Abstract Microcancilla phoenix sp. nov., collected from the Southeast and South coast of Brazil represents the southernmost record of the genus in the Atlantic Ocean. The new species differs from the other congeners of the Atlantic mainly by the presence of microscopic pustules covering the whole shell and by dimensions of the protoconch. “Axelella brasiliensis” Verhecken, 1991, known from the Northeast to South coast of Brazil, is transferred to Microcancilla based on a similar sculpture of microscopic pustules on the protoconch and on other features of the teleoconch discussed in the present study.

ABSTRACT Berthella currently comprises five valid species recorded from the western Atlantic, of which only Berthella agassizii (MacFarland, 1909) and Berthella stellata (Risso, 1826) have been recorded from Brazil. Two species of Berthellina occur in Brazil: Berthellina quadridens (Mörch, 1963) and Berthellina circularis (Mörch, 1863); however, based on a literature review and the anatomical study presented here, we only recognize B. circularis as occurring in the country. This study gives a detailed re-description of B. agassizii, B. stellata and B. circularis based on material from Brazil, and adds two new species to the genus, from the Brazilian coast, Berthella punctata sp. nov. and Berthellina ignis sp. nov. Berthellina circularis and B. quadridens are considered distinct species based on the denticulation of the radular teeth. B. quadridens presents the majority of teeth with two denticles, rarely three-four denticles, while in B. circularis from Brazil the radular teeth are highly denticulate with up to 17 denticles. Berthella and Berthellina do not form a monophyletic group, and cluster in a large polytomy within Pleurobranchidae. A detailed anatomical study is performed to improve the understanding of the evolutionary history of Pleurobranchidae. The comparison with available data on the odontophoric muscles of Pleurobranchoidea shows that Berthella and Berthellina present a pair of the muscle m10v that connects the mj with the ventral portion of the m5, while in Pleurobranchus and Pleurobranchaea the m10v connects the mj with the ventral portion of the m4; Berthella and Berthellina do not present the muscle m10d, which is present in Pleurobranchus and Pleurobranchaea. Based on these characters, Berthella seems to be more closely related to Berthellina than to Pleurobranchus.

Fusceulima Laseron, 1955 and Halielloides Bouchet & Warén, 1986 are reported from the southwestern Atlantic for the first time. Halielloides ingolfiana Bouchet & Warén, 1986 is considered a valid name, and the taxon is distinct from its previous senior synonym Eulima verrilliana Bush, 1909 in shell shape and absence of an umbilicus. Fusceulima saturata sp. nov. is characterized by a conical shell, domed at the apex, a short ovoid aperture, and a distinct dark-brown spiral band near the suture. Fusceulima toffee sp. nov. also has a conical shell and a dome-shaped apex, but has a taller high aperture and the entire shell is dark brown. Halielloides cf. ingolfiana, Fusceulima cf. boscheineni, and Fusceulima cf. minuta, are here recorded from the continental shelf off southeastern Brazil. The nominal species of these taxa were originally described from the northeastern Atlantic. Their status remains dubious because of lack of information on their biology, anatomy and molecular data. Regarding shell morphology, we cannot distinguish the Brazilian specimens from species in the northeastern Atlantic with the material available. A series of short grooves close to the suture of the protoconch in all species of Fusceulima, including the type species Fusceulima jacksonensis Laseron, 1955, is a possible diagnostic character for this genus.

Four new species of the pyramidellid Odostomiinae from Brazil are described: Chrysallida conifera sp. nov., characterized by a small and regularly conical shell with prominent nodules; Parthenina biumbilicata sp. nov., characterized by a deep and wide umbilicus and a regularly increasing aperture diameter at the protoconch, which bears a small circular umbilicus; Eulimastoma franklini sp. nov., which is very similar to Eulimastoma dydima (Verrill & Bush, 1900) but has a prominent helicoid protoconch; Eulimastoma exiguum sp. nov., similar to Eulimastoma weberi (Morrison, 1965) but without spiral ridges. Fargoa diantophila (Wells & Wells, 1961) and Chrysallida nioba (Dall & Bartsch, 1911) are reported from the southwestern Atlantic for the first time.

The taxonomy of the species of Metaxia Monterosato, 1884 from Brazil is revised. Previously to this study, only Metaxia excelsa Faber & Moolenbeek, 1991 was known to occur in this country, under its older name Metaxia exilis (C.B. Adams, 1850). The review of a large amount of shells in malacological collections in Brazil revealed the occurrence of three known additional species: Metaxia taeniolata (Dall, 1889); Metaxia rugulosa (C.B. Adams, 1850); Metaxia prompta Rolán & Fernández-Garcés, 2008, all previously reported from the southeast coast of the USA and/or the Caribbean region. Metaxia gongyloskymnus sp. nov., diagnosed by the globose protoconch with continuous axial ribs and microscopic spiral sculpture, is restricted to localities off the Southeastern Brazilian coast.

The gastropods Costaclis egregia (Dall, 1889), Thaleia nisonis (Dall, 1889), Tjaernoeia michaeli Engl, 2001 and the bivalves Bathyarca sp., Myonera aff. ruginosa (Jeffreys, 1882) are recorded for the first time in Brazilian waters. This paper presents a brief description of these species and also include ilustrations.