Bryophyte species concepts are founded predominantly on gametophytic features, especially the gametophore. Natural variability of these features poses difficulties in sharp delineation of many species. Considerable experience and study of living plants is often essential in refining species concepts. Scrupulous typification is also vital. Some examples are presented from the main bryological evolutionary lines and the particular characters used in discrimination are noted.

  Chiloscyphus hattorii (Hepaticae) of New Zealand is described as new. It differs from the allied C. novaezeelandiae by characters involving the underleaves, branching, oil-bodies and spores. Heteroscyphus sexdentatus (Steph.) Engel, Leptoscyphus belmoranus (Steph.) Engel, L. excipulatus (Steph.) Engel and L. innovatus (Hodgs.) Engel are new combinations.

  Four species of Radula (Radulaceae, Hepaticae) from Bolivia, Brazil and Ecuador are described as new to science.

  Colura hattoriana spec. nov. and Cololejeunea magillii spec. nov. are described from the Comoro Archipelago. A brief analysis on the epiphyllous bryoflora of the islands is given.

  Description and illustration of two unusual species of Lejeuneaceae discovered in southeastern Brazil by the junior author (A. S.-V.) and his wife: Cheilolejeunea revoluta (Herz.) Gradst. & Grolle comb. nov. (=Pycnolejeunea revoluta Herz.) (C. subg. Euosmolejeunea sect. Revolutae Gradst. & Grolle, sect. nov.), a rare species described from Colombia and characterized by many “ptychanthoid” features including robust stem with broad ventral merophytes, flagelliform branches and androecia with bracteoles throughout the spike, and Leucolejeunea caducifolia Gradst. & Schäfer-Verwimp, a species new to science characterized by copious production of caducous leaves. Both species grow in areas with high precipitation, mostly in montane environments.

  Bryopteris bispinosa n. sp. is described and figured from Dominican amber (Miocene). For its bispinose lobule and irregularly coarsely dentate lobe this fossil species has an intermediate position between the extant B. diffusa (Sw.) Nees with lobule (2)3(4)-laciniate and lobe entire or almost so on the one hand and on the other all other extant Bryopteris species as well as the fossil B. succinea Grolle, previously described from Dominican amber. These all have an entire lobule, whereas their lobe can be entire or irregularly ± coarsely dentate.

  Sphaerocarpos stipitatus Bisch. ex Lindenb., recently segregated as Subg. Austrosphaerocarpos Schust., is reported from high altitude in East Nepal. Previously known from Chile and South Africa, and recently as an adventive in Portugal, this is the first report of Order Sphaerocarpales from Eastern Asia. Spore ornamentation under SEM is used to support the identification and differentiation from other species of Sphaerocarpos.

  Spore wall development in Fossombronia wondraczekii (Corda) Dum. is centripetal, beginning with the deposition of a distinctly patterned spore special wall around the young spores of the tetrad. This special wall appears to function as a primexine in which the pattern of the mature outer layer of exine is established during the early tetrad stage. Neither the common sporocyte wall or the special wall stained for callose. Next, an inner layer of exine is initiated by the production of tripartite lamellae (TPL) at the surface of the plasma membrane. The TPL form separate shallow discs of several layers which closely invest cytoplasmic lobes. Both the TPL discs and the underlying plasma membrane stain intensely with phosphotungstic acid-chromic acid. The discs of the TPL accumulate and compress into one or two continuous multilaminar bands. Sporopollenin impregnates the outer homogenous sculptured exine and the multilaminar bands of inner exine. The innermost layer of fibrillar intine is the last wall layer to be initiated. Developmentally, the Fossombronia spore wall represents a distinct type within the Metzgeriales and has no clear homology to other hepatic spores studied. The primexine-like spore special wall of Fossombronia differs from the preprophasic wall precursors in Pallavacinia, Haplomitrium and Apotreubia in that it is deposited in the tetrad stage and is non-callosic in nature. On the basis of spore wall ontogeny, the Metzgeriales appears to be a heterogenous assemblage.

  Description of two species of the genus Riccia (subgen. Riccia) collected in la Réunion: 1) R. hortorum Bory ex Lindenb., known only by the type whose spores are subspherical; 2) R. Helenae n. sp. having wide lobes (3-5.2 mm) and tetraedric spores with 9-10 alveolae in the diameter of the distal face and living until 1100 m alt. Fig. and photos of spores by SEM.

  A cladistic analysis of the genera of Anthocerotophyta is presented. The analysis was based on forty characters and included all nine genera currently accepted in the group. Only one most parsimonious tree was found. According to the results, the hornworts are treated as two orders: Anthocerotales Limpricht and Notothylales Hyvönen and Piippo, ord. nov. (merely with Notothylas Sull.). Anthocerotales comprises two families: Anthocerotaceae Dum. (Anthoceros L. emend. Prosk., Folioceros Bharadw., Leiosporoceros Hässel, Mesoceros Piippo, Phaeoceros Prosk., and Sphaerosporoceros Hässel), and Dendrocerotaceae (Milde) Hässel (with Dendroceros Nees and Megaceros Campbell).

  Twenty-five liverworts were investigated chemically and 20 new compounds isolated and their structures characterized by spectroscopic evidence, X-ray analysis and chemical correlation. The chemosystematics of each species is discussed.

  Evidence is offered that Cardot's name was inadvertently omitted in the protologue of Sphagnum fitzgeraldii. The authorship should be Renauld & Cardot instead of Renauld. A specimen in one of three packets of this moss in the Cardot Herbarium (PC) is designated the lectotype.

  Five species of Sphagnum are described as new: sect. Cuspidata, S. curvatulum (Ecuador) and S. steerei (Ecuador); sect. Subsecunda, S. santanderense (Colombia); sect. Acutifolia, S. austro-americanum (Chile) and S. lewisii (Colombia).

  Isozyme variation in eight enzyme systems in plants from 15 fens from three regions (boreal, subarctic, and high arctic) indicate that the gene diversity of Meesia triquetra, at 0.151, and genetic identity values (0.80-1.00) between populations of M. triquetra are comparable to those reported for many tracheophyte plant species. Gene diversity decreases significantly with increasing latitude, however patterns of gene diversity of the site level were more complex and suggest a highly dynamic species. In particular, subarctic sites have high between site gene diversity, while boreal sites have high within site gene diversity and high arctic sites are consistently low. Genetic identities are highest among the high arctic sites and lowest among the subarctic sites. The data suggest that the present-day regional gene diversity has evolved differently in each region.

  A study of British material of Ulota crispa (Hedw.) Brid. var. crispa and U. crispa var. norvegica (Grönvall) Smith & Hill showed good correlation between capsule shape, capsule-mouth areolation and peristome ornamentation as seen with SEM; over 95% of specimens could be positively identified using these characters, although mouth areolation is a complex and sometimes difficult character requiring careful use. Gametophyte characters are less well correlated and appear to be plastic, and are of little practical value for identification. We conclude that var. norvegica should be restored to specific status (as U. bruchii Hornsch. ex Brid.) even though the two taxa are not always easy to separate.

  Thuidium hattorii Touw is a new dioicous species belonging to the Lorentzia assemblage. It has been collected in the Philippines, Borneo, Sulawesi, Seram, and New Guinea. The Lorentzia assemblage consists of four species forming two very distinct groups differing in sexual condition and properties of the perichaetium, the calyptra, and the sporophyte. The type species (T. velatum) is the only monoicous one. The dioicous group comprises T. bifarium, T. hattorii, and T. plumulosum (previously accommodated in Thuidium subg. Thuidium). T. watanabei is a new species previously mistaken for T. contortulum and T. sparsifolium.

  The spores of 10 species of Atrichum were studied under the scanning electron microscope. The spores of Atrichum altecristatum, A. androgynum, A. angustatum, A. crispum, A. cylindricum, A. hausknechtii, A. oerstedianum, A. selwynii and A. undulatum all have gemmate ornamentation that often verge toward the verrucate type. Atrichum tenellum has spores that are usually gemmate ornamented but occasionally some spores in the same capsule have pilate sculpturing. The gemmate or verrucate spore ornamentation occurring in Atrichum is similar to that found in only two other Polytrichaceae genera, Psilopilum and Oligotrichum. The spore sculpturing of all 10 species is shown on micrographs.

  Field work in 1984 yielded at least 26 unreported species for the island group bringing to 53 the number of species reported. Two species (Bryum apiculatum and B. capillare) are reported only from Philip Island.

  Fifty-five species of mosses, including two fossils determinable only to genus, are reported from deposits associated with Lake Hitchcock, which occupied a major part of the Connecticut River Valley during the late Pleistocene. The Matianuck Avenue moss assemblage (from Windsor, Connecticut) is about 13,500 yr B.P., whereas the age of mosses from the Canoe Brook site (from Dummerston, Vermont) is 12,350 yr B.P. Both are AMS ages of Salix twigs found with the mosses. Vascular plant macrofossils, the moss assemblages, and pollen spectra from the organic beds indicate an open, floristically tundra-like vegetation in which many species of plants of present arctic and arctic-alpine distribution grew. The two moss assemblages share many species with the younger late-Pleistocene Columbia Bridge paleobryoflora from 250 km northward in the Connecticut Valley, indicating that a high degree of floristic similarity existed among sites in western New England that date to the period 13,500 to 11,500 yr B.P., although the tundra-like vegetation at the southern sites had given way to open boreal woodland by 11,500 yr B.P. The moss assemblages contain species that today are absent from New England but occur as disjuncts in the Gulf of St. Lawrence region and otherwise in arctic or arctic-alpine areas to the north. The fossils demonstrate how widespread these and other mosses were on glaciated surfaces south of areas to which they are now restricted. Some of the mosses are thought to indicate survival in ice-bound refugia near the Gulf of St. Lawrence, but late-Pleistocene occurrences in glaciated areas south of that region suggest that migration from sources to the south is an equally plausible explanation.

