Gomphosphenia vallei Beauger, C. E. Wetzel, Allain & Ector 2022, sp. nov.
Creators: name: Beauger, Aude
name: Allain, Elisabeth
name: Voldoire, Olivier
name: Blavignac, Christelle
name: Rossi, Sofia
name: Wetzel, Carlos E.
name: Ector, Luc
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Chromista
Bacillariophyta
Bacillariophyceae
Cymbellales
Rhoicospheniaceae
Gomphosphenia
Gomphosphenia vallei

description: Gomphosphenia vallei Beauger, C.E.Wetzel, Allain & Ector sp. nov. (Figs 2 –45)
Light microscopy observations (Figs 2–25): Valves linear-clavate in larger specimens to clavate in smaller ones and elliptical in the smallest individuals. Headpoles rounded, footpoles narrowly rounded. Valve dimensions (n = 30): length 4.2–13.1 µm, width 1.5–2.5 µm. Raphe straight, filiform. Striae visible in LM, almost parallel throughout the valve to slightly radiate in the mid-valve, 23–29 in 10 µm. Axial area linear and narrow. Central area from absent to asymmetrical with round and distinct central nodule. In girdle view, frustules almost rectangular to slightly wedgeshaped.
Scanning electron microscopy observations (Figs 26–33): Valve face flat. Externally, striae composed of single slit-like areolae, becoming very short slit near the poles (Figs 26–30). Striae slightly radiate in central part of valve, becoming convergent towards both head and footpoles. Raphe straight, filiform, with slightly dilated distal and proximal raphe endings (Figs 26–30). Distal raphe fissures terminating on the valve face, not extending onto the valve mantle (Fig. 28). Internally, proximal raphe endings bent in the same direction (Fig. 31). Internal terminal raphe fissures ending in helictoglossae (Fig. 31). Single row of slit-like areolae located on the valve mantle (Figs 26, 28, 30, 32), sometimes rounded in shape near the mid-valve and towards the footpole (Figs 27, 33). Central area with a unilateral fascia, with a short areola on one side and absence of areola on the other side (Figs 26–29). Central nodule slightly raised (Fig. 31). Apical pore fields absent (Fig. 28). In girdle view, frustules with cingulum composed of open bands, each bearing one row of small round pores (Figs 28, 30, 32–33).
Type locality: — FRANCE. Chambon-sur-Lac, “Réserve Naturelle Nationale de la Vallée de Chaudefour”: Pérouse Stream, sample PER _200821, 1,184 m a.s.l., E688534.487, N6493049.143 (Lambert 93), collection date 20 August 2021 (assigned here, holotype: CLF!, slide no. CLF310234; isotype: BR! slide no. BR-4707. The holotype is represented by Fig. 12).
Etymology: — This species is named for Eric Vallé, curator of the National Nature Reserve and passionate about botany.
Ecology and associated diatom taxa: — The Pérouse Stream, situated in the glacial cirque of Chaudefour Valley, is characterized by a low conductivity (35 μS cm-1), a low temperature (11.9 °C) and is well oxygenated (92.9% of dissolved oxygen) (Table 1). The pH is 7.09. As underlined the conductivity, the concentrations of the measured ions are low with a maximum for the sodium concentration (2.53 mg L- 1).
The type population of G. vallei was found in Pérouse Stream associated with other taxa. In August 2021, the two co-dominant taxa were Planothidium lanceolatum (Brébisson ex Kützing 1846: 247) Lange-Bertalot (1999: 287) (36%) and Rhoicosphenia abbreviata (C. Agardh 1831: 34) Lange-Bertalot (1980: 586) (30%). The other species well represented (<10%) were Achnanthidium subatomus (Hustedt 1939: 554) Lange-Bertalot (1999: 273) (7.1%), Gomphonema sp. cf. minutum C. Agardh (1831: 34) (6.4%), Navicula reichardtiana Lange-Bertalot in Lange-Bertalot & Krammer (1989: 163) (2.3%), Odontidium mesodon (Ehrenberg 1839: 57) Kützing (1849: 12) (2.3%), Gomphosphenia vallei (2.3%), Reimeria sinuata (W. Gregory 1856: 4) Kociolek & Stoermer (1987: 457) (1.9%), Planothidium curtistriatum C.E.Wetzel, Van de Vijver & Ector in Wetzel et al. (2019: 61) (1.9%), Cocconeis rouxii Héribaud & Brun in Héribaud (1893: 45) (1.9%) and Encyonema minutum (Hilse in Rabenhorst 1862: No. 1261) D.G.Mann in Round et al. (1990: 667) (1.1%). At last, Chamaepinnularia obsoleta (Hustedt 1942a: 69) C.E.Wetzel & Ector in Wetzel et al. (2013: 158), Cyclotella antiqua W. Smith (1853: 28), Geissleria acceptata (Hustedt 1950: 398) Lange-Bertalot & Metzeltin (1996: 64), Gomphonema clavatum Ehrenberg (1832: 88), Gomphonema exilissimum (Grunow in Van Heurck 1880: pl. 25, fig. 12) Lange-Bertalot & E.Reichardt in Lange-Bertalot & Metzeltin (1996: 70), Humidophila perpusilla (Grunow 1860: 552) R.L.Lowe, Kociolek, J.R.Johansen, Van de Vijver, Lange-Bertalot & Kopalová (2014: 358), Mayamaea permitis (Hustedt 1945: 919) Bruder & Medlin (2008: 327), Meridion constrictum Ralfs (1843: 458), Nitzschia hantzschiana Rabenhorst (1860: 40), Nitzschia soratensis E.Morales & M.L.Vis (2007: 128), Nupela lapidosa (Krasske 1929: 350) Lange-Bertalot (1999: 274), Pantocsekiella ocellata (Pantocsek 1901: 134) K.T.Kiss & Ács in Ács et al. (2016: 62), Pinnularia sinistra Krammer (1992: 105), Psammothidium helveticum (Hustedt 1933: 385) Bukhtiyarova & Round (1996: 8), Psammothidium subatomoides (Hustedt in Schmidt 1936: pl. 404) Bukhtiyarova & Round (1996: 13) and Sellaphora atomoides (Grunow in Van Heurck 1880: 107) C.E.Wetzel & Van de Vijver in Wetzel et al. (2015: 219) represented less than 1% of the whole community.
description: Published as part of Beauger, Aude, Allain, Elisabeth, Voldoire, Olivier, Blavignac, Christelle, Rossi, Sofia, Wetzel, Carlos E. & Ector, Luc, 2022, Gomphosphenia vallei (Bacillariophyta), a new diatom species from a stream in the " Réserve Naturelle Nationale de la Vallée de Chaudefour ", Massif Central (France), pp. 167-179 in Phytotaxa 542 (2) on pages 170-173, DOI: 10.11646/phytotaxa.542.2.4, http://zenodo.org/record/6415941