Achnanthes licunese W. Chen, P. Yu & G.F. Song & R. Abate, sp. nov.
Creators: name: Chen, Wei
name: Yu, Pan
name: Song, Gaofei
name: Abate, Rediat
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Chromista
Bacillariophyta
Bacillariophyceae
Achnanthales
Achnanthaceae
Achnanthes
Achnanthes licunese

description: Achnanthes licunese W. Chen, P. Yu & G.F. Song & R. Abate, sp. nov. (Figs 1–40)
LM description: Frustule usually chain-forming in colonies (Figs 1–8), with concave raphid valves (RV) and convex araphid valves (ARV) (Figs 9–20). Each cell possesses two chloroplasts, separated by median transapical plane. Valves linear to linear-lanceolate with obtuse apices, slightly constricted at center. Valves length 38.0–53.5 μm, width 10.0– 12.5 μm (n = 200). Single row of areolae located between transapical costae, and 9–10 striae in 10 μm on both RV and ARV. RV with stauros reaching valve margins, while longitudinal raphe sternum runs along apical axis to center of valve. ARV without stauros but with sternum, often shifted to valve margin, narrow and linear.
SEM description (Figs 21–40): External RV valve face gently concave around transapical axis in girdle view, with at least three bands connecting two valves (Fig. 21). 2–4 rows of areolae present on mantle, no areolae in center (Figs 21–23). Band areolae similar to those on valve face. Rows of silica granules of varying sizes present at margin of valve mantle (Figs 22–23, wavy arrows). RV raphe filiform and straight, with proximal raphe ends straight and teardrop-shaped (Figs 24, 26), distal raphe ends deflected to same side (Figs 24–25, 27). Internally, RV with distinct stauros and costae extending from raphe sternum. Stauros robust (Figs 28–29), costae more robust at margin of valve (mantle) (Figs 28, 31). Central raphe fissure appears small and hooked-shaped (Fig. 29); terminal fissures turn slightly in opposite direction of proximal ends, terminate in small C-shaped helictoglossae (Fig. 31). External valve surfaces of ARV slight depression around valve margin (Figs. 32–35). Cone-shaped spines distributed along margin on ARV (Figs 21, 32–33, 35, arrows). Internally, transapical costae thickened, sternum offset from center, elevated higher than costae (Figs 36–37). Areolae round or oval. Uniseriate striae composed of 2–7 areolae in middle portion of valve (Figs 24, 27), 1–7 areolae at apex (Figs 24–25, 27). On both valves, areolae occluded by complex cribra, often supported by 2–8 pegs, at almost same level with external valve surface of RV and ARV (Figs 25˗27, 33˗35). Occlusions evidently absent internally from valve surface of RV and ARV (Figs 29–31, arrows, 37–40). Marginal ridge and terminal orbiculi not observed.
Type: — CHINA, Shandong Province, Licun River, 36°9′24.77″N, 120°25′37.92″E, 18 m a.s.l., Wei Chen, 4 th December 2021. Slide no. HBI! LC06, holotype, retained in: Freshwater Algal Herbarium (HBI), Institute of Hydrobiology, Chinese Academy of Science, Wuhan, China. Representative specimens on Figs 11 and 18.
Etymology: —The species name was coined after the name of the river it was discovered, the Licun River in Shandong Province (China).
Distribution: —The newly described species is currently known only from its type locality.
Ecology: —Water temperature was 11.9 ℃, pH was 7.3, dissolved oxygen was 11.5 mg ·L- 1, oxidation-reduction potential was 135 mv, and turbidity was 4.2 NTU. The concentrations of nitrate, nitrous, ammonia, and total phosphorus were 4.8 mg ·L- 1, 0.026 mg ·L- 1, 0.27 mg ·L- 1, and 0.17 mg ·L- 1, respectively.
description: Published as part of Chen, Wei, Yu, Pan, Song, Gaofei & Abate, Rediat, 2024, A new freshwater species Achnanthes licunese sp. nov. (Achnanthaceae, Bacillariophyta) from pebbles of Licun River, Shandong Province, China, pp. 69-82 in Phytotaxa 649 (1) on pages 71-79, DOI: 10.11646/phytotaxa.649.1.4, http://zenodo.org/record/13215897