Background: The brittle star Ophiothela mirabilis has recently invaded and is expanding its range in the southwest Atlantic.

To determine how benthic, tropical, rocky shore communities were affected by the invasive coral species Tubastraea coccinea and T. tagusensis, 8 sites were studied during 2 yr on rocky shores in the southwest Atlantic Ocean (Brazil) by using both fixed and random sampling techniques. Overall, mean cover of T. tagusensis was 0.7% and T. coccinea was 0.4%, (the eleventh and sixteenth most abundant taxa, respectively, throughout the sites). Forty-two major space occupying taxa were registered. In fixed quadrats there was a 76.6% increase per year in density of Tubastraea spp. over the study period. For percent cover no significant difference in cover over time was detected for T. coccinea, but for T. tagusensis and overall (both species) cover increased significantly. The random quadrats data showed subtle differences from the fixed quadrats. There was an increase in density of Tubastraea spp. through time (67.8% per year over the study period). In random samples the density of T. coccinea increased during the study but that of T. tagusensis did not. The cover of both corals also increased over time. The sites where Tubastraea spp. were most abundant possessed higher diversity, evenness and richness of species. Sites where Tubastraea was present tended to group in ordination. The presence of Tubastraea in the communities caused a mean dissimilarity of 4.8% in the invaded communities. A strong positive relationship between invader cover and change in community structure was found, which suggested complete (100%) community dissimilarity at an invader cover of 45%. The negative effects are sufficient to disturb the native benthic communities throughout the tropical Atlantic Ocean.

Inclusion of fossils can be crucial to address evolutionary questions, because their unique morphology, often drastically modified in recent species, can improve phylogenetic resolution. We performed a cladistic analysis of 45 cassidulids with 98 characters, which resulted in 24 most parsimonious trees. The strict consensus recovers three major cassiduloid clades, and the monophyly of the family Cassidulidae is not supported. Ancillary analyses to determine the sensitivity of the phylogeny to missing data do not result in significantly different topologies. The taxonomic implications of these results, including the description of a new cassiduloid family and the evolution of some morphological features, are discussed. Cassiduloids (as defined here) most probably originated in the Early Cretaceous, and their evolutionary history has been dominated by high levels of homoplasy and a dearth of unique, novel traits. Despite their high diversity during the Palaeogene, there are only seven extant cassiduloid species, and three of these are relicts of lineages dating back to the Eocene. Future studies of the biology of these poorly known species, some of which brood their young, will yield further insights into the evolutionary history of this group.

Tetractinellida Marshall 1876 [Borchiellini et al. 2004] comprises the Orders Spirophorida and Astrophorida. A surveyof their diversity in the Bocas del Toro archipelago (Panama) was conducted. A total of ten species of Tetractinellidawere encountered: Cinachyrella alloclada, Cinachyrella apion, Cinachyrella kuekenthali, Ecionemia megastylifera,Stelletta fibrosa, Stelletta sp., Stryphnus raratriaenus sp. nov., Erylus formosus, Geodia gibberosa and Geodiapapyracea. Five of these species are new to the Atlantic sponge fauna of Panama, one of which is new to science.Stryphnus raratriaenus sp. nov. is very similar to Caribbean Asteropus species but it possesses triaenes. It is the firstspecies of this genus in the Caribbean. The description of Ecionemia megastylifera Wintermann–Kilian & Kilian, 1984 ishere revised and the species fully redescribed. A cytochrome c oxidase subunit I (COI) gene partial fragment and/or a 28S ribosomal gene partial fragment (C1–D2 domains) were sequenced for some of the species collected.