Cymbella pulchra Li & Lange-Bertalot, 2013

Gong, Zhijun, Li, Yanling, Metzeltin, Ditmar & Lange-Bertalot, Horst, 2013, New species of Cymbella and Placoneis (Bacillariophyta) from late Pleistocene Fossil, China, Phytotaxa 150 (1), pp. 29-40 : 30-31

Cymbella pulchra Li & Lange-Bertalot sp. nov.

Plate 1 , Figures 1–4; holotype specimen is represented in plate 1, figure 1.

Description: Valves dorsiventral, broadly rhomboid-lanceolate, dorsal margin strongly arched, ventral side nearly straight to tumid at the center. Valve ends obtusely rounded, not protracted. Valve length 144–259 µm; breadth 34–68 µm, maximal length/breadth ratio about 4.2. Axial area neither distinctly narrow or broad, central area more or less apically elliptical, about 1/4 the valve breadth. Raphe slightly ventrally displaced, distinctly lateral, reverse-lateral towards the distal ends and filiform towards the proximal ends. Striae in central parts moderately, in other parts more distinctly radiate throughout, distinctly punctate-lineolate, have 6–8 in 10 µm. Areolae 14–17 in 10 µm. The ultrastructure of the internal valve view shows the distal raphe endings are prominent with terminus dorsally deflected (Figs 1 b,c). The areolae openings are located in uniseriate rows separated by thickened costae although small struts between the areolae are lacking (Figs 1 b– d). The areolae seem to lack internal papillae (Figs 1 c, d).

Holotype: JH 91010-1, Museum of Nanjing Institute of Geography and Limnology, CAS, Nanjing, China

Type locality: Jianghan Plain , Hubei Provice. 30 o 11 ’ 18”N, 112 o 35 ’ 33”E .

Etymology: The Latin name pulchra means “beautiful”.

Differential diagnosis: Cymbella balatonis Grunow in Schmidt et al. (1875:10) is distinguished mainly by smaller dimensions of all cell-cycle stages and by possessing 3–8 small stigmata on the ventral side of the valve which are lacking in the new taxon. Moreover the central raphe endings are distinctly hooked to the dorsal side instead of slightly deflected to the ventral side concerning C. pulchra . Cymbella suavis Pantocsek (1905:45) is likewise distinguished by smaller sizes, 81–120µm long, 28–32µm broad, and more widely spaced areolae, 8–13 in 10 µm.

Figures

PLATE 1, Figure 1. Cymbella pulchra Li & Lange-Bertalot sp. nov. in Light microscopy Figure 2. SEM, Internal valve in view, Figure 3. Internal view of the valve end showing the distal raphe endings terminating dorsally, Figure 4. Internal view of the central area. Scale bar represents 10 µm except in Figs 3, 4 where scale bar = 2 µm and 3 µm, respectively.