Coralline algae (Corallinophycideae) are calcifying red algae that are foundation species in euphotic marine habitats globally. In recent years, corallines have received increasing attention due to their vulnerability to global climate change, in particular ocean acidification and warming, and because of the range of ecological functions that coralline algae provide, including provisioning habitat, influencing settlement of invertebrate and other algal species, and stabilising reef structures. Many of the ecological roles corallines perform, as well as their responses to stressors, have been demonstrated to be species-specific. In order to understand the roles and responses of coralline algae, it is essential to be able to reliably distinguish individual species, which are frequently morphologically cryptic. The aim of this study was to document the diversity and distribution of coralline algae in the New Zealand region using DNA based phylogenetic methods, and examine this diversity in a broader global context, discussing the implications and direction for future coralline algal research. Using three independent species delimitation methods, a total of 122 species of coralline algae were identified across the New Zealand region with high diversity found both regionally and also when sampling at small local spatial scales. While high diversity identified using molecular methods mirrors recent global discoveries, what distinguishes the results reported here is the large number of taxa (115) that do not resolve with type material from any genus and/or species. The ability to consistently and accurately distinguish species, and the application of authoritative names, are essential to ensure reproducible science in all areas of research into ecologically important yet vulnerable coralline algae taxa.

Coralline algae perform important ecological roles in nearshore marine ecosystems globally by promoting the settlement of invertebrate larvae and enhancing biodiversity by creating habitat. However, these roles are severely threatened by global environmental changes. Most coralline algae are extremely difficult to identify, and DNA sequencing has revealed rampant inaccuracy of morpho-anatomical approaches to distinguish species, and even genera. If appropriate identification methods are not reported, or even used, we will be left with an uninterpretable body of literature where the species-specific biology of coralline algae cannot be validated. This will make it difficult to determine the impact a changing ocean may have on these ecologically important species. We reveal the magnitude of the issue in coralline algal research—both the identification methods used and the reporting of identification protocols. An analysis of 341 articles over the past decade revealed that only 7.6% used molecular methods, with over 70% not reporting any details of how species were identified. While many coralline algal taxonomists understand that the majority of species cannot be identified morphologically, this message has not disseminated to the ecological and physiological community. We provide a series of guidelines for conducting DNA-based identifications and strongly recommend the use of these methods over less informative morpho-anatomical techniques. Most importantly, the methods of identification should be adequately reported. Without following these guidelines, research on coralline algae runs the risk of collecting uninterpretable data, and conducting irreproducible science, slowing our ability to determine how these important species will respond to future ocean conditions.

Rhodolith beds provide heterogeneous and complex threedimensional habitats, providing ecosystem services disproportionate to their size (Lundquist et al., 2017), and meeting the definition of foundation species provided by Dayton (1972). Rhodoliths, or maerl, are calcified red algae that are free-living (Foster, 2001;Riosmena-Rodríguez et al., 2017) and are found globally from high to low latitudes (McCoy & Kamenos, 2015). Their morphological complexity and the interstitial spaces they provide serve as a refuge from predation for small invertebrates, as well as important settlement and nursery substrates for epiphytes, epifauna, and

No abstract

A new genus in the order Sporolithales (Corallinophycidae, Rhodophyta), Roseapetra farriae gen. et sp. nov. is described, based on material from northern New Zealand. Previously placed in the genus Heydrichia on the basis of morpho-anatomical characters, phylogenetic analyses have shown that this northern New Zealand taxon is not resolved with either Heydrichia or Sporolithon, the two genera currently recognized in this order. Roseapetra displays the key diagnostic features of the order, namely the production of cruciately divided tetrasporangia singly within calcified sporangial compartments. In Roseapetra the tetrasporangia are surrounded by an involucre, and mature tetrasporangia are subtended by up to three stalk cells. The tetrasporangial compartments are shed once spores have been released. Gametangial conceptacles are not shed but become buried, with secondary meristem producing lens-like areas of regrowth. While there are several morpho-anatomical characters that separate Roseapetra and Sporolithon, there are none that can be used to distinguish Roseapetra from Heydrichia: recognition of Roseapetra requires sequence data. Roseapetra farriae is found growing in the low intertidal zone on rocky reefs in shaded, understorey habitats.

Investigations of the strong environmental gradients within intertidal and subtidal rocky reefs have contributed significantly to our understanding of ecological processes, but studies exploring how algal community structure responds to the extreme environmental transition of the intertidal-subtidal interface are rare. Our objective was to examine patterns in macroalgal distribution and species richness with depth on temperate rocky reefs. Standing algal biomass and richness were measured on 6 representative reefs in southern New Zealand, across 5 depth strata from the high intertidal zone, 1.5 m above mean low water (MLW), to the subtidal zone, 10 m below MLW. We found a unimodal relationship between algal richness and biomass across the depths, where maximum species richness occurred at intermediate levels of biomass. These results are consistent with many terrestrial plant studies across strong environmental gradients. Biomass decreased down the shoreline, with the exception of the high intertidal where the lowest biomass was recorded, whilst species richness increased down the shoreline. Additionally, strong patterns of dominance were observed, with a single species (not always the same species) contributing >56% of the total biomass across all depth strata examined. This dominance could have important implications for ecosystem provisioning across this system, particularly if dominant species are found to be vulnerable to the impacts of local and/or global change. The strong environmental gradients that characterise the intertidal-subtidal transition on rocky reefs over relatively small and experimentally tractable spatial scales enable opportunities to further advance our understanding of the mechanisms controlling the distribution of biodiversity.

A new epiphytic species, Jania sphaeroramosa sp. nov., is described from rocky reef intertidal zones around the coast of New Zealand and associated islands. This species forms round tufts on a range of hosts. Thalli display a unique three-dimensional growth form, built up with multiple layers of dichotomous fronds. The thalli are dichotomously branched with intergenicula that are 190–330 µm long and 80–140 µm wide. Previously identified as Jania micrarthrodia in New Zealand, phylogenetic analyses of this epiphytic species, using psbA and nSSU genes, resolved New Zealand specimens separately from Australian specimens of Jania micrathrodia. This epiphyte does not conform to the description of any previously described species of Jania from New Zealand.

No abstract