The ichthyofauna of limnic systems in Quaternary deposits of extreme southern Brazil.

Cindy Marques,Daniel Loebmann,Fabiano Corrêa,Fernando Quintela

doi:10.3897/zookeys.638.9199

Abstract

The Quaternary in the state of Rio Grande do Sul (RS), southern Brazil, is geologically represented by the coastal plain and was originated by successive events of Pleistocene-Holocene marine transgressions and the occurrence of alluvial deposits. This paper aimed to characterize the fish assemblage occurring in a swampy Quaternary area adjacent to Lagoa Pequena, a lacustrine system connected to the west margin of the Laguna dos Patos estuary. A checklist is also provided of the ichthyofauna so far recorded in limnic systems of Quaternary deposits in the state of Rio Grande do Sul. A total of 42 species was recorded, distributed in nine orders, 18 families and 31 genera. Characidae and Cichlidae were the most representative families, comprising 15 and 4 species respectively. A bibliographic revision associated to our sample data revealed the occurrence of 156 species in limnic systems inserted in RS Quaternary deposits (114 limnic, 15 marine/estuarine/limnic, ten marine/estuarine, nine estuarine/limnic and eight marine). Characiformes and Siluriformes are the most diverse orders, corroborating the Neotropical pattern. Seven species can be considered endemic to RS Quaternary deposits.

Highlights

The Quaternary in the state of Rio Grande do Sul (RS), southern Brazil, is geologically characterized by a sequence of four depositional events resulting from marine transgressions that occurred around 400,000 and 5,000 years ago, in addition to the occurrence of extensive alluvial systems (Tomazelli and Villwock 2000; Villwock and Tomazelli 2007)
The swamps we studied are located around Lagoa Pequena, a lacustrine system with an area of approximately 4,000 km2, in the boundaries of the Pelotas and Turuçu municipalities (Fig. 1)
They were distributed in nine orders, 18 families, 31 genera and 42 species

Summary

Introduction

The Quaternary in the state of Rio Grande do Sul (RS), southern Brazil, is geologically characterized by a sequence of four depositional events resulting from marine transgressions that occurred around 400,000 and 5,000 years ago, in addition to the occurrence of extensive alluvial systems (Tomazelli and Villwock 2000; Villwock and Tomazelli 2007) These Quaternary deposits are hydrographically heterogeneous and can be found in swamps, extensive floodplains (várzeas), coastal lagoons, coastal streams and lower stretches of fluvial systems originated from older geological formations in RS (Vieira 1984). Information on fish assemblages present in limnic systems of Quaternary deposits located at the west margin of the Patos-Mirim complex is scarce Data available on this segment is restricted to investigations by Becker et al (2007) on the Butiazais region of the Tapes and the recent inventories produced by Volcan et al (2012) and Burns et al (2015) on the lower courses of the Corrientes and Turuçu streams, respectively. A checklist is presented of species recorded in limnic systems far in this geological formation, along with a brief discussion on distribution patterns of the species

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Conclusion