Gaetano M. Gargiulo

Molecular systematics and phylogenetics of Gracilariacean species from the Mediterranean Sea

Mediterranean reports of Gracilariaceae species, in particular those assigned to the G. verrucosa complex, were re-examined with the use of molecular tools, in order to verify their systematic position and better understand their distribution. Within this complex, we recognized four distinct taxa: Gracilariopsis longissima, Gracilaria gracilis, Gracilaria longa and a possible new species. The rbcL gene sequences, together with those of other terete Mediterranean entities, were included in a broad molecular phylogeny of the family. The reproductive characters of the studied taxa do not fit completely with published hypothesis on the generic and intrageneric relationships, suggesting that the anatomy of some subgroups should be better characterized.

A Re-Assessment of Reproductive Anatomy and Postfertilization Development in the Systematics of Grateloupia (Halymeniales, Rhodophyta)

Abstract The red algal family Halymeniaceae has been recently the subject of taxonomic revisions based strictly on molecular data. As a result, the number of genera ascribed to it has been decreasing and many generic definitions changed profoundly owing to inconsistencies in diacritical vegetative and particularly reproductive characters in standard literature. Reproductive uniformity within this family has been claimed since the late 19th century and is generally supported by recent authors. In this study we report on consistent significant differences in the architecture of carpogonial and auxiliary cell ampullae, as well as in early postfertilization events, among Mediterranean species currently assigned to the genus Grateloupia C. Agardh and provide new interpretations of these features. We recognize several distinct types of ampullae and postfertilization events that distinguish groups of species, these groups proving to be strongly supported by rbcL phylogenies. As a result we conclude that the genus Grateloupia as presently circumscribed should be segregated into multiple genera. In addition to Grateloupia sensu stricto, we resurrect Dermocorynus P.L. Crouan et H.M. Crouan, Pachymeniopsis Y. Yamada ex S. Kawabata, Phyllymenia J. Agardh and Prionitis J. Agardh, all of which have been subsumed in Grateloupia by previous authors. New genera based on our anatomical and rbcL results for G. doryphora (Montagne) M. Howe, G. subpectinata Holmes and G. proteus Kützing will be described in subsequent papers.

Thallus morphology and spore formation in cultured Erythrocladia irregularis rosenvinge (Rhodophyta, Bangiophycidae)

The discoid thallus of Erythrocladia irregularis is the result of a pattern of cellular divisions expressed by mono‐and endospores; the latter are described for the first time in Erythrocladia. In nutrient enriched growth conditions the discoid thallus becomes a shapeless aggregate of unicells with a wrinkled wall surface, whose plane of division is unpredictable. The cells are able to produce monosporangia with a curved wall or they form eight‐celled endosporangia. Chloroplasts have an internal pyrenoid, as is characteristic of the Erythropeltidaceae.

Taxonomic Considerations of a Foliose Grateloupia Species from the Straits of Messina

Grateloupia turuturu Yamada is the currently accepted name for the invasive red alga that is present on coasts of the North Atlantic. Previously considered as G. doryphora (Montagne) M.A. Howe, populations of this invasive species were examined and their taxonomic position revised using molecular and morphological techniques. It was also thought that similar invasive populations in the Mediterranean should be identified as G. turuturu. This investigation used rbcL based molecular analyses to clarify the taxonomic position of Grateloupia “doryphora’ from the Straits of Messina. Our results indicate that this population is neither G. doryphora nor G. turuturu. It was placed separately in all analyses and grouped consistently with other Grateloupia species from the Pacific. On the basis of molecular data from this and previous investigations, it is evident that the status of the foliose Atlantic and Mediterranean entities is still unclear and a re-evaluation of the old names connected to them should be undertaken.

Sexual and asexual reproduction in a freshwater population of Bangia atropurpurea (Bangiales, Rhodophyta) from eastern Sicily (Italy)

Abstract The life history of Bangia atropurpurea (Bangiales, Rhodophyta) from the Alcantara River (Sicily, Italy) was studied in the field and laboratory. An alternation between a macroscopic phase and a microscopic filamentous conchocelis phase was found, and spermatia and carpogonia are described for the first time in a freshwater population of the species. Endosporangia have also been discovered on gametophytic plants in culture. In addition, the conchocelis phase produced either conchosporangia or monosporangia, and reproduction by fragmentation was common. Sexuality was indicated by chromosome counts of n = 3 and 2n =6 in gametophytes and sporophytes, respectively; resting cells were observed in both.

