Rhoicosphenula Lange-Bert., Kociolek, A.A.Saber & Cantonati, stat. nov.

(Figs 2, 3)

Rhoicosphenula Lange-Bert. Nova Hedwigia 60: 244 (1995).

Cells solitary, not forming colonies or aggregates, growing as epiphytes on small mucilaginous stalks. Frustules almost rectangular in girdle view, sometimes appearing slightly broadly wedge-shaped (Fig. 2 G-I). Pseudosepta present on both poles of the valves. Raphe branches straight, with large, well-separated proximal ends (Fig. 2 A-F), and with T-shaped distal fissures (Fig. 3A). Internal fissures extend onto the central nodule, with short and very faintly bent proximal ends (Fig. 3C, H). Foramina of the areolae simple, more or less slit-shaped, forming two systems, one on the valve face and one on the mantle, respectively, separated by a hyaline mantle margin (Fig. 3A, B). Areolae are covered internally by flat hymenes (similar to those of Brachysira), developing from the sternum to the mantle without any visible interruption (Fig. 3F, G). The cingulum composed of six unilaterally open bands (Fig. 3B), including the valvocopula and first copula (each with a septum at one of the poles), as well as the four further copulae (Fig. 3C, D).

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New combinations within Rhoicosphenula stat. nov.: