The distribution of Hemiragis aurea (Brid.) Ren. & Card. (Hookeriaceae, Musci) and related notes of interest

The horizontal and vertical range of Hemiragis aurea (Musci) is subdivided into four regions: I - N. Panama, Costa Rica, S. Nicaragua; II - circum-Caribbean; III - Guyana Highlands; IV - Andean. Ecological evidence is discussed in the context of the effects of volcanic eruptions, hurricanes, climactic changes and other factors

Altitudinal additamenta to the uppermost ranges of mosses in Ecuador

Of the 26 mosses listed in this report Amblystegium varium, Calliergonella cuspidata, Chrysoblastella chilensis, Drepanocladus aduncus, D. revolvens, Racomitium geronticum, and Scorpidium turgescens are new to the Ecuador moss-flora. The others listed provide updated reports on what was previously stated as their highest altitudinal ranges in both this country and the Neotropics. The taxonomic status of Drepanoclaus leitensis, D. polycarpus, Hypnum lacunosum and Racomitrium geronticum are discussed. Collections were made at: Chimborazo Volcano 4700-5200m, Cotopaxi Volcano 3900-4500m, Laguna Toreadore - peak of Patul Mt. 3800-4500m and on N. Tungurahua Mt., close to the tree limit at ca. 3800m

A supplement to the moss flora of Paraguay

In “A Preliminary List of the Mosses of Paraguay” Buck (1985) commented on the low level of bryological knowledge in this country. He also pointed out the need for muscological studies and encouraged collectors “to gather bryophytes whenever possible”. The present article follows this recommendation

Mosses of Tikehau Atoll (Tuamotu Archipelago, South Pacific)

Six moss species found on Tikehau Atoll in the Tuamoto Archipelago of French Polynesia are discussed in the context of their habitats and distribution. Selected ecological observations and some bryo-geobotanical problems are considered

Adaptations of lowland jungle mosses to anthropogenic environments in Guyana

Sixteen lowland jungle mosses growing in anthropogenic habitats at Santa and The Bell - Ituni localities on the Demerara River in Guyana were examined in detail with the aim of detecting any features which would indicate their adaptations to new habitats. Amounts of chlorophyll in leaf cells, protective coloration, alterations in leaf morphology, characteristics of old stems, rhizoid tomentum and fertility are considered as the most pronounced adaptive features of these species to new localities. The ecology, general appearance and morpho-anatomical changes of specimens from anthropogenic habitats were observed and compared with their equivalents from habitats occurring in the closest natural environments. No one species grows or has local centers of occurrence only in anthropogenic habitats. Generally, invasion of lowland jungle mosses into anthropogenic environments is considered as difficult, slow and limited

The discovery of a second locality in Peru for Pleuridum andinum Herz. (Ditrichaceae, Musci)

Pleuridium andinum Herz., a rare moss previously known from only 3 sites in South America, is here reported from a second locality in Peru. The new locality is near Aquas Caliente, Peru, ca. 5720 m a.s.l. This discovery is only one of three collections made since this species was first collected at the “locus classicus” in Bolivia in 1911. The holotype was examined and the original Latin diagnosis is amended in English as a result of examination of both the holotype and the newly discovered specimens. Previously unknown taxonomic features are figured

From Layers to Nanotubes: Transition Metal Disulfides TMS2

MoS2 and WS2 layered transition-metal dichalcogenides are indirect band gap semiconductors in their bulk forms. Thinned to a monolayer, they undergo a transition and become direct band gap materials. Layered structures of that kind can be folded to form nanotubes. We present here the electronic structure comparison between bulk, monolayered and tubular forms of transition metal disulfides using first-principle calculations. Our results show that armchair nanotubes remain indirect gap semiconductors, similar to the bulk system, while the zigzag nanotubes, like a monolayer, are direct gap materials, what suggests interesting potential applications in optoelectronics.Comment: published in EPJ B, 9 pages, 8 figure