Coenogonium missouriense, a New Lichen Species from Missouri

Abstract

The filamentous microlichen Coenogonium missouriense sp. nov. (Coenogoniaceae, ascolichens) is described from the wet walls of a dimly lit dolomite cave in Missouri. The highly characteristic pastel green filaments are long, profusely branched, and 7-13 im wide. Thephycobiont, Physolinum monilia (De Wildem.) Printz (Trentepohliaceae, Chlorophyta), is tightly corticated by a flattened single layer of laterally adherent hyaline fungus cells. Hyaline ovate spores with walls covered by short spines occurred in groups of about eight near the mycobiont. Hair lichens composed of microscopic filaments with trentepohliaceous phycobionts (e.g., Jahns 1988) include species of Coenogonium, Cystocoleus, and Racodium. Racodium rupestre Pers. and Cys- tocoleus niger (Huds.) Hariot are sterile (Tscher- mak-Woess 1988) and have branching filamentous thalli that form brown-black crusts or cushions 3- 5 mm in height and 5-7 mm long. The dark colors are due to their brown to black fungus partners whose unbranching cylindrical hyphae are parallel to each other and laterally fused in a single layer that com- pletely covers the algal components (e.g., Jahns 1988). These hair lichens with dark fungus partners commonly occur in temperate climates (e.g., Shade 1932), and they are not related to Coenogonium.