are P. pilimanus and P. brasiliensis, but they rarely reach a size over 10cm.
Parastacus defossus is a small, strongly burrower species, which constructs very deep habitations in swampy grounds. Species biology is poorly known. Frequently, animals of different generations can be found inside a same burrow: sexual mature male and female and juveniles. In the summer, the habitat humidity is reduced and these crays seal the burrow opening to avoid dessication. Intersexed, not hermaphrodite species. Geographic distribution: Rio Grande do Sul and Uruguay
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