Introduction to Fungi, Third Edition

EUROTIALES
299
penicilli, a further branch, the ramulus, is
inserted between the ramus and the metula.
Paecilomyces, another important anamorphic
genus in the Eurotiales, has conidiophores similar
to those of Penicillium, except that the phialides
are more loosely arranged and have a different
shape, being more elongated with a narrow
drawn-out tip (Fig. 11.11c). Conidia of
Paecilomyces are usually pale rather than pigmented
green or blue.
The order Eurotiales is thought by some to
consist of only a single family, Trichocomaceae,
and these two terms are often used interchangeably.
However, Geiser and LoBuglio (2001) also
included the Monascaceae (not discussed further
here) and Elaphomycetaceae (see p. 313). Many
species of the Trichocomaceae are much better
known by their anamorphic names, and these will
continue to be used by most mycologists, especially
those working in applied fields. Correlations
of anamorphic and teleomorphic taxa are
given in Table 11.2 (Pitt et al., 2000). These data
show that a teleomorph has been found only for
about 40% of all Aspergillus species described
to date, and 31% of Penicillium spp. The taxonomy
of the Eurotiales is still in a considerable state of
confusion because it is not possible unequivocally
to correlate the various anamorphs with the
appearance of cleistothecia and other features
such as DNA sequence data and biochemical
features (Ogawa et al., 1997; Ogawa & Sugiyama,
2000).
11.4.1 Aspec ts of morphogenesis
in Aspergillus
To recapitulate on our discussion of
conidiogenesis on p. 235, a phialide, according
to Kendrick (1971), is:
a conidiogenous cell in which at least the first
conidium initial is produced within an apical
extension of the cell, but is liberated sooner or
later by the rupture or dissolution of the upper
wall of the parent cell. Thereafter, from a fixed
conidiogenous locus, a basipetal succession of
enteroblastic conidia is produced, each clad in
a newly laid-down wall to which the wall of the
conidiogenous cell does not contribute . . . The
length of the phialide does not change during
the production of a succession of conidia . . .
The development of phialoconidia in Aspergillus
niger is illustrated in Fig. 11.12. Young phialides
are somewhat club-shaped in outline. In A. niger,
A. nidulans and many other species of
Aspergillus and Penicillium, the phialoconidia are
uninucleate, but in some species they are multinucleate.
The tip of the phialide expands to form
a spherical knob which is the initial of the firstformed
spore. Meanwhile, the single nucleus in
the phialide divides, and a daughter nucleus
passes into the spore which begins to be
separated by the formation of a septum at the
phialide tip. The expansion of the first conidium
leads to the rupture of the phialide wall near its
tip, and the remnants of the broken phialide wall
persist as a cap around the first-formed conidium.
Before the rupture of the phialide wall,
a layer of cell wall material is laid down
(Fig. 11.12d). This layer becomes the outer wall
Table 11.2. A summary of some anamorphic
states found in the Trichocomaceae, and their
associated teleomorphs.
Anamorphic name
Teleomorphic name
Aspergillus (218) Chaetosartorya (3)
Emericella (33)
Eurotium (24)
Fennellia (3)
Hemicarpenteles (2)
Neosartorya (19)
Petromyces (3)
Sclerocleista (2)
Geosmithia (10) Talaromyces (3)
Paecilomyces (48) Byssochlamys (4)
Talaromyces (3)
Thermoascus (4)
Penicillium (249) Eupenicillium (44)
Talaromyces (33)
For each taxon, the numbers of species are
indicated in brackets. Numerically important
genera are highlighted in bold.Note that only a
few ofthe 48 Paecilomycesspecies arereferable
to theTrichocomaceae, many others belong to
Pyrenomycetes (see p. 360). Summarized from
Pitt et al. (2000) and Samson (2000).