Hantzschia beksinskii M.Rybak, Kochman-Kędziora sp. nov. (Figs 38–45, 68–74)

LM observations (Figs 38–45):— Valves distinctly dorsiventral appearing comparatively strongly silicified. Ventral margins slightly convex, dorsal margins convex in distal parts and concave in the middle. Apices protracted, rostrate and slightly deflected towards dorsal side. Valve dimensions (n=15): length 62.5–92.0 μm, width 7.5–10.5 μm in middle to 8.0–11.5 μm in widest part of valve face. Fibulae 5–6 in 10 μm, unequally spaced, middle two fibulae clearly more distant. Striae equidistant, weakly radiate in the middle, 18–21 in 10 μm. Areolae not discernible.

SEM observations (Figs 68–74):— Valves on ventral side bordered by clearly thickened keel with shorted striae (with 2–3 areolae), which are separated from rest of valve face by longitudinal depression (Figs 68, 70, 74). Striae composed of round areolae occluded by individual hymenes, 35–40 in 10 µm (Figs 70, 74), forming narrow, deep, parallel grooves on valve face. Areolae near dorsal margin became more separated and not forming continuous grooves (Figs 68, 70, 74). Striae on valve mantle not forming parallel grooves, separated by not thickened virgae (Fig. 72). External central and distal raphe endings hooked (Figs 68, 70, 72). Internally, fibulae not equidistant (Fig. 69). Each fibulae connected to 1–5 transapically costae (Fig. 69). Central raphe endings deflected to same direction and clearly separated (Fig. 63). Distal raphe endings forming distinct helictoglossae (Figs 69, 71).

Type:— Indonesia, Kepulauan Banda, Banda Neira, 4°30’16.98”S 129°53’57.01”E coll. date. 18 June 2018, holo - slide no. SZCZ28483! and the unmounted material with the same number at the Szczecin Diatom Collection (University of Szczecin, Poland), iso- slide no. 2018/432 and the unmounted material with the same number at the University of Rzeszow, Poland. The type population is illustrated on Figs 38–45 and 68–74.

Etymology:— The species is named to honour Zdzisław Beksiński (1929–2005), a famous Polish painter, photographer and sculptor.

Distribution:— So far, the species is only known from the type locality.

Associated diatom flora:— The most abundant taxa in assemblage were: Hantzschia amphioxys (Ehrenberg) Grunow (in Cleve & Grunow 1880: 103), Humidophila pantropica (Lange-Bertalot) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot & Kopalová (2014: 354), Pinnularia borealis Ehrenberg (1843: 420), and unidentified Adlafia sp. and Nitzschia sp. Hantzschia beksinskii sp. nov. occurred rarely in analyzed material and only few specimens were observed on each slide.