Bulletin of the British Museum (Natural History)
Bulletin of the British Museum (Natural History)
Bulletin of the British Museum (Natural History)
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66 BRIAN JOHN COPPINS<br />
Fig. 36 Suggested pathway for evolution <strong>of</strong> a sporodochium (D, as in M. adnata) from a pycnidium (A).<br />
The step A^B can be seen in <strong>the</strong> macroconidial conidiomata <strong>of</strong> e.g. M. cinerea and M. peliocarpa, and<br />
<strong>the</strong> mesoconidial conidiomata <strong>of</strong> e.g. M. denigrata and M. sylvicola. No structure equivalent to 'C is<br />
known from Micarea.<br />
gaping ostioles which eventually expose <strong>the</strong> 'hymenium' . The<br />
<strong>of</strong>ten dubious distinctions<br />
between pycnidia, acervuli, and o<strong>the</strong>r types <strong>of</strong> conidiomata are discussed by Nag Raj (1981).<br />
Although <strong>the</strong> sporodochial anamorph <strong>of</strong> M. adnata has unusually large, oblong-elHpsoid conidia<br />
and <strong>the</strong> longest conidiogenous cells known in <strong>the</strong> genus, <strong>the</strong>re seems to be no fundamental<br />
difference in <strong>the</strong>se features from those in o<strong>the</strong>r Micarea anamorphs, and <strong>the</strong> mode <strong>of</strong><br />
conidiogenesis is apparently <strong>the</strong> same in all cases (see below).<br />
Conidia<br />
Vobis & Hawksworth (1981) estimate that perhaps as many as 8000 species <strong>of</strong> Uchenized fungi<br />
have conidial anamorphs, and that in most cases a given species has only one conidium type.<br />
However, it is becoming increasingly evident that a large number <strong>of</strong> lichens (especially crustose<br />
lichens) have two conidium types, although many <strong>of</strong> <strong>the</strong> examples have not yet been notified in<br />
<strong>the</strong> literature. Some examples from my own studies include Anisomeridium biforme, A.<br />
juistense, Catillaria globulosa, Lecania cyrtellina, Lecanora quercicola, and Opegrapha niveoatra.<br />
Hedlund (1895) found M. denigrata and M. prasina to each have two conidium types and<br />
during <strong>the</strong> present study 16 <strong>of</strong> <strong>the</strong> 45 European species <strong>of</strong> Micarea have been found to have two<br />
conidium types. Even more surprising has been <strong>the</strong> discovery that three species {M. denigrata,<br />
M. nitschkeana, and M. lignaria) each have three conidium types (Figs 42, 45), and to my<br />
knowledge <strong>the</strong>se are <strong>the</strong> first reported instances <strong>of</strong> fungi (whe<strong>the</strong>r lichenized or not) with more<br />
than two pycnidial (coelomycetous) anamorphs. There are, however, a few species <strong>of</strong> sooty