ABSTRACT Two new Melobesioideae, Tectolithon fluminense gen. et sp. nov. and Crustaphytum atlanticum sp. nov., were described based on specimens collected at depths from 2 to 30 m in a tropical to subtropical transitional region of Southeast Brazil. Analyses of the plastid-encoded markers psbA and rbcL demonstrated that these taxonomic novelties belong to the clade formed by the typically subarctic/arctic Clathromorphum complex. Tectolithon fluminense has tetra/bisporangial and carposporangial conceptacles that typically become buried in the thallus because of an enveloping process caused by the development of a vegetative rim that grows from the margins of the conceptacle. The rim then fuses and creates a vegetative cover. The development of this vegetative cover is described in detail and its possible convergent evolution in other taxa is discussed. Crustaphytum atlanticum differed morpho-anatomically from the generitype, C. pacificum (the only other known species in this genus), by thallus thickness, maximum number of epithallial cell layers, relative size of subepithallial initials and tetra/bisporangial conceptacle chamber dimensions. The observation of specimens from Tectolithon and Crustaphytum with subepithallial initials that are both longer and shorter than their immediate inward derivatives indicates that this morpho-anatomical character should be used with caution for generic delimitation in the Melobesioideae.

中文翻译：

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巴西东南部新发现的珊瑚藻：Tectolithon fluminense gen。等 sp. 十一月 和 Crustaphytum atlanticum sp。十一月 （红藻目、红藻目）

摘要 两个新的 Melobesioideae，Tectolithon fluminense 基因。等 sp. 十一月 和 Crustaphytum atlanticum sp。11 月，根据在巴西东南部热带到亚热带过渡区 2 至 30 m 深度收集的标本进行描述。对质体编码标记 psbA 和 rbcL 的分析表明，这些分类新奇属于由典型的亚北极/北极 Clathromorphum 复合体形成的进化枝。Tectolithon fluminense 具有四/双孢子囊和carposporangial 概念器，由于从概念器边缘生长的营养边缘的发育引起的包络过程，它们通常被埋在叶状体中。然后边缘融合并形成植物覆盖。详细描述了这种植物覆盖的发展，并讨论了它在其他分类群中可能的趋同进化。Crustaphytum atlanticum 在形态解剖学上与普通型 C. pacificum（该属中唯一的其他已知物种）的不同之处在于叶状体厚度、上皮细胞层的最大数量、上皮下首字母的相对大小和四/双孢囊概念室尺寸。对来自 Tectolithon 和 Crustaphytum 的标本的观察，其上皮下首字母比它们的直接向内衍生物更长和更短，表明这种形态解剖特征应谨慎用于 Melobesioideae 的通用划界。由叶体厚度、上皮细胞层的最大数量、上皮下首字母的相对大小和四/双孢囊概念室尺寸决定。对来自 Tectolithon 和 Crustaphytum 的标本的观察，其上皮下首字母比它们的直接向内衍生物更长和更短，表明这种形态解剖特征应谨慎用于 Melobesioideae 的通用划界。由叶体厚度、上皮细胞层的最大数量、上皮下首字母的相对大小和四/双孢囊概念室尺寸决定。对来自 Tectolithon 和 Crustaphytum 的标本的观察，其上皮下首字母比它们的直接向内衍生物更长和更短，表明这种形态解剖特征应谨慎用于 Melobesioideae 的通用划界。