ABSTRACT

We describe five new araphid diatom species belonging to the genus Pseudostaurosira. These new taxa were found in modern and fossil material collected from five southern Patagonian waterbodies (49–52°S), four from the Santa Cruz province, Argentina and one from the Magallanes Region, Chile. When observed under light and scanning electron microscopy, each species differs by a single or a combination of valve character(s). Pseudostaurosira australopatagonica sp. nov. has unique volae that are profusely, dichotomously branched, internally anastomosed, and affixed to the virgae. Pseudostaurosira hyalopatagonica sp. nov. has fusiform valves with cuneate, elongate ends, narrow valves and round to slightly elliptical areolae. Pseudostaurosira catalinae sp. nov. has broadly fusiform valves with cuneate to subrostrate ends; volae form a circular to elliptical ring at the centre of the areolar opening and, externally covering the mantle areolae, it has a watch glass-like flap. Pseudostaurosira tehuelcheana sp. nov. has lanceolate valves with broadly rounded apices, solid incipient conical spines and marginal, transapically elongate areolae occluded by profusely branched volae. Pseudostaurosira zolitschkae sp. nov. is a relatively large-valve species with subrostrate apices, hollow spines, marginal areolae sometimes separated by a thin vimen. The volae in this latter, new taxon, only originate from a position parallel to the transapical axis of the valve, an origin that is uncommon within the genus. We discuss the validity of describing species based on morphological data and highlight the importance of increasing taxonomic resolution on isolated regions such as Patagonia.

摘要

我们描述了属于Pseudostaurosira属的五种新的蜘蛛硅藻物种。这些新分类群是在从巴塔哥尼亚南部五个水体（49-52°S）、四个来自阿根廷圣克鲁斯省和一个来自智利麦哲伦地区的现代和化石材料中发现的。在光学显微镜和扫描电子显微镜下观察时，每个物种的不同之处在于阀门特征的单个或组合。Pseudostaurosira australopatagonica sp. 十一月 具有独特的 volae，其大量分枝，内部吻合，并附在处女座上。Pseudostaurosira hyalopatagonica sp. 十一月 有梭形瓣膜，末端呈楔形，细长，瓣膜狭窄，乳晕呈圆形至略呈椭圆形。蝾螈sp. 十一月 具有广泛的梭形瓣，楔形到基体末端；volae在乳晕开口的中心形成一个圆形到椭圆形的环，外面覆盖着地幔乳晕，它有一个像玻璃一样的瓣。Pseudostaurosira tehuelcheana sp. 十一月 有披针形瓣，顶端宽圆，实心的初生圆锥棘和边缘的、经心尖细长的乳晕被大量分枝的卷叶封闭。绿松鼠sp. 十一月 是一种相对较大的瓣膜物种，具有基体顶端、空心刺、边缘乳晕，有时被薄的波形膜隔开。后一种新分类群中的 volae 仅起源于平行于瓣膜经心轴的位置，这一起源在该属内并不常见。我们讨论了基于形态学数据描述物种的有效性，并强调了在巴塔哥尼亚等孤立地区提高分类分辨率的重要性。