M. Saikawa, LIGHT AND ELECTRON-MICROSCOPY OF ZOOPHAGUS-TENTACLUM, A REDISCOVERED ROTIFER-CAPTURING AQUATIC FUNGUS FROM JAPAN, Mycologia, 89(2), 1997, pp. 268-273
Zoophagus tentaclum Karling was recovered from submerged dead leaves c
ollected in a mountain stream at Mito-sawa, Hinohara-mura, Tokyo, Japa
n. This is the first report of this fungus since its discovery. The tr
apping organ of the fungus is a short, lateral branch distally bearing
several narrow tentacle-like hyphae, each terminating in a knob. The
morphology of the rotifer-capturing fungus was almost identical to tha
t described by Karling. Infection is initiated when a rotifer attempts
to swallow the whole trapping organ. Electron microscopy revealed tha
t the apical portion of one of the tentacles was pinched by a pair of
unci of the rotifer's trophi, and an adhesive exuded only from that po
rtion of the tentacle found in the trophi. Then, an accessory infectiv
e branch developed, not from the tentacle, but from the distal portion
of the lateral branch before penetration into the rotifer. Such a bra
nch, developing before penetration of the host, has not been reported
for the other two species of the genus, Z. insidians and Z. pectosporu
s. The fungus was also found to capture a species of testaceous rhizop
od.