The existence of massive cryptic diversity in algae makes linking DNA‐based lineages to existing taxa exceedingly difficult. A better integration of historical collections into modern taxonomic research is therefore highly desirable. Using the brown algal genus Lobophora as a test case, we explore the feasibility of linking taxonomic names to clades in modern phylogenies. Despite Lobophora being a pantropical genus with probably more than 100 species, traditionally only a handful of species have been recognized. In this study we reevaluated the identity of 17 historical taxa thought to belong to Lobophora by attempting DNA amplification of herbarium material as well as specimens recently collected from the type localities (epitypes). In an attempt to assign them to Molecular Operational Taxonomic Units, the obtained sequences were integrated in a global Lobophora phylogeny based upon data derived from more than 650 specimens. Our results indicate that although five sequences were obtained from type specimens, exclusive reliance on information preserved in type specimens is problematic. Epitype material proved a more successful way forward, but this route often comes with a considerable degree of uncertainty, especially in tropical regions where the extent of sympatry among Lobophora lineages is often considerable. More problematic from a broader perspective is the fact that for 35% of historical taxa, either the type could not be traced or permission was not granted to extract DNA from the types. Such a low accessibility rate may reduce our reliance on type material and jeopardize future efforts to integrate historical taxa into a framework of a modern DNA‐based taxonomy.

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Coexistence in a homogeneous environment requires species to specialize in distinct niches. Sympatry of cryptic species is of special interest to both ecologists and evolutionary biologists because the mechanisms that facilitate their persistent coexistence are obscure. In this study, we report on two sympatric Dictyota species, D. dichotoma (Huds.) J. V. Lamour. and the newly described species D. cymatophila sp. nov., from the Canary Islands. Gene sequence data (rbcL, psbA, nad1, cox1, cox3, and LSU rDNA) demonstrate that D. dichotoma and D. cymatophila do not represent sister species. Rather, D. cymatophila and D. dichotoma have converged on a nearly identical morphology, only to be distinguished with detailed morphometric observations. Both species co-occur in eulittoral pools and the shallow subtidal in Tenerife. Even though D. cymatophila was more dominant in wave-exposed places and D. dichotoma in less exposed areas, the spatial distribution of both species overlapped in intermediate habitats. The species display radically different phenologies. D. dichotoma reached its highest density in winter and early spring and disappeared nearly completely in autumn, while D. cymatophila dominated the study site from July until November. The timing of gamete release also differs between both species, D. dichotoma releasing gametes twice every lunar cycle, while the release of gametes in D. cymatophila occurred roughly every other day.

‘Onium’ compounds, including ammonium and phosphonium salts, have been employed as antiseptics and disinfectants. These cationic biocides have been incorporated into multiple materials, principally to avoid bacterial attachment. In this work, we selected 20 alkyl-triphenylphosphonium salts, differing mainly in the length and functionalization of their alkyl chains, in fulfilment of two main objectives: 1) to provide a comprehensive evaluation of the antifouling profile of these molecules with relevant marine fouling organisms; and 2) to shed new light on their potential applications, beyond their classic use as broad-spectrum biocides. In this regard, we demonstrate for the first time that these compounds are also able to act as non-toxic quorum sensing disruptors in two different bacterial models (Chromobacterium violaceum and Vibrio harveyi) as well as repellents in the mussel Mytilus galloprovincialis. In addition, their inhibitory activity on a fouling-relevant enzymatic model (tyrosinase) is characterized. An analysis of the structure-activity relationships of these compounds for antifouling purposes is provided, which may result useful in the design of targeted antifouling solutions with these molecules. Altogether, the findings reported herein provide a different perspective on the biological activities of phosphonium compounds that is particularly focused on, but, as the reader will realize, is not limited to their use as antifouling agents.