Stucture and reproduction of Cordylecladia guiryi sp. nov. (Rhodophyta, Rhodymeniales) from the Mediterranean Sea

Abstract Cordylecladia guiryi sp. nov. is described from the Mediterranean Sea, after a comparison of habit, morphology and reproduction with C. erecta, the only species of the genus. The species is characterized by the small dimension of its axes which arise single from the basal crust and by its habitat, growing epiphytically on Posidonia oceanica Delile leaves. Tetrasporangial and gametangial plants as well as the development of the carposporophyte have been studied in detail. The carpogonial branch is 4-celled and it is formed on a supporting cell that also bears a 3-celled auxiliary branch. Tetrasporangia are cruciately divided. The reproductive details confirm Sparlings view about the great variation existing in the organization of the procarp in members of this order.

Structure and reproduction of Gracilaria longa sp. nov. (Rhodophyta, Gigartinales) from the Mediterranean Sea

Abstract Gracilaria longa sp. nov. is described from the Mediterranean Sea, after a comparison of habit, morphology and reproduction with other species from the same area. The species is characterized by elongate second order axes, slender ultimate branchlets, «verrucosa-type» spermatangial conceptacles, a lobed fusion cell and a poorly developed inner pericarp. Karyological observations on meiotic tetrasporangia showed that n=24. A comparison with other Mediterranean species of Gracilaria with terete thalli is presented. The morphological similarities between some species of the genus in the Mediterranean are considered to be a result of low evolutionary divergence due to a relatively recent origin.

The Mediterranean Endemic New genus Felicinia (Halymeniales, Rhodophyta) Recognized by a Morphological and Phylogenetic Integrative Approach

Abstract Recently, DNA phylogenies resulted in the transfer of some species of the halymeniacean genus Aeodes, namely A. orbitosa and A. ulvoidea, to the genus Pachymenia leaving the former supposedly as a monotypic genus based on the type species, A. nitidissima. Nevertheless, that work overlooked the presence of A. marginata, a red foliaceus alga endemic to the Mediterranean Sea with a convoluted nomenclatural history. In the present study, we provided a thorough description of A. marginata based on both anatomical and molecular data and inferred its phylogenetic relationships among halymeniacean genera using both chloroplastic (rbcL) and nuclear genes (LSU). Based on our data, A. marginata allied with Halymenia, Cryptonemia, and associated genera rather than with the generitype A. nitidissima, and presented a unique set of characters deserving the status of genus within the Halymeniaceae. Therefore, we proposed the new genus Felicinia based on Felicinia marginata comb. nov. A description of the multiaxial vegetative of F. marginata construct was provided, highlighting a unique characteristic among red algae: the presence, in the medulla, of peculiar oblique multicellular filaments connecting periclinal filaments. These filaments are produced secondarily as branches from axial filaments and are possibly homologous to the anticlinal filaments observed in the medulla of Halymenia.

A REVIEW OF LIFE HISTORY PATHWAYS IN BRYOPSIS

The genus Bryopsis comprises siphonous green algae widely distributed from tropical to polar seas. Despite the early reports on the simplicity of its life history, subse- quent culture observations showed variety of life history patterns, even within a single species. Karyological data and reports on DNA quantification led to somewhat contradic- tory conclusions about the ploidy level of the two life history phases and about the moment of meiosis. Long term observations on Mediterranean species highlighted new alternatives in recycling of the two morphological phases. Looking at all published experimental data, we summarize all life history pathways of Bryopsis species.

A study on Gracilaria dendroides sp. nov. (Gigartinales, Rhodophyta) from the Bay of Naples

Gracilaria dendroides sp. nov. is described from the Bay of Naples, Italy, where it thrives on the rocks in the upper littoral. The species has a typical branching pattern resulting in the dendroid habit of the plant. G. dendroides is also characterized by lanceolate branchlets which become longer and taper in the distal part of the branches. Tetrasporangia, spermatangial conceptacles and cystocarps are localized in the lanceolate branchlets. The cortex in which tetrasporangia are deeply immersed is modified, the cells being less vacuolized and with a thick cell wall. The spermatangial conceptacles are as in G. verrucosa. The gonimoblastic tissue is lobate with connective filaments to the pericarp. The morphological and structural features are considered stable thus supporting the description of a new species.