Molecular assessment of the tribes Streblocladieae and Polysiphonieae (Rhodomelaceae, Rhodophyta) in the British Isles reveals new records and species that require taxonomic revision Author Piñeiro-Corbeira, Cristina Coastal Biology Research Group, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of A Coruña, 15071, A Coruña (Spain) Author Maggs, Christine A. Queen’s University Belfast, Marine Laboratory, Portaferry, Newtownards BT 22 1 PF (United Kingdom) Author Rindi, Fabio Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy) Author Bunker, Francis MarineSeen, Estuary Cottage, Bentlass, Hundleton, Pembrokeshire, Wales SA 71 5 RN (United Kingdom) Author Baldock, Lin Dorset Wildlife Trust, Brooklands Farm, Forston, Dorchester DT 2 7 AA (United Kingdom) Author Díaz-Tapia, Pilar Coastal Biology Research Group, Faculty of Sciences and Centre for Advanced Scientific Research (CICA), University of A Coruña, 15071, A Coruña (Spain) and Instituto Español de Oceanografía (IEO), Centro Oceanográfico de A Coruña, Aptdo. 130, 15080, A Coruña (Spain) pdiaz @ udc. es (corresponding author) pdiaz@udc.es text Cryptogamie, Bryologie 2020 2020-06-05 20 8 55 72 journal article 10.5252/cryptogamiealgologie2020v41a8 380efeb5-6e5b-4c5d-9edf-fb35647c83c6 1776-0992 7827761 Vertebrata fruticulosa (Wulfen) Kuntze MOLECULAR IDENTIFICATION In total 18 rbc L sequences, 16 newly determined, are available for specimens morphologically identified as Vertebrata fruticulosa from the United Kingdom , the Atlantic Iberian Peninsula and the Mediterranean. They were resolved in the rbc L phylogeny ( Fig. 2 ) in a fully supported clade that also included sequences of V.thuyoides (Harvey) Kuntze , V. tripinnata (Harvey) Kuntze , V. subulifera (C.Agardh) Kuntze and V. furcellata (C.Agardh) Kuntze.Within this clade, specimens assigned to V. fruticulosa formed two clades that diverged by 3-3.3% (21-24 bp) and that are labelled in Figure 2 as V. fruticulosa and V. martensiana . Two haplotypes of V. fruticulosa were 0.6% (4 bp) divergent. Specimens of the V. fruticulosa clade were only found in the Mediterranean, including the Adriatic Sea, its type locality. Vertebrata martensiana has a wider distribution including the Adriatic Sea, the Atlantic Iberian Peninsula and the United Kingdom . Two haplotypes were found in the Atlantic and a third one in the Mediterranean and they diverged by 0.3-0.4% (4-6 bp). MORPHOLOGICAL OBSERVATIONS Specimens that were initially identified as Vertebrata fruticulosa ( Fig. 4 ) were predominantly erect, attached to the substratum by short prostrate axes that bear rhizoids cut off from the pericentral cells. Thalli were composed of several main axes that bear branches pseudodichotomously at wide angles (>30°) ( Fig. 4A, E, I ). They were 250-900 in diameter in mid-parts of the thallus. Trichoblasts were absent or scarcely developed. Axes had 8-12 pericentral cells and were corticate ( Fig. 4D, H, L ). Specimens of the V. fruticulosa and V. martensiana clades can be distinguished by the morphological characters indicated below. Specimens placed in the V. fruticulosa clade had main axes of indeterminate growth that were alternately branched at regular intervals and bore alternate branches of determinate growth ( Fig. 4A, B ). Determinate branches, in turn, bore 2-3 orders of branches mostly every 3 segments ( Fig. 4C ) and were 7-9 mm in length. Axes had 11-12 pericentral cells ( Fig. 4D ). The specimens in the V. martensiana clade had main axes branched at irregular intervals and bore branches of determinate growth ( Fig. 4E, F, I, J ). Mediterranean specimens had simple or once-branched determinate branches that were 1.5 mm in length ( Fig. 4G ). Axes had 8-10 pericentral cells ( Fig. 4H ). Atlantic specimens had determinate branches 3-5 mm in length that were simple or bore up to 2 branching orders ( Fig. 4K ) and axes with 8-12 pericentral cells ( Fig. 4L ).