Caloneis nanyiensis Pan Yu & Qing-Min You 2025, sp. nov.

Caloneis nanyiensis Pan Yu & Qing-Min You sp. nov. Figs 1, 2, 3 Type material. Holotype. Specimen circled on slide NYH-20180801 (= Fig. 1 A), deposited in the Herbarium of Shanghai Normal University (SHTU), China. Isotype. Specimen circled on slide 652047 (= Fig. 1 D), deposited in the Herbarium of University of Colorado, Boulder, USA. Type locality. China. Anhui Province: Nanyi Lake, sampling site with the coordinates 31°01'N, 118°50'E. Diatom samples collected by Pan Yu, 19 August 2018. Description. LM (Fig. 1 A – M): Valve length 14.5–28.5 μm, width 8.0–10.2 μm. Valves rhombical in shape with acutely rounded apices. Raphe narrow and arched, with slightly unilaterally bent central pores and slightly curved terminal fissures. Axial area linear-lanceolate, becoming wider at the central area. Striae are slightly radiate to parallel in the central area, becoming more radiate towards the apices, 16–18 in 10 μm. SEM valve exterior (Fig. 2 A – E): Valve face usually uneven, with slightly raised ends and a slightly concave middle (Fig. 2 A, B). Central area nearly rhombic, with a width accounting for 1 / 4–1 / 3 of the valve, the striae pattern in the central area is obviously shorter. (Fig. 2 A, B, E). Raphe branches arched with proximal raphe ends weakly unilaterally deflected and dilated, drop-like in shape (Fig. 2 A, B, E). Distal raphe fissures hooked and continuing on to the mantle (Fig. 2 C, D). Striae multiseriate, composed of 4–5 rows of small, rounded areolae, which are occluded by heavy silicified, perforated hymenes (Fig. 2 D, E). Girdle with a single row of linear poroids (Fig. 2 A). SEM valve interior (Fig. 3 A – E): The raphe is filiform and slightly arched (Fig. 3 A). The proximal raphe endings are deflected to the same sides (Fig. 3 B, C) and curve towards a central nodule that is positioned to one side of the central area. The raphe terminates distally as an elevated helictoglossa (Fig. 3 D, E). An axial plate covers the alveoli, leaving small marginal openings bordered by costae thickened and raised from the valve face (Fig. 3 A, B). Striae composed of 2–4 areolae are present on the mantle (Fig. 3 D, E). Etymology. The new species is named after the type locality, Nanyi Lake. Distribution and ecology. So far, the new species has only been collected at the type locality in Nanyi Lake. The habitat of the new species is characterised by pH 8.1, water temperature 30.2 ° C, TDS 0.204 g. l - 1, conductivity 175.7 μs. cm - 1, collected in one sample (NYH –20180801) on Cladophora. In the type sample, this new species occurred at less than 2 % relative abundance, established from a total count of 400 valves. Amongst the species co-occurring with Caloneis nanyiensis sp. nov., only four species accounted for more than 5 % of the assemblage: Fragilaria pararumpens Lange-Bertalot, Hofmann & Werum (Hofmann et al. 2013) (25.75 %), Achnanthidium jackii Rabenhorst (Rabenhorst 1861) (18.75 %), Aulacoseira granulata (Ehrenberg) Simonsen (Simonsen 1979) (11.5 %) and Encyonopsis microcephala (Grunow) Krammer (Krammer 1997) (%).