THE “PARADOX” DIATOM BACILLARIA PAXILLIFER (BACILLARIOPHYTA) REVISITED 1
THE “PARADOX” DIATOM BACILLARIA PAXILLIFER (BACILLARIOPHYTA) REVISITED 1
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DOI：
10.1111/j.1529-8817.2006.00299.x
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发表时间：
2007-02
影响因子：
2.9
通讯作者：
A. Schmid
中科院分区：
文献类型：
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作者：
A. Schmid
Bacillaria paxillifer（O. F. Müll。）Hendey被许多植物学家认为是一个单一的，流行的物种。然而，对不同生境的菌落重新调查发现了三个不同的群体：（A）半咸水/淡水，（B）海洋沿岸的，和（C）海洋浮游生物类群。不同群体的菌落和细胞的形式，缝凸缘（RF），形状和位置的经心尖肋（Tr的），和形态发生。线形种仅限于A组：Tr主要向内部增厚。披针形仅限于组B和C：瓣膜形成从内部基层进行到外部。不同的物种在其中缝缝的形状不同，以及带（GBs）转化为“小翼”。分类群在叶绿体的形状和数量上也有差异。所有物种形成能动的殖民地。海绵体通过中缝分泌的弹性纤维粘附。中缝肋骨通过硅质夹（腓骨）固定在适当位置，固定在平行于中缝肋骨的额外一对轴向肋骨（腓骨肋骨）中。这种中缝系统类似于双锥藻，而不是菱形藻的“中缝管”。许多瓣膜沿顶轴沿着是不对称的，这是由于突出的RF在菌落内以1：1的比例穿梭，但中缝缝是镜像，腓骨的生长方向和质体的位置也是镜像，其中蛋白核向同一方向倾斜。物种的每个上皮有四个开放的GB;第三条带总是具有内部有机脊，以帮助卵裂期间质膜的粘附。结果表明，这些分类群是一个自然的系统发育群，需要精确确定其分类位置。
Defined by its unique colonial locomotion, Bacillaria paxillifer (O. F. Müll.) Hendey was recognized as a single, pandemic species by many phycologists. However, reinvestigation of colonies from different habitats revealed three distinct groups: (A) brackish/freshwater, (B) marine littoral, and (C) marine planktonic taxa. Groups differed in colony and cell form, raphe flanges (RFs), shape and position of transapical ribs (Tr's), and morphogenesis. Linear‐shaped species were restricted to group A: Tr's thickened principally to the interior. Lanceolate forms were confined to groups B and C: valve formation proceeded from an internal base layer to the exterior. The planktonic species differed in the shape of its raphe slit, and the transformation of girdle bands (GBs) into “winglets.” Taxa also differed in chloroplast shape and number. All species formed motile colonies. Siblings adhered via elastic fibrils secreted through their raphe. Raphe ribs were held in position by siliceous clamps (fibulae), anchored in an extra pair of axial ribs (fibular ribs) parallel to the raphe ribs. This raphe system resembled that of Cylindrotheca rather than the “canal raphe” of Nitzschia. Many valves were asymmetric along the apical axis due to protruding RFs shuttling in a 1:1 ratio within a colony, but raphe slits were mirror images, as were the growth direction of fibulae and position of plastids, with pyrenoids tilted in the same direction. Species possessed four open GBs per epitheca; the third band invariably bore an internal, organic ridge to aid in adhesion of the plasmalemma during cleavage. The results suggested that these taxa are a natural phylogenetic group, requiring precise determination of their taxonomic position.