Caloneis nanyiensis Pan Yu & Qing-Min You, 2025

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

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3

Type material.

Holotype. Specimen circled on slide NYH-20180801 (= Fig. 1 A View Figure 1 ), deposited in the Herbarium of Shanghai Normal University ( SHTU), China. GoogleMaps

Isotype. Specimen circled on slide 652047 (= Fig. 1 D View Figure 1 ), deposited in the Herbarium of University of Colorado, Boulder, USA.

Type locality.

China. Anhui Province: Nanyi Lake   GoogleMaps , 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 View Figure 1 ): 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 View Figure 2 ): Valve face usually uneven, with slightly raised ends and a slightly concave middle (Fig. 2 A, B View Figure 2 ). 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 View Figure 2 ). Raphe branches arched with proximal raphe ends weakly unilaterally deflected and dilated, drop-like in shape (Fig. 2 A, B, E View Figure 2 ). Distal raphe fissures hooked and continuing on to the mantle (Fig. 2 C, D View Figure 2 ). Striae multiseriate, composed of 4–5 rows of small, rounded areolae, which are occluded by heavy silicified, perforated hymenes (Fig. 2 D, E View Figure 2 ). Girdle with a single row of linear poroids (Fig. 2 A View Figure 2 ).

SEM valve interior (Fig. 3 A – E View Figure 3 ): The raphe is filiform and slightly arched (Fig. 3 A View Figure 3 ). The proximal raphe endings are deflected to the same sides (Fig. 3 B, C View Figure 3 ) 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 View Figure 3 ). An axial plate covers the alveoli, leaving small marginal openings bordered by costae thickened and raised from the valve face (Fig. 3 A, B View Figure 3 ). Striae composed of 2–4 areolae are present on the mantle (Fig. 3 D, E View Figure 3 ).

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) (%).