This volume contains three contributions:
1. Polyporaceae from Venezuela 1:
Polyporaceae from Venezuela is based on collections made by Bassett Maguire, Julian A. Steyermark, John J. Wurdack, and Richard S. Cowan during recent expeditions conducted by The New York Botanical Garden, as well as on some earlier collections found at NY and FH. Detailed studies of 8 species are included: Fomitiporella johnsoniana Murr., Phellinus gilvus (Schw.) Pat., Pelloporus hamatus Romell, Coltricia spathulata (Hook. in Kunth) Murr., Gloeoporus conchoides Mont. in de la Sagra, Polyporus gallinaceus Berk. & Cooke, Polyporus modestus Kunze in Fr. and Coriolus caperatus (Berk.) Pat. Three are new records for Venezuela: Fomitiporella johnsoniana, Pelloporus hamatus and Polyporus gallinaceus.
2. The genus Hexagona:
The genus Hexagona Fr. is emended to contain species with brown fruiting bodies, strigose to velutinous pilear surface (trichoderm associated with a cutis or hymeniderm), corky-coriaceous to corky, context brown and subhomogeneous, trimitic hyphal system, skeletal hyphae with yellowish-brown walls, generative hyphae with clamps at septa, binding hyphae shortbranched, hymenial surface poroid with angular-hexagonal to subcircular pores, hymenium lacking cystidia and setae but frequently interrupted by yellowish-brown hyphal pegs, basidia clavate, usually collapsing very early and forming a honeycombed structure, basidiospores hyaline, smooth, cylindric, nonamyloid.
The genus is limited to three sections: Hexagona sect Hexagona, sect Applanata Lloyd emend and sect Velutina Lloyd emend. Section Hexagona is composed of: H. apiaria, H. aspera, H. capillacea, H. hirta and H. hydnoides; sect Applanata is reduced to H. pobeguini; and sect Velutina contains only H. papyracea.
Species formerly placed by Lloyd (1910a) in the sections Tenuis Lloyd, Pallidus Lloyd, Ungulaeformis Lloyd, Pseudofavolus (Pat.) Lloyd and Resupinatus Lloyd are not considered as congeneric with Hexagona Fr. emend.
3. Phellinus pachyphloeus and its allies
Phellinus pachyphloeus (Pat.) Pat., P. lamaensis (Murr.) Heim in Pascalet, P. noxius (Corner) G. H. Cunn., P. melanodermus (Pat.) O. Fid., P. magnosporus (Lloyd) O. Fid. and P. portoricensis (Overh.) O. Fid. are considered to belong to the "pachyphloeus" group and have, besides the general characters of Phellinus, setal skeletal hyphae present in the context. New combinations are proposed for the last three species. Macroscopic and microscopic characteristics of all accepted species are described in detail. Phellinus noxius and P. melanodermus do not have hymenial setae which are present in all other species. General discussion, geographic distribution, habitat, host and economic importance are included for each species. It was found possible to compare the natural sequence in the variation of the structures from the most simple progressively to the more complex ones, with the geographic progression of the group and the frequency of specimens in herbaria as well as frequency of references in the literature. This scheme suggested southeastern Asia as a possible center of origin of the group, P. melanodermus and P. magnosporus, possibly, being the oldest species and P. portoricensis the youngest. Phellinus lamaensis and P. noxius were found to be closely related and show some variation from the basic "pachyphloeus type" of setal skeletal hyphae. Phellinus pachyphloeus was found to be connected on one side to P. magnosporus and P. melanodermus and on the other side to P. portoricensis. The scheme showed also that P. pachyphloeus is more related to P. lamaensis than to P. noxius.