Spyridia hypnoides (Bory) Papenf.

Scientific Description

Habit and structure. Thallus to 10 mm tall. Growth from a prominent apical cell, producing a series of short cells before initiation of lateral branches and nodal cortication. Determinate or indeterminate lateral branches arising singly from each axial cell in a spiral pattern. Determinate laterals 14–16 cells long, ending in a 2- or 3-celled, persistent monosiphonous spine 25–30 μm long; all cells of determinate lateral branches with nodal cortication except the basal cell and spine cells. Axial cells of determinate lateral branches with L:B <2, tapering evenly from base to apex; basal cells 55–60 μm diam. Nodal cortication of determinate laterals with a ring of c. 15 or 16 periaxial cells, each producing 1–3 cells acropetally, these in turn producing 1 or 2 cells; basipetal development lacking. Primary axes completely corticated with alternating bands of large and small cells, then with secondary cortication by rhizoidal filaments.

Reproduction. Reproductive structures not seen.

Distribution. S. hypnoides has been reported from a broad geographical range, including many localities in the Indian and Pacific Oceans.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 592–593 (2018)]