Studies of Paleozoic Fungi IV: Wall Ultrastructure of Fossil Endogonaceous Chlamydospores

Abstract

Fossil endogonaceous chlamydospores are described from the aerial axes and roots of several Paleozoic plants preserved in calcilutite nodules and calcareous coal balls. Specimens come from six Paleozoic localities extending from the uppermost Lower Devonian through the Upper Pennsylvanian. Although fossil chlamydospores are markedly similar to the modern Endogonaceae in transmitted light, ultrastructural comparisons have not previously been made. The fine structure of the walls of these spores is consistent with past interpretations which relate them to the modern Endogonaceae, but thorough comparisons cannot be made due to the lack of comparable ultrastructural information from extant VA mycorrhizae. The evidence from mycorrhizal associations in the fossil record is evaluated.

Plant paleopathology and the roles of pathogens and insects

“…Other instances represent passive colonization of leaf surfaces by disseminating agents such as fungal spores or wind-dispersed viral particles. These plant pathogens should be recognizable in much of the compression fossil record, given what is known about their preservation potential in more exceptional deposits (Stubblefield et al, 1984a(Stubblefield et al, , 1984b. Potential identification of fossil plant pathogens, however, requires that the following three questions be addressed.…”

“…To a lesser extent, the carbonate-permineralized Calhoun Coal of the Illinois Basin, and other Late Carboniferous coal-ball deposits, also are a primary source of detailed hyphal structures, spores and fructifications, and examples of apparent plant pathogens. For example, fungi found associated with hypertrophied tissues of the seed Nucellangium, and the gymnospermous cone Lasiostrobus produced cells with wall appositions and excessive resin as an apparent response to fungal hyphae residing within their tissues (Stidd and Cosentino, 1975;Stubblefield et al, 1984aStubblefield et al, , 1984b.…”

Vesicular‐arbuscular Mycorrhizae From the Triassic of Antarctica

“…15) are morphologically identical to chlamydospores and vesicles of the extant genus, Glomus. They also resemble fossil Glomus-like chlamydospores from Pennsylvanian coal balls (Wagner and Taylor, 1982;Stubblefield and Taylor, 1985) and the Devonian trimerophyte, Psilophyton (Stubblefield and Banks, 1983). The thin-walled inflated structures with attached hyphae are also morphologically identical to vesicles produced by extant endogonaceous fungi (Fig.…”

“…tron microscopy to supplement earlier light microscopy studies (e.g., Wagner and Taylor, 1982;Stubblefield and Taylor, 1985). Opinion regarding the existence of such associations in the Paleozoic is mixed, as is the evidence on which these reports are based (Stubblefield and Taylor, 1985). To date, more recent, pre-Cenozoic, fossil representatives of vesicular-arbuscular mycorrhizae have not been reported.…”

A Possible Endogonaceous Fungus from the Triassic of Antarctica

“…Permineralized representatives of the Endogonaceae are known from the Devonian through- out the Triassic (Wagner and Taylor, 1982;Stubblefield and Banks, 1983;Stubblefield et al, 1985;Stubblefield, Taylor, and Trappe, 1987). To date, all previously described Paleozoic and Mesozoic endogonaceous fungi resemble Glomus.…”