Herpothallon rubrogranulosum, a new species with granular pseudoisidia from the Mid-Atlantic Coastal Plain of southeastern North America1

Abstract

Herpothallon rubrogranulosum is described from forested wetlands in the Mid-Atlantic Coastal Plain of southeastern North America. It appears to be infrequent throughout its range, but locally abundant on bald cypress trees in areas of Francis Marion National Forest, South Carolina, USA. The species is characterized by a cream colored, ecorticate thallus with small, coarse granular pseudoisidia that are covered with variable amounts of orange-red pigment that reacts K+ red-pink, and the production of abundant psoromic acid. It was previously confused with H. rubroechinatum, which is a rarer tropical species that differs markedly in having large, conspicuous pseudoisidia.