Maria Pia Miglietta

Phylogenetics of Hydroidolina (Hydrozoa: Cnidaria)

Hydroidolina is a group of hydrozoans that includes Anthoathecata, Leptothecata and Siphonophorae. Previous phylogenetic analyses show strong support for Hydroidolina monophyly, but the relationships between and within its subgroups remain uncertain. In an effort to further clarify hydroidolinan relationships, we performed phylogenetic analyses on 97 hydroidolinan taxa, using DNA sequences from partial mitochondrial 16S rDNA, nearly complete nuclear 18S rDNA and nearly complete nuclear 28S rDNA. Our findings are consistent with previous analyses that support monophyly of Siphonophorae and Leptothecata and do not support monophyly of Anthoathecata nor its component subgroups, Filifera and Capitata. Instead, within Anthoathecata, we find support for four separate filiferan clades and two separate capitate clades (Aplanulata and Capitata sensu stricto ). Our data however, lack any substantive support for discerning relationships between these eight distinct hydroidolinan clades.

A silent invasion.

Invasions mediated by humans have been reported from around the world, and ships’ ballast water has been recognized as the main source of marine invaders worldwide. Some invasions have dramatic economic and ecological consequences. On the other hand, many invasions especially in the marine realm, can go unnoticed. Here we identify a human mediated, worldwide introduction of the hydrozoan species Turritopsis dohrnii. The normal life cycle of hydrozoans involves the asexual budding of medusae from colonial polyps. Medusae of Turritopsis, however, when starved or damaged, are able to revert their life cycle, going back to the polyp stage through a process called transdifferentiation. They can thus easily survive through long journeys in cargo ships and ballast waters. We have identified a clade of the mitochondrial 16S gene in Turritopsis which contains individuals collected from Japan, the Pacific and Atlantic coasts of Panama, Florida, Spain, and Italy differing from each other in only an average of 0.31% of their base-pairs. Fifteen individuals from Japan, Atlantic Panama, Spain, and Italy shared the same haplotype. Turritopsis dohrnii medusae, despite the lack of genetic differences, are morphologically different between the tropical and temperate locations we sampled, attesting to a process of phenotypic response to local conditions that contributes to making this grand scale invasion a silent one.

Reconciling genealogical and morphological species in a worldwide study of the Family Hydractiniidae (Cnidaria, Hydrozoa)

The Hydractiniidae are a family of globally distributed marine hydrozoans (class Hydrozoa, phylum Cnidaria). Despite being one of the most well‐studied families of the Hydrozoa, their genus and species‐level taxonomy is unsettled and disputed. The taxonomic difficulties of the Hydractiniidae are due to many inadequate species descriptions, a paucity of available morphological characters, many cryptic species, and the often‐extreme plasticity seen when colonies of the same species are found at different stages of growth or different environmental conditions. This confusion over species identity is especially important because some species of the family Hydractiniidae are well‐established model organisms for a wide array of studies ranging from gene expression to developmental biology and colony growth. Here we report the species‐level implications of 226 mitochondrial large ribosomal subunit (16S) rDNA sequences from around the world and 52 nuclear DNA sequences (Elongation Factor 1α) with the intent to reconcile described morphospecies with genealogical lineages.

The rediscovery of Codonorchis octaedrus (Hydroidomedusae, Anthomedusae, Pandeidae), with an update of the Mediterranean hydroidomedusan biodiversity

Abstract Codonorchis octaedrus is recorded for the first time since its discovery by Haeckel in 1879. A hydroid colony collected in a cave of the Apulian Coast (between the Ionian and the Adriatic Seas) produced several medusae which have been reared to maturity. This is the first complete description of the species, which was previously considered as doubtful, as was the genus Codonorchis. The diagnostic features for the genus are: hydroid small, naked, sessile, with a single row of few tentacles, gono‐phores on hydrorhiza, medusa with apical projection with apical process from the manubrium, perradial, interradial and adradial ocellate bulbs, two perradial tentacles, horseshoe‐shaped interradial gonads, small mesenteries. The list of Mediterranean hydroidomedusae is updated with the new (or overlooked) records since the last published list (1993). The increase in species number is great (about 10%), showing that the knowledge of biodiversity of even a well‐studied sea as the Mediterranean is far from be...

