Hantzschia pseudobardii, You & Kociolek, 2015

You, Qingmin, Kociolek, John Patrick & Wang, Quanxi, 2015, The diatom genus Hantzschia (Bacillariophyta) in Xinjiang Province, China, Phytotaxa 197 (1), pp. 1-14 : 3-4

Hantzschia pseudobardii Q-M You & J. P. Kociolek, sp. nov. (Figs 1–13; figure 3 = holotype)

Valves asymmetrical to the apical axis. Ventral margins slightly concave at center, slightly convex at the poles. Dorsal margins with similar angle of bend to the ventral margins along most of the length of the valves except at the apices. Valve poles with obvious “shoulders”; poles obliquely cuneate and finally protracted, commonly narrow-rostrate, with a little bend to dorsal margins. Length 105–125 μm, breadth 9–11 μm. Fibulae, 5–7 in 10 μm, almost equidistant, the median two more distant than the others, each of them connected with 1 transapical costa (Fig. 12). External raphe branches straight and continuous in valve center ( Figs 9, 10 ); internal raphe branches not detected clearly in SEM. Striae parallel throughout, some slightly radiate in the center, 16–18 in 10 μm. Striae puncta not discernible in LM. In SEM, puncta appear as small, rounded poroids ( Figs 9 –13), c. 26–32 in 10 μm. Helictoglossae prominent and aligned with the raphe at both ends of the valve interior (Fig. 13).

Type: — CHINA. Akesu ( SHTU, slide XJ-010116! Holotype = Figure 3).

Etymology:— The specific epithet reflects its similarity to H. bardii Lange-Bertalot (in Lange-Bertalot et al. 2003: 54).

Distribution and ecology:— Found in samples 010116, 010181 and 071054.

Observations:— Based on its valve outline, H. pseudobardii most closely resembles H. bardii . There are distinct differences between the two in outline, as H. pseudobardii has clear “shoulders” on the dorsal margins (see arrow in Fig. 3), while the “shoulders” in H. bardii ’s in the corresponding part of the valve are weakly developed. The two species also differ in several morphometric features (see Table 1). For example, H. pseudobardii is larger and broader, and has lower striae density, fewer number of puncta per 10 μm.

Figures

PLATE 2: Figures 9–13. Hantzschia pseudobardii. SEM micrographs. Figs 9, 10. Detail of the continuous external central raphe endings and areolae. Fig. 11. Detail of the external distal raphe fissure. Fig. 12. Detail of the internal fibulae and areolae, internal central raphe endings are not clear. Fig. 13. Helictoglossae at apex, positioned on the extreme terminus of the valve. Scale bars=1 μm for all figures.