In September 1990, 74 sporocarps of Battarrea stevenii
were observed on the floodplain of the ephemeral Kuiseb River in western
Namibia. Herein we report subsequent studies of the distribution, abundance,
nutritional role, phenology, and sporocarp development
of this fungus in the hyper-arid Namib Desert. Included are full descriptions
of developing and mature sporocarps. B. stevenii is a
common associate of riparian forests on silty floodplain terraces, but
does not form mycorrhizal associations with the dominant
woody species, Faidherbia albida or Tamarix usneoides.
Rather, clamped mycelium extends throughout floodplain soils decomposing
coarse and fine particulate organic material (4–7% of soil dry weight).
Sporocarp production occurs 4·5–12 mo post-flooding in
response to soil desiccation at depths of 20–35 cm. The extensive
mycelium, duration of vegetative growth post-flooding, and large
size and abundance of B. stevenii sporocarps suggest that it is
an important component of the subsurface decomposer community in
the Namib's ephemeral rivers. Given that the fungus has also been
recorded from floodplain soils of Angola, Hungary, and New
Mexico (U.S.A.), and is known to have a world-wide distribution, we predict
that further biogeographical studies will reveal that B.
stevenii is a characteristic element of the riparian biota in dryland
rivers, which drain approximately one-third of the earth's land surface.