Galeolaria caespitosa Lamarck, 1818 is an endemic, gregarious serpulid annelid, ubiquitous along the intertidal zone of southern Australia, occurring from Queensland to Western Australia. We sampled specimens across this range and utilised morphological features and sequences of mitochondrial (cytochrome-b) and nuclear (ITS2) markers to assess the taxonomic status of this morphospecies. No taxonomically significant morphological differences were observed across the range of G. caespitosa. However, the molecular data revealed the existence of the following two well supported clades that were also geographically concordant for the two markers: an eastern clade, consisting of New South Wales and southern Queensland samples, and a south-western group that encompassed samples from the rest of its range. The minimum pairwise distance between members of the two groups was more than 24% for cytochrome-b, with a maximum of 1% within-group variation. In addition, analysis of molecular variation showed a high proportion (97%) of the total variation distributed among the two groups, indicative of long-term isolation of the two clades. These results suggest that G. caespitosa comprises at least two cryptic species. Here, we discuss the merits of naming new Galeolaria species, given there were no consistent morphological differences detectable and the absence of details on the type locality for G. caespitosa. We conclude that a new species of Galeolaria is warranted and describe it here as G. gemineoa.

Relatively few studies have characterized basal content and variability of arsenic in polychaetes, despite the potential importance of this element as a pollutant of marine environments. Even less have investigated the chemical speciation of arsenic, occurring as inorganic and organic forms, which reflect a different biological reactivity of the element. In the present paper we integrate existing literature with new data in order to summarize the status quo on arsenic bioaccumulation in polychaetes. We consider species with different trophic habits, phylogenetic relationships, geographic distribution and ecology. Reported data indicate a high variability in arsenic concentration with levels ranging from <1 μg·g−1 to more than 2500 μg·g−1 in different species; some additional species analyzed in this work confirm species‐specific characteristics which are not easily explained by biological or ecological factors. The profile of arsenic compounds in polychaetes is different to that of most aquatic organisms. Typically this element occurs in non‐toxic organic forms, however several polychaete species have been shown to accumulate relatively toxic molecules and subsequently biotransform them by processes such as methylation. Conclusions from the literature review reveal a complex array of arsenic actions in the environment and suggest a biological role of this element in the life history of some polychaete species.

Planktonic cnidarians are principal predators in the vast habitats between the ocean's surface and the deep‐sea floor. Almost nothing is known, however, about the chemical ecology of these fragile midwater animals because of difficulties associated with collecting healthy specimens and con‐ducting experiments in the field. With the use of a remotely operated vehicle, we found that the hydromedusa Mitrocoma cellularia is not a passive “drift‐net” predator. This relatively simple gelatinous organism reacted to both the taste and smell of prey in the laboratory and in situ. Our results comprise the first definitive demonstration that a species of pelagic cnidarian responds behaviorally to chemical signals, and they lend new insight into the role of chemoreception in structuring mid‐water communities.

The type genus of Serpulidae, Serpula Linnaeus, 1758, along with closely related genera Crucigera Benedict, 1887 and Hydroides Gunnerus, 1768, accounts for approximately one-third of all described species in the family. Although previous morphological and molecular studies unequivocally indicate that these three genera constitute a monophyletic group, the status of each genus remains unknown. In this study, the relationships among and within the genera Serpula, Crucigera, and Hydroides were investigated using maximum parsimony and Bayesian analyses of nuclear (18S and 28S rDNA) and mitochondrial (cytochrome b) genomic molecular markers plus morphology. The phylogeny supports the monophyly of Hydroides, but Serpula forms a paraphyletic basal grade and Crucigera is polyphyletic. The lack of close relationship between Hydroides and Crucigera indicates that their similar opercular features are not homologous.