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

我们描述了属于假se虫属的五种新的阿拉伯硅藻物种。这些新的分类单元是在现代和化石材料中发现的，这些现代化石材料来自五个巴塔哥尼亚南部水体（49-52°S），四个来自阿根廷圣克鲁斯省和一个来自智利马加拉内斯地区。当在光学显微镜和扫描电子显微镜下观察时，每个物种的特征是单个或多个阀特性的不同。拟南芥（Pseudostaurosira australopatagonica sp。）十一月 具有独特的田鼠，其大量地，二分地分支，内部吻合，并附着于处女。假单胞菌透明质酸菌。十一月 有梭形瓣，具楔形，长形末端，狭窄的瓣膜和圆形至略椭圆形的乳晕。假单胞菌sp。十一月 有宽梭形瓣，具楔形到末端。volae在乳晕开口的中心形成一个圆形到椭圆形的环，并在外部覆盖住幔乳晕，它有一个像手表玻璃一样的襟翼。Pseudostaurosira tehuelcheana sp。十一月 具披针形瓣，具宽圆形的顶端，刚开始的圆锥形棘和边缘的，经顶端的细长的乳晕，被大量分枝的卷毛虫闭塞。假单胞菌sp。十一月 是一种比较大的瓣膜种类，具顶生的先端，空心的刺，边缘的乳晕，有时被薄的维膜隔开。后一种新的分类单元中的挥发物仅起源于平行于瓣膜经心尖轴的位置，该起源在属内不常见。我们讨论了基于形态学数据描述物种的有效性，并强调了在诸如巴塔哥尼亚等偏远地区提高分类学分辨率的重要性。