Перегляд Автор "Stephenson, Steven L."

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An annotated checklist of myxomycetes from the Seychelles Islands, Indian Ocean
(Finnish Mycological Society, 2020) Kryvomaz, Tetiana; Michaud, Alain; Stephenson, Steven L.; L.
The checklist provided herein contains 143 species and infra-specific taxa of myxomycetes representing six orders, 12 families and 29 genera known from the Seychelles Islands. These records are the result of 878 field collections and 468 samples processed with the use of the moist chamber techinque. The overall study involved expeditions to the granitic group of islands Mahé, Praslin, La Digue, Curieuse, Félicité, and data from the literature for the coral Aldabra atoll. The taxonomic structure of the myxomycete biota for the islands studied indicates a predominance of members of the order Physarales (74 taxa). The main genera are Physarum (38 species and two varieties), Didymium (17 species), Cribraria (11 species), Arcyria (eight species) and Stemonitis (six species and two varieties). For all six islands only a single species of myxomycete (Physarum crateriforme) was shared in common. For the total assemblage of species recorded from all of the islands, 4% species were abundant, 12% species were common, 29% were found occasionally, 42% were rare, and 13% species had only a single record. The most abundant species were Arcyria cinerea, A. denudata, Diderma effusum, Hemitrichia calyculata, Physarum compressum, and P. melleum. Based on data from 50 different localities with 90 collecting plots, 32% of all specimens were associated with coastal vegetation, 30% with lowland localities, 19% with intermediate forests, 9% with riverine forests, 8% with mountain forests, and only 2% with mangrove swamps. In general, this annotated checklist clearly shows that isolated tropical islands can support a diverse assemblage of myxomycetes.
First survey for myxomycetes on Mahe island in the Seychelles
(2017) Kryvomaz, Tetyana; Michaud, Alain; Stephenson, Steven L.
The results of the first survey for myxomycetes on Mahé Island in the Seychelles in the Indian Ocean are reported. Forty-seven species and infraspecific taxa were recorded. All of these are new for Mahé Island, 23 are reported for the first time from the Seychelles, four species (Diderma chondrioderma, Didymium dubium, Perichaena dictyonema and Physarum auriscalpium) and two infraspecific taxa (Fuligo septica var. candida and Physarum melleum f. luteum) are new records for islands in the Indian Ocean. Another species (Physarum sp.) is probably new to science but will require additional material before being formally described. Thirty-three taxa of myxomycetes were identified from field collections and 21 species were recovered from moist chambers cultures prepared with samples of the bark from living lianas. The survey was designed to assess the biodiversity and ecology of the assemblages of myxomycetes associated with three types of plant communities and several different types of substrates on the island. Most of the species recorded occurred on plant litter and on different the different types of substrates provided by coconut trees. A comparison of the myxomycetes assemblage of Mahé Island with the Aldabra Atoll, La Réunion Island and Madagascar show less than 50% similarity among these islands in terms of species diversity.
Myxomycete biodiversity on five islands of the Seychelles
(Magnolia Press, 2020) Kryvomaz, Tetiana; Michaud, Alain; Stephenson, Steven L.
A survey of myxomycete diversity on five islands of the Seychelles yielded 105 species and 10 infra-specific taxa, which included 89 species on La Digue, 66 on Praslin, 63 on Mahé, 31 on Curieuse and 4 on Félicité. Among these records, 64 species are new for the Seychelles and together with data from the literature, 143 species of myxomycetes are now known for all of the Seychelles. Most collecting on all five islands was carried out in low elevation areas. Forty-four species (73% of all specimens of myxomycetes) were found in low-elevation localities, and among these were Arcyria helvetica,Dictydiaethalium dictyosporum, Echinostelium paucifilum, Physarum aeneum, Ph. echinosporum, Reticularia olivacea, and Stemonaria longa. From 54 species of plants used by myxomycetes as substrates, eight species provided 63% of the specimens of myxomycetes, with most samples recorded from Calophyllum inophyllum. On the basis of substrate type, myxomycetes were distributed as follows: 37% of specimens were collected on dead wood and decaying palm stems, 16% on the bark and stems of living plants, 25% on ground litter, and 22% on aerial litter. A comparison of the assemblages of myxomycetes found in zones with different levels of human impact indicated that 84 species were found in forests, 74 in anthropogenic areas, and 62 in recreational coastal areas. The Seychelles provide a good background for a high level of myxomycete diversity, as a consequence of favorable climatic conditions and their location between Asia and Africa.
Preliminary evalution of the possible impact of climate change on myxomycetes
(2017) Kryvomaz, Tetyana; Stephenson, Steven L.
The myxomycetes (plasmodial slime molds or myxogastrids) are likely to be affected by climate change, since temperature and moisture are the main factors limiting their occurrence in nature. However, the resilience of myxomycetes to climate change is extremely difficult to determine due to their cryptic life history. It is possible that myxomycetes may represent one of the least affected groups of organisms, although all available evidence suggests that the anticipated changes in climate regimes are going to have a significant impact upon their distribution and ecology. This will be especially true for those species of myxomycetes restricted to particular types of microhabitats (e.g., alpine snowbanks) or which are confined to geographical areas that are limited in extent (e.g., small oceanic islands). The composition of assemblages of myxomycetes species associated with deserts, the polar regions and other ecosystems of the world also could be affected.