Hypoxylon placentiforme Berk. & M. A. Curtis



In the protologue of H. placentiforme, Berkeley and Curtis (1869) cited two Cuban specimens of C. Wright, nos. 324 and 492. Specimen no. 324 is immature and yields purplish pigment in KOH solution; it may be H. polyporum. In the type of H. sclerophaeum var. macrospora [º H. areolatum Starb.], the ascospore size range is 11-14.5 x 5.5-6.5 mm, similar to that of the type of H. placentiforme. Hypoxylon mulleri was erected by Miller (1961) in contrast to H. sclerophaeum sensu J. H. Miller merely by the lack of the vinaceous tone on the stromatal surface and by the more conspicuous perithecial mounds. In our opinion, these characteristics are not sufficient to warrant species status for H. mulleri. No material of H. rubiginosum f. robustum was found at LPS. It was described as having stromata 1-3 cm thick and having ascospores 10-15 x 8 mm (see Saccardo, 1891).

Most specimens belonging to H. placentiforme were considered to be H. sclerophaeum by Miller (1961). They are readily separated by stromatal pigments and ascospore morphology. Among other Hypoxylon with massive stromata, only H. tortisporum has similar olivaceous or greenish stromatal pigments. Hypoxylon placentiforme and H. tortisporum differ primarily in ascospore morphology.

Collections from New Zealand appear to be highly associated with Nothofagus, and generally have more massive stromata and a more purplish tone on the surface than those from other areas. Further studies may show that the New Zealand material represents a distinct taxon. See also NOTES on H. anthochroum.