Nitzschia lacuum Lange-Bertalot, 1980

Olszynski, Rafal M., Zakrzewski, Piotr K., Rimet, Frederic, Sulkowska, Julia, Peszek, Lukasz & Zelazna-Wieczorek, Joanna, 2024, Morphology and phylogeny of Nitzschia nandorii sp. nov. (Bacillariophyceae), a new small-celled lanceolate species from a post-mining reservoir, PhytoKeys 241, pp. 1-26 : 1

Nitzschia lacuum Lange-Bertalot, 1980

Figs 3AF-AW , 9

Notes.

The outline of the frustules is lanceolate with capitate to acutely rounded apices (Fig. 3AF-AW). Valves are 13-22 µm length and 2.0-3.5 µm in width. The ratio of length and width is 4.38-10.00. Striae 36-37 in 10 µm (undistinguished in LM). Fibulae are visible 11-18 in 10 µm. Striae are uniseriate, arranged transapically. Along the edge of the valve, where the raised raphe canal is located, two longitudinal rows of areolae are present (Fig. 9A, D ) - a doublet nearer to the raphe and a single areola at the junction with the valve face opened to the interior of the raphe canal. Distal raphe endings are strongly hooked and deflect on each valve in different directions (Fig. 9A, B, D ). The central nodule is absent (Fig. 9B ). The proximal mantle possesses three rows of areolae (Fig. 9C ). Valvocopula possess scalloped edges (opened pores) (Fig. 9C ). The distal mantle is narrow and has scallops on the edge (Fig. 9B, C ). Internally, fibulae have equal spacing, there is no wider gap between centre fibulae. Distal raphe fissures terminate with small helictoglossa (Fig. 9E ).

Figures

Figure 3. Light microscope photomicrographs of Nitzschia spp. A-L N. nandorii sp. nov. from natural population K type species (marked by an asterisk (* )) M-AE N. nandorii sp. nov. from culture AF-AW N. lacuum AX-BI N. alpinobacillum. Scale bar: 10 µm.

Figure 9. SEM photomicrographs of Nitzschia lacuum A-C valve view A visible two rows of areolae on the raphe canal (white arrow), distal raphe fissures are strongly hooked and deflect (black arrow) B frustule with a visible proximal mantle, the arrangement of areolae in the proximal mantle is the same as in the raphe canal, central view with raphe without central fissures, the small ridge on the raphe canal (white arrow) C decompose frustule, proximal mantle with areole and at least one open into the raphe canal (white arrow), valvocopula with scalloped edges (black arrow) D apex with strongly hooked distal raphe fissure E internal view of the apex with visible distal raphe fissure terminate with helictoglossa. Scale bars: 5 µm (A-C); 0.5 µm (D, E).