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PHYLOGENY
the fungus genus Verrncula. It was established by Steiner 1 to include two
species, V. cahirensis and V. aegyptica, their perithecia being exactly similar
to those of Verrucaria? in which genus they were originally placed. Both
are parasitic on species of Caloplaca (Placodium}. The former, on C. gilvella,
transforms the host thallus to the appearance of a minutely lobed Placodium ;
the latter occupies an island-like area in the centre of the thallus of Caloplaca
interveniens, and gives it, with its accompanying parasite, the character of
an Endopyrenium (Dermatocarpon), while the rest of the thallus is normal
and fertile.
Zahlbruckner may have argued rightly, but it is also possible to regard
these rare desert species as reversions from an originally symbiotic to a purely
parasitic condition. Reinke came to the conclusion that if a parasitic
species were derived directly from a lichen type, then it must still rank as
a lichen, a view that has a direct bearing on the question. The parallel
family of Pyrenulaceae which have Trentepohlia gonidia is considered by
Zahlbruckner to have originated from the fungus genus Didymella.
Compound or stromatoid fructifications occur once and again in lichen
3
families; but, according to Wainio , there is no true stroma formation, only
a pseudostroma resulting from adhesions and agglomerations of the thalline
envelopes or from cohesions of the margins of developing fruit bodies.
These pseudostromata are present in the genera Chiodecton and Glyphis
(Graphidineae) and in Trypethelium, Mycoporium, etc. (Pyrenocarpineae).
This view of the nature of the compound fruits is strengthened, as Wainio
points out, by the presence in certain species of single apothecia or perithecia
on the same specimen as the stromatoid fruits.
b. CONIOCARPINEAE. This subseries is entirely isolated. Its peculiarity
lies in the character of the mature fruit in which the spores, owing to the
early breaking down of the asci, lie as a loose mass in the hymenium, while
dispersal is delayed for an indefinite time. This type of fruit, termed a
mazaedium by Acharius, is in the form of a stalked or sessile roundish head
the capitulum closed at first and only half-open at maturity rarely, as in
Cyphelium, an exposed disc. There is a suggestion, but only a suggestion, of a
similar fructification in the tropical fungus Camillea in which there is some-
times a stalk with one or more perithecia at the tip, and in some species early
disintegration of the asci, leaving spore masses 4 . But neither in fungi nor in
other lichens is there any obvious connection with Coniocarpineae. In some
of the genera the fungus alone forms the stalk and the wall of the capitulum ;
in others the thallus shares in the fruit-formation growing around it as an
amphithecium.
The semi-closed fruits point to their affinity with Pyrenolichens, though
1 Steiner 1896.
2
Muller-Argau 1880.
3 Wainio 1890, p. xxiii.
4
Lloyd 1917.