DOI: 10.15468/7pmtws
title: Checklist of the benthic marine algae of the Azores archipelago

description: Background The macroalgal flora of the Azores archipelago has attracted the interest of many researchers in the past, the first publications going back to the nineteenth century. Initial studies were mainly taxonomic, resulting in the publication of species lists, which were compiled by Neto (1994) in the first checklist of the Azorean benthic marine algae. Later, research directed at the benthic marine macroalgae and littoral communities, encompassing presence and occurrence data recorded at littoral and sublittoral levels down to a depth of approximately 40 m around the islands, has resulted in floristic, taxonomic and ecological publications, academic thesis, and technical reports (see revision in Neto et al. 2014 and Haroun et al. 2019). Most of this recent research also resulted in voucher specimens deposited in the AZB Herbarium Ruy Telles Palhinha and the LSM - Molecular Systematics Laboratory, both at the Faculty of Sciences and Technology of the University of the Azores. New information A total of 498 taxa (including species, subspecies, varieties and forms) are recorded, comprising 331 Rhodophyta, 75 Chlorophyta 92 Ochrophyta (Phaeophyceae). Of the 417 likely native taxa, 8 are Azorean endemics (5 Rhodophyta, Lithophyllum azorum Me.Lemoine, Lithophyllum bipartitum Me.Lemoine, Polysiphonia azorica O.C.Schmidt, Polysiphonia hochstetteriana O.C.Schmidt and Predaea feldmannii subsp. azorica Gabriel, and 3 Chlorophyta, Cladophora michalensis O.C.Schmidt, Cladophora theotonii O.C.Schmidt and Cladophora weizenbaurii O.C.Schmidt) and6 are Macaronesian endemics (5 Rhodophyta, Botryocladia macaronesica Afonso-Carrillo, Sobrino, Tittley & Neto, Laurencia viridis Gil-Rodríguez & Haroun, Meristotheca decumbens Grunow, Millerella tinerfensis (Seoane-Camba) S.M.Boo & J.M.Rico, Phyllophora gelidioides P.Crouan & H.Crouan ex Karsakoff and the Chlorophyta Codium elisabethiae O.C.Schmidt). In addition, about 39 taxa have been introduced (30 Rhodophyta, 3 Chlorophyta and 6 Ochrophyta) and 42 have an uncertain status for the region (27 Rhodophyta, 8 Chlorophyta and 7 Ochrophyta). Introduction The marine benthic macroalgae of the Azores soon attracted the interest of researchers and naturalists. Research on the subject started in the mid nineteenth century (1838) when Guthnick and the two Hochstetters, father and son, visited the archipelago (Neto 1994). These initial taxonomic studies were followed by several other visitors, including the German botanist Otto Christian Schmidt, who was responsible for the first comprehensive ecological approach to the Azorean algal flora, describing species associations and their spatial organization (Schmidt, 1931). More recently research expanded to include studies on species biology, ecology, and the structure and functioning of intertidal and shallow subtidal communities. The first checklist of the Azorean benthic marine algae (Neto, 1994) brought together the resulting floristic information, providing distributional records within the archipelago for the 307 reported species. This checklist was revised by Parente (2010), increasing the number of algae species to 327, but without providing distributional information. A year later Rosas-Alquicira et al. (2011a) published a catalog of non-fossil geniculate coralline red algae (Corallinales, Rhodophyta) of the Macaronesia in which they made a critical review of species and infraspecific taxa and an assessment of the species diversity in the region. Investigations on algae biodiversity, biogeography, conservation, ecology, taxonomy and biotechnological applications have continued generating knowledge on the Azorean macroalgae flora, its biotechnological potential and the structure and functioning of littoral communities (see revisions by Neto et al. 2014 and Haroun et al. 2019). The paper by Freitas et al. (2019) compiled the published floristic data, increased the number of macroalgae species recorded for the Azores to 405 and reported that, amongst the mid-Atlantic archipelagos, the Azores is second in species richness after the Canary Islands, with 689 species, and followed by Madeira (396), Cabo Verde (333) and Selvagens (295 species). In the last few years, a major effort, mainly by local research teams, has resulted in several publications on the Azorean benthic macroalgae (see, for example, Patarra et al. 2017, 2019, 2020, Bruno de Sousa et al. 2019, Cacabelos et al. 2019, 2020, Freitas et al. 2019, Kellaris et al. 2019, Martins et al. 2019a, Parente et al. 2019, 2020, Faria et al. 2020a, b, Neto et al. 2020a, b, c, d, e, f, g, 2021a, b, Vieira et al. 2020). Purpose: The present paper aims to give an updated, systematic review of the red, green and brown benthic marine macroalgae of the Azores, bringing together all the published information to date (including the currently accepted taxon names and all the previous bibliographic records for the region) and compiling general information on each species’ occurrence and distribution in the archipelago. By doing this, it contributes to address several biodiversity shortfalls (see Cardoso et al. 2011, Hortal et al. 2015), namely the need to catalogue the Azorean macroalgae (Linnean shortfall) and to improve current information on their local and regional geographic distribution (Wallacean shortfall). This paper also aims to provide a valuable marine biological tool to aid research on the systematics, diversity and conservation, climate change, which will be of assistance to a wide range of focal groups including academics, students, governments, private organizations and the general public.