Abstract

The gradual disappearance of ferns due to biodiversity loss occasioned by anthropogenic activities and global climate change necessitated the need to document and study palynologically pteridophytes in Lagos State. Their peculiar habitat is fast declining in many urban centres of the world, including Nigeria. Previous studies in Nigeria mainly addressed their distribution, with limited reports on their morphology and systematic significance. Hence, we conducted a field survey and characterised the spore morphology of the encountered ferns in Lagos State, Nigeria, using light microscopy (LM) and scanning electron microscopy (SEM). We recorded nine species belonging to nine genera and five families. The studied species varied in spore size, shape, and ornamentation. Spores’ sizes ranged between 30 μm × 32 μm in Nephrolepis biserrata and 122 μm × 127 μm in Ceratopteris cornuta. Symmetrically, they were bilateral or radial, and ranged in size between very large, large, and medium. Despite marginal differences in polar to equatorial diameter ratios (P/E ratios), the oblate-spheroidal shape class was found to be a synapomorphic character. We observed relationships between the spore shape and the corresponding aperture type. SEM revealed different spore ornamentation types – tuberculate, canaliculate, rugate/rugulate, reticulate, verrucate, tuberculate, and echinate. Our findings propose the potential use of spore P/E ratio and SEM as taxonomic diagnostic tools in Pteridophyte systematics. However, further studies with more representative species are needed to evaluate the factors influencing spore morphology and its taxonomic significance. Overall, this study provides insights into the systematics of ferns in Lagos State and would aid fern identification in palynology and palaeopalynology.

摘要

由于人为活动和全球气候变化导致生物多样性丧失，蕨类植物逐渐消失，因此需要在拉各斯州记录和研究孢粉植物。在包括尼日利亚在内的世界许多城市中心，它们独特的栖息地正在迅速减少。以前在尼日利亚的研究主要涉及它们的分布，关于它们的形态和系统意义的报道有限。因此，我们进行了实地调查，并使用光学显微镜 (LM) 和扫描电子显微镜 (SEM) 对尼日利亚拉各斯州遇到的蕨类植物的孢子形态进行了表征。我们记录了属于 9 个属和 5 个科的 9 个物种。研究的物种在孢子大小、形状和纹饰方面各不相同。孢子的大小在 30 μm × 32 μm 之间Nephrolepis biserrata和 122 μm × 127 μm in Ceratopteriscornuta. 对称地，它们是双边的或放射状的，大小在非常大、大和中等之间。尽管极地与赤道直径比（P/E 比）存在边际差异，但发现扁球体形状类别是一种突触特征。我们观察了孢子形状与相应孔径类型之间的关系。SEM 揭示了不同的孢子纹饰类型——结核状、小管状、皱褶/皱褶状、网状、疣状、结核状和棘状。我们的研究结果提出了孢子 P/E 比和 SEM 作为蕨类植物系统学中分类诊断工具的潜在用途。然而，需要对更具代表性的物种进行进一步研究，以评估影响孢子形态的因素及其分类学意义。全面的，