Free-living Microturbellarians (Platyhelminthes) from Wetlands in Southern Brazil, with the Description of Three New Species

The Taim strict nature reserve (ESEC Taim) is a protected wetland (Ramsar site) in southern Brazil. Although the ESEC Taim harbours a broad conspicuous flora and fauna, this area lacks studies on free-living Platyhelminthes. Here, we describe three new species to science, one belonging to Macrostomorpha (Macrostomum itai n. sp.) and two belonging to Dalytyphloplanoida (Gieysztoria duopunctata n. sp. and G. hermes n. sp.). Macrostomum itai n. sp. differs from their congeners for its distinct stylet in "J"-shaped. Gieysztoria duopunctata n. sp. is distinguishable based on the crown-like penis stylet, this species possesses 12-18 spines of similar sizes and two smaller spines (one a bit longer than the other). Gieysztoria hermes n. sp. clearly differs from its congeners owing to its fibrous girdle, which bears two groups of complexes of spines and three different-in-length ventral spines. Moreover, we identified twenty-three species, eleven belonging to Catenulida, three to Macrostomorpha, seven to Dalytyphloplanoida, one to Kalyptorhynchia, and one to Prorhynchida. We recorded three species for the first time in Brazil (Myostenostomum vanderlandi, Macrostomum quiritium and Strongylostoma elongatum). This new information on these free-living Platyhelminthes makes this protected area a more valuable and reinforces the actions that are being done to protect it.

Echinococcus granulosus: Insights into the protoscolex F-actin cytoskeleton

Echinococcus granulosus is a cestode parasite whose cytoskeleton plasticity allows it to enter and develop inside its hosts, completing thus its life cycle. We focused our attention on F-actin organization and distribution in E. granulosus protoscoleces (PSC) in order to contribute to the knowledge of the parasite cytoskeleton. In particular, we addressed some aspects of F-actin rearrangements in PSC at different stages of the evagination/invagination process. The use of light microscopy allowed us to identify different PSC structures and phalloidin staining displayed a parasite's highly organized F-actin cytoskeleton. Suckers exhibit an important musculature composed of a set of radial fibers. At the rostellum, the F-actin filaments are arranged in a bulbar shape with perforations that appear to be the attachment places for the hooks. Also, "circular" structures of F-actin were identified, which remind the flame cells. Furthermore, parasite F-actin filaments, unevenly distributed, seem to have remained substantially unchanged during the evagination/invagination process. Finally, we showed that the scolex of an evaginated E. granulosus PSC reinvaginates in vitro without any treatment.