Vertebrata tripinnata (Harvey) Kuntze

MOLECULAR IDENTIFICATION

Two new sequences were obtained for specimens from Donegal (Ireland) which were identical to a sequence from Portugal. They diverged by only 0.2-0.8% (1-5 bp) from sequences from northwestern Spain and the Mediterranean. In the rbc L phylogeny Vertebrata tripinnata was placed as sister to V. subulifera with moderate support. Sequence divergence between the two species was 3.8% (Fig. 2).

MORPHOLOGICAL OBSERVATIONS

Thalli forming dense tufts up to 3 cm high, dark red to brown in colour, covering rocky surfaces to ca. 20 cm 2 in extent. Thalli radially organized with indeterminate erect axes becoming decumbent when developing rhizoids in their basal parts (Fig. 5A), forming an extensive system of prostrate interwoven axes and bearing unicellular rhizoids cut off from pericentral cells (Fig. 5B, C). Axes ecorticate with 17-19 pericentral cells (Fig. 5D). Erect axes rigid in texture, alternately branched up to three orders and mostly every six segments. Erect axes 150- 400 (-500) µm in diameter, with segments 0.4-0.8 (-1.75) L/D. Trichoblasts abundantly formed on every segment at the apices of erect axes and branches, dichotomously branched up to five orders (Fig. 5E), with multinucleate cells (Fig. 5F). Trichoblasts deciduous and leaving conspicuous scar cells when shed (Fig. 5G). Reproductive structures not observed.