Achnanthidium maritimo-antarcticum Van de Vijver & Kopalova 2014, sp. nov.

• Main Authors: Vijver, Bart Van De, Kopalová, Kateřina
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2014
• Subjects: Biodiversity; Taxonomy; Chromista; Bacillariophyta; Bacillariophyceae; Achnanthales; Achnanthidiaceae; Achnanthidium; Achnanthidium maritimo-Antarcticum; Antarc*
• Online Access: https://doi.org/10.5281/zenodo.3851711; http://treatment.plazi.org/id/EA238799B913ED608146FD14FD2AF8B7

Achnanthidium maritimo-antarcticum Van de Vijver & Kopalová sp. nov. Figs 29-53 Morphological observations Light microscopy (Figs 29-49) Frustules in girdle view rectangular, bent around the transapical axis (Figs 29, 30).Valves linear-lanceolate with parallel to slightly convex margins and clearly protracted, rostrate, occasionally subcapitate apices (Figs 31-49). Valve dimensions (n=25): length 12–15 µm, width 2.3–2.7 µm. Raphe valve (Figs 31-40) concave with a linear axial area, narrow to almost absent near the valve apices, hardly widening towards the central part of the valve. Central area irregular, formed by several more widely spaced striae. Raphe straight, filiform, invisible, with indistinct straight, simple proximal raphe endings. Distal raphe hardly discernible in LM. Striae slightly radiate throughout the entire valve, becoming more radiate and more densely spaced near the apices, 30– 33 in 10 µm, up to 40–42 in 10 µm near the valve apices. Rapheless valve (Figs 41-49) slightly convex with very narrow, linear axial area, widening to form a weakly elliptically, never transapically elongated central area, never forming a fascia or subfascia. Central striae slightly more distantly spaced. Striae slightly radiate throughout, only slightly more denser near the apices, 30–32 in 10 µm. Scanning electron microscopy (Figs 50-53) Striae in the raphe valve composed of a series of 3 – 4 distinct, rounded to square areolae terminating in one transapically elongated, rectangular areola (Fig. 50). Central striae composed of 2 rounded areolae and one transapically elongated areola near the valve margin (Fig. 50). Occasionally, short slit-like areolae interposed between the central striae. Near the apices, striae only composed of 2–3 rounded areolae (Fig. 50). Mantle areolae elongated, slit-like. Striae on the rapheless valve composed of 2–5 irregularly shaped (mostly rounded or elongated rectangular) areolae (Fig. 51). Near the apices, striae showing lowest number of areolae (Fig. 51). Internal areolae openings ...