Ceramium deslongchampsii Chauvin ex Duby (A)

This rather distinctive species typically forms turfs underneath intertidal fucoids in the lower to mid intertidal (Image A), although some specimens form more distinct individuals in mid to low intertidal pools. Erect axes are 2-10 cm tall on exposed rock and inverts; reaching 12 cm for individuals growing at the fringe of the tidepools. Branching is typically subdichotomous with the primary branches produced every 5-15 segments, although adventitious branches are common in most individuals lending an irregular branching pattern overall (Image B). This species has prostrate axes (Image C), which are attached by generous production of multicellular, branched rhizoids (Image D), and also bear erect axes (Image C). The tips of the erect axes are relatively straight or slightly incurved, but not strongly inrolled as in some other species of this genus, and viewing them under the microscope reveals the domed apical cells of this uniaxial species (Image E). Erect axes, even near the tips, can form adventitious attachment rhizoids (Image F). This species is not fully corticated with a clear alternation of corticated nodes and ecorticate internodes (Image G). Near the tips axes are 84-102 µm wide and the segments 0.8-1 diameters long with the internodes < in length to the nodes (Images G, H). Mid thallus the segments are 190-220 µm wide and ~2 diameters long and the internodes are ~1.5 X longer than the nodes (Image I). Lower thallus the segments are 245-280 µm wide and ~2-2.5 diameters long with the internodes ~2.5 X longer than the nodes (Image J) and the relatively ordered pattern of the nodal cortication is clearly visible (Image K). Gland cells absent. In section there are 4-5 periaxial cells at each node (Image L). None of our collections are cystocarpic or spermatangial. Tetrasporangial production is concentrated at the nodes with the sporangia initially covered by cortication (Image M). They are later emergent, irregularly cruciate to tetrahedral in division, and 60-68 µm wide by 75-80 µm tall, and surrounded by thick laminated walls (Image N).

Typically growing on rock in the mid to low intertidal, we have genetically verified collections from ME, NB and NS. More specimens are needed to better understand the full range of this species in our flora. Although highly distinctive, Plumaria plumosa (Hudson) Kuntze similarly forms turfs under fucoids in the same zone as Ceramium deslongchampsii. Careful observation in the field easily distinguishes between the two; Ceramium deslongchampsii has a banded pattern, which results from the uncorticated internodes alternating with corticated nodes. Plumaria plumosa (Hudson) Kuntze has a distinct feathery habit.

OLYMPUS DIGITAL CAMERAImage A. Turf of this species on low mid intertidal rock under fucoids at Lepreau , Bay of Fundy, NB (EGWS000390).

Image B. Subdichotomous primary branching and adventitious (arrow) branches (low intertidal turf on rock, Lepreau exposed biodiversity site, Bay of Fundy, NB; GWS010927; rehydrated from press).

Image C. Prostrate axis with descending multicellular branched rhizoids (arrow), as well as two erect filaments (low intertidal on rock, Letete exposed biodiversity site, Bay of Fundy, NB; GWS010960; rehydrated from press).

Image D. Close up of anchoring rhizoids from a prostrate axis (low intertidal on rock, Bay Shore Beach, Saint John Harbour, NB: EGWS000919).

EGWS000390002 copy.jpgImage E. Close-up of tips, relatively straight to slightly incurved with domed apical cells (EGWS000390).

FGWS032301_Field_0015Image F. Rhizoids formed from the nodes near the tips of the branches (drift, Maces Bay, Lepreau, Bay of Fundy, NB; GWS032301; rehydrated from press).

EGWS000390001 copy.jpgImage G. Uncorticated internodes between the light bands of cortication near the branch tip in fresh material (EGWS000390).

H_GWS003537_Field_0010Image H. Uncorticated internodes between the light bands of cortication near the branch tips (mid intertidal on rock wall, Blacks Harbour, NB; GWS003537; rehydrated from press).

I_GWS010960_Field_0004Image I. Axis mid thallus (GWS010960; rehydrated from press).

J_GWS010960_Field_0005Image J. Axis lower thallus (GWS010960; rehydrated from press).

K_GWS010960_Field_0006Image K. Close up of nodal cortication on a mature region of an axis (GWS010960; rehydrated from press).

L_GWS000686_Field_0001Image L. Cross section revealing 4(5?) periaxial cells around the central axial cell (mid intertidal pool on rock, North end of beach between Deep Cove and Seal Cove, Grand Manan, NB; GWS000686; rehydrated from press).

M-GWS032301_Field_0014Image M. Tetrasporangia are formed in whorls at the nodes (GWS032301; rehydrated from press).

N_GWS032301_Field_0016Image N. Tetrasporangia have an irregularly cruciate to tetrahedral division pattern and are emergent from the cortical layer when mature (GWS032301; rehydrated from press).