Morphology and systematics of Holmsella pachyderma (Pterocladiophilaceae, Gracilariales)
1990; Taylor & Francis; Volume: 25; Issue: 1 Linguagem: Inglês
10.1080/00071619000650041
ISSN2331-2238
AutoresSuzanne Fredericq, Max H. Hommersand,
Tópico(s)Plant and Fungal Species Descriptions
ResumoThe vegetative and reproductive development of Holmsella pachyderma, a parasite on Gracilaria verrucosa and Gracilariopsis sp. in Great Britain and Ireland, shows that it is incorrectly placed in the family Choreocolacaceae. Instead, Holmsella shares significant characters with members of the Gracilariaceae and with Gelidiocolax and Pterocladiophila, genera parasitic on Gelidiaceae. Similarities include the pattern of vegetative growth based on concavo—convex and transverse divisions of apical cells, the transverse cutting off of spermatangia which leads to chains in the parasitic species, the apparent absence of an auxiliary cell, and the presumed direct development of the gonimoblasts from a fertilized carpogonium, probably after fusion with unspecialized neighbouring gametophytic cells. Gonimoblasts of Holmsella consist of horizontal filaments fused at numerous points with gametophytic cells, and clusters of erect filaments bearing carposporangia in chains, interspersed among cortical filaments. We propose that Holmsella be placed in the Pterocladiophilaceae Fan et Papenfuss, along with Gelidiocolax and Pterocladiophila, and that the family be transferred to the order Gracilariales Fredericq et Hommersand.
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