Taxonomic implications of macro and micromorphological characters in the genus Brachythecium (Brachytheciaceae, Bryopsida) from the Western Himalayas: A combined light and scanning electron microscopic analysis.

Abstract

Brachythecium Schimp. is one of the most complex and diverse genus among the pleurocarpous mosses, having almost 150 species distributed around the world. The current study presents a detailed morphological analysis of the six species of the genus Brachythecium in Western Himalayas, Pakistan. The study reports the first detailed micromorphological investigation of the leaf surfaces (gametophyte) of the studied species because in pleurocarpous mosses, mostly sporophyte micromorphology has been studied. The objective of the study was to present a comparative light (LM) and scanning electron microscopic (SEM) analysis to describe the detailed morphology of bryophytes in Pakistan. A systematic method was used in the field as well as in their microscopic studies. Based on these findings, morphological and micromorphological features based on LM and SEM observations, qualitative and quantitative characters, taxonomic keys, distribution and habitat are discussed. The size of the leaf, leaf cells, seta, and other parts were noted, but slight variation was observed when we compare these measurements with the same species collected from different geographical regions. The leaf micromorphology reveals some interesting features like the nature of cell walls, cell shapes, and the surface of the lumen. Because the specimens used for SEM were air-dried, the cells were mostly constricted and compressed. In almost all species except in Brachythecium garovaglioides, the papillae or cell wall ornamentations were absent. The study will help to contribute to the taxonomy of this genus or its family, especially in relation to the Western Himalayas.