Urosolenia truncata Liu & Kociolek, 2016

Liu, Yan, Kociolek, J. P. & Fan, Yawen, 2016, Urosolenia and Acanthoceras species from Hainan Province, China, Phytotaxa 244 (2), pp. 161-173 : 166-167

Urosolenia truncata Liu & Kociolek , sp. nov. ( Figs 19–34 )

LM: frustules solitary, subcylindrical. Valve asymmetrical, conical, forming a long tubular extension. Total frustule length: 120–206 μm, pervalvar length: 33–87 μm, width: 5.8–13.0 μm, extension length: 57–85 μm, girdle band density: 6–8 per 10 μm. SEM: valve areolae regularly arranged, round and small, 11–12 rows per 1 μm, with several poroids irregularly located ( Fig. 30 ) and extending to the base of the extension. Poroids large, round to elongated, with no rib-like structures present. Girdle band width: 1–2 μm, with small, regularly arranged areolae, 6–10 rows per band, 5–6 rows per 1 μm. Round poroids on the bands and valve ( Figs 31, 34 ). Imbrication line visible. Ending of the extension blunt, without any teeth, ligula or seta (figs 29, 32).

Type:— CHINA. Hainan Province: Orchid valley, unnamed stream, in sediments, Y. Liu & L. Li, 14 February 2012 (holotype: HANU!, individual in slide THGZ 2012015, here illustrated as Fig. 20 , isotype: COLO! JPK material no. 12HN15).

Etymology: —This species epithet “truncata ” refers to the special shape of the extension tip.

Remarks: —This species similar to U. yalongii , but has a longer extension and denser girdle bands. The most important difference between these two species, however, is the tip of the extension. Urosolenia yalongii has 3–5 teeth at the tip of the extension, but U. truncata has blunt ends. Another species that has a blunt apex of the extension is U. extensa Karthick & Kociolek (2011: 34) , but this species differs by having small branch-like projections on the process, a shorter extension and more narrow frustules ( Karthick & Kociolek 2011).

Figures

FIGURES 19–27: Urosolenia truncata, LM. Type material from Yalong valley forest park, Fig. 20 is of the holotype. Scale bar = 10 μm.

FIGURES 28–34: Urosolenia truncata, SEM. 28. External view of valve and extension, scale bar = 10 μm. 29. Magnification of the bluntly extension end, scale bar = 500 nm. 30. External view of valve, showing the elongate poroids (black arrow), scale bar = 5 μm. 31. External view of bands and valve, showing the round poroids on the bands (black arrow), scale bar = 10 μm. 32. Magnification of bluntly extension end, scale bar = 500 nm. 33. External view of bands and valve, scale bar = 10 μm. 34. External view of the valve, showing the round poroid on the base of the extension (black arrow), scale bar = 2 μm.