Gomphonema tumida Liu & Kociolek, 2018

Jiang, Ziyi, Liu, Yan, Kociolek, John Patrick & Fan, Yawen, 2018, One new Gomphonema (Bacillariophyta) species from Yunnan Province, China, Phytotaxa 349 (3), pp. 257-264 : 259-261

Gomphonema tumida Liu & Kociolek sp. nov.

Figures 1–22 . Figure 3 is of the holotype

Description: Valve outline clavate. Margins clearly triundulate, biconstricted towards both apices, headpole broadly rhomboid, formed with a shoulder with a protracted and rostrate apex. Valve swollen towards footpole, tapering quickly, footpole acutely rounded. The headpole is less rhomboid and has flattened “shoulders” (expanded parts of the valve near the headpole) in smaller specimens. The breadth of the headpole and footpole are narrower than mid-valve. Length 58–87 μm, breadth at the mid-valve 9.0–11.4 μm. Raphe lateral. Axial area linear to linear-lanceolate, narrow. Central area small, round-elliptic, both sides bearing a shortened stria. One stigma present at the end of the central transpical stria. Striae almost parallel in the middle (8–9/10 μm), slightly radiate towards the apices (9–10/10 μm). Areolae clearly visible with LM.

SEM observations: Externally, raphe nearly straight, distal raphe fissures curved to the same direction of the valve, proximal raphe ends small, not dilated, straight. Stigma round-elliptic. Striae uniseriate, with “C”-shaped areolae. At footpole, apical pore field relatively small, positioned on the mantle only, composed of small round porelli, separated by the raphe into two parts. Internally, proximal raphe endings hooked to the same side of the valve, distally they terminate as helictoglossae. The stigma opening is slit-like ( Figs 19–20 ). At each pole, a helictoglossa and pseudoseptum are evident ( Fig. 22 ). Both helictoglossae are slightly offset from the main axis of the raphe. “C”-shaped areolae are evident between the thickend interstriae ( Figs 21–22 ).

Type:— CHINA. Yunnan Province: Lashi Lake. Epiphytic on vascular plant, Coll. Y. Liu July 2014 (holotype: HANU! Individual in slide THHN 2014460, here illustrated as Fig. 3 , isotype: COLO! JPK material No. 11744, slide No. 612095)

Etymology: — This species is named for being widest at the middle of the valve.

Figures

FIGURES 1–10. Gomphonema tumida Liu & Kociolek sp. nov. LM pictures. Valve views showing size diminution series. Figure 3 is of the holotype. Scale bar=10 μm.

FIGURES 11–17. Gomphonema tumida Liu & Kociolek sp. nov. SEM pictures, External view. Figures 11: The whole valve; Figures 12–13: Headpole, showing the terminal fissures, and C-shaped areolae; Figures 14–15: Central area, showing the stigma, and the proximal raphe ends; Figures 16–17: Footpole, showing the terminal fissures and the apical pore field.

FIGURES 18–22. Gomphonema tumida Liu & Kociolek sp. nov. SEM pictures, Internal view. Figure 18: The whole valve; Figures 19–20: Central area, showing the internal opening of the stigma and proximal raphe ends; Figure 21: Magnification of part of the valve, showing the internal opening of the areolae; Figure 22: Footpole, showing the helictoglossa, and pseudosepta.