Sellaphora constrictum J. P. Kociolek
Creators: name: You, Q-M.
name: Kociolek, J. P.
name: Cai, M-J.
name: Lowe, R. L.
name: Liu, Y.
name: Wang, Q-X.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Chromista
Bacillariophyta
Bacillariophyceae
Naviculales
Naviculaceae
Sellaphora
Sellaphora constrictum

description: Sellaphora constrictum J.P. Kociolek & Q-M You, sp. nov. (Figs 1–17; Fig. 1 is of the holotype)   
DESCRIPTION: Valves broadly linear, slightly constricted at the middle, margin appearing wavy or undulate, with rounded apices, length: 29.0–52.0 μm, width in the middle: 9.0–10.5 μm, greatest width: 9.5–11.0 μm. Raphe filiform to lateral and undulate. Axial area narrow and undulate with a small, sub-rounded or elliptical central area. Central striae relatively sparse and slightly radiate, 14–16/10 μm, striae more dense and radiate at the ends, 17–20/10 μm. Longitudinal ridges appear on either side of the axial area (see arrow in Fig. 5, this feature is not apparent in all LM images). Areolae not resolved with LM.  
The valve exterior has a slightly elevated narrow and undulate conopeum (Fig. 10: arrow A; Fig. 12: arrow C), and is bordered on each side by a narrow trough (Fig. 10: arrow B). The trough is continuous and weakly expanded laterally through the central area (Fig. 12: arrow A) but not evident near the apex (Fig. 13). The axial area is narrow, undulate, slightly elevated in the central and continues in the trough bordering the raphe branches. Towards the margin, there are three longitudinal ridges: one ridge borders the trough (Fig. 10: arrow C; Fig. 12: arrow B); the other ridge is straight, near the valve margin (Fig. 11: arrow A) and the third ridge is almost along the border of the valve face and the mantle (Fig. 11: arrow B). The central area is slightly wider, forming an elliptical area (Fig. 12). The raphe is undulate, with proximal raphe ends small, elliptical, and deflected slightly to one side and ending with small pores (Fig. 12). Distal raphe ends are deflected to the same side and onto the mantle (Fig. 13). Externally, there are two types (I and II) of areolae: type I areolae are present near the axial area and are small and rounded (48–54 / 10 μm). These areolae exist in narrow and deep grooves. The areolae are expanded in the central area and form the shape of a diamond or subdiamond that occupies up to 1/2 of the valve face (Fig. 12). Type II areolae occur between type I areolae and the valve margins (40–46 / 10 μm). The type II areolae are with two longitudinal ridges on each side of the valve (Fig. 11: arrows A and B).  
Internally, the valves are relatively flat (Fig. 14). The axial area is narrow and straight, slightly expanded in the central area. Raphe is straight, with proximal raphe ends not expanded, asymmetric, and deflected to the same side (Fig. 15). Distal raphe ends terminate in elongated helictoglossae. There is a larger foramen-like pit at the end of valve that does not penetrate to the exterior (Fig. 16). The striae have rounded areolae that are not differentiated internally. Areolae possess hymenate occlusions (Figs 16–17).  
 Type:— CHINA. Guizhou Province: Maolan Nature Reserve, 25º15′42” N, 108º04′13” E, The new species was found in mixed samples of benthos, roots and scrapings from rocks from a tree-lined stream, collected by Q-X. Wang & J.P. Kociolek, 4 October 2015 (holotype: SHTU! slide and material GZ-1510089, Biology Department Diatom Herbarium, Shanghai Normal University, Shanghai, China, here illustrated as Fig. 1; isotype: COLO! material 10464, Kociolek Collection, University of Colorado, Museum of Natural History Diatom Herbarium, Boulder, USA).   
 Etymology:—The species is named for its outline, which is slightly constricted in the middle part of the valve.   
 Remarks:— Sellaphora constrictum sp. nov. was found in two regions that are located in the south of China, within similar habitats (clear, alkaline freshwater streams). The new species is rare in samples from Wuzhishan Mountain. In this study, the frustule in fig. 4 is from Wuzhishan Mountain, and all other frustules in the images are from Maolan Nature Reserve.
description: Published as part of You, Q-M., Kociolek, J. P., Cai, M-J., Lowe, R. L., Liu, Y. & Wang, Q-X., 2017, Morphology and ultrastructure of Sellaphora constrictum sp. nov. (Bacillariophyta), a new diatom from southern China, pp. 261-268 in Phytotaxa 327 (3) on pages 262-263, DOI: 10.11646/phytotaxa.327.3.5, http://zenodo.org/record/13723289