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

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 orangered pigment that reacts Kthornred-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.

Automated summary

Herpothallon rubrogranulosum is a unique lichen species with limited distribution but local abundance. Previously confused with H. rubroechinatum, the two species differ markedly in the size of their pseudoisidia.