THE GENUS THEISSENIA

This is a monotypic genus, containing only one species, T. pyrenocrata (Theiss.) Maublanc. Images of this species are given on the left. Information on the genus can be found below.
* Dennis, R. W. G. 1964. Further records of Congo Xylariaceae. Bull. Jard. Bot. État 34: 231-241.

This genus has the following characteristics:

stromatal tissue quantity: distributed above, around, and beneath perithecia
stromatal layers: bipartite
stromatal surface level: erumpent or superficial
stromatal interior: essentially homogeneous
stromatal orange granules surrounding perithecia: absent
stromatal KOH pigments: absent
stromatal conidium-bearing discs: absent
stromatal bases: sessile and attached to substrate entirely
stromatal aggregation: not forming a crust
stromatal shapes: other than wiry
coremial pegs or remnants: absent
subiculum: absent
substrates: associated with substrates other than dung or insect nests
ascomatal number per stroma: mostly multiperitheciate
ascomatal ostioles: present
ascomatal configurations: not valsoid
ascomatal diameter: more than 2 mm
ascomatal orientation: mostly oriented vertically
ascal apical rings: absent
ascospore cell number: one-celled
ascospore shapes: other than cuboid
ascospore color: colored
ascospore ornamentation: smooth
ascospore germination site morphology: slit-like
perispore dehiscence: indehiscent
anamorphs: unknown
cultural gross morphology on oatmeal agar: not highly furrowed or distorted