The life history of Liagora harveyana (Nemaliales, Rhodophyta) from South-eastern Australia

Spores collected at Port Phillip Bay, Victoria, Australia from plants of the red alga Liagora harveyana Zeh (“L. harveyiana”) forming quadripartite carposporangia, gave rise in culture to uniaxial, prostrate, filamentous plants. These formed monosporangia and regularly or slightly irregularly cruciately divided tetrasporangia after 6 to 8 weeks in culture. Thereafter, fewer tetrasporangia were formed and production ultimately ceased. Tetraspores from cultured plants formed creeping, profusely branched, filamentous growths that gave rise to erect, multiaxial fronds under long-day (LD) and short-day (SD) daylength regimes at 16–18°C. Under SD, fewer erect axes were formed and axial elongation ceased after a short time. The erect axes, although remaining sterile, were morphologically identical to field-collected gametophytes. Previous assumptions that all quadripartite carposporangia, generally referred to as “carpotetrasporangia”, are the result of reduction division thus appear to be unfounded. A “Liagora tetrasporifera-type” life history for marine red algae cannot thus be inferred merely on the basis that carposporangia are cleaved into four spores.