Hantzschia zidarovae, Bulínová & Kochman-Kędziora & Kopalová & Vijver, 2018

Bulínová, Marie, Kochman-Kędziora, Natalia, Kopalová, Kateřina & Vijver, Bart Van De, 2018, Three new Hantzschia species (Bacillariophyta) from the Maritime Antarctic Region, Phytotaxa 371 (3), pp. 168-184 : 173

Hantzschia zidarovae sp. nov. ( Figs 11–21 )

LM ( Figs 11–17 ):—Valves typically dorsiventral with a concave to almost straight ventral margin and a slightly convex dorsal margin, often more or less straight in the middle of the valve. Apices shortly protracted, subcapitate, never clearly elongated. Valve dimensions (n=10): length 45–60 μm, width 8.0–10.5 μm. Fibulae 5–6 in 10 μm, almost equidistantly spaced, the middle two fibulae more distant than the others. Each fibula connected to 2–3 transapical costae. Transapical striae slightly radiate in the middle, becoming parallel and even convergent near the apices, 19–20 in 10 μm. Areolae not discernible in LM. SEM ( Figs 18–21 ): Valves showing a rather broad hyaline, weakly thickened margin. Dorsally, margin entirely covered with isolated areolae, arranged in transapical series ( Fig. 18 ). Areolae on the valve face located in deep, transapically running grooves, externally covered by individual hymenes ( Fig. 19 ). Mantle striae composed of a series of isolated, rounded areolae ( Figs 19, 20 ). External proximal raphe endings clearly bent, unclear whether interrupted or not ( Figs 19, 20 ). Occasionally, deep groove present below the proximal endings ( Fig. 20 ). Internally, fibulae clearly unevenly distributed, connected to 1–4 transapical costae ( Fig. 21 ). Transapical striae located in deep grooves ( Fig. 21 ).

Type:— SOUTH SHETLAND ISLANDS, Livingston Island, sample LIV-BY16A (62°38’10.8”S / 61°6’27.4”W), leg. M. Toro, coll. date 16 December 2006 (holotype, slide BR 4513 ; isotype, slide PLP –343, University of Antwerp , Belgium) .

Ecology:— Hantzschia zidarovae was found with certainty in sample LIV-BY16A, taken from a biofilm in a flooded area between stones on Byers Peninsula close to the main plateau. The sample is dominated by various taxa of Luticola , Hantzschia , Pinnularia and Humidophila . On King George Island, another small population was found in a sample collected from soil on the Ecology Glacier Forefield area close to the Polish Arctowski station.

Etymology:—The species is named after our colleague and friend Dr. Ralitsa Zidarova in honour of her work on the diatoms of the Maritime Antarctic Region.

Figures

FIGURES 11–21. Hantzschia zidarovae. LM and SEM observations of the type population (Livingston Island, Byers Peninsula, sample LIV-BY16A). Figs 11–17. Light micrographs showing a reduction in valve length. Fig. 18. External view of an entire valve showing the thickened ventral hyaline border and the very deep grooves with the striae. Fig. 19. External detail of the central area with the deflected, interrupted, proximal raphe endings and the deep striae grooves. Fig. 20. Internal detail of the central area showing the external, interrupted proximal raphe endings. Note the groove under the raphe endings. Fig. 21. Internal view of an entire valve showing the irregularly placed fibulae. Scale bar represents 10 μm except for figs 19 & 20 where scale bar = 1 μm.