Hantzschia abundans Lange-Bertalot, 1993

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 : 176

Hantzschia abundans Lange-Bertalot ( Figs 66–76 )

LM ( Figs 66–73 ):—Valves dorsiventral with a convex dorsal and a concave ventral margin, typically ventrally constricted near the middle. Apices protracted, clearly elongated. Valve dimensions (n=20): length 55–65 μm, width is 7.0–8.0 μm. Fibulae 5–8 in 10 μm, unequally spaced, the middle two fibulae clearly more distant. Each fibula connected to 1–4 transapical costae. Striae equidistant, weakly radiate in the middle becoming more parallel near the apices, 19–21 in 10 μm. Central striae usually slightly more distant. Areolae not discernible in LM. SEM ( Figs 74–76 ): Valves on the ventral side bordered by a narrow hyaline keel ( Fig. 74 ). Striae composed of small, rounded areolae, towards the ventral margin located in rather broad, shallow grooves ( Figs 74, 75 ). Isolated areolae bordering the ventral keel ( Fig. 75 ). External proximal raphe branches straight, clearly interrupted near the valve middle ( Fig. 75 ). Internal proximal raphe endings interrupted, straight ( Fig. 76 ).

Ecology:—So far, the species was only with certainty confirmed from a seepage area on James Ross Island.

Figures

FIGURES 66–76. Hantzschia abundans. LM and SEM observations of a population from James Ross Island (sample S1E). Figs 66–73. Light micrographs showing a reduction in valve length. Fig. 74. External view of an entire valve showing the very narrow ventral hyaline border and striae composed of rounded areolae. Fig. 75. External detail of the central area with the straight, interrupted, proximal raphe endings. Note the striae that are weakly depressed near the ventral area. Fig. 76. Internal detail of the central area with the interrupted proximal raphe endings. Scale bar represents 10 μm except for figs 75 & 76 where scale bar = 1 μm.