EVOLUTION OF LIFE CYCLE, COLONY MORPHOLOGY, AND HOST SPECIFICITY IN THE FAMILY HYDRACTINIIDAE (HYDROZOA, CNIDARIA)

Biased transitions are common throughout the tree of life. The class hydrozoa is no exception, having lost the feeding medusa stage at least 70 times. The family hydractiniidae includes one lineage with pelagic medusae (Podocoryna) and several without (e.g., Hydractinia). The benthic colony stage also varies widely in host specificity and in colony form. The five‐gene phylogeny presented here requires multiple transitions between character states for medusae, host specificity, and colony phenotype. Significant phylogenetic correlations exist between medusoid form, colony morphology, and host specificity. Species with nonfeeding medusae are usually specialized on a single host type, and reticulate colonies are correlated with nonmotile hosts. The history of feeding medusae is less certain. Podocoryna is nested within five lineages lacking medusae. This requires either repeated losses of medusae, or the remarkable re‐evolution of a feeding medusa after at least 150 million years. Traditional ancestral reconstruction favors medusa regain, but a likelihood framework testing biased transitions cannot distinguish between multiple losses versus regain. A hypothesis of multiple losses of feeding medusae requires transient selection pressure favoring such a loss. Populations of species with feeding medusae are always locally rare and lack of feeding medusae does not result in restricted species distribution around the world.

Hydractinia antonii sp. nov.: a new, partially calcified hydractiniid (Cnidaria: Hydrozoa: Hydractiniidae) from Alaska

A new partially calcified hydroid species of the family Hydractiniidae, was found in offshore waters of the Aleutian Islands (Alaska), dredged from the bottom at 139-145 m depth. This is the third known species of extant calcified Hydractiniidae, and it shows a unique colony structure. The base is heavily calcified and the distal parts are ramified and have a solid chitinous structure. Branches are all in one plane and the colony reaches up to 18 cm in height.

Evolution of Calcium-carbonate Skeletons in the Hydractiniidae

Biomineralization has mostly been studied in the class Anthozoa (Phylum Cnidaria), but very little is known about the evolution of the calcified skeleton in the class Hydrozoa or about the processes leading to its formation. The evolution of the calcified skeleton is here investigated in the hydrozoan family Hydractiniidae. A phylogenetic analysis of ribosomal, mitochondrial, and nuclear-protein-coding DNA sequences supported two independent origins of the calcified skeleton within the Hydractiniidae and indicates a case of parallel evolution, as suspected in the Anthozoa. Neither of the two origins of skeleton in the Hydractiniidae has led to either speciose or numerically abundant species, in contrast with other skeletonized hydrozoan families. Finally, we show that the origin of calcified skeletons in the Hydractiniidae is significantly correlated with the distribution of species with calcium carbonate granules within a polyps gastrodermal cells. This suggests that the presence of these granules precedes the origin of a full skeleton.

