Coccocarpia palmicola (Sprengel) Arvidsson & D. Gallow.
Salted Shell Lichen
Basis for Listing
Coccocarpia is primarily a tropical genus, and the previously known range of C. palmicola extended north only to southern Ohio. When this lichen was listed as a special concern species in Minnesota in 1984, it was known from only one site in Cook County, which represented a significant range extension to the north. Most of the populations between northern Minnesota and southern Ohio have probably been eliminated by air pollution and habitat destruction. The Cook County discovery suggested that further survey work might result in additional locations in the state, but intensive searches for this species have yielded only one additional location in Chisago County. Coccocarpia palmicola was subsequently reclassified as a threatened species in 1996.
A foliose (leaflike) lichen, the thallus (lichen body) of C. palmicola is blue-gray, smooth, and has small, cylindrical isidia (fingerlike projections on upper surface). Apothecia (disc-like fruiting bodies) are absent or rare. The lower surface of the thallus is dark in the center and pale at the margins, with a matted tomentum, making it appear fuzzy. The lower surface lacks veins, pores, and rhizines (root-like structures). When wet, this species becomes gelatinous. Coccocarpia palmicola has blue-green algae (Wetmore 2005).
This rare lichen occurs on the bases of deciduous trees and mossy rocks, in shaded conditions. In Minnesota, it has been found around rock ledges in a Picea mariana (black spruce) and Abies balsamea (balsam fir) forest, and around rock ledges near the St. Croix River with hardwoods and a few Pinus strobus (white pines).
Biology / Life History
Coccocarpia palmicola reproduces asexually, through the use of isidia. These fingerlike projections, which contain both fungal and algal cells, break off the upper surface of the lichen and are dispersed by wind, water, animals, or insects. When dispersed isidia find suitable habitat, the cells reproduce and a new thallus begins to grow.
Conservation / Management
Because this lichen is so rare, it is difficult to say with certainty what the major threats to its long-term survival are. However, habitat loss caused by global climate change, certain timber harvesting practices, and natural events most likely pose a serious threat to the survival of this lichen.
Conservation Efforts in Minnesota
Scientists are searching for this and other rare lichens in an attempt to identify and possibly preserve local populations.
References and Additional Information
Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. Lichens of North America. Yale University Press, New Haven, Connecticut. 795 pp.
Wetmore, C. M. 1981 (revised 2005). Keys to the Lichens of Minnesota. Department of Plant Biology, University of Minnesota, St. Paul, Minnesota. 92 pp.