B. Papp szerk.: Studia Botanica Hungarica 35. 2004 (Budapest, 2004)
Wojtal, A.; Buczkó, Krisztina: Comparative study of Navicula hasta and N. rakowskae: their morphology and distribution
(2001) the only certain recent locality is the geologically very old Lake Aokiko in Japan, whereas specimens from other localities appear to be similar, but also show some differences and "certainly or probably do not belong to this taxon". The uncertainty of the status of Navicula hasta was taken into account by LANGE-BERTALOT (2001). The problem of Navicula hasta identity extends back to the early 20th century. This has been caused by some LM observations in which N. hasta was identified in Central Europe (e.g. HUSTEDT 1930). Recognising taxonomic problems with N. hasta, recently LANGE-BERTALOT (2001) was able to differentiate a number of morphological entities from Europe including description of a few novel taxa. One of the newly described species, Navicula rakowskae LANGE-BERTALOT (2001) and the long established N. hasta show a certain extent of morphological similarity under the light microscope. The length, width and arrangement of transapical striae are similar for both species and partially overlap. The separating feature for both taxa was the density of the lineolae (LANGE-BERTALOT 2001). The aim of our study was a comparison of other ultrastructural features of both species i.e. Navicula hasta and N. rakowskae. MATERIALS AND METHODS The type material of A/. hasta deposited in the Pantocsek collection was re-investigated. The small portion of the type material from Bodos was treated with distilled water and mounted in Naphrax. The recent material containing N. rakowskae from the Krakowsko-Czçstochowska Upland (Poland) was collected from springs and their outlets (Kobylanka stream, Krztynia river and Wiercica river). Water temperature was 6.2-9.0 °C, conductivity was moderate, generally 240^480 uScnr 1 , and the pH values usually varied from 6.1 to 8.0. The recent samples were treated with HCl, washed several times with distilled water, and boiled in concentrated H,0, with small amount of KCIO, in order to remove organic matter. After washing several times with distilled water, the material was air-dried on coverglasses and mounted in Naphrax. The LM observations were made with a Nikon Optiphot microscope equipped with Nomarski interference optics and Nikon FX-35 photomicroscopy unit. SEM observations (Philips ESEM-35) were made on cleaned Au-sputtered material. Data on the distribution of the species were obtained from various published sources including: monographs, papers and Iconotheca of Algae of the Department of Phycology, W. Szafer Institute of Botany, Polish Academy of Sciences, Krakow. The material studied is deposited in the collection of the Department of Phycology, W. Szafer Institute of Botany, Polish Academy of Sciences, Krakow and the Department of Botany, Natural History Museum, Budapest.
