RESUMO
A new species of the genus Diachea (order Physarales, Myxomycetes, Amoebozoa) is described from Peru. Relevant details on spore germination, as well as morphological and phylogenetic data, are provided. At first glance, the new species shares some morphological similarities with both D. leucopodia, type of the genus, and D. koazei, but it strikingly differs from all other species of its genus by combining a short dark stalk, with a reticulate columella, and clustered spores. Moreover, it seems to be the only species of Diachea exclusively associated with Polylepis tropical forests at elevations above 3500 m. Apart from a comprehensive morphological study of 31 specimens, we here provide phylogenetic evidence to confirm the inclusion of this species in the genus Diachea. Specifically, our phylogenetic analyses of the nuclear 18S rDNA (18S), mitochondrial 17S rDNA (17S), and elongation factor-1 alpha (EF-1α) genes show that the new species is related to D. leucopodia and D. bulbillosa. The remarkably different morphological characters distinguishing the new Diachea from all other species of its genus, along with its particular ecological preferences and geographic distribution, indicate that it is a distinct entity deserving recognition as an independent species.
Assuntos
Mixomicetos , DNA Ribossômico/genética , Florestas , Mixomicetos/genética , Peru , FilogeniaRESUMO
A new nivicolous myxomycete is described as a result of a comprehensive study of Didymium nivicola collections from the entire range of its occurrence. Statistical analysis of 12 morphological characters, phylogenetic analyses of nuc 18S rDNA and elongation factor 1-alpha gene (EF1A), and a delimitation method (automatic barcode gap diversity) have been applied to corroborate the identity of the new species. A preliminary morphological analysis of D. nivicola revealed high variability of South American populations where four types of spore ornamentation were noted. However, results of molecular study and statistical analysis of morphological characters did not support recognition of these four forms but the distinction of two morphotypes. Consequently, two species have been recognized: D. nivicola and the newly proposed D. pseudonivicola. The new species can be distinguished from D. nivicola by distinctly larger and mostly plasmodiocarpic sporophores, which are scattered to gregarious, paler spores, and by the paler, more delicate and more elastic capillitium. Spore ornamentation of D. pseudonivicola is uniform and can be described as distinctly spiny (pilate under scanning electron microscope [SEM]), whereas those of D. nivicola is more variable, where spines (pilae under SEM) are delicate, distinct, or conspicuous. Additionally, whereas D. nivicola is a species distributed worldwide, D. pseudonivicola occurs only in the austral Andes of Argentina and Chile.
Assuntos
Mixomicetos , Physarida , Argentina , DNA Ribossômico/genética , Mixomicetos/genética , Filogenia , Physarida/genéticaRESUMO
Nivicolous myxomycetes are a group of amoebozoan protists dependent on long-lasting snow cover worldwide. Recent fine-scale analysis of species diversity from the austral Andes revealed high intraspecific variability of most taxa, suggesting independent evolutionary processes and significant differences in species compositions between the Northern (NH) and Southern (SH) Hemispheres. The present study is the second part of this analysis based on representatives of Trichiales. A total of 173 South American collections were studied based on morphological and molecular data, and 15 taxa have been identified. Two of them, Hemitrichia crassifila and Perichaena patagonica, are proposed as new species confirmed by a phylogeny of Trichiales. However, their affinity to the genera in which they are proposed are not confirmed due to polyphyletic character of all genera of Trichiales. Four species, Dianema subretisporum, Trichia contorta var. karstenii, T. nivicola, and T. sordida, are reported for the first time from the Southern Hemisphere. One species, T. alpina, is new for Argentina. Additionally, we provide the first record of Perichaena megaspora from Chile. Specimen frequency and species diversity of Trichiales found at nivicolous localities in the austral Andes are unexpectedly high, exceeding those of Stemonitidales, the most numerous group in the Northern Hemisphere, where Trichiales play a marginal role. By contrast, Trichiales appear the main component of nivicolous assemblages in the Andes. Results of the present work, together with the earlier analysis of Stemonitidales, indicate that the Andes constitute an exceptionally important evolutionary hot spot for nivicolous myxomycetes characterized by an outstanding species diversity.
