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new order, Glomales, is proposed to include all soil-borne fungi which form
arbuscules in obligate mutualistic associations with terrestrial plants.
The proposed suborder, Glomineae, consists of the type family Glomaceae
and Acaulosporaceae fam. nov. Glomus and Sclerocystis are
genera in the Glomaceae characterized by "chlamydospores" borne
singly, in aggregates, or in compact sporocarps on one or more cylindrical
to flared subtending hyphae. Acaulospora and Entrophospora
in the Acaulosporaceae are historically equivalent sister groups. Species
in these genera are distinguished by "chlamydospores" formed laterally
from or within a hypha terminating in a sporiferous saccule. Intermediate
species in Acaulosporaceae show a progressive transformation from spores
resembling Glomus to those which are uniquely sessile. Gigasporineae
subord. nov. is proposed to include Gigasporaceae fam. nov. Both genera
in this family, Gigaspora and Scutellospora, produce "azygospores"
borne terminally on a sporogenous cell. Taxa in Gigasporineae produce extraradical
auxiliary cells and no intraradical vesicles, whereas taxa in Glomineae
form intraradical vesicles. The Endogonales was emended to contain only
one family, Endogonaceae, with a single genus, Endogone. A key
to supraspecific taxa in Glomales is provided. |
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