ABSTRACT The two genera Planktosphaeria (the type Pl. gelatinosa G.M.Smith) and Follicularia (the type F. paradoxalis Miller) have numerous chloroplast segments, each with a single pyrenoid. Autospore reproduction was described only in Planktosphaeria; whereas naked, biflagellate zoospores were known in Follicularia. The generic circumscription of Planktosphaeria was once changed to zoospore-producing forms based on P. gelatinosa sensu Starr UTEX 124, but some authors did not accept the amendment. Recent molecular analyses showed that Pl. botryoides and Pl. texensis belonged to a clade separate from Pl. gelatinosa sensu Starr, and then, the two former species were dealt with as members of Follicularia; whereas the latter was retained in Planktosphaeria. However, the ground for assigning these species to the two genera was not ascertained. To resolve the taxonomic confusions, 18S rDNA phylogenetic relationships, and morphological and ultrastructural features of selected species of these genera and closely related taxa were examined. It is concluded that identification of UTEX 124 as P. gelatinosa and the amendment of the generic circumscription of Planktosphaeria were not acceptable. By comparing the original line drawings of F. paradoxalis with morphological and ultrastructural features of other zoosporic species of Planktosphaeria, the former was inferred to belong to a clade including both Pl. gelatinosa sensu Starr UTEX124 and Pl. maxima (Sz-group), all of which were assigned to Follicularia. For Pl. botryoides and Pl. texensis (Rz-group), Herndonia gen. nov. was proposed, that was also characterised ultrastructurally. The taxonomic states of Pl. gelatinosa and other autosporic members of Schizochlamydaceae and Radiococcaceae are discussed.

中文翻译：

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Planktosphaeria, Follicularia 和 Herndonia gen 的系统发育和分类学。十一月 (Sphaeropleales, Chlorophyceae) 基于超微结构和 18S rDNA 分析

摘要 Planktosphaeria（Pl. gelatinosa GMSmith 型）和 Follicularia（F. paradoxalis Miller 型）两个属有许多叶绿体节段，每个节段都有一个核糖体。自孢子繁殖仅在浮游生物中被描述过；而裸的双鞭毛游动孢子在毛囊中是已知的。根据 P. gelatinosa sensu Starr UTEX 124，Planktosphaeria 的通用范围曾经更改为产生游动孢子的形式，但一些作者不接受该修正。最近的分子分析表明，Pl。葡萄球菌和 Pl。texensis 属于一个独立于 Pl 的进化枝。gelatinosa sensu Starr，然后，前两个物种被处理为 Follicularia 的成员；而后者保留在浮游生物中。然而，将这些物种归入这两个属的依据尚未确定。为了解决分类学上的混淆，检查了这些属和密切相关分类群的选定物种的 18S rDNA 系统发育关系以及形态和超微结构特征。得出的结论是，将 UTEX 124 鉴定为 P. gelatinosa 和对浮游生物属的一般范围的修改是不可接受的。通过将 F. paradoxalis 的原始线条图与浮游生物其他游动孢子物种的形态和超微结构特征进行比较，推断前者属于包括 Pl. gelatinosa sensu Starr UTEX124 和 Pl。maxima (Sz-group)，所有这些都被分配到 Follicularia。对于 Pl。葡萄球菌和 Pl。texensis (Rz-group), Herndonia gen. 十一月 被提出，这也被表征为超微结构。Pl的分类状态。