Rybak Mateusz, Witkowski Andrzej, Peszek Łukasz, Kociolek John P, Risjani Yenny, Nguyen Duc Hung, Zhang Jinpeng, Nguyen Van Duy, Gastineau Romain, Duong Thi Thuy, Rosa Philippe, Meleder Vona
Department of Agroecology and Forest Utilization, Institute of Agricultural Sciences, Land Management and Environmental Protection, University of Rzeszów, ul. Ćwiklińskiej 1a, 35-601 Rzeszów, Poland.
University of Szczecin, Institute of Marine and Environmental Sciences, Mickiewicza 16A, 70-383 Szczecin, Poland.
PhytoKeys. 2021 Oct 22;183:115-142. doi: 10.3897/phytokeys.183.71049. eCollection 2021.
In this study, samples were collected from the Java Sea coasts, from the South China Sea in Hainan Island coasts and Quảng Yên region and Rú Chá mangrove near Hue in Central Vietnam. In studied samples a total of eight species have been observed. Three of the taxa studied are described herein as species new to science - , and Under light microscopy (LM) and are similar with rhombic-lanceolate to rhombic/ elliptic-lanceolate to elliptic valve shapes and narrowly rounded apices. Both species can be easily distinguished by stria density (higher density in ). Under SEM is characterized by cribrate areola occlusions, a character thus far observed only in three established species. The remaining species of the whole genus known thus far are characterized by hymenate areola. Similar morphology species have been observed from tropical mangrove forests from Madagascar but they all can be easily distinguished based on the lack of grooves in the central area. The third species - has rhombic-elliptic to rhombic-lanceolate valves with broadly rounded to slightly protracted apices in larger specimens. This species has a relatively broad central area. Also unique among brackish-water is the small, rounded stigma positioned almost midway between the valve center and valve margin. In the habitats from which the new species are described we also identified five established taxa including, , , , and . For those species we provide detailed SEM characteristics of valve ultrastructure, as well as the range of environmental conditions and geographic distribution within the study area.
在本研究中，样本采集自爪哇海沿岸、海南岛沿岸的中国南海、广宁地区以及越南中部顺化附近的茹茶红树林。在所研究的样本中，共观察到8个物种。本文将所研究的3个分类单元描述为科学上新发现的物种—— 、 和 。在光学显微镜下， 和 的瓣膜形状为菱形披针形至菱形/椭圆披针形再到椭圆形，顶端狭窄且圆润。这两个物种可以通过条纹密度轻松区分（ 的条纹密度更高）。在扫描电子显微镜下， 的特征是筛状网孔闭塞，这一特征迄今为止仅在3个已确定的物种中观察到。迄今为止已知的该属其余物种的特征是膜状网孔。在马达加斯加的热带红树林中也观察到了形态相似的物种，但它们都可以根据中心区域没有凹槽而轻松区分。第三个物种—— 的瓣膜为菱形椭圆形至菱形披针形，在较大的标本中顶端宽圆至略突出。该物种的中心区域相对较宽。在咸淡水物种中也很独特的是，小而圆的柱头几乎位于瓣膜中心和瓣膜边缘之间的中间位置。在描述新物种的栖息地中，我们还鉴定出了5个已确定的分类单元，包括 、 、 、 和 。对于这些物种，我们提供了瓣膜超微结构的详细扫描电子显微镜特征，以及研究区域内的环境条件范围和地理分布。
