Arcanodiscus saundersianus Goeyers & Van de Vijver 2020, sp. nov.

• Main Authors: Goeyers, Charlotte, Vijver, Bart Van De
• Format: Other/Unknown Material
• Language: unknown
• Published: 2020
• Subjects: Biodiversity; Taxonomy; Chromista; Ochrophyta; Bacillariophyceae; Arcanodiscales; Arcanodiscaceae; Arcanodiscus; Arcanodiscus saundersianus; Antarctic; Campbell Island; Pacific; Saunders; Antarc*
• Online Access: https://zenodo.org/record/4329150; https://doi.org/10.5281/zenodo.4329150

Arcanodiscus saundersianus Goeyers & Van de Vijver sp. nov. http://phycobank.org/ 102320 Figs 97–115, 132–138 Etymology The species is named in honour of our colleague Dr Krystyna Saunders (Australian Nuclear Science and Technology Organisation, Kirrawee, Australia) to acknowledge her for her ecological and paleoecological diatom research on the sub-Antarctic islands in the Pacific Ocean. Material examined Holotype CAMPBELL ISLAND • sub-Antarctic region; sample BAS272; 26 Dec. 1969; D. Vitt leg.; BR-4581. Isotype CAMPBELL ISLAND • same collection data as for holotype; slide at University of Antwerp, Belgium; PLP-372. Description Light microscopy (Figs 97–115) Frustules broadly discoid, almost square to rectangular with broadly rounded edges and convex valve faces. Frustules often found attached to each other. Chains composed of more than 2 cells however never observed. Multiple discoid chloroplasts present. Girdle bands not discernible in LM. Valves rather strongly silicified, rounded with a thick mantle and convex, weakly domed valve face. Valve dimensions (n = 25): valve diameter 6–17.5 μm, frustule height (n = 10): 4.5–7.0 μm. Central area is a large, smooth, hyaline zone, 3.0–7.5 μm, 50–55% of the total valve diameter, surrounded by a more rugose, irregularly shaped, marginal zone where striae are difficult to distinguish. Visible processes lacking. Scanning electron microscopy (Figs 132–138) Frustules discoid with very heavily silicified valves, visible as a thick mantle (Figs 132, 137). Cingulum comprises several, narrow, very thin, non-perforated, open copulae (Fig. 132). Pars interior of the copulae clearly fimbriate giving the impression of perforations on the copulae when girdle not eroded (Figs 132, 133, arrows). Copulae clearly open, ligulate (Fig. 132, double arrows). Valve face with large, flat hyaline, clearly rounded central area, lacking areolae and any other ornamentation (Figs 134–136). Marginal zone gently sloping towards the mantle, entirely covered with rounded to slit-like areolae, ca ...