Barge Edward G, Cripps Cathy L, Osmundson Todd W
Plant Science and Plant Pathology Department, Montana State University, Bozeman, Montana 59717
Plant Science and Plant Pathology Department, Montana State University, Bozeman, Montana 59717.
Mycologia. 2016 Mar-Apr;108(2):414-40. doi: 10.3852/15-177. Epub 2016 Jan 6.
Lactarius (Russulales) is an important component of ectomycorrhizal fungal communities in cold-dominated contiguous arctic and disjunct alpine habitats where it associates primarily with Betula, Dryas and Salix However, little is known of this genus in the central and southern Rocky Mountain alpine zone (3000-3900 m) of North America. Molecular phylogenetic analyses of nuc rDNA ITS1-5.8S-ITS2 (ITS barcode) and the second largest subunit of the RNA polymerase II gene (RPB2) partial sequences in conjunction with detailed morphological examination confirm at least six species occurring above treeline. Most have intercontinental distributions in North America and Eurasia according to molecular comparison with type material and collections from Europe, Fennoscandia, Svalbard and Alaska. Rocky Mountain collections of L. lanceolatus (subgenus Russularia), along with the type from Alaska are paraphyletic with respect to L. aurantiacus and North American taxa L. luculentus and L. luculentus v. laetus Rocky Mountain collections of L. nanus, L. glyciosmus, L. repraesentaneus and L. salicis-reticulatae (subgenus Piperites) all form clades with European material from type localities and other arctic-alpine habitats. The arctic-alpine L. pseudouvidus/L. brunneoviolaceus group appears to be a complex containing additional taxa. North American material originally described as part of this group is well-separated phylogenetically and is described here as L. pallidomarginatus sp. nov. Lactarius lanceolatus, L. nanus and L. salicis-reticulatae appear largely restricted to arctic-alpine habitats with Salix Lactarius glyciosmus and L. repraesentaneus occur in arctic-alpine, subalpine and boreal habitats with Betula and also Picea and possibly Salix for the latter. Species distributions are hypothesized to be shaped by host ranges, glaciation and long distance dispersal.
乳菇属（红菇目）是北极连续和高山间断寒冷生境中外生菌根真菌群落的重要组成部分，在这些生境中它主要与桦木属、仙女木属和柳属植物共生。然而，对于北美落基山脉中部和南部高山带（海拔3000 - 3900米）的该属真菌，人们了解甚少。通过对核糖体DNA ITS1 - 5.8S - ITS2（ITS条形码）和RNA聚合酶II基因第二大亚基（RPB2）部分序列进行分子系统发育分析，并结合详细的形态学检查，确认至少有6个物种出现在林线以上。根据与模式标本以及来自欧洲、斯堪的纳维亚半岛、斯瓦尔巴群岛和阿拉斯加的标本进行分子比较，大多数物种在北美和欧亚大陆具有洲际分布。落基山脉的披针乳菇（红菇亚属）标本，连同来自阿拉斯加的模式标本，相对于橙黄乳菇以及北美分类群亮黄乳菇和亮黄乳菇变种而言是并系的。落基山脉的矮小乳菇、甜乳菇、代表乳菇和网脉柳乳菇（派珀乳菇亚属）的标本均与来自模式产地及其他北极 - 高山生境的欧洲标本形成分支。北极 - 高山的假淡黄乳菇/褐紫乳菇组似乎是一个包含其他分类单元的复合体。最初被描述为该组一部分的北美标本在系统发育上与其他标本有明显区分，在此被描述为苍白缘乳菇新种。披针乳菇、矮小乳菇和网脉柳乳菇似乎主要局限于与柳属植物共生的北极 - 高山生境。甜乳菇和代表乳菇出现在北极 - 高山、亚高山和北方生境，与桦木属植物共生，对于后者还与云杉属植物共生，可能也与柳属植物共生。据推测，物种分布受宿主范围、冰川作用和远距离扩散的影响。
