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

Holotype.

Slide no. 20-093 stored at the South African National Diatom Collection (SANDC) at North-West University, Potchefstroom, South Africa.

Isotype 1.

Slide no. 27525 and unmounted material with the same number at the Szczecin Diatom Collection (SZCZ) hosted by the University of Szczecin.

Isotype 2.

Slide no. 2018/426 and unmounted material with the same number at the University of Rzeszów, Poland.

Type locality.

Jonkershoek Nature Reserve, Western Cape, South Africa, 33°59.695'S, 18°58.726'E, leg. W. Morek and B. Surmacz, 20.09.2018.

Etymology.

The specific epithet refers to the size and shape of valve apices.

Description. LM (Fig. 1A-V ). Valves linear-lanceolate to lanceolate with convex margins and clearly protracted, capitate, small apices, rectangular in girdle view. The width of apices is approximately one third of the valve width. Valve dimensions (n = 25): length 14.0-24.0 μm, width 4.5-6.6 μm. Axial area linear, narrow. An isolated pore present in the central area, located halfway between valve margin and proximal raphe endings. Central area rectangular to slightly bow-tie-shaped and asymmetric, bordered on both sides with 3-4 areolae. Irregularly-scattered areolae and shallow depressions present in the central area. Raphe branches straight, proximal raphe endings deflecting away from isolated pore. Transapical striae radiate throughout, 19-22 in 10 μm.

Description. SEM (Fig. 1W -AD). Externally, striae composed of 1-4 areolae, decreasing from 3-4 in striae next to the central area to only one next to the apices. Areolae elongated, becoming larger towards the valve margin (Fig. 1W, X , AA, AB). On both sides, the central area bordered by 3 round, isolated areolae. Several ghost areolae present in the central area (Fig. 1AA, AC). Raphe branches positioned on the slightly raised sternum (Fig. 1Z ). Proximal raphe endings shortly bent away from the small, round isolated pore (Fig. 1 AA, AC). Distal raphe fissures hooked, first deflected towards the same side as the proximal raphe endings, then hooked towards the opposite side, continuing on to the mantle (Fig. 1W, X , AB). Single row of large, usually elongated areolae present on the mantle (Fig. 1Y ). Only close to the apices and in the central part of the valve, areolae becoming smaller and rounded (Fig. 1Y, Z ). Copulae numerous with 1 to 3 rows of areolae (Fig. 1Z ). Internally, areolae occluded by hymenes forming continuous strip (Fig. 1AD). Isolated pore opening rounded, covered by a lipped slit (Fig. 1AD). Longitudinal channel visible internally along valve edges.

Figures

Figure 1. A-AD Holotype population of Luticola microcephala M. Rybak, Peszek & Kochman-Kedziora, sp. nov. A-V LM images of valve views W-AD SEM images W-X external view of valves Y external view of frustule girdle view Z partial valve view and girdle view of middle frustule section AA central area with several shallow depressions AB raphe structure with detailed view on distal raphe endings AC proximal raphe endings AD internal view of valve. Scale bars: 10 µm (A-Y), 5 µm (Z-AA), 4 µm (AB), 3 µm (AC, AD).