Laurencia longiramea sp. nov. for Brazil and an emendation of the generic delineation of Corynecladia (Ceramiales, Rhodophyta)

Abstract

ABSTRACTStudies of the Laurencia complex based on phylogenetic and DNA barcoding analyses revealed a new species, Laurencia longiramea Cassano, G.N. Santos, J.M.C. Nunes, M.C. Oliveira & M.T. Fujii sp. nov., on the Brazilian coast. The rbcL phylogenetic analysis resolved L. longiramea as sister to Laurencia species from the North Atlantic (L. pyramidalis, L. viridis and L. obtusa) and the Caribbean Sea and Gulf of Mexico (L. intricata), with a divergence of 2.4%–3.7%. Using the DNA barcode COI-5P, L. longiramea was closest to L. pacifica from the United States, with a divergence of 4.2%. The new species has the typical features of the genus Laurencia and is characterised by: sparse branching, axes smaller than 1 mm diameter, often long branchlets, lenticular thickenings always present and abundant, and absence of cortical cells projected near branch apices. Morphologically, L. longiramea is similar to Laurencia filiformis. However, an rbcL sequence of L. filiformis from the type locality (Western Australia) confirmed that they are distinct species, with 4.3% divergence. Examination of Laurencia clavata from Brazil, deposited in the University of São Paulo (SPF) herbarium, were misidentified and corresponded to the new species, L. longiramea. In addition, the rbcL and COI-5P sequences of L. clavata from the type locality (Australia) did not join with L. longiramea. Laurencia clavata formed a well-supported clade with the two species of Coronaphycus. Priority supported the recognition of Corynecladia over Coronaphycus, requiring the new combinations Corynecladia elata (C.Agardh) comb. nov. and Corynecladia nova (Metti) comb. nov. Based on our results, Corynecladia clavata does not occur in the Brazilian marine flora.