NAME Asterothyrites canadensis
AGE Late Paleocene-Early Eocene.   AGE span: 58.7...40.4 mya
K&J CLASSIFICATION (2000) Ascomycetes, Microthyriales.
FIGURE(S)
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FIGURE REFERENCE Kalgutkar RM. 1985. Fossil fungal fructifications from Bonnet Plume Formation, Yukon Territory; Geological Survey Canada, Paper 85-1B, p. 259-268.
SPECIES, AUTHORITY A. canadensis (Kalgutkar) Kalgutkar & Jansonius 2000
LOCATION Peel River, Yukon Territory, Canada.
ORIG DESCRIPTION* Ascomata subcircular, radiate, ostiolate, with more or less entire margin. Ascomata consist of radiating rows of cells, pseudoparenchymatous, with a central group of squarish, thin-walled cells and slightly thicker-walled, brownish, irregularly rectangular cells outside the central region (figs. 5, 6). Bordering the ostiole, the inner cells of the radiating rows seem somewhat loosely arranged. Except for the thickened walls, the ostiole is not surrounded by any specialized cells. Ascomata one-layered, flattened, 55 to 115 µm in diameter, the fully formed ostiole about 19 µm in diameter (fig. 6).
COMMENTS* Paramicrothallites is segregated from other dispersed forms of ascomata by its simple type of ostiole, without any specialized bordering cells. The ostiole is probably formed lysigenously from the dissolution of the central group of thin-walled cells (fig. 7) which probably become indistinct and gradually disintegrate during the development of the thyriothecia.

Jain & Gupta (1970) proposed the new genus Paramicrothallites to include fossil dispersed ostiolate forms of Microthallites, and M. spinulatus was made the type species of Paramicrothallites. P. canadensis resembles P. spinulatus (Dilcher) Jain & Gupta 1970 and P. menonii Jain and Gupta 1970 in its shape, radiating cell pattern, and in the presence of an ostiole that is not encircled by specialized cells. However, P. spinulatus and P. menonii can be distinguished from P. canadensis in their lack of a matrix of darkened rows of cells exterior to the central region which eventually develops into an ostiole, and in their generally smaller size.
PUBLICATION REFERENCE Kalgutkar RM. 1985. Fossil fungal fructifications from Bonnet Plume Formation, Yukon Territory; Geological Survey Canada, Paper 85-1B, p. 259-268.
K&J REMARKS
TYPE
ALL NAMES (Including synonyms) Paramicrothallites canadensis Kalgutkar 1985, p. 264, pl. 31.1, fig. 6.; Asterothyrites canadensis
SERIAL NUMBER 67
PUBLIC COMMENTS
 *For source, see Publication Reference.