The Zancleidae is a hydrozoan family that currently comprises three genera and 42 nominal species. The validity of numerous taxa in this family still needs to be assessed with integrative analyses and complete life cycle descriptions. The vast majority of its species live symbiotically with other organisms, among which cheilostomate bryozoans are the most common hosts. These bryozoan-associated zancleids are host-specific and encompass all species of the genera Halocoryne and Zanclella, as well as several species in the genus Zanclea. Zancleids show variable morphologies, including highly reduced polyps and medusae. Their phylogenetic history is uncertain due to the often intergrading morphologies and the shortage of molecular data. In the present study, two species of Zanclea from the Indian Ocean and the Red Sea are analysed, using morphological and DNA-based approaches. Morphological analyses of the polyp and medusa stages show that, despite a general resemblance with each other and with Zanclella diabolica, the two species differ in some characters, and this is supported also by molecular investigations. The DNA analyses show that the two species are monophyletic and closely related, but divergent from other Zanclea lineages. This newly recovered clade may correspond with the genus Zanclella or with a cryptic genus. The lack of both morphological and molecular data for several zancleid species did not allow to address this issue. Additionally, the single-and multi-locus phylogeny reconstructions reveal that both the family Zancleidae and the genus Zanclea are polyphyletic taxa, since they are composed of at least three divergent lineages. Most zancleid species have polyps and medusae similar to other closely related taxa, and this conserved general morphology poses a challenge in the delimitation of species, genera and even families in this group. Consequently, further conjunct morphological and molecular efforts are strongly needed to clarify the diversity and evolution of the family Zancleida as a whole.
The scleractinian species Psammocora explanulata and Coscinaraea wellsi were originally classified in the family Siderastreidae, but in a recent morpho-molecular study it appeared that they are more closely related to each other and to the Fungiidae than to any siderastreid taxon. A subsequent morpho-molecular study of the Fungiidae provided new insights regarding the phylogenetic relationships within that family. In the present study existing molecular data sets of both families were analyzed jointly with those of new specimens and sequences of P. explanulata and C. wellsi. The results indicate that both species actually belong to the Cycloseris clade within the family Fungiidae. A reappraisal of their morphologic characters based on museum specimens and recently collected material substantiate the molecular results. Consequently, they are renamed Cycloseris explanulata and C. wellsi. They are polystomatous and encrusting like C. mokai, another species recently added to the genus, whereas all Cycloseris species were initially thought to be monostomatous and free-living. In the light of the new findings, the taxonomy and distribution data of C. explanulata and C. wellsi have been updated and revised. Finally, the ecological implications of the evolutionary history of the three encrusting polystomatous Cycloseris species and their free-living monostomatous congeners are discussed.
An integrated approach using morphological and genetic data is needed to disentangle taxonomic uncertainties affecting the hydrozoan families Sphaerocorynidae and Zancleopsidae. Here we used this approach to accurately characterise species in these families, identify the previously unknown polyp stages of the genera Euphysilla and Zancleopsis, which were originally described exclusively based on the medusa stages, describe a new sphaerocorynid genus and species, and assess the phylogenetic position of the two families within the Capitata. The monotypic genus Astrocoryne was found to be a synonym of Zancleopsis. Astrocoryne cabela was therefore transferred to the genus Zancleopsis as Zancleopsis cabela comb. nov. The new polyp-based genus and species Kudacoryne diaphana gen. nov. sp. nov. was erected within the Sphaerocorynidae. Both taxa are primarily based on genetic data, but the introduction of this new genus was made necessary by the fact that it clustered with the genera Heterocoryne and Euphysilla, despite showing Sphaerocoryne-like polyps. Interestingly, the species analysed in this work showed contrasting biogeographical patterns. Based on our data and literature records, some species appear to have a wide circumtropical range, whereas others are limited to few localities. Overall, these results lay the ground for future investigations aimed at resolving the taxonomy and systematics of these two enigmatic families.