Benthic macrofauna associated to the invasive bivalve Mytilopsis leucophaeata (Dreissenidae) in a coastal lagoon in Rio de Janeiro, Brazil.

The invasion record for the estuarine bivalve Mytilopsis leucophaeata in Brazil is in Rio de Janeiro city, including the Rodrigo de Freitas Lagoon, where high densities of this invader were registered. This work aimed to (1) assess the composition and structure of the benthic macrofauna associated with this invader in Rodrigo de Freitas Lagoon, (2) analyze the spatiotemporal variation of richness, density and diversity of the associated benthic community, and (3) correlate changes on the density of the associated benthic species with some water quality variables and the density of M. leucophaeata. Clusters of M. leucophaeata were collected monthly (two years) in four sites. Nine taxa associated with M. leucophaeata were found; Heleobia sp. (Gastropoda) and Melita mangrovi (Amphipoda) showed the highest densities. The structure of the benthic macrofauna slightly differed among sampling sites, but not between dry and wet seasons. The water quality parameters, specific patterns of each taxon and high densities of M. leucophaeata contribute to variations in density of the associated species. Oscillations in the densities of M. leucophaeata and the native bivalve Brachidontes darwinianus suggest some agonistic relationship between them, such as a competition for space.

The spreading of the invasive bivalve Mytilopsis leucophaeata (Dreissenidae) into estuaries of Rio de Janeiro, Brazil.

An extensive field survey was conducted to evaluate the spreading of the invasive estuarine bivalve Mytilopsis leucophaeata into the metropolitan region of Rio de Janeiro (Brazil), in which the single invaded site so far recorded is Rodrigo de Freitas Lagoon. A novel record is made to the Marapendi coastal lagoon, where M. leucophaeata mainly colonizes mangrove roots. A reef composed of druses above the unconsolidated substratum is recorded for the first time for this species. The fauna associated to agglomerates of M. leucophaeata was composed of eight taxa: polychaetes Alitta succinea and Polydora sp., amphipods Melita mangrovi and Elasmopus sp., barnacles Amphibalanus eburneus and A. improvisus, the crab Eurypanopeus cf. dissimilis and the gastropod Heleobia spp. Based on COI sequences, the haplotype diversity of M. leucophaeata invasion in Marapendi Lagoon is high, like that previously recorded in Rodrigo de Freitas Lagoon. The expansion of M. leucophaeata demands a continuous investigation, including the knowledge of its impacts on the biota.

Five new species and two records of Triphorinae (Caenogastropoda, Triphoridae) from Brazil.

Triphoridae is one of the most speciose families of marine mollusks, being mainly represented by the subfamily Triphorinae. The present study aims to describe five new species of Triphorinae, and to report two species in Brazil previously known only from the Caribbean: Nanaphora verbernei (Moolenbeek & Faber) comb. nov. is herein disregarded as belonging to the genus Cheirodonta, owing to differences especially related to shell morphology; Triphora portoricensis Rolán & Redfern has its known geographic distribution greatly increased, despite its non-planktotrophic development; Cheirodonta mizifio sp. nov. has a brown shell, with the median spiral cord emerging weakly in the beginning of sixth to eighth whorl of teleoconch; Eutriphora costai sp. nov. has a beige shell, with the median spiral cord emerging in the fifth whorl of teleoconch; Nanaphora leei sp. nov. has a large shell for the genus, with the median spiral cord emerging between the eighth and ninth whorl of teleoconch; Triphora charybdis sp. nov. has a white adapical spiral cord, brown median/abapical cords, with the median one usually emerging in the seventh whorl of teleoconch; Triphora scylla sp. nov. has a reticulated embryonic shell, with the median spiral cord of teleoconch emerging between the end of the sixth to the end of the tenth whorl.