NAME Brefeldiellites argentinus
AGE Early Cretaceous.   AGE span: 145.5...99.6 mya
K&J CLASSIFICATION (2000) Ascomycetes, Microthyriales.
FIGURE(S)
Image of
Pl.24fig.9.jpg
FIGURE REFERENCE Martínez A. 1968. Fossil Microthyriales (fungi, Ascomycetes) from the lower Cretaceous of Santa Cruz Province, Argentina; Revista de la Associación Paleontológica Argentina, Ameghiniana, v. 5, p. 257-263.
SPECIES, AUTHORITY B. argentinus Martínez 1968, p. 260, pl. 2, fig. 5. Holotype: on Taeniopteris (microscope sample no. 531).
LOCATION Santa Cruz Province, Bajo Grande, Argentina.
ORIG DESCRIPTION* Stroma membranous, with a single layer of cells, more or less circular (600-1260 µm), rarely elongated (1500 µm), yellow-reddish brown, with crenate-lobed margin or with slightly developed lobes. Stromatic hyphae radially united, dichotomising, diverging and forming lobes that by coalescing produce an entire shield with a crenate or lobed margin. Hyphal cells yellow-reddish brown, subglobose, cuboidal or polygonal (4.7-5 µm), oval (10-12 x 5-8 µm) or rectangular-elongated, angular or irregular (4.25 x 2.5-5 µm), the more peripheral tissues consisting of predominantly elongated cells.

Ascostromata circular (30-90 µm) or subcircular (75-100 x 50-90 µm), slightly convex, dark reddish-brown, consisting of subglobose and cuboidal cells (5 x 5-7.5 x 7 µm), elongated (7.5 x 5 µm) or irregular, angular, generally randomly distributed. Central ostiolar aperture elongated or irregularly triangular (11-20 x 6-8 µm); cells bordering the ostiole more or less elongated and arranged parallel or perpendicular to the ostiolar cavity. No spores are observed.
COMMENTS* Epiphyllous fungi upon Podocarpus dubius, Dictyozamites sp., Ruflorina sierra and an undetermined conifer. This species is similar to Brefeldiellites fructiflabellus Dilcher both in form and in general structure of the stroma; the new species differs from the latter, however, in the well-defined coloration of the thallus and the form, structure and distribution of the ascostromata in the thallus.

This new fossil fungus is relatively similar in its morphology and structure of the stroma and distribution of its ascostromata to the modern form B. brasilensis Speg., whose type was thoroughly studied; however, the lack of spores in the fossil specimens, does not allow to establish its possible identity.

Another feature of possible importance can be observed in the new species, but has not been described for B. fructiflabellus and is not present in the modern form B. brasiliensis. The radial hyphae of B. argentinus, that surround more or less concentrically most of the fruiting bodies, end at the extreme of the growth of the hyphae, producing a similar feature of modern Trichopeltaceae when the thallus finds an obstacle in its way (Stevens, 1925, p. 83, fig. 17e; Fraser, 1936, p. 278). From this we can infer that the fruiting bodies of B. argentinus are formed mainly at the margin of growth, mainly at the enclosures, and that they are produced where the thallus is growing. This species is the second described for this genus, and geochronologically the oldest; the other one is from the Eocene and described by Dilcher (1965).

Regarding B. fructiflabellus, which has completely hyaline stromata, it should be pointed out that B. argentinus also has areas of hyaline or little colored thallus; however, in this case we can see that the less colored stroma is reduced, in these areas, to the lower wall by disappearance of the upper one, a feature that can be observed also in specimens of Trichopeltinites.
PUBLICATION REFERENCE Martínez A. 1968. Fossil Microthyriales (fungi, Ascomycetes) from the lower Cretaceous of Santa Cruz Province, Argentina; Revista de la Associación Paleontológica Argentina, Ameghiniana, v. 5, p. 257-263.
K&J REMARKS In his text, Martínez designated the specimen(s) LP 524-526, growing on Podocarpus dubius, as holotype. However, he illustrated only the specimen numbered LP 531 (growing on Taeniopteris), in pl. 2, figs. 5-6, which he identified as holotype also, in the legend of these figures. Kalgutkar and Jansonius (2000) accept this latter specimen as the holotype, and accept the name of this species as validly published by Martínez (1968).
TYPE Holotype: on Taeniopteris (microscope sample no. 531).
ALL NAMES (Including synonyms) Brefeldiellites argentinus
SERIAL NUMBER 139
PUBLIC COMMENTS
 *For source, see Publication Reference.