Speciation: Where Are We Now? An Introduction to a Special Issue on Speciation

Although modern evolutionary biology started with a seminal volume whose title identified the origin of species as the central theme of the new theory (Darwin 1859), the topic of speciation received relatively little attention for several decades following the publication of the origin of species. Darwin and his contemporaries devoted much more attention to explain how changes occurred within species rather than how species originated. In fact, a search of the published scientific literature using web of science reveals that between 1864 and 1939 only 21 journal articles had the word speciation in their title (Fig. 1). As already summarized by Coyne and Orr (2004) interest in the origin of species greatly increased during the development of the modern synthesis, when mendelian genetics was reconciled with biogeography and natural selection by people like Dobzhansky (1937) and Mayr (1942). Mayr was the first to focus on the importance of species, introducing the biological species concept (BSC), which has dominated speciation research for the past seven decades, and championed the idea of speciation in allopatry. Dobzhansky’s work pointed out the importance of understanding how changes in allele frequencies could produce genetically distinct groups and the importance of reproductive isolating mechanisms. Between the 1940s and the 1970s, while the biogeography of speciation remained an active area of research for systematists and naturalists, the mechanisms of origin of barriers to reproductive isolation received relatively little attention by geneticists. During that time period most workers in fact remained more interested in demonstrating the strength and influence of natural selection in the wild, and in explaining how genetic variation accumulates and persists within species (e.g., Lewontin 1974). Starting in the 1980s however, the availability of new empirical tools such as molecular genetics, and theoretical and methodological approaches, such as phylogenetic and comparative methods, led to resurgence in interest in the origin of species. Speciation research, once predominantly the domain of systematists, paleontologists, and some geneticists, started to attract the interests of workers in other fields of biology, such as ecologists, ethologists, genome biologists, and developmental biologists. This caused a shift from largely pattern-oriented studies of speciation, in which often the description of patterns was accompanied by the suggestion of some (often untestable) hypotheses regarding what might have caused the events, to more process-oriented studies, in which attempts were made to directly test and explore the process. This resurgence of interest in speciation has been one of the main developments in evolutionary biology during the past 25 years, and has led to a new phase of speciation studies (Coyne and Orr 2004). During this new phase many of the major conclusions about speciation reached since 1859 have been re-examined. The debate over species concepts, once mostly the domain of systematists and philosophers, was reinvigorated through the active involvement of students of different branches of biology (e.g., F. Santini (&) Department of Ecology and Evolutionary Biology, University of California at Los Angeles, 610 Charles Young Dr. South, Los Angeles, CA 90095, USA e-mail: santini@ucla.edu

Life cycle of Bougainvillia nana (Cnidaria: Hydrozoa: Bougainvilliidae) from Italy, including a discussion of Bougainvillia muscus in the Mediterranean Sea

The life cycle of a species of the genus Bougainvillia (Cnidaria: Hydrozoa), found in the southern Mediterranean Sea, Italy, is here described. Hydroid colonies produced immature medusae with two tentacles and two ocelli per bulb and four unbranched oral tentacles. The number of tentacles and ocelli, which remained constant during the entire life cycle, are here considered diagnostic characters to identify the present as a new species. Female medusae lived up to 47 days (with an average of 30 days) when reared at 17 °C, while males, reared at the same temperature, were short-lived, concluding their life cycle in no more than 15 days. The medusa of this species resembles B. ramosa var. nana described by Hartlaub in 1911 on the basis of few specimens and no polyp stage. After the complete life cycle has been observed, and given its peculiar medusa stage, Hartlaubs subspecies (variant) must be promoted to species rank as Bougainvillia nana.

TaxaGloss - A Glossary and Translation Tool for Biodiversity Studies

Abstract Background Correctly identifying organisms is key to most biological research, and is especially critical in areas of biodiversity and conservation. Yet it remains one of the greatest challenges when studying all but the few well-established model systems. The challenge is in part due to the fact that most species have yet to be described, vanishing taxonomic expertise and the relative inaccessibility of taxonomic information. Furthermore, identification keys and other taxonomic resources are based on complex, taxon-specific vocabularies used to describe important morphological characters. Using these resources is made difficult by the fact that taxonomic documentation of the worlds biodiversity is an international endeavour, and keys and field guides are not always available in the practitioners native language. New information To address this challenge, we have developed a publicly available on-line illustrated multilingual glossary and translation tool for technical taxonomic terms using the Symbiota Software Project biodiversity platform. Illustrations, photographs and translations have been sourced from the global community of taxonomists working with marine invertebrates and seaweeds. These can be used as single-language illustrated glossaries or to make customized translation tables. The glossary has been launched with terms and illustrations of seaweeds, tunicates, sponges, hydrozoans, sea anemones, and nemerteans, and already includes translations into seven languages for some groups. Additional translations and development of terms for more taxa are underway, but the ultimate utility of this tool depends on active participation of the international taxonomic community.