Morphology and systematics of the red algal parasite Dawsoniocolax bostrychiae (Choreocolacaceae, Rhodophyta)

Abstract

Abstract The vegetative and reproductive development of the parasitic red alga Dawsoniocolax bostrychiae (Joly et Yamaguishi-Tomita) Joly et Yamaguishi-Tomita, a parasite on Bostrychia, was studied. The thallus is a colourless multiaxial pustule which forms secondary pit connections with cells of its host. Reproductive structures develop from outer cortical cells. Tetrasporangia are tetrahedrally or cruciately cleaved. A four-celled carpogonial branch is borne on an intercalary supporting cell, which also functions as the generative auxiliary cell. After fertilization, the carpogonium fuses with the supporting (auxiliary) cell. The mature carposporophyte consists of a central fusion cell supporting a hemispherical cluster of gonimoblast filaments bearing terminal carposporangia. Carposporophyte development is similar to Harveyella mirabilis (Reinsch) Schmitz et Reinke and Leachiella pacifica Kugrens. Spermatangia develop in globose clusters formed by divisions in several planes of the spermatangial initia...