RESUMEN
Free-living turbellarians mostly live in marine and freshwater environments, but they have been little considered in ecological studies. The coastal plain in southern Brazil harbors a diverse fauna and flora, but only a few studies have related environmental factors to the abundance, richness, and distribution of turbellarians. Hence, we analyzed the structure of turbellarian communities in floating vegetation in three differently sized limnic environments. We aimed to determine differences in abundance, density, and richness of turbellarians among these habitats in relation to environmental factors. We found 1,225 turbellarians (34 species) distributed among 6 taxa. The most abundant was Tricladida with 49.4% relative abundance; the remaining (Catenulida, Dalytyphloplanida, Macrostomorpha, Kalyptorhynchia, and Prorhynchida) were less abundant. We found no significant differences among population parameters and environments. Small shallow lakes are a potentially rich environment, while water channels are the richest environment. Larger shallow lakes are not very diverse for turbellarians. Similarities regarding turbellarian communities among close limnic systems could be explained by the connectivity of bodies of water that presents similar aquatic macrophytes and hydrological subsystems, while larger shallow lakes have a different community because they have their own contributing basin and could be influenced by other factors.
Asunto(s)
Filogenia , Turbelarios , Brasil , Especificidad de la EspecieRESUMEN
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.
RESUMEN
Within Dalyelliidae Graff, 1905, Gieysztoria Ruebush Hayes, 1939 is the most widely distributed and speciose genus, members of which live in marine, brackish, or freshwater habitats (Van Steenkiste et al., 2012). Gieysztoria is composed by ~97 free-living species (Tyler et al. 2016), and species identification is mainly made on the male copulatory system, which has an armed penis (stylet) with different configurations of spines (Noreña et al., 2016). The stylet configuration of Gieysztoria species is traditionally split into two groups: Aequales (spines of similar shape and size) and Inaequales (spines of different shape and size) (Luther, 1955). In the neotropics, specimens of Gieysztoria belong to both the Aequales and Inaequales group and are well represented (Damborenea et al., 2005; Noreña et al., 2003). According to Braccini et al. (2016, 2017), there are 16 species of Gieysztoria in Brazil, mainly distributed in the southern region. South Brazil harbours a mosaic of wetlands that are considered hot spots of biodiversity, including the Taim Ecological Station (ESEC Taim) protected area that was designated as a Ramsar site (Ramsar, 2017). In the present study, Gieysztoria falx Brusa, Damborenea Noreña, 2003 is registered in the ESEC Taim, located in Rio Grande do Sul. It represents the first record of G. falx in Brazil. Illustrations and comments on stylet configuration are given.