Spore morphology of Taenitis, Syngramma, and Austrogramme species (Pteridoideae, Pteridaceae) from South-Eastern Asia and Oceania. II

This paper continues consideration of the spores of three paleotropical fern genera - Taenitis, Syngramma, and Austrogramme (Pteridoideae, Pteridaceae) from South-Eastern Asia and Oceania. At the second stage, we carried out a comparative scanning electron microscopy study of spores of three species of Austrogramme, four species of Syngramma, and six species of Menitis and added information about previously studied spores of seven species of these genera. Spores of all examined species are trilete. tetrahedral or tetrahedral-globose with convex to hemispherical distal side and plane, convex or conical proximal side. The spores of Austrogramme species are the smallest, simplest in ornamentation and similar to each other. Sculpture of the proximal and distal sides are microverrucate, the surface of the spores is covered by granular deposits. Spores of most Syngramma species are very similar to spores ofAustrogramme species in shape and surface sculpture: their distal and proximal surfaces are microvemicate, whereas the spores of S. borneensis and S. cartilagidens have the low-tuberculate sculpture. Spores of Taenitis species are very different from the spores of Austrogramme and Syngramma. Seven of nine studied species have spores with well-expressed cingulum (T. blechnoides, T. cordata. T. diversifolia. T. interrupta. T. luzonica. T obtusa, and T. requiniana), three species (T. cordata,T. hookeri. and T. pinnata) have spores with prominent laesural ridges. The spores have well-expressed ornamentation - tuberculate, baculate, rugate, tuberculate-rugate. The most conspicuous character of the ornamentation of spore surfaces is the presence of rodlets associated with sculpture elements. The densest rodlets are characteristic of Menitis diversifolia, T. luzonica, T. obtusa, and T. requiniana. Spore size (equatorial diameter) ranges on average between 22 mu m and 37 mu m in Austrogramme. between 27 mu m and 41 gm in Syngramma, and between 26 and 51 mu m in Taenitis species.

Automated summary

This paper continues to study the spores of three paleotropical fern genera from South-Eastern Asia and Oceania. Austrogramme species have the smallest, simplest ornamentation and similar spore shapes, while most Syngramma species have spores similar to Austrogramme. Spores of Taenitis species are very different from Austrogramme and Syngramma spores.