An uncommon fossil fungus
hyphae and resting spores are abundant in the Lower Devonian Rhynie
chert. Often one can see dark cells arranged as a ring
cross-sections. The dark aspect is due to tangles of hyphae inside
cells, known as arbuscules, of the symbiotic glomeromycotan fungus Glomites rhyniensis
. Other details of fungi in chert have been described in  and
elsewhere but many questions had to be left unanswered.
For example, the strange clusters of vesicles grown from the surface of
(Fig.1) are not mentioned in .
arrangement of the clusters on the surface of Aglaophyton
resembles that of a blastocladian fungus in the Rhynie
[1,2] but this similarity is most probably only superficial.
Fig.1: Clusters of fungus vesicles grown on the surface
of largely decayed Aglaophyton.
Width of the picture 4.3mm.
for the poorly preserved central strand, no trace of plant tissue is
left in Fig.1. The contour of the section is marked by the cuticle.
When looked at edgewise, the cuticle appears
as a narrow black line, otherwise it is
transparent light-brown sheet, as in Fig.1 below right. As seen on the
left, and enlarged in Fig.2, the vesicles had grown on a mound bulging
out from the surface. Obviously the mound had been formed below the
cuticle, probably induced by the fungus in the
The clusters on the right are not detached but thought to be
likewise connected to the slightly inclined shoot. The
sizes of the vesicles vary from 0.02mm (or smaller) to 0.1mm.
Their shapes may deviate from spherical by deformation due to mutual
of more or less globular shapes are known from numerous species of
fossil chytrids, a group of fungi thought to have separated from the
rest as early as during the Proterozoic . The vesicles are
zoosporangia, with a "discharge pore" occasionally visible as a
characteristic feature . Two big vesicles in Fig.2 have got a kind
short funnel, very dimly seen, which might have served as a
discharge pore. (Note the pale short extension pointing left on the big
vesicle on the left.)
Hence, the assumption may be justified that
the clustered vesicles shown here are zoosporangia of a fungus of the
chytrid clade. This implies the following statement: The vesicles
presented here are bigger than any fossil chytrid zoosporangium
described in .
The flower-like aspect of the cluster in Fig.3
(right) is an illusion: One sees only the bigger outer vesicles while
most of the cluster is unseen in the depth.
Figs.2,3: Details from Fig.1, clusters most probably of
chytrid zoosporangia. Note the bulge grown below
the cuticle (Fig.2) and the transparent light-brown cuticle in Fig.3.
Height of the images 0.5mm.
According to M. Krings (private communication), this fungus has been
described as Trewinomyces
annulifer, with unresolved systematic affinity.
It offers a rare view of the morphology of a distinctive Early Devonian
saprotrophic microfungus .
 T.N.Taylor, M. Krings, E.L. Taylor:
Fossil Fungi, Elsevier 2015.
 W. Remy, T.N.
Taylor, H. Hass: Early Devonian fungi. Am. J.
Ch. Strullu-Derrien, T. Goral, J.E. Longcore, J. Olesen, P. Kenrick,
A New Chytridiomycete Fungus Intermixed with Crustacean Resting Eggs
a 407-Million-Year-Old Continental Freshwater Environment.
11(12): e0167301. doi:10.1371/journal (2016).
 M. Krings, T.N. Taylor, H.
An enigmatic fossil fungus ... , Mycologia 108 (2016), 303-312.