Two subgeneric taxa of Hypoxylon
are accepted by us: section Hypoxylon
and section Annulata.
These two sections are primarily differentiated by the presence or absence of a layer of
carbonaceous stromatal tissue enclosing perithecia. When the perispore of ascospores is
dehiscent and when the ostiolar discs are present, they also provide additional major
characters to separate these two sections. Only taxa of section Hypoxylon
possess coil-like ornamentation on the perispore, and only those of section Annulata
possess a localized thickening on the perispore. Annulate ostiolar discs are found
exclusively in section Annulata. |
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1. Carbonaceous stromatal material surrounding individual
perithecia absent.
![peritheciumH.JPG (8851 bytes)](Images/Hypoxylon/peritheciumH.JPG) |
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1. Carbonaceous stromatal material surrounding individual
perithecia present.
![peritheciumA.JPG (9786 bytes)](Images/Hypoxylon/peritheciumA.JPG) |
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2. Ostioles usually lower than the level of
stromatal surface, less frequently at the same level or slightly higher than the level of
stromatal surface, never encircled with an annulate disc.
![ostioleH.JPG (6193 bytes)](Images/Hypoxylon/ostioleH.JPG) |
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2. Ostioles always higher than the level of
surrounding stromatal surface, encircled with an annulate disc except in H.
cohaerens, H. multiforme
and their respective varieties, and H. nothofagi.
![ostioleA.JPG (7867 bytes)](Images/Hypoxylon/ostioleA.JPG) |
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3. Perispore, when dehiscing, with conspicuous to
inconspicuous transverse coil-like ornamentation visible.
![perisporeH.JPG (15028 bytes)](Images/Hypoxylon/perisporeH.JPG) |
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3. Perispore, when dehiscing, with a thickened area visible
at the position of ca. 1/3 ascospore length on the same side as the germ slit.
![perisporeA.JPG (8061 bytes)](Images/Hypoxylon/perisporeA.JPG) |