NAME Spirotremesporites disciformis
AGE    AGE span:  mya
K&J CLASSIFICATION (2000) Fungi Imperfecti, Amerosporae.
FIGURE(S)
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Pl.4fig.48.jpg
FIGURE REFERENCE Sheffy MV, Dilcher DL. 1971. Morphology and taxonomy of fungal spores; Palaeontographica, Abt. B, v. 133 p. 34-51.
SPECIES, AUTHORITY S.? disciformis (Sheffy & Dilcher 1971) Elsik 1990a, p. 162.
LOCATION
ORIG DESCRIPTION* Disk-shaped spore 6.8 x 16.4 µm, psilate, medium pigment, wall 1 µm thick.

EMENDED DESCRIPTION (Elsik 1990a, p. 162): Aseptate, psilate fungal spores with a fusiform shape and outline. The furrow is somewhat shallowly S-shaped, i.e. vaguely signoidal, and reaches the ends of the spore. The furrow is 0.25-0.5 µm wide. Overall size of the spore is ca. 7 x 22 µm; thickness of the spore wall is stated to be 1 µm.
COMMENTS* (Elsik): The outline of Sprirotremesporites disciformis (Sheffy & Dilcher) emend. is more narrowly fusiform than the outline of Hypoxylonites washingtonensis; H. washingtonensis also has a straight furrow in the uncompressed state.

The specific epithet is a misnomer, as the spore is not disk-shaped. The longitudinal furrow was interpreted by Sheffy & Dilcher as a preservational feature.
PUBLICATION REFERENCE Sheffy MV, Dilcher DL. 1971. Morphology and taxonomy of fungal spores; Palaeontographica, Abt. B, v. 133 p. 34-51.

Elsik WC. 1990. Hypoxylonites and Spirotremesporites, form genera for Eocene to Pleistocene fungal spores bearing a single furrow; Palaeontographica, Abt. B, v. 216, p.137-169.
K&J REMARKS Kalgutkar and Jansonius (2000) follow Elsik's judgement in assigning this species to Spirotremesporites, but not without reservation. The furrow is distinct, but lacks the sigmoidal curve that characterizes most species included in this genus. Indeed, its appearance doesn't differ much from that of some forms included in Hypoxylonites, e.g. H. elongatioides or H. washingtonensis. The line drawing of I. disciformis given by Sheffy & Dilcher also appears to show an affinity to the genus Hypoxylonites, as it represents the furrow as straight, not oblique, wavy or spiral.
TYPE
ALL NAMES (Including synonyms) Inapertisporites disciformis Sheffy & Dilcher 1971, p. 39, pl. 13, fig. 8; pl. 15, fig. 8.; Spirotremesporites disciformis
SERIAL NUMBER 1589
PUBLIC COMMENTS
 *For source, see Publication Reference.