Rannyele Passos Ribeiro

A new species of Paraonis and an annotated checklist of polychaetes from mangroves of the Brazilian Amazon Coast (Annelida, Paraonidae)

Abstract The polychaete fauna from the mangroves of the Amazon Coast in Maranhão state, Brazil, is reported in this study. Fourteen species are listed, namely Alitta succinea (Leuckart, 1847); Arabella (Arabella) iricolor Montagu, 1804; Capitella capitata (Fabricius, 1780) complex; Exogone (Exogone) breviantennata Hartmann-Schröder, 1959; Heteromastus filiformis (Claparède, 1864); Isolda pulchella Müller, 1858; Mediomastus californiensis Hartman, 1944; Namalycastis fauveli Nageswara Rao, 1981; Namalycastis geayi (Gravier, 1901); Namalycastis senegalensis (Saint-Joseph, 1901); Nephtys simoni Perkins, 1980; Paraonis amazonica sp. n.; Sigambra bassi (Hartman, 1945); and Sigambra grubii Müller, 1858. Among them, Namalycastis fauveli and Namalycastis geayi are recorded for the first time in Brazil. Paraonis amazonica sp. n. is a new species for science, characterized by a rounded prostomium, 4–8 pairs of foliaceous branchiae, absent eyes, and two types of modified neurochaetae, acicular and hook-shaped.

Patterns of mollusc distribution in mangroves from the São Marcos Bay, coast of Maranhão State, Brazil

The diversity and distribution of molluscs from the Amazon Coast of Maranhao State, Brazil, are poorly understood. The aim of this study was to investigate how molluscs in two mangrove creeks (Buenos Aires and Tronco) at the Sao Marcos Bay, coast of the Maranhao State, respond to spatial and temporal variations in the environment. Sampling was performed in the intertidal area along three zones established using a straight line transect of 100 m. Abiotic variables of water and sediment were measured at each creek. We found 5,912 specimens belonging to 23 species and 15 families of epifaunal and infaunal molluscs. The patterns of their distribution in the two creeks were different. Salinity, dissolved oxygen, and rainfall were the main variables that affected the temporal distribution of molluscs. We found low species richness in the overall mollusc composition. Diversity in the Buenos Aires Creek was lower than that observed in the Tronco Creek, possibly because of activities of a port located in proximity to the former. The spatial distribution of molluscs along the zones followed an abundance and diversity gradient, mainly influenced by exposure time during low tide. Port activities may influence the patterns of mollusc distribution in the surrounding mangroves, and we thus highlight the importance of management and monitoring of these areas.