The following paper represents one of a series on the current status of the tropical genus Leucoloma Brid. The first portion of the paper summarizes the morphological characters of the genus to set the foundation for the revision of Subgenus Leucoloma. Two additional papers on Leucoloma are found in this volume of THE BRYOLOGIST. The results presented here incorporate the phylogenetic and biogeographic analyses that have been published previously (La Farge-England 1998). The focus of this paper is the revision of Leucoloma subgenus Leucoloma in Africa and Madagascar. This includes a revision of 25 species, including two new species, two new subspecific taxa, and one new combination (Leucoloma madagascariense sp. nov., L. membranaceum sp. nov., L. chrysobasilare ssp. africana ssp. nov., L. ochrobasilare ssp. longifolium comb. nov., L. zuluense var. ovatum var. nov.), new synonymy, a key to species and subspecific taxa, distribution maps, and illustrations of each species.

The current study is a revision of Leucoloma Brid. Subgenus Syncratodictyon Series Holomitrioidea (Ren.) La Farge-England that includes two new species–Leucoloma circinale La Farge sp. nov., endemic to Tanzania and Leucoloma marojeziense La Farge sp. nov., an endemic from the massif of Marojezy in northeastern Madagascar. The series includes four species that are characterized by having hyaline margins restricted to the lower portion of the leaf; differentiated, bulging, scalariform alar cells; strongly contorted, apiculate leaves; unusual biseriate papillae formation; and sharply differentiated, sinuose upper cells, with the basal cells extending up along the margins. The species are endemic to the lowland to elfin rainforests of Madagascar, East African Islands, and East African montane forests of central Tanzania. The phylogenetic and phytogeographic relationships of Series Holomitrioidea have been considered elsewhere (La Farge-England 1998).

The current synopsis of Leucoloma Brid. nom. cons. is an annotated list of the accepted names that includes nomenclatural novelties, type citations, protologue data, and synonyms. The list includes 131 taxa with 118 synonyms. No type material was seen for five species and two varieties. One species is listed as a nomen nudum until the necessary nomenclatural changes can be made and is included here for completion sake. Another species is tranferred to Dicranoloma with two synonyms, whereas two species previously described as Dicranoloma species are transferred here to Leucoloma [Leucoloma onraedtii (Biz.) La Farge, comb. nov. and Leucoloma entabiense (Magill) La Farge comb. nov.]. A condensed alphabetical list of species, subspecies, varieties, and forms provide a ready reference for all accepted names and synonymy currently in Leucoloma. Each taxon has its subgeneric placement indicated. An additional alphabetical list of 106 excluded taxa with generic placement is included for a nomenclatural synopsis of Leucoloma.

Floras facilitate the identification of plants from a particular region. This essay reviews the historical development of printed lichen floras utilizing dichotomous keys for North America. In the future ‘virtualfloras' utilizing a more flexible electronic keying system will be possible. Additionally, essential components of such virtual floras include several databases–for characters, collections, images, synonyms and accepted names, literature, and terminology (glossary). Integration of the various components utilizing both centralized and distributed approaches is now possible, and will lead to a comprehensive on-line lichen determination system. Proposed ways, in which the data can be used beyond simple species determination, are also briefly discussed.

The type material of Plagiothecium drepanophyllum Renauld & Cardot from Cocos Island off the Pacific coast of Costa Rica is re-assessed, and some details of its gametophyte are illustrated. It is inseparable from, and thus synonymous with Lepidopilum scabrisetum (Schwägr.) Steere. Accordingly the correct name for the widely distributed and most common Neotropical species of Plagiothecium, which has so far been called P. drepanophyllum, is P. standleyi E. B. Bartram, described from Guatemala. The type material of P. standleyi is briefly assessed and some of its diagnostic characters are illustrated.

Fourteen new species are described from western North America– Rinodina aurantiaca, R. badiexcipula, R. boulderensis, R. californiensis, R. endospora, R. grandilocularis, R. innata, R. juniperina, R. lignicola, R. lobulata, R. macrospora, R. pacifica, R. perreagens, and R. verruciformis. Characters on which they are based are discussed in detail and a new spore type for Rinodina is introduced. The new species are compared to others, with which they might be confused and a key provided. Rinodina dolichospora is recorded for the first time from North America.

Abundant canopy lichen communities characterize wet-temperate rainforests on the windward slopes of interior mountain ranges in north-central British Columbia, Canada. Historically, these forests have regenerated through gap-dynamics; however, our knowledge of lichen colonization within gaps is limited. We have now compared lichen biomass on regenerating trees in naturally occurring 1–3 ha gap-disturbances (these gaps presumed to have originated from insect out-breaks in the late 1800's) with those on regenerating trees of similar age growing in the understory of the surrounding old growth forest. Only small differences were seen in total lichen biomass on regenerating trees between the two settings, however, analysis of the individual lichen groups (Alectoria, Bryoria, Foliose, and Cyanolichen) revealed striking differences. The Bryoria group was 35% more abundant on gap trees (632 g/tree) and was distributed vertically through a larger proportion of the tree crown. The Cyanolichen functional group was largely absent from gap trees, despite high levels of biomass loading (1,332 kg/ha) in the surrounding old-growth stand. Alectoria and Foliose functional groups did not differ significantly in biomass or distribution between regenerating trees of the two types. Tree size positively affected lichen loading. Total lichen biomass was 38% greater on the larger size class (31–44 cm dbh) regenerating trees, with the Alectoria functional group alone having 45% greater biomass on larger trees. Presence or absence of leaves on branch substrate had no effect on lichen loading. Stand-level projections indicate that the old growth forest had 19% more arboreal lichen biomass (2,684 kg/ha) and contained greater lichen species diversity than did the “second-growth” regenerating forest patches. The low cyanolichen biomass in naturally occurring gap openings poses concern for the proposed utility of “new-forestry” type harvesting practices to retain canopy biodiversity using current harvest rotation intervals.

Three species of the hepatic genus Isotachis are reported from China. The occurrence of Isotachis japonica in China is confirmed; I. armata is reported as new to China; and I. chinensis Gao, Cao & Sun is described as new. The latter is characterized by bifid, sometimes trifid leaves, with nearly entire margins and leaf cells with distinctly thickened transverse walls. Descriptions, illustrations, and distributions of each species are presented.