Crucicostulifera bebourensis Coste, Le Cohu & Gassiole 2014, sp. nov.
Creators: name: Cohu, René Le
name: Gassiole, Gilles
name: Coste, Michel
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Chromista
Bacillariophyta
Bacillariophyceae
Cymbellales
Crucicostulifera
Crucicostulifera bebourensis

description: Crucicostulifera bebourensis Coste, Le Cohu & Gassiole sp. nov.
Figures 1–27, Figs 1–8 are of the holotype.
Description: Valves lanceolate with obtusely rounded apices. Frustule more or less rectangular in girdle view. Length: 25.4–69.0 µm; breadth: 7.9–12.5 µm. Raphe lateral near the poles; terminal fissures hooked to the secondary side of the valve; proximal raphe endings almost straight and enlarged; central pores inconspicuous. Axial area lanceolate without distinct central area. Striae slightly radiate and distinctly punctate, 12–14 in 10 µm in the middle part of the valve, up to 18 in 10 µm towards the poles. SEM. External view: raphe slit curved to the secondary side of the valve becoming axial with proximal endings almost straight and enlarged; terminal fissures strongly hooked to the secondary side of the valve and terminating at the valve face / mantle junction. Vaulted valves with junction between valve face and mantle unclear, and a system of longitudinal ribs discernible. Striae with x-shaped areolar openings and extending without interruption onto the mantle. Internal view: raphe fissure straight with proximal endings hooked towards the same side of the valve. Striae in depressions with areolar openings oval and occluded. Cingulum composed of at least three open bands.
Holotype: PC0143222. Laboratoire de Cryptogamie. Muséum d'Histoire Naturelle. Paris.
Isotype: BR–4277. Jardin Botanique National de Belgique. Département de Bryophyta et Thallophyta. Domaine de Bouchout. Meise. Belgique.
Type locality: Bébour, rivière des Marsouins, Île de la Réunion (Longitude: 55°33'58.0"E –Latitude: 21°06'45.3"S)
Etymology: The specific epithet refers to the sample site.
LM Morphology (Figs 1–12)
The cells (Figs 9–12) are more or less rectangular in girdle view (6 – 11 µm broad). The valves (number of valves observed: 196) are lanceolate with obtusely rounded apices (Figs 1–8). The raphe is lateral near the poles and the terminal fissures are strongly hooked to the secondary side of the valve (Figs 1, 7 and 8). The proximal raphe endings are almost straight and enlarged; the central pores are inconspicuous. The distance between the proximal raphe endings decreases from the largest to the smallest individuals. The axial area is lanceolate, relatively wide (up to 4 µm), slightly asymmetric in the middle part of the valve and without a distinct central area. The striae, slightly radiate throughout, appear distinctly punctate, 12–14 in 10 µm in the middle part of the valve, up to 18 in l0 µm towards the poles.
Ecology and distribution
C. bebourensis was most abundant (51% relative abundance) in a sample with a pH of 5.5, very low conductivity (6–8 µS.cm -1) and very low nutrient concentration (Table 2). It was associated with Kobayasiella bebourensis Le Cohu, Gassiole & M. Coste (2012: 402) and Stenopterobia schweickerdtii (Cholnoky) Brassac, Ludwig & Torgan (2003: 186) which contributed respectively 11% and 4% of the total number of diatoms counted. Other taxa not yet identified were represented by Achnanthidium sp .. C. bebourensis was recorded from an other sampling site of the “rivière des Marsouins” (Takamaka) but with a very low relative abundance (0.2%).
description: Published as part of Cohu, René Le, Gassiole, Gilles & Coste, Michel, 2014, Three new species of Cymbellales (Bacillariophyceae) from Réunion Island, pp. 117-132 in Phytotaxa 156 (3) on pages 119-120, DOI: 10.11646/phytotaxa.156.3.3, http://zenodo.org/record/5127779