Parenchymatous cell division characterizes the fungal cortex of some common foliose lichens.

PREMISE OF THE STUDY: Lichen-forming fungi produce diverse vegetative tissues, some closely resembling those of plants. Yet it has been repeatedly affirmed that none is a true parenchyma, in which cellular compartments are subdivided from all adjacent neighbors by cross walls adjoining older cross walls. METHODS: Using transmission electron microscopy (TEM), we tested this assumption by examining patterns of septum formation in the parenchyma-like cortex of three lichens of different phylogenetic affinities: Sticta canariensis, Leptogium cyanescens, and Endocarpon pusillum. KEY RESULTS: In the cortex of all three lichens, new septa adjoined perpendicularly or obliquely to previous septa. Septal walls possessed an electron-transparent core (median) layer covered on both sides by layers of intermediate electron density. At septal junctures, the core layer of the newer septum was not continuous with that of the older septum. Amorphous, electron-dense material often became deposited in the core region of older septal walls, and the septum gradually delaminated along its median into what could then be recognized as the distinct walls of neighboring cells. However, cells maintained continuity at pores, where adjacent remnants of the electron-transparent core layer suggested septal partition rather than secondary establishment of a lateral wall connection via anastomosis. CONCLUSIONS: Although fungal tissues first arise by the coalescence of filaments early in lichen ontogeny, the mature cortical tissues of some lichens are comparable to true parenchyma in the unrestricted orientation of their septal cross walls and the resulting ontogenetic relationship among neighboring cell compartments.

Notes on the lichen genus leptogium (collemataceae, ascomycota) in South Korea.

Leptogium (Ach.) Gray is distributed throughout South Korea; however, for nearly two decades no detailed taxonomic or revisionary research on this lichen genus has been conducted. This study examined the specimens deposited in the lichen herbarium at the Korean Lichen Research Institute, and samples were identified using descriptions recently published in the scientific literature. In this revisionary study, a total of fourteen species of Leptogium were documented, including new records of Leptogium delavayi Hue, Leptogium denticulatum Nyl., and Leptogium trichophoroides P. M. Jørg. & A. K. Wallace. Detailed descriptions of each species are given, including their morphological, anatomical, and chemical characteristics. A key to all Leptogium species known to occur in South Korea is also presented.

Notes on the Lichen Genus Leptogium (Collemataceae, Ascomycota) in South Korea

Leptogium (Ach.) Gray is distributed throughout South Korea; however, for nearly two decades no detailed taxonomic or revisionary research on this lichen genus has been conducted. This study examined the specimens deposited in the lichen herbarium at the Korean Lichen Research Institute, and samples were identified using descriptions recently published in the scientific literature. In this revisionary study, a total of fourteen species of Leptogium were documented, including new records of Leptogium delavayi Hue, Leptogium denticulatum Nyl., and Leptogium trichophoroides P. M. Jorg. & A. K. Wallace. Detailed descriptions of each species are given, including their morphological, anatomical, and chemical characteristics. A key to all Leptogium species known to occur in South Korea is also presented.