Smpb. Guimaraes, MORPHOLOGY AND SYSTEMATICS OF THE RED ALGAL PARASITE DAWSONIOCOLAX-BOSTRYCHIAE (CHOREOCOLACACEAE, RHODOPHYTA), Phycologia, 32(4), 1993, pp. 251-258
The vegetative and reproductive development of the parasitic red alga
Dawsoniocolax bostrychiae (Joly et Yamaguishi-Tomita) Joly et Yamaguis
hi-Tomita, a parasite on Bostrychia, was studied. The thallus is a col
ourless 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 fertiliz
ation, 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 carpo
sporangia. Carposporophyte development is similar to Harveyella mirabi
lis (Reinsch) Schmitz et Reinke and Leachiella pacifica Kugrens. Sperm
atangia develop in globose clusters formed by divisions in several pla
nes of the spermatangial initials. This information supports placement
of Dawsoniocolax in the family Choreocolacaceae (together with Choreo
colax, Harveyella and Leachiella) which is retained in the Gigartinale
s.