Kato Aki, Baba Masasuke, Suda Shoichiro
Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko, Motobu, Okinawa 905-0227, JapanMarine Ecology Research Institute, Kashiwazaki, Niigata 945-0017, JapanDepartment of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru, Nishihara, Okinawa 903-0213, Japan.
J Phycol. 2011 Jun;47(3):662-672. doi: 10.1111/j.1529-8817.2011.00996.x. Epub 2011 May 4.
The subfamily Mastophoroideae (Corallinaceae, Rhodophyta) is characterized by species possessing nongeniculate, uniporate tetrasporangial conceptacles without apical plugs, the presence of cell fusions, and the absence of secondary pit connections. However, molecular phylogenetic studies not including the type genus Mastophora indicated that the Mastophoroideae was polyphyletic. Our molecular phylogenetic analysis of the subfamily including the type genus using DNA sequences of SSU rDNA and plastid-encoded gene of PSII reaction center protein D1 (psbA) revealed that Mastophora formed a robust clade only with Metamastophora. The other mastophoroid genera were divided into six lineages within the family Corallinaceae. Five supported lineages-(i) Pneophyllum; (ii) Hydrolithon gardineri (Foslie) Verheij et Prud'homme, Hydrolithon onkodes (Heydr.) Penrose et Woelk., and Hydrolithon pachydermum (Foslie) J. C. Bailey, J. E. Gabel et Freshwater; (iii) Hydrolithon reinboldii (Weber Bosse et Foslie) Foslie; (iv) Spongites; and (v) Neogoniolithon-were clearly distinguished by the combination of characters including the presence or absence of palisade cells and trichocytes in large, tightly packed horizontal fields and features of tetrasporangial and spermatangial conceptacles. Therefore, we amend the Mastophoroideae to be limited to Mastophora and Metamastophora with a thin thallus with basal filaments comprised of palisade cells, tetrasporangial conceptacles formed by filaments peripheral to fertile areas, and spermatangia derived only from the floor of male conceptacles. This emendation supports Setchell's (1943) original definition of the Mastophoroideae as having thin thalli. We also propose the establishment of three new subfamilies, Hydrolithoideae subfam. nov. including Hydrolithon, Porolithoideae subfam. nov. including the resurrected genus Porolithon, and Neogoniolithoideae subfam. nov. including Neogoniolithon. Taxonomic revisions of Pneophyllum and Spongites were not made because we did not examine their type species.
桅杆藻亚科（石珊瑚藻科，红藻门）的特征是，其物种具有无关节、单孔的四分孢子囊果胞，无顶端塞，存在细胞融合，且没有次生纹孔连接。然而，不包括模式属桅杆藻属（Mastophora）的分子系统发育研究表明，桅杆藻亚科是多系的。我们使用小亚基核糖体DNA（SSU rDNA）序列和光系统II反应中心蛋白D1（psbA）的质体编码基因，对包括模式属在内的该亚科进行分子系统发育分析，结果显示，桅杆藻属仅与后桅杆藻属（Metamastophora）形成一个有力的分支。其他桅杆藻类属被分为石珊瑚藻科内的六个谱系。五个得到支持的谱系——（i）叶状珊瑚藻属（Pneophyllum）；（ii）加氏水石枝藻（Hydrolithon gardineri (Foslie) Verheij et Prud'homme）、瘤状水石枝藻（Hydrolithon onkodes (Heydr.) Penrose et Woelk.）和厚皮水石枝藻（Hydrolithon pachydermum (Foslie) J. C. Bailey, J. E. Gabel et Freshwater）；（iii）雷氏水石枝藻（Hydrolithon reinboldii (Weber Bosse et Foslie) Foslie）；（iv）海绵石枝藻属（Spongites）；以及（v）新角石枝藻属（Neogoniolithon）——通过包括在大的、紧密排列的水平区域中是否存在栅栏细胞和毛细胞以及四分孢子囊果胞和精子囊果胞特征等性状组合而得以明确区分。因此，我们将桅杆藻亚科修订为仅限于桅杆藻属和后桅杆藻属，其藻体薄，具由栅栏细胞构成的基部丝状体，四分孢子囊果胞由可育区域周边的丝状体形成，精子囊仅源自雄性果胞的底部。这一修订支持了塞奇尔（Setchell，1943年）对桅杆藻亚科藻体薄的原始定义。我们还提议建立三个新亚科，即包括水石枝藻属的水石藻亚科（Hydrolithoideae subfam. nov.）、包括复活属石枝藻属（Porolithon）的石枝藻亚科（Porolithoideae subfam. nov.）以及包括新角石枝藻属的新角石藻亚科（Neogoniolithoideae subfam. nov.）。由于未对叶状珊瑚藻属和海绵石枝藻属的模式种进行研究，因此未对其进行分类修订。
