Frustulia hengduanensis, Luo & You & Yu & Wang, 2022

Luo, Fen, You, Qingmin, Yu, Pan & Wang, Quanxi, 2022, Frustulia hengduanensis sp. nov. a new diatom (Bacillariophyceae) from Hengduan Mountains, China, Phytotaxa 559 (2), pp. 193-199 : 195-196

Frustulia hengduanensis sp. nov. Fen Luo & Quanxi Wang (LM Figs 1–14 , SEM Figs 15–24 )

Description:— LM: Valves elliptico-lanceolate or rhomboid with slightly undulate margins. Apices narrowly rounded and moderately protracted. Valve length 43–55 μm, breadth 11–14 μm (n=30). The longitudinal ribs slightly curved. On the valve face, the striation patterns are weakly discernible under LM. Striae absent within the central area, forming a dumbbell-shaped hyaline zone ( Figs 1–14 ).

SEM: External view, the striae parallel at the valve center and slightly convergent towards the apices, with 36–40 striae per 10 μm ( Fig. 15 ). Striae wavy along the length of the valve ( Figs 15–16 ). The valve ends circumradiated by one or two rows of areolae ( Figs 18–19 ). Areolae rounded to elliptical at the valve center and more slit-like distally, with 33–36 areolae per 10 μm ( Figs 17–18 ). Striae absent within the central area, forming a dumbbell-shaped hyaline zone ( Figs 16–17 ). The raphe is filiform, and both the proximal and the terminal raphe ends are T-shaped ( Figs 17–19 ). Internal view, areolae have circular to rectangular hymenes ( Fig. 22 ). Both the longitudinal ribs and the raphe slightly curved ( Fig. 20 ), while both proximal and terminal raphe ends are straight ( Figs 21–24 ). At the apices, the longitudinal ribs and the helictoglossae fuse to form a small porte-crayon ( Fig. 24 ).

Type: — CHINA. Sichuan Province: Hengduan Mountains , Q.X. Wang, F. Luo and colleagues, August 2015 (holotype SHTU! SC201508131 , Biology Department Diatom Herbarium, Shanghai Normal University, Shanghai, China = Fig. 2 . Isotype YXNU! SC201508131 , Biology Department Diatom Herbarium, Yuxi Normal University, Yuxi City, Yunnan Province, China) .

Etymology: —The species is named for its type locality in the Hengduan Mountains.

Ecology: —All samples were collected from fen peat and a stream fen at elevations of 4160–4750 m asl in freshwater at 5.3–15.3 °C, with pH 6.9–8.1, salinity 0.01–0.08 ‰, and conductivity 20–91 μs∙ cm-1 ..

Distribution: —This species is known from five samples collected in the Haizi Mountain Reserve, Daocheng County, Sichuan Province, China (slide nos. SC201508127, SC201508128, SC201508131, SC201508132, and SC201508137) and from one sample collected in Zuogong County, Tibet (slide no. HDS201810304).

Figures

FIGURES 1–14. Light micrographs of Frustulia hengduanensis sp. nov. from type material. Scale bar = 10 μm.

FIGURES 15–19. SEM micrographs, external views of Frustulia hengduanensis sp. nov.from type material. 15. Complete external valve. 16. Dumbbell-shaped hyaline central area. 17. Proximal raphe end. 18. Valve apices, with the terminal raphe ends and the valve ends circumradiated by two rows of areolae. 19. Valve ends circumradiated by one or two rows of areolae.

FIGURES 20–24. SEM micrographs, internal views of Frustulia hengduanensis sp. nov. from type material. 20. Complete internal valve. 21. Dumbbell-shaped hyaline central area. 22. Proximal raphe ends and areolae with rectangular hymens. 23. Valve apices. 24. Terminal raphe ends; the longitudinal ribs and the helictoglossae fuse to form a small porte-crayon.