NAME Palaeomycites gracilis
AGE (Renault) Permian.   AGE span: 299...251 mya
K&J CLASSIFICATION (2000) Chytridiomycetes, Chytridiales; or: Zygomycetes, Endogonales; or: Oomycetes, Peronosporales.
FIGURE(S)
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Pl.20fig.18.jpg
FIGURE REFERENCE Renault B. 1896. Bassin Houiller et Permien d' Autun et d'Épinac, Flore Fossile, pt. I; Études des gîtes minéraux de la France, Paris, Fascicule 4, 578 p.
SPECIES, AUTHORITY P. gracilis Renault ex Meschinelli 1902, p. 9.
LOCATION (Renault) Saône et Loire, France.
ORIG DESCRIPTION* (Renault): Mycelium branched, branches dichotomous (a’ in fig, 88), showing numerous irregular inflations of 3-4 μm diameter the appearance of which suggests that they have grown in a liquid environment; aerial fructifications unknown.

Asexual reproduction: The branches of the mycelium often end in a club-shaped expansion (c, b’ in fig. 89), separated from the rest of the thallus by a septum. These pyriform or spherical cells measure 35-38 μm in length, 25-35 μm in width, the spherical ones being 35 μm in diameter. These voluminous cells probably were destined to be the source of fructiferous filaments; however, having been unable to attain the surface of the liquid, they had to satisfy themselves to give birth to a mycelial filament (c in fig. 89). This filament may issue immediately from the cells, or from an inflated structure immediately adjacent to the latter. These pyriform or spherical cells should not be taken for sporangia; the lack of color in their interior indicates that their protoplasm had not condensed.

In some filaments (a, b in figs. 88, 89) one can see inflations (b) of 35-40 μm that are neither pyriform nor spherical like those just discussed, but ovoidal, placed somewhat off the axis of the filament. Their walls are thicker and darker than those of the latter; two septa isolate these inflations from the rest of the thallus; one may consider them as cysts or chlamydospores.

We do know that some of the Mucorinaceae, when their living conditions become difficult, store their protoplasm here and there in the extent of a filament, as round masses that are separated from the rest of the thallus and secrete their own membrane, and that will produce new thalli when favourable circumstances return. Such encystment permits the plants which we are dealing with here, to withstand the frequent periods of drought to which they are exposed.
COMMENTS*
PUBLICATION REFERENCE Renault B. 1896. Bassin Houiller et Permien d' Autun et d'Épinac, Flore Fossile, pt. I; Études des gîtes minéraux de la France, Paris, Fascicule 4, 578 p.
K&J REMARKS Palaeomyces gracilis Renault is a nomen nudum, as the genus name was not validly published because no generic diagnosis was provided.

Meschinelli (1902) introduced the fossil genus Palaeomycites Meschinelli 1902 (non Renault 1896) with a proper generic diagnosis. It replaced Palaeomyces Renault 1896 (non Palaeomyces Kidston & Lang 1921). See remarks from Kalgutkar and Jansonius (2000) under Palaeomyces.
TYPE
ALL NAMES (Including synonyms) Palaeomyces gracilis Renault 1896, p. 439, figs. 88-89 (nom. nud.).; Palaeomycites gracilis
SERIAL NUMBER 1215
PUBLIC COMMENTS
 *For source, see Publication Reference.