Assuntos
Biodiversidade , Mixomicetos/classificação , Argentina , Chile , DNA de Protozoário/genética , Mixomicetos/citologia , Mixomicetos/genética , Mixomicetos/crescimento & desenvolvimento , Fator 1 de Elongação de Peptídeos/genética , Filogenia , RNA Ribossômico 18S/genética , Análise de Sequência de DNA , Neve/parasitologiaRESUMO
A new species of myxomycete, Perichaena longipes, is described from 56 sporocarp specimens that appeared in moist chamber cultures prepared with samples of decaying plant materials collected in Panama, Costa Rica and Brazil. This new species is distinguished from the morphologically similar species P. pedata on the basis of the much longer stipe, lighter peridium and the unique ornamentation of the capillitium. The nuc 18S ribosomal DNA sequences obtained from four specimens of P. longipes support the distinction of this new taxon and its separation from P. pedata. Furthermore, maximum likelihood phylogeny supports earlier evidence that species currently within the genus Perichaena do not form a monophyletic clade. Instead they appear to form three separate branches within the bright-spored clade. The first clade includes P. longipes together with several species of Trichia and Metatrichia, the second includes P. pedata and P. chrysosperma, and the third clade is composed of P. corticalis, P. depressa and P. luteola.
Assuntos
DNA Fúngico/genética , Mixomicetos/classificação , Mixomicetos/genética , Microscopia Eletrônica de Varredura , Mixomicetos/ultraestrutura , Panamá , RNA Fúngico/genética , RNA Ribossômico 18S/genética , Especificidade da EspécieRESUMO
A new species of Didymium (Myxomycetes), D. xerophilum, is described, and some details of its life cycle are provided. The new species was collected during studies of arid areas of Argentina and Peru. It can be distinguished by the persistent funnel-shaped invagination of the peridium, the top of which appears as a deep umbilicus in closed sporothecae, and the calcareous hypothallus shared among several sporocarps. This combination of characters, with a circumscissile dehiscence of the sporotheca and a cream stalk packed with rhombic lime crystals, is unknown in other described species. Morphology was examined with scanning electron microscopy and light microscopy, and micrographs of relevant details are included here. Phylogenetic analysis with 18S rDNA sequences of different species of Didymium supports the distinct identity of this new species. Some collections of this myxomycete were made at up to 4600 m, an altitude almost unknown for this group of microorganisms.
Assuntos
Mixomicetos/classificação , Mixomicetos/isolamento & purificação , Altitude , Argentina , Dados de Sequência Molecular , Mixomicetos/genética , Mixomicetos/crescimento & desenvolvimento , Peru , Filogenia , Esporos de Protozoários/classificação , Esporos de Protozoários/enzimologia , Esporos de Protozoários/genética , Esporos de Protozoários/isolamento & purificaçãoRESUMO
Based on morphological investigations and a phylogeny constructed with partial sequences of the SSU rDNA gene, we revalidate the genus Alwisia and propose the combination Alwisia bombarda Berk. & Broome to be used against Tubifera bombarda (Berk. & Broome) G.W. Martin. Two new species, Alwisia morula and A. repens, are described based on material collected respectively in Costa Rica and Australia. Both new species lack a capillitium and possess individually stalked subspherical sporothecae. Alwisia repens differs from A. morula by its procumbent stalks and iridescent peridium. A comparison of 83 sequences of species in the genera Lycogala, Reticularia and Tubifera with a recent two-gene phylogeny of the bright-spored myxomycetes resulted in a similar topology of both Bayesian and maximum likelihood trees and placed A. bombarda, A. morula and A. repens in one well delimited clade within Reticulariaceae.
Assuntos
Mixomicetos/classificação , Austrália , Sequência de Bases , Teorema de Bayes , Costa Rica , DNA Ribossômico/química , DNA Ribossômico/genética , Carpóforos , Microscopia Eletrônica de Varredura , Técnicas de Tipagem Micológica , Mixomicetos/genética , Mixomicetos/isolamento & purificação , Mixomicetos/ultraestrutura , Filogenia , RNA Ribossômico 18S/genética , Análise de Sequência de DNARESUMO
It is often discussed whether the biogeography of free-living protists is better explained by the 'everything is everywhere'(EiE) hypothesis, which postulates that only ecology drives their distribution, or by the alternative hypothesis of 'moderate endemicity' in which geographic barriers can limit their dispersal. To formally test this, it would be necessary not only to find organisms restricted to a geographical area but also to check for their presence in any other place with a similar ecology. We propose the use of environmental niche models to generate and test null EiE distributions. Here we have analysed the distribution of 18S rDNA variants (ribotypes) of the myxomycete Badhamia melanospora (belonging to the protozoan phylum Amoebozoa) using 125 specimens from 91 localities. Two geographically structured groups of ribotypes congruent with slight morphological differences in the spores can be distinguished. One group comprises all populations from Argentina and Chile, and the other is formed by populations from North America together with human-introduced populations from other parts of the world. Environmental climatic niche models constructed separately for the two groups have significant differences, but show several overlapping areas. However, only specimens from one group were found in an intensively surveyed area in South America where both niche models overlap. It can be concluded that everything is not everywhere for B. melanospora. This taxon constitutes a complex formed by at least two cryptic species that probably diverged allopatrically in North and South America.