Cystoclonium purpureum (Hudson) Batters (A)

Plants range from 10-40 cm in height, are brownish red in colour, but can become yellow/greenish toward the tips, and are distinct in our flora for the robust basal attachment stolons (Image A). In some individuals the vegetative tips can become elongate tendrils (Image B) that can spiral and tangle branches together amongst themselves (Image C) and other algae, but they do not develop as thickened distinct hooks as in some other species (e.g. Bonnemaisonia hamifera Hariot). In whole mount the tips display the characteristic single apical cell of this uniaxial species (Image D and some individuals produce surface hairs (Image E). Terete in transverse section, the medulla is loosely composed of predominantly longitudinal filaments, lacking an obvious central filament, transitioning to a compact cortex of cells that reduce in size toward the pigmented thallus surface (Image F).

This species is widely distributed in our flora with genetically confirmed records from CN to the island of NL. This species grows attached to rock or other hard substrata, as well as on fleshy brown and red algae, from the lower mid intertidal to subtidal (18 m). Although not closely related, this species can be confused with Dumontia contorta (Gmelin) RuprechtDevaleraea ramentacea (Linnaeus) Guiry and Gracilaria tikvahiae McLachlan to the inexperienced collector, but differs from these three species by the production of basal stolons (Image B) and its filamentous medulla (Image F). It also bears a superficial resemblance to the more closely related Agardhiella subulata (C. Agardh) Kraft & M.J.Wynne, but that species lacks a distinct apical cell at the branch tips, has a more interwoven filamentous medulla (in Cystoclonium purpureum the filaments are largely longitudinal), and lacks basal stolons. Individuals with twisted and coiled branch apices are referred to Cystoclonium purpureum var. cirrhosum Harvey, but this variation does not appear to correlate with genetic differentiation (Image B).

EGWS000389a copy.jpgImage A. Typical irregularly branched individuals of this species with the robust basal stolons clearly evident (arrows) (low intertidal on rock, Lepreau, NB; EGWS000389).

GWS007683.jpgImage B. An individual in which some branches terminate in elongated tendrils (low intertidal on rock, ST. Brides, NL; GWS007683).

 

Image C. Tips can become spiralled and tangle the branches together (subtidal (3 m) on Phyllophora pseudoceranoides (S.G.Gmelin) Newroth & A.R.A.Taylor ex P.S.Dixon & L.M.Irvine, east of Cape Spencer, NB; GWS042866).

GWS003613-0002.jpg

Image C. Closeup of the distinct apical cell (ignore the diatoms) terminating the axis (subtidal (4 m), Cape Neddick, ME; GWS003613).

GWS003613-0001.jpgImage D. Low power amplification of a vegetative axis covered with distinctive hairs (GWS003613).

G1001(20X)001.jpgImage E. Transverse section displaying the sparsely filamentous medulla (low intertidal on rock; Lepreau, NB; G1001).