Luticola asymmetrica M. Rybak, Kochman-Kedziora & Peszek, 2021

Rybak, Mateusz, Kochman-Kedziora, Natalia & Peszek, Lukasz, 2021, Description of four new terrestrial diatom species from Luticola and Microcostatus genera from South Africa, PhytoKeys 182, pp. 1-26 : 1

Luticola asymmetrica M. Rybak, Kochman-Kedziora & Peszek sp. nov.

Holotype.

Slide no. 20-091 stored at the South African National Diatom Collection (SANDC) at North-West University, Potchefstroom, South Africa.

Isotype 1.

Slide no. 27523 and unmounted material with same number stored at the Szczecin Diatom Collection (SZCZ) hosted by the University of Szczecin.

Isotype 2.

Slide no. 2018/425 and unmounted material with the same number at the University of Rzeszów, Poland.

Type locality.

Prince Alfreds’s Pass, Knysna, Western Cape, South Africa, 33°58.475'S, 23°08.797'E, leg. W. Morek and B. Surmacz, 20.09.2018.

Etymology.

The specific epithet refers to the species asymmetry in valve outline and proximal raphe endings.

Description. LM (Fig. 2A-R ). Valves weakly asymmetric with convex margins, rectangular in girdle view. Larger valves lanceolate with protracted, subrostrate apices; smaller valves elliptic-lanceolate to rhombic lanceolate with broadly-rounded apices. Valve dimensions (n = 25): length 12.5-36.0 μm, width 6.0-8.0 μm. Axial area linear, slightly widening towards both the central area and the apices. Central area bow-tie-shaped, bordered by 3-5 shortened striae. One isolated pore present in the central area. Raphe branches straight. Proximal raphe endings unilaterally deflected away from the isolated pore. Terminal raphe fissures elongated, hooked. Striae radiate throughout, 17-20 in 10 µm.

Description. SEM (Fig. 2S-Z ). Striae composed of 2-5 elongated areolae. Areolae close to the valve margin larger (Fig. 2S, T, Z ). Usually 3-5 isolated areolae positioned on both sites in central area, close to the valve margin. Small, round isolated pore located in the central area, halfway between the valve margin and proximal raphe endings (Fig. 2S-U, X, Y ). In some specimens, small, irregular depressions present on the valve face producing uneven appearance of the valve face (Fig. 2S, X-Z ). Raphe branches straight. Proximal raphe fissures long, unilaterally deflected to the side opposite to stigma and expanded into small pores. In some specimens, proximal raphe endings asymmetrical (Fig. 2T, U, X, Y ). Distal raphe fissures hooked towards opposite side, terminating shortly before valve edge (Fig. 2S-V, Z ). Distal raphe fissures interrupting row of areolae on the valve mantle (Fig. 2Z ). One row of round areolae present on the valve mantle (Fig. 2T-V ). Copulae with 2 rows of areolae (Fig. 2V ). Internally, areolae occluded by hymenes forming irregular strip. Isolated pore opening rounded, covered by a lipped slit (Fig. 2W ).

Figures

Figure 2. Holotype population of Luticola asymmetrica M. Rybak, Kochman-Kedziora & Peszek, sp. nov. A-R LM images of valve views S-Z SEM images S-V external view of an entire valve W internal valve face view of an entire valve X-Y different shape of proximal raphe endings Z distal raphe endings. Scale bars: 10 µm (A-T), 5 µm (U-Z).