Daniela Gabriel

A new order of red algae based on the Peyssonneliaceae, with an evaluation of the ordinal classification of the Florideophyceae (Rhodophyta)

Abstract The Peyssonneliaceae Denizot comprises a worldwide group of non-calcified or calcified, crust-forming red algae found in diverse, intertidal to deep subtidal marine habitats. Eight genera have been recognized in the family, with Peyssonnelia Decaisne having the largest number of species. Both comparative morphology and rbcL and nuclear LSU rDNA sequence data support the monophyly of the family and show that it cannot be maintained in the order Gigartinales Schmitz. A new order, Peyssonneliales, is herein proposed to accommodate the Peysonneliaceae, with only two of the genera (i.e., Peyssonnelia and Sonderopelta), and its relationship to the other red algal orders is discussed. We also propose the transfer of one species, Peyssonnelia capensis Montagne to Sonderopelta Womersley & Sinkora.

Molecular diversity of the Caulerpa racemosa-Caulerpa peltata complex (Caulerpaceae, Bryopsidales) in New Caledonia, with new Australasian records for C. racemosa var. cylindracea

Sauvage T., Payri C., Draisma S.G.A., Prud′homme van Reine W.F., Verbruggen H., Belton G.S., Gurgel C.F.D., Gabriel D., Sherwood A.R. and Fredericq S. 2013. Molecular diversity of the Caulerpa racemosa–Caulerpa peltata complex (Caulerpaceae, Bryopsidales) in New Caledonia, with new Australasian records for C. racemosa var. cylindracea. Phycologia 52: 6–13. DOI: 10.2216/11-116.1 Molecular characterization (plastid-encoded tufA gene) of New Caledonian members of the Caulerpa racemosa–Caulerpa peltata complex identified five lineages, each possibly harboring multiple species-level entities. On a global scale, the complex encompassed six lineages, two of which were pantropical and the remainder seemingly were restricted to the Indo-Pacific basin. Caulerpa racemosa var. cylindracea, a fast-spreading introduced taxon in the Mediterranean Sea and the Canary Islands, was previously thought to be restricted to southwestern Australia; it was newly reported here for New Caledonia and several northern Australian locations, including the Great Barrier Reef.

A Dynamic Approach to the Study of Rhodoliths: A Case Study for the Northwestern Gulf of Mexico

Abstract In the northwestern Gulf of Mexico, beds of rhodoliths and unconsolidated rubble at 55–70 m depth are associated with unique offshore deep bank habitats known as salt domes or diapirs. Prior to the 2010 BP Deepwater Horizon oil spill these harbored the highest known seaweed diversity in the northern Gulf of Mexico. Six post-spill cruises led offshore Louisiana to two sites previously documented with rich algal assemblages (i.e. prespill) revealed a dramatic post-spill die-off of seaweeds at both sites, with dredged rhodoliths appearing bleached and mostly denuded of fleshy algae, or “bare” (with a few crustose genera only, e.g. Corallinales and Peyssonneliales). This rubble, brought to the laboratory and maintained in a series of ∼75 liter microcosm tanks, gradually became covered by a suite of red, green and brown seaweed germlings that to this day continue to grow to adult size, reproduce, disappear and re-emerge, and whose species composition reflects pre-spill assemblages. These experiments revealed the expression of biodiversity from alternative life stages or resting stages apparently repressed in the Gulf at the time of sampling, including new, previously overlooked diversity. The rate of algal succession was documented by biweekly photography, and species taxonomic identity is being confirmed by ongoing molecular and morphological evidence. The implications of these exciting results, namely that undetected propagules, spores and endolithic filaments collected along with the “bare” substrata and in situ seawater have been triggered to germinate, grow, and reproduce under laboratory conditions are far-reaching. We hypothesize the function of rhodoliths and rubble as marine seedbanks for biological diversity and explore the role of this ecosystem for community resilience following a major anthropogenic disaster. This is a speculative paper since we currently lack many rigorous, quantitative data. The paper is envisioned as a “first step” in approaching the dynamics of rhodoliths and associated diversity following a catastrophic anthropogenic event, from which the algal and invertebrate diversity has not recovered, as of October 2013, our last collecting expedition to Ewing Bank in the NW Gulf of Mexico.

Taxonomic studies in the Schizymeniaceae (Nemastomatales, Rhodophyta): on the identity of Schizymenia sp. in the Azores and the generic placement of Nemastoma confusum

Gabriel D., Schils T., Parente M.I., Draisma S.G.A., Neto A.I. and Fredericq S. 2011. Taxonomic studies in the Schizymeniaceae (Nemastomatales, Rhodophyta): on the identity of Schizymenia sp. in the Azores and the generic placement of Nemastoma confusum. Phycologia 50: 109–121. DOI: 10.2216/09-67.1 Comparative rbcL sequence analysis indicates that the species going under the name Schizymenia dubyi in the Azores should be referred to as S. apoda. Sequences of Schizymenia specimens from China and Namibia were also identified as S. apoda, of which the type locality is the Cape Province in South Africa. Schizymenia dubyi, described from Atlantic France, is clearly a distinct species that we here report for Japan and Sicily in the Mediterranean Sea. Both Schizymenia species, along with an unreported species from Japan, are distinct from S. pacifica described from Washington, in the Pacific Coast of North America. Secondary pit connections were observed in gametophytes of S. apoda from the Azores, a previously unknown character for the Nemastomatales. Examination of type material of Nemastoma confusum indicates that this species, currently placed in the Nemastomataceae, should be transferred to the genus Platoma in the Schizymeniaceae. A morphological comparison between Platoma confusum (Kraft & John) comb. nov. with descriptions of P. cyclocolpum and P. chrysymenioides suggests that the three species are closely related.

