基于rDNA ITS序列对绒泡菌目黏菌系统发育的探讨

绒泡菌目Physarida是黏菌纲Myxogastria最大的一个目,对其系统发育关系的研究一直是根据形态特征。为了从分子水平探讨绒泡菌目乃至黏菌纲的系统发育关系,以黏菌r DNA ITS通用引物对绒泡菌目5属8种黏菌的r DNA ITS进行扩增和测序,结合Gen Bank中已有的黏菌r DNA ITS序列,利用贝叶斯推断法(Bayesian inference,BI)和最大似然法(Maximum likelihood,ML)构建系统发育树。结果表明:绒泡菌目不同物种的r DNA ITS区在碱基组成和长度上差异明显,长度为777–1 445bp,G+C mol%在53.4%–61.9%之间。绒泡菌目与发网菌目Stemonitida聚类为两个明显的分支,在绒泡菌目分支上,绒泡菌科Physaraceae和钙皮菌科Didymiaceae各聚为一支,支持了形态学上以孢丝是否具有石灰质为依据区分这两个科的观点。由多份不同地理来源的鳞钙皮菌Didymium squamulosum材料组成的钙皮菌科又形成3个分支,证实了这个形态种是由地域来源广泛、繁殖亲和性各异和遗传变异较大的不同生物种组成的复合体。

Myxomycete diversity in the Tarim basin and eastern Tian-Shan,Xinjiang Prov.,China

We report the results of a survey for myxomycetes in the Chinese province of Xinjiang,covering the northern part of the Tarim basin and the eastern Tian-Shan mountains.Sampling in the hyperarid Tarim basin focused on monospecific Tugai forests;these are park-like stands of the phreatophyte Populus euphratica.In a transect from the Tarim basin to the mountains,trees vanish outside the basin,but reoccur at ca.1,400 m elevation as monospecific forests of Picea schrenkiana;the second focal area of the study.From a total of 362 substrate samples(245 from the Tarim basin,177 from the mountains)we obtained 477 determinable records of myxomycetes,plus a total of 206 field collections,the latter almost exclusively from the spruce forests in the mountains.From the 80 taxa recorded 53 are represented by field collections,and 32 were found in moist chamber cultures;with a very low overlap in species assemblages found in the field and in cultures.Although receiving less than 50 mm annual precipitation,corticolous myxomycetes were common in the Tugai forests,with Physarum pseudonotabile ad.int.,Didymium anellus,Echinostelium colliculosum and Protophysarum phloiogenum as the most common species.Compared to the Tarim basin(21 taxa)the mountains were much richer in myxomycetes(75 taxa),although the diversity recovered from cultures was comparable(21 vs.28 taxa).Most species from the mountains fruited on decaying spruce,often collected under or even inside the logs due to the extremely dry air.Our results suggest first that there is no lower limit of annual precipitation for myxomycetes,as long as at least some days with nightly dew fall allow these organisms to complete their life cycle.Second,the two examples of surprisingly diverse myxomycete assemblages from monospecific forests demonstrate,that species richness of this group is not necessarily connected with plant diversity of the habitat.This survey is the most eastern of a large-scale study of myxomycete diversity throughout Middle and Central Asia.

Biodiversity studies of myxomycetes in Madagascar

The results of the first comprehensive study of myxomycetes from the island of Madagascar,a world biodiversity hotspot,are reported in this paper.The island is of continental origin,the fourth largest in the world,and has been geographically isolated for more than 160 million years,since its separation from Gondwanaland.The isolation,size and topography of Madagascar have triggered the development of a great variety of different habitats and favoured multiple evolutionary pathways,resulting in many animals and plants that exist nowhere else on earth.Fieldwork for the biodiversity survey of the central and southern parts of the island took place in May 2009,to coincide with the end of the rainy season.Tropical moist forest,sclerophyll forest and dry forest were selected for sampling in Ranomafana,Andringitra,Andohahela and L’Isalo National Parks.Some unique vegetation was sampled in the spiny dry forest and succulent scrub with plants from the genera Alluaudia,Euphorbia,Kalanchoe and Pachypodium.The survey produced 124 species from 22 different genera in more than 750 myxomycete collections.In this paper one species,Perichaena madagascariensis,is described as new to science,21 species are new records for Africa,and 106 are reported for the first time from Madagascar.Some unusual collections included Physarum lakhanpalii that appeared on Ravenala madagascariensis,Fuligo intermedia and Licea nannengae found on Adansonia grandidieri,Perichaena pulcherrima,Physarum dictyosporum,and P.echinosporum on Euphorbia and Licea rufocuprea on bark.The scope,methods and results of this survey are included in this paper,and comments are made on the ecology,distribution and substrate association of the myxomycetes of these areas of Madagascar.Macrographs,micrographs and SEM images of interesting species are included.The results indicate that the island of Madagascar has a unique assemblage of species of myxomycetes,different from neighbouring islands and from similar but distant environments.

