The relationships among the Aurearenophyceae, Phaeothamniophyceae, Phaeophyceae and Xanthophyceae lineages of the Heterokontophyta SI clade are not well known. By adding previously unexamined taxa related to these classes in a five gene phylogeny (SSU rRNA, atpB, psaA, psaB, rbcL), we recovered an assemblage of taxa previously unrecognized. We propose the class Phaeosacciophyceae class. nov., that includes Phaeosaccion collinsii, Phaeosaccion multiseriatum sp. nov., Phaeosaccion okellyi sp. nov., Antarctosaccion applanatum, Tetrasporopsis fuscescens, Tetrasporopsis moei sp. nov., and Psammochrysis cassiotisii gen. & sp. nov. We re-examine the literature for Chrysomeris, Nematochrysis, Chrysowaernella and the invalid name “Giraudyopsis” and conclude some taxa in previous studies are misidentified or misnamed, i.e. Chrysomeris and Chrysowaernella, respectively. We also show that Nematochrysis sessilis var. vectensis and Nematochrysis hieroglyphica may belong in the recently described class Chrysoparadoxophyceae. The phylogenetic relationships of Phaeobotrys solitaria and Pleurochloridella botrydiopsis are not clearly resolved, but they branch near the Xanthophyceae. Here we describe a new class Phaeosacciophyceae, a new order Phaeosacciales, a new family Tetrasporopsidaceae, a new genus Psammochrysis and four new species.

杂种植物SI进化枝的金黄色葡萄球菌科，草杆菌科，古菌科和黄藻科谱系之间的关系尚不清楚。通过在五个基因系统发育（SSU rRNA，atp B，psa A，psa B，rbc L）中添加与这些类别相关的先前未经检查的分类单元，我们获得了先前无法识别的分类单元组合。我们建议使用Phaeosacciophyceae类。十一月，其中包括Phaeosaccion collinsii，Phaeosaccion multiseriatum sp.。十一月 ，Phaeosaccion okellyi sp.。十一月 ，南极Applanatum，福氏四孢子虫，Tetrasporopsis moei sp.。十一月，和沙门氏菌gen。＆sp。十一月 我们重新审视了金鸡菊，线虫病，金藻和无效名称“ Giraudyopsis ”的文献，并在先前的研究中得出了一些被误认为或错误命名的类群，分别是金鸡菊和金藻。我们还表明，线虫sessilis var。vectensis和象鼻线虫病可能属于最近描述的金蝶科。茄属植物和博氏多孢菌的系统发育关系尚不清楚，但它们在黄藻科附近分支。在这里，我们描述了一个新的类球菌科，一个新的Phaeosacciales科，一个新的四孢菌科，一个新的沙眼菌属和四个新种。