应用典范对应分析探讨长白山金发藓科植物的生态位分化

应用典范对应分析(Canonical Co rrespondence Analysis, CCA)对长白山主要生态系统30个样点中的13种金发藓科植物分布与环境因子间的关系进行了研究。发现在长白山地区,金发藓科植物在海拔高度、土壤含砂量、含水量、酸度、光照条件等资源维上存在明显的生态分化现象。13种金发藓科植物中,球蒴金发藓(Polytrichum sphaerothecium(Besch.)C.Mull.、高山异发藓短叶变种(Polytrichastrum alpinum var. brevifolium(R.Br.)Brid.)在海拔上,拟异发藓(Polytrichastrum formosum(Hedw.)G.L.Smith)、变形异发藓(Polytrichastrum dicipensLimpr.)、毛尖金发藓(Polytrichum piliferum Schred.ex Hedw.)、桧叶金发藓(Polytrichum juniperinum Willd.ex Hedw.)在光照上以及大金发藓(Polytrichum commune Hedw.)、直叶金发藓(Polytrichum juniperinum ssp. strictum(Brid.)Nhy.&Sael.)在土壤酸度与水分上的生态要求比较接近。     

Gametophytic simplicity in Laurasian and Gondwanan Polytrichopsida — the phylogeny and taxonomy of the Oligotrichum morphology

Abstract

Phylogenetic analyses have largely resolved generic and higher level relationships within the Polytrichopsida, enabling polarisation of characters and the identification of macro-evolutionary trends. Topologies show strong geographic patterning, with major groups having predominantly Northern or Southern Hemisphere distributions and some general morphologies having arisen independently on either side of the equator. While most cases of apparent convergence have been taxonomically visible due to sufficient higher-level characters being present to distinguish unrelated genera, convergent reduction may have resulted in conflation of similar gametophytic morphologies in classification. We present further evidence for the polyphyly of Oligotrichum DC. as currently circumscribed, showing how this morphology has probably arisen through reduction on multiple occasions to produce distinct lineages that have lacked taxonomic identity. We present a preliminary arrangement of the species currently recognised in Oligotrichum, accommodating selected Southern Hemisphere taxa in Itatiella G.L.Sm., and combining Atrichopsis compressa (Hook.f. & Wilson) G.L.Sm. and Oligotrichum tenuirostre (Hook.) A.Jaeger under Notoligotrichum G.L.Sm. For several species that clearly do not belong in Oligotrichum but remain of ambiguous affinity to other genera we avoid making new combinations, as ongoing combined molecular and morphological studies have considerable potential to elucidate their relationships in the near future.     

贵州喀斯特高原金发藓原变种(Polytrichum commune Hedw.var.commune)蒴齿水湿运动研究

为探究线齿藓类植物在水湿运动中蒴齿结构的变化及对孢子散发的影响,选取贵州喀斯特高原金发藓原变种(Polytrichum commune Hedw.var.commune)为研究对象,通过观察湿度变化下蒴齿结构差异及孢子释放规律,拟揭示水湿运动对孢子释放的影响和功能。结果显示:①湿度增加引起蒴齿间距及盖膜面积的显著增大,并在干燥时恢复。其中齿间距从8.33μm显著增加到11.53μm,同时盖膜面积扩大20%。②在连续风吹试验中,水湿运动初期孢子释放量显著提高,随蒴齿结构的恢复呈下降趋势,并最终保持在极低的孢子释放数量。同时发现,湿度增加导致孢子释放中簇孢占比的提高,并随孢子释放量的减少呈上升趋势,并在蒴齿结构恢复时达到显著差异。③通过单独对干燥期、水湿运动初期及蒴齿结构恢复期进行风吹试验发现,水湿运动初期孢子释放量显著高于干燥期和蒴齿结构再恢复期。当蒴齿结构恢复时,由于簇孢占比的提高,孢子的释放数量仍能显著高于干燥期。本研究表明在水湿运动中金发藓原变种蒴齿结构发生改变,进而显著提高孢子的释放量,并在蒴齿结构恢复时仍能保持高于干燥时的孢子释放能力,这对该物种的传播及繁衍具有积极的意义。     

The Genus Malenchus (Nematoda:Tylenchida) with Descriptions of Two Species from Michigan

Malenchus truncatus n. sp. and M. bryanti n. sp. from Michigan are describes and presented es the first record of Malenchus in North America. M. acarayensis Andrassy, 1968 is recorded and males of this species described. Notes on the geographical distribution of Malenchus and a key to the species are given.     

Discocriconemella repleta n.sp., and the male of Criconemoides inusitatus Hoffmann, 1974 (Criconematidae: Nematoda)

Discocriconemella repleta n.sp. from Brazil is described. The male of Criconemoides inusitatus Hoffmann, 1974, is described here for the first time.     

A new species of Bentleya. Bennett (Pittosporaceae) from southern Western Australia

CRISP, M. D. & TAYLOR, J. M., 1990. A new species of Bentleya E. Bennett (Pittosporaceae) from southern Western Australia. Hitherto Bentleya has been a monotypic genus known from a restricted area in south-west Western Australia. This paper describes a second species which was discovered recently in the same region. The new species differs from B. spinescens in its remarkable habit but shares with it several floral characters which are unique within the family.     

Laticifers in Euphorbiaceae–a conspectus

Laticifers in Euphorbiaceae–a conspectus. Despite the multitude of references on laticifers in Euphorbiaceae, much of the work concentrated on economically important, and often highly specialized genera, particularly Euphorbia and Hevea, the evolution of the laticifer in the family is poorly understood. In this paper, laticifers, in a representative sample of genera of Euphorbiaceae, are investigated with respect to morphology and distribution. This information is supplemented with a review of existing literature. It seems probable that the articulated and non-articulated types are not as divergent as commonly supposed, since both may undergo intrusive growth, although more ontogenetic studies are needed to clarify the relationship between them.