Hantzschia incognita Zidarova & Van de Vijver, 2010

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 : 176-180

Hantzschia incognita Zidarova & Van de Vijver ( Figs 77–89 )

LM ( Figs 77–85 ):—Valves clearly dorsiventral with a moderately convex but never straight dorsal side. Ventral side concave in the middle part becoming convex near the apices, never constricted in the middle. Valve apices weakly protracted, rostrate, never subcapitate to capitate. Valve dimensions (n=20): length 48–67 μm, 7.5–8.0 μm. Fibulae, more or less spaced, the middle ones usually not more distant than the others, 5–8 in 10 μm, connected to 1–3 transapical costae. Striae parallel, equidistant throughout, becoming convergent near the apices, 18–20 in 10 μm. Areolae not discernible in LM. SEM ( Figs 86–89 ): Valves on the ventral side bordered by a narrow, irregularly shaped, hyaline keel ( Fig. 86 ). Striae uniseriate, composed of small, rounded areolae, situated in a shallow, continuous groove, externally covered by small, individual hymenes, ca. 45 in 10 μm ( Fig. 87 ). External ( Fig. 87 ) and internal ( Fig. 88 ) raphe branches continuous, lacking a central interruption. Fibulae irregularly shaped ( Fig. 89 ).

Ecology:— Hantzschia incognita is a common species in soil and on mosses in the Maritime Antarctic Region. The type population was found in sample П1а/04, taken from wet soil near a stream, close to the Spanish Juan Carlos I base ( Zidarova et al. 2010).

Figures

FIGURES 77–89. Hantzschia incognita. LM and SEM observations of the type population (Livingston Island, Hurd Peninsula, sample Π1a). Figs 77–85. Light micrographs showing a rather limited morphological variability. Fig. 86. External view of an entire valve showing the thickened ventral hyaline border and the grooves with the striae. Fig. 87. External detail of the central area with the continuous proximal raphe endings and the deep stria grooves. Fig. 88. Internal detail of the central area with the continuous proximal raphe endings. Fig. 89. Internal view of an entire valve showing the irregularly placed fibulae. Scale bar represents 10 μm except for figs 87 & 88 where scale bar = 1 μm.