Gomphonema Ehrenberg (Bacillariophyceae, Gomphonemataceae) of the São Francisco Falso River, Paraná, Brazil

Abstract: Gomphonema Ehrenberg is a genus well represented in periphytic algal flora of epicontinental environments. The substrate colonization is facilitated by the secretion of mucilage by the pore field, allowing cell adhesion. Samples were scraped off and analyzed from vegetative portions of the macrophyte Eichhornia azurea Kunth, collected in São Francisco Falso River, located in Santa Helena City, Paraná State. The sampling occurred in four different sites, in four different periods, totaling 16 samples. The quantitative material analysis resulted in 28 identified taxa, in which Gomphonema brasiliense ssp. pacificum, Gomphonema neoapiculatum Lange-Bertalot, Reichardt & Metzeltin Gomphonema pantropicum Reichardt and Gomphonema perapicatum Metzeltin & Lange-Bertalot represented pioneer citations for Paraná diatomflorula. The ultrastructure observations of some species were crucial to distinguish a few taxa, as Gomphonema brasiliense and Gomphonema brasiliensoide D. Metzeltin, Lange-Bertalot & F. García-Rodríguez. We suggest future studies in this environment, once it has propitious characteristics to the development of epilithic diatoms. Moreover, phylogenetic studies are also recommended for a better distinction of taxa with a wide morphologic variation.

摘要：异极藻属（Gomphonema Ehrenberg）是陆表水生环境周丛藻类区系（periphytic algal flora）中极具代表性的类群。该属通过孔区分泌黏液以促进基质定殖，实现细胞黏附。研究样本采自巴西巴拉那州圣海伦娜市圣弗朗西斯科法尔索河（São Francisco Falso River）中的大型水生植物（macrophyte）紫花凤眼莲（Eichhornia azurea Kunth）的营养体部分，通过刮取方式获取并开展分析。采样共设置4个不同点位，分4个时期进行，总计获得16份样本。定量材料分析共鉴定出28个分类群，其中巴西异极藻太平洋亚种（Gomphonema brasiliense ssp. pacificum）、新针状异极藻（Gomphonema neoapiculatum Lange-Bertalot, Reichardt & Metzeltin）、泛热带异极藻（Gomphonema pantropicum Reichardt）以及近针异极藻（Gomphonema perapicatum Metzeltin & Lange-Bertalot）为巴拉那州硅藻区系的首次报道类群。部分物种的超微结构（ultrastructure）观察对区分部分分类群至关重要，例如巴西异极藻（Gomphonema brasiliense）以及类巴西异极藻（Gomphonema brasiliensoide D. Metzeltin, Lange-Bertalot & F. García-Rodríguez）。鉴于该环境具备利于石生硅藻（epilithic diatoms）生长的适宜特性，我们建议在此环境中开展后续研究。此外，为更好地区分形态变异度较高的分类群，系统发育（phylogenetic）研究同样值得推进。