These photos are of Gonimochaete latitubus, a
lagenidioid parasitoid of the nematode Rhabditis marina (bar
in each figure = 10 µm). The newly released propagules
(asexual; no sexual stage known) are zoospore-like, but they have
no flagella and are immotile (aplanospores, photo 27). Eventually
the aplanospores develop an adhesive protuberance at the narrow end
(photo 28). If a nematode comes into contact with the
protuberance, the spore sticks very tightly to the worm. The spore
produces a penetration tube and enters the nematode's body cavity,
where it produces a refractive infection structure (photo 29).
From the infection structure, a sporangial thallus is produced,
which eventually digests and replaces the nematode's insides
(photos 30, 31). Mature thalli produce discharge tubes that extend
out of the nematode carcass (photos 32 [discharge-tube bud], 33
[mature tubes]). The cytoplasm of the thalli flows into the tubes,
leaving behind bubble-like structures at the sealed-off bases of
the tubes (photos 33, 34). Aplanospores are released in bursts
from the tips of discharge tubes, and if a tube tip is aerial (a
common tendency), the spores gather in a ball, perhaps awaiting passage of a
susceptible host. See Newell SY, R Cefalu, JW Fell. 1977.
Myzocytium, Haptoglossa, and Gonimochaete (fungi) in
littoral marine nematodes. Bull Mar Sci 27:177-207 [note that we
now know that these are stramenopiles {or maybe some are
plasmodiophoromycetes?!}, not fungi]; Beakes GW. 1998.
Relationships between lower fungi and protozoa, p.351-373. In:
Evolutionary Relationships Among Protozoa (eds, GH Coombs, K
Vickerman, MA Sleigh, and A Warren). Chapman & Hall, London; Beakes
GW and SL Glockling. 1998. Injection tube differentiation in gun
cells of a Haptoglossa species which infects nematodes.
Fungal Genet Biol 24:45-68.