Phylogenetic appraisal of the genus Platoma (Nemastomatales, Rhodophyta), including life history and morphological observations on P. cyclocolpum from the Azores.

Gabriel D., Parente M.I., Neto A.I., Raposo M., Schils T. and Fredericq S. 2010. Phylogenetic appraisal of the genus Platoma (Nemastomatales, Rhodophyta), including life history and morphological observations on P. cyclocolpum from the Azores. Phycologia 49: 2–21. DOI: 10.2216/07-99.1 The red algal genus Platoma Schmitz (Schizymeniaceae, Nemastomatales) with type Platoma cyclocolpum (Montagne) Schmitz was originally described from the Canary Islands. Life history studies were conducted on P. cyclocolpum from the Azores under 10°C/8∶16 light (L)∶dark (D), 15°C/16∶8 L∶D, and 23°C/natural daylight regimes in culture. Three nonreproductive modes of thallus development resulted from germinating carpospores: (1) a permanent crust, (2) a filiform, nonfoliose erect thallus occasionally attached by a holdfast composed of cell aggregations, and (3) a filiform, nonfoliose erect thallus has been reported previously for populations from the Canary Islands, but the latter two have not been described before. Platoma cyclocolpum is widely reported in the literature, but specimens under that name from Madagascar are identified here as Platoma chrysymenioides Gavio et al., a deepwater species first described from the northern Gulf of Mexico and now recorded for the entire gulf. Genuine P. cyclocolpum specimens from the Azores, Madeira, and the Canary Islands were sequenced for chloroplast-encoded rbcL, and phylogenetic relationships of four Platoma species are discussed. A table listing diagnostic morphological and anatomical features of Platoma species is provided.

Beneath the hairy look: the hidden reproductive diversity of the Gibsmithia hawaiiensis complex (Dumontiaceae, Rhodophyta)

The tropical alga previously recognized as Gibsmithia hawaiiensis (Dumontiaceae, Rhodophyta) was recently suggested to represent a complex of species distributed throughout the Indo‐Pacific Ocean and characterized by a peculiar combination of hairy (pilose) gelatinous lobes growing on cartilaginous stalks. Phylogenetic reconstructions based on three genetic markers are presented here with the inclusion of new samples. Further diversity is reported within the complex, with nine lineages spread in four major phylogenetic groups. The threshold between intra‐ and interspecific relationships was assessed by species delimitation methods, which indicate the existence of 8–10 putative species in the complex. Two species belonging to the G. hawaiiensis complex are described here: Gibsmithia malayensis sp. nov. from the Coral Triangle and Gibsmithia indopacifica sp. nov., widely distributed in the Central and Eastern Indo‐Pacific. Morphological differences in the vegetative and reproductive structures of the newly described species are provided and compared to the previously described species of the complex. Additional lineages represent putative species, which await further investigation to clarify their taxonomic status. Gibsmithia hawaiiensis sensu stricto is confirmed to be endemic to the Hawaiian Islands, and Gibsmithia eilatensis is apparently confined to the Red Sea, with an expanded distribution in the region. New records of the G. hawaiiensis complex are reported from Egypt, Saudi Arabia, Indonesia, Philippines, and the Federated States of Micronesia, indicating that the complex is more broadly distributed than previously considered. The isolated position of Gibsmithia within the Dumontiaceae is corroborated by molecular data.

First report of the invasive macroalga Acrothamnion preissii (Rhodophyta, Ceramiales) in the Atlantic Ocean

Abstract Acrothamnion preissii is an invasive species in the Mediterranean Sea, and is listed among the 100 worst non-indigenous species. In July and August 2009, this non-native red macroalga was found for the first time in the Azores (on Santa Maria), and this represents the first record of this species in the Atlantic. Here, we describe the establishment of this invasive species in the Atlantic. In recent surveys, A. preissii displayed an invasive behaviour. As suggested for the Mediterranean Sea, hull fouling is the most likely vector for its introduction into the Azores.

Life history and morphological studies of Punctaria tenuissima (Chordariaceae, Phaeophyceae), a new record for the Azores

Punctaria tenuissima (Chordariaceae, Phaeophyceae) is reported for the first time from the Azores. Erect thalli were collected on the Island of Sao Miguel; they were up to 3 cm long, flattened and often twisted. The plurilocular sporangia were formed from surface cells that were quadrate or rectan- gular in surface view. Unilocular sporangia were not observed in the field. In culture, the plurispores of P. tenuis- sima developed into Hecatonema-like, tufted, prostrate thalli that formed plurilocular sporangia. The plurispores of the prostrate thalli cultured at 158C with a long day (LD) pho- toperiod developed into new prostrate thalli, which in turn formed plurilocular sporangia. This cycle was repeated 5 times, resulting in several generations of reproductive pros- trate thalli. When these cultures were cooled to 108C with a short day (SD) photoperiod, new erect thalli developed from the prostrate thalli resembling the thalli collected in the field. These erect blades produced unilocular and plurilocular spo- rangia on the same or on different thalli. The plurispores and unispores produced by the erect thalli at 108C under SD con- ditions once again developed into new prostrate thalli. This is the first report of unilocular sporangia formed in cultures of P. tenuissima. Sexual reproduction was not observed. The culture conditions, particularly temperature and daylength, appeared to influence the formation of erect blades. The Punctaria-like thalli were produced in 108C/SD conditions, whilst the Hecatonema-like thalli were produced under 108-158C/LD and SD conditions. These results are similar to those reported for P. tenuissima from other locations and suggest the occurrence of both direct and heteromorphic life histories in the Azorean algae.