Symbiotic fungus Glomites in the early land plant Aglaophyton
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Glomites inside AglaophytonThe globular bodies often seen arranged inside Aglaophyton, partially connected to peculiar bags, have been thoroughly described in [1] as "acaulosporoid glomeromycotan spores" of the symbiotic fungus Glomites rhyniensis [2,3] forming "spore-saccule complexes".

Fig.1: Lengthwise section of Aglaophyton with "acaulospores" of the symbiotic fungus Glomites rhyniensis; inclined section of empty sporangium with broken palisade wall above. Image width 10mm.

The sample in Fig.1 represents a stage of decay with no cortex tissue left and most spores having lost their connection to the related vesicle which, when partially decayed and looking like a tail, make what may be called a "tadpole aspect". The empty sporangium with the characteristic palisade wall shows that the plant is really Aglaophyton.

Glomites inside Aglaophyton
Fig.2: Aglaophyton with spore-saccule complexes of Glomites rhyniensis inside exceptionally well preserved cortex tissue, also cells filled with tiny dark Glomites arbuscules seen here in loose rows. Image width 5mm. (Note the magnification about twice that of Fig.1)

Additional information is provided by Fig.2 with well preserved cortex tisse, dark dots of Glomites arbuscules within cortex cells in two rows at some distance from the outer boundaries, and impressive examples of the globular acaulospores, some of them seen with attached vesicle (Fig.3) called saccule in [1].
chlamydospore-vesicle complex of GlomitesFig3: Spore-vesicle complex of
        Glomites rhyniensis

Spore-saccule complexes, separate spores, separate collapsed saccules, hypha fragments, and two rows of dark dots, all together in one image as in Fig.2, may be confusing but nevertheless indicating Glomites. Even with less convincing fossil evidence as in Rhynie Chert News 182, the collapsed or cell-size dark dots in shaky rows are indicative of Glomites
The peculiar features shown here, as acaulospores grown only in connection with vesicles of about same size, are not restricted to Glomites, as pointed out in [4]. The present state of research concerning "the abundance and morphological diversity of arbuscular mycorrhizal fungi" has been characterized concisely as "... there is still considerable undocumented diversity in the form of new specimens and hitherto unknown or unrecognized features of mycorrhizal fungi in the Rhynie chert" [4]. That may justify this contribution although it does not really offer news. The sizes of the acaulospores (often called only spores) in this contribution agree with those in [1], thus being much bigger than those in [4].

Samples: Fig.1: Rh6_17.5 (2002);  Fig.2: Rh11_10.1 (2003),  Fig.3: Rh7_10.2 (2003)

H.-J. Weiss     2022  

[1]  N. Dotzler, Ch. Walker, M. Krings, H. Kerp, T.N. Taylor, R. Agerer:
      Acaulosporoid glomeromycotan spores with a germination shield from ... Rhynie chert.
      Mycol. Progress (2009) 8, 9-18.
T.N. Taylor et al.: Fossil arbuscular mycorrhizae from the Early Devonian, 
      Mycologia 87(1995), 560-73.

[3] T.N. Taylor et al.: Fossil Fungi. Elsevier Inc. 2015, p.122.

[4] C. J. Harper, Ch. Walker et al.: Archaeosporites rhyniensis gen. et sp. nov. (Glomeromycota, Archaeosporaceae) from the Lower Devonian Rhynie chert: ...
     Annals of Botany 126 (2020): 915–928.

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