  Fifteen specimens of fossil mosses in Dominican amber have been studied. These are the first mosses from Dominican amber to be investigated and probably the first records of fossil mosses from the tropics. This is also the first critical study of mosses from amber in general. The fossils belong to nine species. Four species can be tentatively attributed to extant species, all of which are still widespread in the neotropics. The remaining species can be attributed to extant genera. This shows a remarkable constancy in the moss flora of the Carribbean over then past 25-40 million years. All representatives of the identified fossils are about 50% smaller than present-day specimens.

  Within the framework of a study into competition among chalk grassland bryophytes the light extinction through the canopy was studied in Calliergonella cuspidata, Rhytidiadelphus squarrosus and Ctenidium molluscum on two sampling dates (September and December). By relating the light profile through the canopy to the cumulative light intercepting area (=the moss shoot area index), light extinction coefficients (K) were calculated.

  At both sampling dates the K-values of Ctenidium were higher than those of Calliergonella and Rhytidiadelphus. This corresponds with the more appressed growth-form of Ctenidium.

  For all three species the K-values were higher in September than in December. At the same time shoot areas per unit dry weight were smaller in September than in December. Assuming a more or less constant amount of light-intercepting pigment (chlorophyll) per unit dry weight through the year, this means less light interception per unit shoot area in December, resulting in a lower extinction coefficient.

  This is a revision of some species of Xanthoria with isidia-like propagules, mainly from Mediterranean Europe. The following new taxa are described: X. elegans v. granulifera from Greenland and Spitzbergen, X. mediterranea from the central and southern Mediterranean region, and X. stiligera from the southern Mediterranean region, North Africa and southwestern Asia. X. papillifera is reported from the Karakorum. X. mediterranea should be closely related to X. parietina, whereas the affinities of X. stiligera are still not clear. The name “isidioidea”, which was frequently used for several species treated in this paper, especially for X. mediterranea and X. stiligera, is not applied here because the type material has been apparently lost; in any case, X. isidioidea does not belong to either species. Morphology, ecology and distribution of each species are briefly discussed, and a key for identification is provided.

  Two new species of Anzia, A. minor Yoshim. and A. tianjarana Yoshim. et Elix, and two species of Pannoparmelia, P.angustata (Pers. in Gaud.) Zahlbr. and P. wilsonii (Räs.) D. Gall. are recorded from Australia. A key to the species is given and their chemistry, distribution, ecology and taxonomy described.

  Hale (1987) recently reduced Parmelia psoromoides Räs. as a synonym of P. isidioclada Vain. P. psoromoides was described from the Philippines, whereas P. isidioclada seems to be endemic to Japan. Examination of the holotype of P. psoromoides revealed that the species was conspecific with P. sectilis Hale, the former having the priority. P. psoromoides seems to be endemic to Southeast Asia.

  The deleterious effects of the aggressive colonization by the lichen Dirina massiliensis forma sorediata on 16th century Renaissance frescoes in the Palazzo Farnese, Caprarola, are currently being investigated using Raman microscopic techniques. The physical and chemical characterization of the thallus-substratum interface and encrustation have been undertaken; the major component of the lichen-generated encrustation has been shown to be calcium oxalate monohydrate. Further experiments have given information about the depth of penetration of calcium oxalate in core samples and the distribution of particulate matter and its incorporation into the encrustation. Extension of these studies to other species such as Xanthoria parietina and Ochrolechia parella and their encrustations on natural substrata have demonstrated the sensitivity of Raman microscopic techniques for the quantitative estimation of calcium oxalate, even for low oxalate-producing species such as X. parietina and for spatial resolution of information where different species are growing together on the same substratum.

  The β-orcinol depsidones, convirensic acid (2), conprotocetraric acid (4), confumarprotocetraric acid [Cph-2] (6) and consuccinprotocetraric acid (8) have been identified in the lichens, Sulcaria virens, Usnea trichodeoides, Cladonia phyllophora and Flavoparmelia succinprotocetrarica respectively. These new depsidones have been synthesized and characterized, and their likely modes of biosynthesis discussed.

  In this checklist, Indochina is defined to include the vast geopolitical region south of the border of China and east of the Indian subcontinent, excluding the Malay Peninsula. A checklist of all Indochinese moss taxa reported in literature up to the end of 1992 is compiled. All accepted species are provided with Indochinese synonymy and locality information within the area. At present there are 55 families, 236 genera and 995 species of mosses reported from the region. We found six validly published binomials not included in Index Muscorum and the Index of Mosses 1963-1989. We propose 13 new names and new combinations for use in this checklist.