Taxonomic revision of the genus Zygorhizidium: Zygorhizidiales and Zygophlyctidales ord. nov. (Chytridiomycetes, Chytridiomycota).

Fungal systematics and evolution Pub Date : 2020-06-01 Epub Date: 2019-08-21 DOI:10.3114/fuse.2020.05.02
K Seto, S Van den Wyngaert, Y Degawa, M Kagami
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引用次数: 26

Abstract

During the last decade, the classification system of chytrids has dramatically changed based on zoospore ultrastructure and molecular phylogeny. In contrast to well-studied saprotrophic chytrids, most parasitic chytrids have thus far been only morphologically described by light microscopy, hence they hold great potential for filling some of the existing gaps in the current classification of chytrids. The genus Zygorhizidium is characterized by an operculate zoosporangium and a resting spore formed as a result of sexual reproduction in which a male thallus and female thallus fuse via a conjugation tube. All described species of Zygorhizidium are parasites of algae and their taxonomic positions remain to be resolved. Here, we examined morphology, zoospore ultrastructure, host specificity, and molecular phylogeny of seven cultures of Zygorhizidium spp. Based on thallus morphology and host specificity, one culture was identified as Z. willei parasitic on zygnematophycean green algae, whereas the others were identified as parasites of diatoms, Z. asterionellae on Asterionella, Z. melosirae on Aulacoseira, and Z. planktonicum on Ulnaria (formerly Synedra). According to phylogenetic analysis, Zygorhizidium was separated into two distinct order-level novel lineages; one lineage was composed singly of Z. willei, which is the type species of the genus, and the other included the three species of diatom parasites. Zoospore ultrastructural observation revealed that the two lineages can be distinguished from each other and both possess unique characters among the known orders within the Chytridiomycetes. Based on these results, we accommodate the three diatom parasites, Z. asterionellae, Z. melosirae, and Z. planktonicum in the distinct genus Zygophlyctis, and propose two new orders: Zygorhizidiales and Zygophlyctidales.

Abstract Image

Abstract Image

Abstract Image

壶菌属的分类修订:壶菌科和壶菌科。11 .(壶菌科,壶菌科)。
近十年来,基于游动孢子的超微结构和分子系统发育,壶菌的分类系统发生了巨大的变化。与腐坏性壶菌相比,大多数寄生壶菌迄今为止仅通过光学显微镜进行形态学描述,因此它们具有很大的潜力,可以填补目前壶菌分类中存在的一些空白。合芽属的特点是有一个带盖的游动孢子囊和一个静止的孢子,这是有性繁殖的结果,其中一个雄性菌体和一个雌性菌体通过接合管融合。所有已描述的接合芽孢属都是藻类寄生虫,它们的分类位置仍有待解决。在此,我们对7种Zygorhizidium spp培养物的形态、游动孢子超微结构、寄主特异性和分子系统发育进行了研究。根据菌体形态和寄主特异性,一种培养物被鉴定为寄生在zygnematophycean绿藻上的Z. willei,而其他培养物被鉴定为寄生在硅藻上的Z. asterionellae、Z. melosiraae和Z. plankton。根据系统发育分析,合芽属被划分为两个不同的目级新系;其中一个谱系仅由该属的模式种Z. willei组成,另一个谱系包括3种硅藻寄生虫。游动孢子的超微结构观察表明,这两个系在壶菌已知目中都具有独特的特征。基于这些结果,我们将3种硅藻寄生虫,即Z. asterionellae、Z. melosiraae和Z. plankton .纳入了不同的zygophylyctis属,并提出了两个新目:zygophylyctidales和zygophylyctidales。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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CiteScore
7.30
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