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The origins of cheilostome bryozoans and parental care in this group are substantially older than previously thought. 

The type of the xeniid soft coral Sansibia flava (May, 1898) is re-described for the first time and its morphological diagnosis is presented. A subsequent integrated analysis of molecular and morphological characters of related Xeniidae, including species indigenous to the Indo-Pacific Ocean and invasive in the Atlantic (Brazil), led to the description of a new Sansibia species, as well as two new genera comprising an additional three new species. All of these taxa are encrusting, with polyps arising directly from a spreading basal membrane. Molecular phylogenetic analyses show that these genera are not sister taxa, thus further emphasizing the remarkable phylogenetic diversity of xeniids with such a growth form. The sclerites of all species are uniformly ellipsoid platelets, abundant throughout the colony. The species exhibit restricted, non-overlapping geographic ranges, with distinct genotypes (molecular operational taxonomic units) found in different marine realms. The results emphasize the importance of re-examination of original old type material while applying molecular phylogenetic analyses in order to delineate species boundaries and to recognize biodiversity patterns. 

Coral reefs are home to the greatest diversity of marine life, and many species on reefs live in symbiotic associations. Studying the historical biogeography of symbiotic species is key to unravelling (potential) coevolutionary processes and explaining species richness patterns. Coral-dwelling gall crabs (Cryptochiridae) live in obligate symbiosis with a scleractinian host, and are ideally suited to study the evolutionary history between heterogeneous taxa involved in a symbiotic relationship. The genus Opecarcinus Kropp and Manning, 1987, like its host coral family Agariciidae, occurs in both Indo-Pacific and Caribbean seas, and is the only cryptochirid genus with a circumtropical distribution. Here, we use mitochondrial and nuclear DNA gene fragments of Opecarcinus specimens sampled from 21 Indo-Pacific localities and one Atlantic (Caribbean) locality. We applied several species delimitation tests to characterise species diversity, inferred a Bayesian molecular-clock time-calibrated phylogeny to estimate divergence times and performed an ancestral area reconstruction. Time to the most recent common ancestor (tMRCA) of Opecarcinus is estimated at 15−6 Mya (middle Miocene—late Miocene). The genus harbours ~ 15 undescribed species as well as several potential species complexes. There are indications of strict host-specificity patterns in certain Opecarcinus species in the Indo-Pacific and Atlantic, however, a robust phylogeny reconstruction of Agariciidae corals—needed to test this further—is currently lacking. The Indo-West Pacific was inferred to be the most probable ancestral area, from where the Opecarcinus lineage colonised the Western Atlantic and subsequently speciated into O. hypostegus. Opecarcinus likely invaded from the Indo-West Pacific across the East Pacific Barrier to the Atlantic, before the full closure of the Isthmus of Panama. The subsequent speciation of O. hypostegus, is possibly associated with newly available niches in the Caribbean, in combination with genetic isolation following the closure of the Panama Isthmus. 

Two new bopyrids, Bopyrinina articulata n. sp. and Bopyrinella asymmetrica n. sp. are described from French Polynesia, the Red Sea, and the Philippines. Bopyrinina articulata n.sp. infests Salmoneus cf. gracilipes Miya, and is distinguishable from other species of this genus by the structure of the maxilliped, pleopods and oostegite 1. Bopyrinella asymmetrica n. sp. is most similar to Bopyrinella albida Shiino, 1958, but females differ from that species because all pereomeres on the short side have round dorsolateral bosses and its pleotelson is greatly distorted. Bopyrina ocellata (Czerniavsky, 1868) is newly recorded from the Western Atlantic, from Florida, USA. Review of the species of Bopyrina revealed that B. choprai Nierstrasz & Brender à Brandis, 1929 and B. sewelli Chopra, 1930 are intermediate in morphology between Bopyrina and Schizobopyrina, the taxonomic assignment of these two species needs further evaluation. Keys to Bopyrinella Nierstrasz & Brender à Brandis, 1925 and Bopyrina Kossmann, 1881 are presented. Hosts and distributions of the seven species of Bopyrinella are summarized.