Phylogeny of Laboulbeniales (Ascomycetes)

小行星9615520 虫囊菌目（Laboulbeniales）包括微小的真菌，它们是专性外寄生在各种节肢动物宿主上的。它们奇异的形态和有趣的生态关系使它们成为进化研究的迷人主题。尽管真菌学家和昆虫学家在一般意义上都知道这些非凡的子囊菌，但很少有人对它们进行持续的研究。2,000个已命名的物种是不稳定的。作为一个群体，Laboulbeniales的特征在于缺乏大多数真菌体的典型管状丝（菌丝体），而是具有由有性孢子分裂引发的少细胞体，然后是穿过节肢动物宿主角质层生长以获得营养的吸器。由于它们通过宿主接触传播，通常在交配过程中，虫囊菌目的物种通常具有可能作为孢子释放触发器的过程和结构。这群真菌的形态如此不寻常，以至于它们一度被认为是红藻的寄生后代。它们生活史的有趣特征为系统发育分析提供了许多形态学特征，但还没有进行这样明确的研究。 目前的研究借鉴了Meredith Blackwell教授以前对具有更典型形态和生命周期（包括其他真菌和节肢动物的寄生阶段）的腐殖菌相关子囊菌真菌的研究。系统发育的工作将包括形态学特征的研究，生活史阶段，核核糖体DNA的核苷酸序列多样性作为一个来源的字符分类分辨率和谱系重建。一个系统发育框架的属和科的顺序，从而改善分类，是一个主要的目标。另一个目标是探索不同节肢动物宿主上虫囊菌目群体之间的宿主转移和物种形成的假说。

9615520 Blackwell The taxonomic order Laboulbeniales includes minute fungi that are obligate ectoparasites on a variety of arthropod hosts. Their bizarre morphology and interesting ecological relationships make them fascinating subjects for evolutionary investigation. Although known in a general sense to mycologists and entomologists, these remarkable ascomycetes have attracted little sustained study, and the taxonomic classification of the c. 2,000 named species is unstable. As a group, the Laboulbeniales are characterized by the absence of the tubular threads (mycelia) typical of the bodies of most fungi, but instead possess few-celled bodies that are initiated by division of the sexual spores, followed by haustoria that grow through the arthropod host cuticle to obtain nutrients. Because they are dispersed through host contact, often during mating, species of Laboulbeniales often have processes and structures that may act as triggers for spore discharge. So unusual is the morphology of this group of fungi that they were once proposed as parasitic descendants of the red algae. The intriguing features of their life cycle provide many morphological characters for phylogenetic analysis, but no such explicit study has yet been undertaken. The current study draws upon Prof. Meredith Blackwell's previous work with putatively related ascomycete fungi with more typical morphology and with life cycles that include parasitic stages on both other fungi and arthropods. The phylogenetic work will include studies of morphological features, of life history stages, and of nucleotide sequence diversity in nuclear ribosomal DNA as a source of characters for taxonomic resolution and genealogical reconstruction. A phylogenetic framework for the genera and families of the order, with consequent improvement in classification, is one major goal. Another goal is to explore hypotheses of host-shifting and speciation among groups of Laboulbeniales on different arthropod hosts.