Daniela Gabriel

Two new mesophotic species of Chrysymenia are reported for the Gulf of Mexico. Chrysymenia oliverhardyii sp. nov. is a broadly foliose species growing attached to rhodoliths (free-living carbonate nodules predominantly accreted by crustose coralline algae) at 58–66 m depth offshore Louisiana (northwestern Gulf) and at ~64–68 m depth in the vicinity of the Dry Tortugas, Florida (southeastern Gulf). A multi-marker phylogenetic analysis based on chloroplast-encoded rbcL and UPA, as well as nuclear LSU rDNA sequences, indicates that this taxon is most closely related to C. stanlaurelii sp. nov., a slender, branched species from the vicinity of the Florida Middle Grounds, Florida (northeastern Gulf), growing at 60 m depth. These two species from the eastern Gulf of Mexico share a basal most recent common ancestor with respect to the other known species of Chrysymenia. Illustrations and discussion are provided for the new species, as well as for the other Gulf of Mexico members C. planifrons, C. littleriana, C. halymenioides and C. nodulosa. A nomenclatural list, morphological figures, a dichotomous key, and a phylogenetic tree of pertinent Chrysymenia are provided.

Up to the present study, only 8.5% of the 522 macroalgal species reported at the Azores have sequences deposited in GenBank and BOLD public repositories. The sequences of four genetic markers (cox1, rbcL, UPA, tufA) were obtained for recently collected samples from two Azorean islands. DNA barcode-assisted identification was conducted on newly generated and unpublished sequences from public repositories. A literature review of recently published studies, including the molecular identifications of Azorean macroalgae, was also performed. The results confirm the occurrence of 51 species (including subspecific ranks) and provide four new records, namely, three cryptogenic species (Olokunia boudouresquei, Padina gymnospora, and Ulva lacinulata) and one introduced species (Ulva australis). This study contributes 23 DNA barcodes generated for the first time to the Azores, which now has 10.5% of its marine flora represented in public repositories. Additionally, UPA sequences were generated for the first time for the five taxa.

Non‐native species (NNS) might become invasive and threaten biodiversity, economy and public health. Therefore, it is essential that their invasiveness risk be quantified to support conservation measures. The Azores, located in the mid‐northern Atlantic, is the crossroad of macroalgal native distributions and also present almost three times the global ratio of macroalgae reported as NNS. Aquatic Species Invasiveness Screening Kit, a decision‐support tool consisting of 49 questions for the Basic Risk Assessment (BRA) and six for the Climate Change Assessment (CCA), was applied to the 42 marine macroalgae classified as NNS in the Azores. The results indicate that 21 species pose a medium risk of becoming invasive, and 15 present a high risk under current climate conditions (BRA scores only). The combined BRA + CCA scores show that Laurencia dendroidea poses a high risk instead of a medium risk. Thirty‐three Rhodophyta species were screened, with 10 (BRA) and 11 (BRA + CCA) classified as high risk. All four Chlorophyta species ranked as high risk. Only one of the five Ochrophyta species was classified as high risk, namely Rugulopteryx okamurae, one of the most invasive species in European waters. High‐risk species are present in all islands, likely spread by the continuous maritime traffic between islands. Six of the high‐risk species are restricted to single islands (BRA and BRA + CCA scores), and efforts should be made to contain their further expansion. Asparagopsis armata, a species introduced in Europe in the 1920s, is the only high‐risk species present in all islands. Conservation measures for prevention, monitoring and control of NNS are proposed for the different islands of the Azores, including regulation of introduction pathways, prospection of areas with high risk of invasion, risk screening, eradication and containment of NNS. The involvement of stakeholders and maritime workers is also recommended.

Non-native species (NNS) represent a threat to biodiversity, and their occurrence and distribution should be periodically updated and made easily available to researchers and policymakers. An updated inventory of macroalgal NNS currently present in the Azores was produced based on published reports. Data concerning the first report and the distribution in the archipelago are provided for each species, as well as their respective native ranges and possible vectors of introduction. The resulting list comprises 42 taxa, i.e., 8.05% of the marine flora presently reported in the Azores, with 16 new NNS recorded over the last decade. The most isolated islands of the Western Group presented lower numbers of NNS (4.25% and 6.25%). In contrast, the two islands with the most used marina for transatlantic recreational sailing presented higher numbers (12.90% and 16.87%). Shipping is the main introduction vector (68%), whereas most macroalgal NNS are originally from the Pacific Ocean (31%) and the Indo-Pacific (31%). The presence of 13 species is restricted to single islands, and no species is reported exclusively in the Western group. Asparagopsis armata is the only algal NNS reported from all islands of the Azores. Future work is proposed to support policymaking.

The gelatinous, calciferous red alga Renouxia antillana was described in 1995 based on material from Guadeloupe, French West Indies, and accommodated in a new family and order (Rhodogorgonaceae, Rhodogorgonales) along with the genus Rhodogorgon from Belize and Caribbean Panama. For more than 20 years, Renouxia has remained monotypic, with rare reports in the Caribbean and the Indo-Pacific (from Réunion Island to French Polynesia). DNA-based analyses of recently collected Renouxia specimens from Egypt showed that they are not conspecific with the Caribbean R. antillana and are described as R. marerubra sp. nov. Uncorrected p-distances between the Red Sea specimens and the generitype were 8.0% for COI, 6.5-7.3% for rbcL and 3.1% for UPA. Morphological and anatomical features are also presented for the newly described species and compared to its congener, with the first documented report of monoecism in the Rhodogorgonales. Besides the new record of Renouxia from the Red Sea, the geographic distribution of the genus is here extended with additional records from Sri Lanka, Indonesia, as well as the islands of Guam and Kosrae in the Western Pacific. The UPA phylogeny suggests that these new distribution records may also represent undescribed species, with representatives in two distinct genetic groups.

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.

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.