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

RESULTS Based on examination of a portion of the type material from Bodos and material collected in karstic springs of the Krakowsko-Czçstochowska highland a morphological comparison of Navicula hasta and N. rakowskae was made. The specimens observed from Bodos type material (e.g. Figs 1-3) conform to N hasta as illustrated by LANGE-BERTALOT (2001), but they differ from the holotype material (Fig. 4). Navicula hasta Pantocsek (Bodos material) (Figs 1-12) Light microscopic observations. Valves rhombic-lanceolate with cuneate apices, 76.8-98 urn long, 16.8-21.6 urn wide. Raphe undulate, thread-like with sickle-like apical external endings. The central external endings slightly expanded and deflected towards secondary side. Axial area moderately broad, parallel, slightly expanding towards central area. Central area small, elliptical, due to gradually shortened middle transapical striae (Figs 1^4). Striae radiate throughout, lineate, 6.2-7.5 in 10 urn. The lineolae parallel to valve margin ca 24 in 10 urn. Electron microscopic observations. External valve view (Figs 5-8): valve face bilaterally curving into raphe sternum and mantle. Raphe sternum raised above valve surface due to shallow depressions running at its both sides (Fig. 8). External central raphe endings expanded, deflected to the secondary valve side. External apical raphe endings slightly hooked. Internal valve view (Figs 9-12): raphe-sternum thickened, internal fissures open laterally, except at centre and poles. Raphe terminates at the apices in a simple helictoglossa (Figs 11-22). Distribution. A survey of the published sources revealed that Navicula hasta (conforming to Bodos population) has been reported mainly from fossil material from Europe (SCHULZ 1926, HAJÓS 1976, GLESER et al. 1974, KHURSEVICH and GORJUNOVA 1986, WITKOWSKI et al. 2001), Asia (SKVORTZOW 1937, OKUNO 1952, HIRANO 1979), and from Africa (GASSE 1980). Navicula rakowskae Lange-Bertalot (Figs 13-21) Light microscopic observations. Valves narrow lanceolate with cuneate apices, 69-94.3 urn long, 11.5-14.0 urn wide. Raphe undulate, thread-like with