Ceramium phillipsiae Huisman

Scientific Description

Habit and structure. Thallus completely erect, to 1.5 mm tall, pale red, solitary, attached by a prominent ecorticate basal cell and initially a single unicellular rhizoid that penetrates the cortex of the host, later with 1 or 2 additional rhizoids arising from lower corticating cells. Axes 25–100 μm wide, unbranched or sparingly sympodially branched, tapering proximally and distally. Apices straight; periaxial cells 4 or 5, similar to corticating cells, each producing acropetally one or two 2-celled branches and one or two basipetal or lateral 1-celled branches, the latter occasionally becoming pseudoperiaxial. Terminal cells of acropetal filaments often with a short hair. Nodal bands mostly merging, not forming distinct rows, more loosely arranged in tetrasporophytes than in gametophytes.

Reproduction. Spermatangia in tufts on nodal cells in distal parts of the thallus. Cystocarps lateral, naked, with 1 or 2 spherical gonimolobes 60–100 μm diam., composed entirely of angular carposporangia 16–20 μm diam. Tetrasporangia arising from periaxial cells, initially immersed in nodal cells, later slightly extruded, spherical, 25–35 μm diam., cruciately or decussately divided.

Distribution. Known only from the Rowley Shoals and Scott Reef, north-western Australia.

Habitat. Epiphytic on a variety of red algae.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 401 (2018)]