Study of the type material of Navicula egregia Hustedt and descriptions of two new aerial Microcostatus (Bacillariophyta) species from Central Europe Author Stanek-Tarkowska, Jadwiga Department of Soil Studies, Environmental Chemistry and Hydrology, Faculty of Biology and Agriculture, University of Rzeszów, Zelwerowicza 8 B, 35 - 601 Rzeszów, Poland Author Wetzel, Carlos E. Luxembourg Institute of Science and Technology (LIST), Environmental Research & Innovation (ERIN) Department, 41 rue du Brill, L- 4422 Belvaux, Grand-duchy of Luxembourg Author Noga, Teresa Department of Soil Studies, Environmental Chemistry and Hydrology, Faculty of Biology and Agriculture, University of Rzeszów, Zelwerowicza 8 B, 35 - 601 Rzeszów, Poland Author Ector, Luc Luxembourg Institute of Science and Technology (LIST), Environmental Research & Innovation (ERIN) Department, 41 rue du Brill, L- 4422 Belvaux, Grand-duchy of Luxembourg text Phytotaxa 2016 2016-10-19 280 2 163 172 http://dx.doi.org/10.11646/phytotaxa.280.2.6 journal article 10.11646/phytotaxa.280.2.6 1179-3163 13650693 Microcostatus egregius (Hustedt) Lange-Bertalot ( Figs 29–56 ) Basionym: Navicula egregia Hustedt (1942a : fig. 26, here reproduced as Fig. 29 ) Valve lanceolate ( Figs 30–52 ). Observed range of valve dimensions (n = 25): length: 7.2–13.9 μm, width: 3.1–3.7 μm. Transapical striae weakly radiate and slightly arcuate, 33–35 in 10 μm ( Figs 53–56 ). Striae in central area shortened, slightly protruding or hidden under pseudoconopeum ( Figs 53, 55, 56 ). Externally on the valve margin a row of elongated striae is present, while on the valve mantle there is a row of pores as a continuation of the striae ( Figs 53, 55 ). Distal raphe ends curved in the same direction onto the mantle ( Figs 53, 55, 56 ). Raphe almost straight, in raised sternum, narrowing at the ends ( Figs 53, 55 ). Conopeum is visible in the axial area. In the place of the sternum and conopeum connection, a continuous row of perforations on each side are present ( Fig. 53 ). In some specimens (in low degree of silification), the conopeum is narrow and rolled up ( Fig. 53 ), while in other valves have wider and flat conopeum ( Figs 55, 56 ). Pseudoconopeum with row of perforation present on the valve margin ( Fig. 53 ). In internal view, the raphe is straight, proximal endings are very slightly curved in the same direction. On distal ends small helictoglossae are present ( Fig. 54 ). Distribution and ecology:— Species noted from Germany , near Bremen , developing beyond the aquatic environment and among mosses ( Krammer & Lange-Bertalot 1986: 202 ). Lange-Bertalot & Steindorf (1996: 655) stated Navicula egregia as an aerophilous diatom, occurring very rarely in Germany (R category). Ettl & Gärtner (1995: 70) concluded that it is an aerophytic species, developing on mosses and in wet places in Germany and Finland . Navicula egregia was recorded from lakes and ponds in the Canadian High Arctic Archipelago, where it occurred in alkaline pH (8.3–8.5) and moderate conductivity (˃240 μS/cm) ( Antoniades et al . 2005: 36 , 2014: 617 ). Similar specimens were observed on the North American continent and named as cf. Microcostatus egregius ( Antoniades et al . 2008: 164 ) or Microcostatus cf. egregius (Silver & Hamilton 2011: 197) .