Free-living bryozoans (Cheilostomatida, Cupuladriidae) from northeastern and northern Brazil

Abstract

Free-living bryozoans, unlike most cheilostomes, live unattached from the substratum on or within soft sedimentary bottoms. Bryozoans of the family Cupuladriidae Lagaaij, 1952 are probably the best-studied free-living representatives. In Brazil, eight species of cupuladriids have been reported to date, including some regarded as species complexes. This paper documents cupuladriid taxa from northeastern and northern Brazil based on the examination of 1236 colonies. Three species previously reported from Brazil are described: Cupuladria monotrema (Busk, 1884), Discoporella gemmulifera Winston & Vieira, 2013 and Discoporella salvadorensis Winston, Vieira & Woollacott, 2014. A new species, Cupuladria minuta n. sp., is erected; it differs from its congeners in having small, flat discoid colonies, with the central area up to the fifth astogenetic generation composed of vicarious avicularia with an auriform opesia, and quadrangular to rectangular basal sectors with 1–6 small openings per sector. Our results suggest that four species previously recorded from Brazil are doubtful—Cupuladria canariensis (Busk, 1859), Cupuladria biporosa Canu & Bassler, 1923, Discoporella umbellata (Defrance, 1923) and Discoporella depressa (Conrad, 1841). Some Brazilian specimens previously assigned to Discoporella umbellata var. conica are re-assigned to D. salvadorensis. The species studied here frequently co-occur on mainly sandy and muddy bottoms at 8–130 m depth, as it is typical of most living populations of cupuladriids. The sedimentation rate, and thus the bottom composition, likely influence the distribution of cupuladriids in Brazil, with Cupuladria species being more common in stabler and coarser sea bottoms than Discoporella species, which tend to be more broadly distributed.