Phylogenetic analysis of rhodolith formation in the Corallinales (Rhodophyta)

Abstract

Although the ecological importance of rhodolith (maerl, free-living coralline algae) beds is well-known, rhodolith-forming species have been neglected in molecular phylogenetic studies. This is the first molecular systematic study aimed at understanding whether the rhodolith habit is a fixed feature in lineages and determining the relationship (phylogenetic vs. environmental) between rhodolith and crustose habits. Phylogenetic relationships of rhodolith-forming species and encrusting coralline algae at generic and species levels were analysed using SSU rDNA and psbA sequences. Extensive sampling in the European North Atlantic, Pacific and Caribbean Mexico of Phymatolithon, Lithothamnion, Lithophyllum and Neogoniolithon taxa forming rhodoliths and crusts was accompanied by examination of type or topotype material. Phylogenetic reconstruction showed that Neogoniolithon contained a monophyletic group of rhodolith-forming species whereas other rhodolith-formers were closely related to encrusting forms in the genera Phymatolithon, Lithothamnion, Mesophyllum, Hydrolithon, Spongites and Sporolithon. DNA analysis showed that the crust-forming Lithophyllum cf. incrustans/dentatum also forms rhodoliths with a stone nucleus that occur on rocky shores. In contrast, species that form beds of non-nucleate rhodoliths (e.g. Neogoniolithon spectabile, N. strictum, Lithophyllum cf. incrustans/dentatum or sp. 1 and Phymatolithon calcareum) rarely form crusts. The rhodolith habit cannot be used to delimit species for taxonomic or identification purposes. Extensive taxonomic revision will be required to deal with problems such as the position of specimens identified as Lithophyllum margaritae in two unrelated lineages.

Molecular and Morphological Diversity of Lithothamnion spp. (Hapalidiales, Rhodophyta) from Deepwater Rhodolith Beds in the Northwestern Gulf of Mexico

“…Results of the psbA analysis (Fig. 1) are similar to the results of the psbA analysis presented by Hernández-Kantún et al (2015, fig. 2) with regards to the relationship between Lithothamnion spp., Phymatolithon calcareum (Pallas) W.H.Adey & McKibbin, and Hapalidiaceae sp.…”

“…I and J and specimen GAL15736 is intriguing considering Hernández-Kantún et al (2015) showed that GAL15736 possessed "flared" epithallial cells. This lineage received strong support in the single-gene analyses of psbA (PP=1, BS=100%) and COI (PP=1, BS=90%) and in the multi-gene phylogeny (BS=100%).…”

Mediterranean Lithophyllum stictiforme (Corallinales, Rhodophyta) is a genetically diverse species complex: implications for species circumscription, biogeography and conservation of coralligenous habitats

“…Therefore, psb A and rbc L sequences of these species (Hernandez‐Kantun et al. ) and cox 2,3 sequences of Lithophyllum sp. (Hernandez‐Kantun et al.…”

“…, , Hernandez‐Kantun et al. ,b; Atlantic Iberian Peninsula, Pardo et al. ; Warm Temperate to Tropical Western Atlantic Ocean, Mateo‐Cid et al.…”

Sequencing type material resolves the identity and distribution of the generitype Lithophyllum incrustans, and related European species L. hibernicum and L. bathyporum (Corallinales, Rhodophyta)

“…, Hernandez‐Kantun et al. ). Herein, we sequenced type material to begin resolving the genus Lithophyllum Phillipi, based on its generitype, L. incrustans Philippi (type locality: Sicily) and related species in Europe.…”