IMC8 Fungus of the Month - July 2006

Pleurotopsis longinqua - found far and wide

Pleurotopsis longinqua was originally described (in the genus Agaricus) in 1847 from far southern Chile, from a collection ‘on dead wood near the sea’ made on Islas Hermite just north of Cape Horn. For English Mycologist Miles Berkeley, this location was indeed very distant from his home in Kent, hence his use of the epithet ‘longinquus’, meaning from a remote location.

The beautiful flabelliform fruit-bodies usually have the pileus in shades of pink, but sometimes almost white or as dark as purplish brown. Below the outer layer of the pileipellis there is a distinct gelatinised zone. The spores are amyloid, and hence the species was placed for a time in Panellus, but DNA sequence data shows that it does not belong alongside the type of Panellus, P. stypticus.

Pleurotopsis longinqua has a wide distribution in wetter forests of south-eastern Australia, New Zealand, southern South America (Argentina, Chile). There is also a considerable disjunction between these southern hemisphere localities and occurrences in the coastal rainforests of western North America (Canada, U.S.A.). Northern hemisphere material was originally recognised as subspecies pacificus of Panellus longinquus. However, isolates from across the distribution have a similar range of morphology, and are intercompatable. In addition, DNA sequence analysis shows remarkable similarity among isolates from New Zealand, Argentina and U.S.A., with only four base pair differences. Therefore Hughes et al. (1998) concluded that the current north/south hemisphere disjunct distribution is not very old.

Further Information
Hughes, K.W., Toyohara, T.L. & Petersen, R.H. (1998). DNA sequence and RFLP analysis of Pleurotopsis longinqua from three disjunct populations. Mycologia 90: 595-600.
Jin, J., Hughes, K.W. & Petersen, R.H. (2001), Phylogenetic relationships of Panellus (Agaricales) and related species based on morphology and ribosomal large subunit DNA sequences, Mycotaxon 79: 7-21.
Libonati-Barnes, S.D. & Redhead, S.A. (1984) Panellus longinquus subsp. pacificus a new west coast North American agaric associated with red alder. Mycotaxon 20: 205-212.
Petersen, R.H. & McCleneghan, S.C. (1995), Mating systems of antipodal agarics: an unreported taxon and range extensions, New Zealand J. Bot. 33: 93-98.

Text supplied by Tom May (Royal Botanic Gardens, Melbourne)