Spore morphology of Onychium ipii Ching (Pteridoideae, Pteridaceae)

The ultrastructure of the spore surface of Onychium ipii Ching (Pteridoideae, Pteridaceae) was investigated by using of scanning electron microscopy. Spores of Onychium ipii are trilete, tetrahedral, with hemispherical distal side and convex proximal one. Equatorial diameter 42.4–48.1 μm, polar axis 35.7–40.6 μm. Distal and proximal sides are separated by an equatorial flange, which protrudes on 4.3–4.8 μm all around the spore. Tubercles of different size form the interrupt “laesura lips” situated on both sides of laesura arms. Proximal side of spore with three stright ridges 3.1–4.5 μm width arranged parallel to spore margins and formed triangle in outline. Fused tubercles on distal side form sinuous folds with a few small areolae. Spores of Onychium ipii in compare with spores of O. moupinense Ching (Figure 3, D–F; Tables 1–2) are larger; their equatorial flange is more prominent; laesura arms are narrower; “laesura lips” are interrupted; stright ridges on the proximal side of spores Onychium ipii are broader, than the same in O. moupinense spores; sinuate folds on the distal side of Onychium ipii spores are more frequent than the same in O. moupinense spores. Spores of Onychium ipii and O. moupinense have the differences in the character of spore ornamentation and form. These features are the addition argument for recognition of Onychium ipii and O. moupinense as separate species.