Hantzschia malaysiana M.Rybak sp. nov. (Figs 28–37, 61–67)

LM observations (Figs 28–37):— Valves distinctly dorsiventral appearing comparatively strongly silicified. Ventral margin slightly convex, dorsal margin slightly more convex in distal parts and concave in middle. Apices protracted, rostrate in small specimens becoming clearly capitate and deflected towards dorsal side in large specimens. Valve dimensions (n=20): length 55.0–130.0 μm, width 9.0–11.5 μm in middle to 9.5–12.0 μm in widest part of the valve face. Fibulae 5–7 in 10 μm, unequally spaced, two middle fibulae clearly more distant. Striae equidistant, weakly radiate in middle, 16–22 in 10 μm. Areolae not discernible.

SEM observations (Figs 61–67):— Valves on ventral side bordered by a clearly thickened keel (Figs 61, 65). Striae composed of round areolae occluded by individual hymenes, 36–40 in 10 µm (Fig. 65), forming narrow, parallel grooves, between raised virgae (Figs 61, 65, 67). Striae on valve mantle organized same as on the valve face (Figs 65, 67). External central raphe endings deflected (Fig. 65). Distal raphe endings clearly hooked (Figs 61, 65). Internally, central raphe endings close to each other and deflected to same direction (Fig. 66). Distal raphe endings forming distinct helictoglossae (Fig. 64). Internally, fibulae not equidistant (Fig. 62). Each fibulae connected to 1–6 transapically costae (Fig. 62).

Type:— Malaysia, Cameron highlands, Kuala Terla, 4°32’43”N 101°25’16”E, coll. date. 02 July 2016, holo - slide no. SZCZ28482! and the unmounted material with the same number at the Szczecin Diatom Collection (University of Szczecin, Poland), iso- slide no. 2016/51 and the unmounted material with the same number at the University of Rzeszow, Poland. The type population is illustrated on Figs 28–37 and 61–67 .

Etymology:— The species epithet refers to the type locality.

Distribution:— So far, the species was only observed from the type locality.

Associated diatom flora:— The most abundant taxa in the assemblage were: Hantzschia amphioxys (Ehrenberg) Grunow (in Cleve & Grunow 1880: 103), Humidophila contenta (Grunow) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová (2014: 357), H. lacunosa (Moser, Lange-Bertalot & Metzeltin) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová (2014: 358), H. aff. elegans (Moser, Lange-Bertalot & Metzeltin 1998: 144) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová (2014: 358), Fallacia insociabilis (Krasske 1932: 114) D.G.Mann and Geissleria ignota (Krasske 1932: 116) Lange-Bertalot & Metzeltin (1996: 65), Luticola tomesii Moser, Lange-Bertalot & Metzeltin (1998: 198), L. intermedia (Hustedt) Levkov, Metzeltin & Pavlov (2013: 138), L. sublagerheimii Levkov, Metzeltin & Pavlov (2013: 229) . Hantzschia malaysiana sp. nov. occurred rarely in analyzed material and only few specimens were observed on each slide.