Pseudostaurosira katharinae Van de Vijver & C. E. Wetzel 2024, sp. nov.
Creators: name: Vijver, Bart Van De
name: Wetzel, Carlos E.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Chromista
Ochrophyta
Bacillariophyceae
Fragilariales
Fragilariaceae
Pseudostaurosira
Pseudostaurosira katharinae

description: Pseudostaurosira katharinae Van de Vijver & C.E.Wetzel sp. nov. (Figs 1–17 LM, 18–27 SEM)
Frustules rectangular in girdle view, solitary or in pairs (Figs 1–2). Ribbon-like colonies so far not observed. Valve mantle broad, with a large hyaline abvalvar part. Mantle plaques small but distinctly present on the mantle edge (Figs 18–19). Girdle composed of several plain, open, ligulate copulae, each bearing a thin siliceous ridge (Figs 18–19). Valvocopula largest, plain (Figs 18–19). Most copulae fracted (Figs 18, 19 & 26, arrows). Valves lanceolate to linearlanceolate in larger specimens, becoming more elliptic-lanceolate to elliptic in smallest valves (Figs 3–17). Valve margins convex to weakly convex, not linear. Apices broadly to cuneately rounded, rarely weakly protracted. Usually, one apex slightly depressed (Fig. 19, white arrow). Valve dimensions (n=30): valve length 9–15 μm, valve width 3.5–4.5 μm. Sternum broad, lanceolate, max width 1.2–1.8 µm. Occasionally sternum narrow but abruptly widening forming a rounded central area (Figs 11, 13). Striae uniseriate, weakly radiate, irregularly shortened throughout the entire valve length, 14–16 in 10 μm, composed of 1–3 areolae on valve face (Figs 20–22), and 1–3 areolae on valve mantle (Figs 18–19, 21). Areolae at valve face/mantle junction markedly larger, decreasing in diameter towards sternum (Figs 20–22). Mantle areolae separated from those on valve face by relatively long spines (Figs 22, 25). Spines and areolae on both mantle and valve face surrounded by small siliceous papillae, arranged in circles (Figs 21, 24). Apical pore fields present on both apices, large, composed of several rows of pores located in linear depressions between raised small siliceous papillae (Fig. 23). Internally, areolae located each in a single depression covered by rounded volae (Fig. 25).
Type:— BELGIUM. Flanders, Province of Limburg, Maaseik, Bosbeek, sample APM 21-91, 51°5.6348’N, 5°45.894’E, coll. date 25 Jun. 2021, leg. Vlaamse Milieu maatschappij (VMM) (holotype slide BR-4850, Fig. 5 represents the holotype, isotype slide 448 in Collection University of Antwerp, Belgium).
PhycoBank registration:— http://phycobank.org/104825.
Etymology:— The new species is named after Katharina Wilfert, oldest stepdaughter of the first author.
Ecology and distribution:— Pseudostaurosira katharinae was described from a small river near Maaseik, in the northeastern part of Belgium. The type locality had an almost circumneutral pH (6.9–7.3), a moderate conductivity (> 200 µS/cm), and higher sulphate (12–30 mg /l) and nitrate levels (1.4–3.3 mg /l). The associated flora was dominated by several small-celled araphid species such as, apart from P. katharinae, also larger populations of Staurosirella marginostriata Van de Vijver & V.Peeters (in Van de Vijver et al. 2024: 142), S. stoksiana, Pseudostaurosira alvareziae and P. brevistriata. Other dominant species in the sample included Aulacoseira ambigua (Grunow in Van Heurck 1882: pl. 88, figs 12–15) Simonsen (1979: 56), A. granulata (Ehrenberg 1843b: 415) Simonsen (1979: 58) and Navicula cryptocephala Kützing (1844: 95), pointing to more meso-eutrophic, alkaline conditions (Lange-Bertalot et al. 2017). The species has also been found in a French lake (“ Mare à Goriaux ”) (Figs 26 & 27). The Mare à Goriaux, an intraforest pond, is located within the perimeter of the Regional Natural Park of the Scarpe and Escaut Plains, at the southern edge of the Raismes, St-Amand, and Wallers state forest (Marchyllie, 1992). The pond, formed from mining subsidence caused by the exploitation of the Vicoigne and Arenberg pits, was originally a wetland due to groundwater outcrops. The exploitation of the Arenberg pit caused the most significant collapses, initially creating three ponds that merged around the 1930s to form the current Mare à Goriaux (Marchyllie, 1992). The high mineral content of the pond’s water is largely due to SO 4 - ions (6 to 700 mg /l), Cl- ions (145 mg /l), as well as Na + ions (560 mg /l) and Ca + ions (110 mg /l).
It is likely that the species is more widespread than currently known due to confusion with similar taxa.
description: Published as part of Vijver, Bart Van De & Wetzel, Carlos E., 2024, A new Pseudostaurosira species (Bacillariophyta, Staurosiraceae) from lowland rivers and lakes in Europe (Atlantic Biogeographic Region), pp. 49-54 in Phytotaxa 663 (1) on pages 50-52, DOI: 10.11646/phytotaxa.663.1.6, http://zenodo.org/record/14515987