NAME Geastrum tepexense
AGE Cenozoic (Miocene to earliest Pleistocene).   AGE span: 23.03...0.781 mya
K&J CLASSIFICATION (2000) Basidiomycetes, Lycoperdales. [The generic diagnosis was emended by Persoon in 1801.]
FIGURE(S)
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FIGURE REFERENCE Magallon-Puebla S, Cevallos-Ferriz SRS. 1993. A fossil earthstar (Geastereceae: Gasteromycetes) from the Late Cenozoic of Puebla, Mexico; American Journal of Botany, v. 80, p. 1162-1167.
SPECIES, AUTHORITY G. tepexense Magallon-Puebla & Cevallos-Ferriz 1993, p. 1163, figs. 2-6.
LOCATION Puebla, Mexico.
ORIG DESCRIPTION* Basidiocarp with open, stellate exoperidium, 2.5 cm in maximum diameter, radially divided into ten rays, each triangular to rectangular in outline, and with the apex curled and folded beneath more proximal parts; some rays with a faint superficial reticulate pattern; endoperidium of circular outline, 1.3 cm in diameter, irregular surface relief and with a small, eccentric ostiole surrounded by a conical protuberance; associated spores globose, verrucate, from 3.5 to 7.0 µm in diameter.
COMMENTS* Features of the fossil fungus indicate that it had reached an advanced stage of maturity, as the exoperidium had split into star-like rays and recurved to expose the endoperidium at its center. The stellate exoperidium morphologically links fungi of the genera Geastrum, Astraeus, and Myriostoma; however, despite the strong morphological resemblance in the mature basiodiocarps of the three, there are important differences between them (Table 1).

The morphological features of the fossil basidiocarp and the spores obtained from its endoperidium link it to the genus Geastrum, rather than to Astraeus or Myriostoma. Nevertheless, the preserved features of the fossil specimen are insufficient for placing it within an extant species. Therefore, Geastrum tepexensis is erected to include a fossil earthstar belonging to Geastrum, but not assignable to an extant species.

The report of a basidiocarp of Geastrum in the plant-bearing strata of the Pié de Vaca Formation represents one of the few reports of fungal microfossils from the tropics, with only a gilled mushroom (Coprinites dominicanus; Coprinaceae; Agaricales) previously known from amber of Eocene age of the Dominican Republic (Poinar & Singer, 1990). Geastrum tepexensis is the oldest known specimen of Geasteraceae. Despite its relative young age, it may provide important clues about the geographic distribution through time and evolutionary history of the Lycoperdales. [Further details in original paper.]
PUBLICATION REFERENCE Magallon-Puebla S, Cevallos-Ferriz SRS. 1993. A fossil earthstar (Geastereceae: Gasteromycetes) from the Late Cenozoic of Puebla, Mexico; American Journal of Botany, v. 80, p. 1162-1167.
K&J REMARKS
TYPE
ALL NAMES (Including synonyms) Geastrum tepexense
SERIAL NUMBER 633
PUBLIC COMMENTS
 *For source, see Publication Reference.