The biodiversity of myxomycetes in central Chile

The results obtained from two expeditions to survey the biodiversity of myxomycetes in Central Chile are reported in this paper.The surveys were carried out as part of Global Biodiversity of Eumycetozoans project funded by the National Science Foundation(USA)and the Myxotropic project funded by the Spanish Government.The expeditions were made to the temperate zone of the central part of the country between 23°and 39°South latitudes,which is characterized by Mediterranean vegetation,as well as to the transition areas between the arid and semi-arid regions of northern Chile,and the humid,cold Valdivian and Andean-Patagonian forests of the far South.Eight of the fifteen regions of the country,from Antofagasta to Araucanía,in selected areas where the native vegetation is well preserved,were included in these surveys.Over 600 collections were obtained,and a total of 110 species of myxomycetes representing 29 genera have been identified.Two of these(Dianema succulenticola,Didymium chilense)are species new to science and are described in this paper,12 species(Collaria nigricapillitia,Comatricha alta,Cribraria oregana,Dianema depressum,Didymium eximium,D.nivicolum,Enerthenema melanospermum,Lepidoderma chailletii,Macbrideola ovoidea,Physarum clavisporum,Ph.newtonii and Trichia alpina)were previously unknown for either the Neotropics or South America,and 49 additional species are new records for Chile.Comments are provided on the morphology,distribution and ecology of selected species and light and SEM micrographs of the most significant species are included.An evaluation of the biodiversity of myxomycetes in Chile,with special emphasis on the endemic plants that provided the substrates with which they were associated,and a comparative analysis of our results with those from other countries of South America is presented.

Diversity of nivicolous myxomycetes of the Teberda State Biosphere Reserve (Northwestern Caucasus,Russia)

Nivicolous myxomycete assemblages were surveyed on the northwest of the Greater Caucasian ridge in May-June 2010 and 2011 at a north facing transect between 1,700 and 2,920 m elevation of the summit Malaya Khatipara situated within the Teberda State Biosphere Reserve.Morphological characters of 396 collections representing 45 taxa(39 species,3 varieties,and 3 forms)of myxomycetes in 8 genera and 5 families were recorded.Many(13)taxa are classified as rare(a species represents<0.5%of all records).Only seven species were found to be widely distributed(present in 50%or more of the 17 studied localities).To confirm the assignment of specimens to morphospecies,we obtained independently from determination 145 partial sequences of the 18S SSU rRNA gene from 35 taxa of Lamproderma,Meriderma,Physarum and Diderma,which turned out to represent 58 genotypes.Most of the taxa represented by more than one sequence had several genotypes,with an average of 1.7 genotypes per taxon.Except for three taxonomically difficult groups of species,partial SSU sequences did well correspond with the respective morphospecies and where similar or identical to sequences of specimens from the European Alps,making this marker a good candidate for barcoding in myxomycetes.Species richness and diversity increased from subalpine crooked-stem birch forests(23 species,2 varieties,H′02.8,E00.88,D00.08)to alpine dwarf shrub communities(34 species and 2 varieties,2 forms,H′03.2,E00.89,D00.05)but decreased again for alpine meadows(27 species and 2 varieties,2 forms,H′03.1,E00.91,D00.06).Species richness and alpha-diversity reached maximum values for ground litter,whereas leaves and stems of living shrubs above ground harboured a more depauperate myxomycete assemblage.