A revision of specimens of Plagiothecium deposited in the herbarium of Pakistan Museum of Natural History (PMNH) collected during a Japanese lead project on Cryptogams in the Western Himalaya (Pakistan) shows that the material consists of five taxa. Of the studied samples, the most common taxa were from the P.denticulatum complex, including Plagiotheciumdenticulatumvar.obtusifolium, new to Pakistan. Examination of the rest of the collection showed that it consists of specimens with a unique combination of qualitative and quantitative characteristics of their gametophyte. For example, for small plants, with small asymmetrical, folded leaves, gradually tapering into long, acuminate, not denticulate apex, whose leaf cells are long and narrow, making the cell areolation tight, the name Plagiotheciumfilifolium is proposed. For other plants with large leaves, loosely arranged on the stem, concave, symmetrical to slightly asymmetrical, with denticulate apex and long decurrency composed of rectangular and spherical, inflated cells, the name Plagiotheciumhiguchii is proposed. However, within this material, specimens differ in terms of the length and width of the leaf cells and therefore, within this taxon, two varieties are distinguished: Plagiotheciumhiguchiivar.higuchii and Plagiotheciumhiguchiivar.brevicellum.
Keywords: Bryophyta; Pakistan; Plagiotheciaceae; South Asia; new taxa; taxonomy.
Grzegorz J. Wolski, Aamir Shehzad Khan, Beata Paszko.