Nitzschia austriaca, Hustedt NAUS, 1959

Földi, Éva Ács Angéla, Wetzel, Carlos E., Vad, Csaba F., Kiss, Keve T., Dobosy, Péter, Trábert, Zsuzsa, Grigorszky, István, Engloner, Attila & Ector, Luc, 2017, Nitzschia austriaca Hustedt: a characteristic diatom of Hungarian inland saline waters including a morphological comparison with the type material, Phytotaxa 308 (1), pp. 54-65 : 56

Comparison of Nitzschia austriaca valves from Apaj ( Hungary) and type material ( Austria)

The data of length, width, the number of striae and fibulae of the population from Apaj and of the type material overlapped with each other ( Table 1). A Mann-Whitney test showed that the medians of the striae and fibulae number were equal, but the width and lengths were not equal in the two studied populations. The results of NMDS also display that the metrics of both populations overlapped, which was also confirmed by the Shepard plot ( Fig. 1 ). Based on these results, we argue that the species of the population from Apaj is the same as the type material of Nitzschia austriaca .

The length, width, number of striae and fibulae in 10 μm of Apaj populations and type material are available in Table 1. The shape of valves is sigmoid with slightly capitate ends ( Figs 2, 12 , 20, 22 ). Transapical striae are visible in LM ( Figs 2–13 ). The fibulae are quite regularly distributed along the raphe canal, with the two median ones usually further apart from each other ( Figs 18, 19 , 23, 24 ). In SEM, externally: the striae are uniseriate and areolae are circular ( Figs 15 , 21 ). On the mantle, the striae are very short, comprising one areola ( Figs 14 , 21 ). The distal raphe endings turn always to the same side, either toward the valve face ( Figs 14 , 20 ) or the valve mantle ( Figs 16 , 21 ). Central raphe fissures are drop-shaped and close to each other, the proximal raphe end follows the valve margin ( Figs 15, 17 , 20, 21 ). Internally: areolae are not covered by hymenes ( Figs 19 , 24 ). The raphe slit is interrupted by a central nodule ( Figs 18 , 24 ). The distal raphe endings end in a helictoglossa ( Figs 19 , 24 ).

Figures

FIGURE 1. Ordination diagram of NMDS (a) with the 95% confidence interval (point: population of Apaj, plus: population of type material) and the Shepard plot (b). R2=0.95.

FIGURES 2–13. LM micrographs of N. austriaca from the Apaj population (Hungary).

FIGURES 20–24. SEM micrographs of N. austriaca from the type material (sample E9708 from Austria). Arrow indicates the central nodule on Fig. 24.

FIGURES 14–19. SEM micrographs of N. austriaca from the Apaj population (Hungary).White arrows indicate the central raphe endings on Fig. 15 and the central nodule on Fig. 18.