Introduction to Fungi, Third Edition

NEMATOPHAGOUS FUNGI
677
Fig 25.3 Arthrobotrys eudermata
(syn. Monacrosporium eudermatum,
Duddingtonia flagrans).
(a) Conidiophore with its single
attached conidium. Several
detached conidia are also shown,
one germinating. (b) Trapped
nematode showing infection
bulb and assimilative hyphae.
(c) Adhesive trapping networks.
in the same way as the non-constricting ring but
differs from it in that the three ring cells are able
to inflate rapidly following stimulation by
mechanical contact with the inner ring surface.
Inflation occludes the lumen of the ring, severely
constricting any nematode trapped in it. The
surface of constricting rings does not carry any
adhesive. Fungi producing constricting rings
have been assigned to the genus Drechslerella by
Scholler et al. (1999) and were formerly distributed
in Arthrobotrys and Dactylella. This type of
trap is illustrated in Fig. 25.6.
The mechanism of ring closure is of interest.
The insertion of a fine glass rod into a ring
by means of a micromanipulator, followed by
gentle friction of one of the cells, can trigger off
the closure of the trap. Other stimuli, such as
heat or a stream of dry air, are also effective. The
enlargement of the cells is accompanied by
vacuolation of their contents, and by elastic
stretching of the inside wall of the ring,
whilst the outer wall does not change shape
(Estey & Tzean, 1976). Ring closure is complete
within 0.1 s. Enlargement of the three cells