6 Wood Discoloration

218 8 Habitat of Wood Fungi
Oligoporus placenta, (Reddish) Sap polypore
Fruit body (Fig. 8.19j): annual, resupinate, either white to grey-brown (form
monticola) or later pink to salmon-violet (reddish form placenta)(Domański
1972), easily passing, to 1 cm thick; 2–4 circular-angular-slitted pores/mm, to
15 mm long; monomitic; hyaline spores 4−6 × 2−2.5µm;
Strands: on wood samples in laboratory culture, white, partly yellowing,
easily refractable, to 1 mm in diameter; fibers and vessels rare or absent.
Significance: The five “indoor polypores” form a group of brown-rot fungi that
are associated with the decay of softwoods in buildings. In Central Europe,
these fungi belong after the Dry rot fungus, Serpula lacrymans, andtogether
with the Coniophora cellar fungi to the most common indoor decay fungi. They
accounted for 14% of indoor decay fungi in Denmark (Koch 1985) and Finland
(Viitanen and Ritschkoff 1991a). A survey in California ranked A. vaillantii,
A. sinuosa, A. xantha and O. placenta with29%occurrenceasthemaingroup
(Wilcox and Dietz 1997).
The polypores have similar biology and distribution (Lombard and Gilbertson
1965; Donk 1974; Breitenbach and Kränzlin 1986; Lombard and Chamuris
1990; Bech-Andersen 1995; Schmidt and Moreth 1996, 2003). They differ in
their fruit body, spore morphology (Jülich 1984; Ryvarden and Gilbertson
1993, 1994) and sexuality. Some species also fruit in laboratory culture, which
supports identification of mycelia and tests for sexuality. Antrodia vaillantii
is tetrapolar heterothallic (Lombard 1990), A. serialis, A. sinuosa and O.
placenta are bipolar (Domański 1972; Stalpers 1978). Three Antrodia species
develop strands (Falck 1912; Stalpers 1978; Jülich 1984), O. placenta only in
vitro. However, the vegetative mycelium that has been isolated from decayed
wood is hardly distinguishable (Nobles 1965). Due to the limited differentiating
features, misinterpretations occur.
Furthermore, the nomenclature has a confusing history and is still not always
uniform (Cockcroft 1981). Fungi have been variously classified as Polyporus,
Poria, Amyloporia, Fibroporia (Domański 1972). Misleading synonyms in the
older literature such as Polyporus vaporarius and Poria vaporaria have been
used for different species, viz. A. vaillantii (Bavendamm 1952c), A. sinuosa,
and O. placenta. According to Ryvarden and Gilbertson (1994), the Reddish
sap polypore, formerly Tyromyces placenta (Fr.) Ryv., was placed in Oligoporus,
since the genus Tyromyces is restricted to fungi causing a white rot. Older
synonyms are Postia placenta (Fr.) M.J. Larsen & Lomb., Poria placenta (Fr.)
Cooke sensu J. Eriksson, Poria monticola Murr., and the haploid standard
strain Poria vaporaria (Pers.) Fr. sensu J. Liese (Domański 1972). Postia is
a nomen provisorium/nudum in the sense of Fries and illegitimate in the sense
of Karsten. Isolate MAD 698 of Postia placenta was thoroughly investigated in
view of brown-rot decay mechanisms (e.g., Clausen et al. 1993; Highley and
Dashek 1998). Difficulties may increase because O. placenta separates into the
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