Plagiothecium higuchii var. brevicellum G.J.Wolski, 2023

Wolski, Grzegorz J., Khan, Aamir Shehzad & Paszko, Beata, 2023, New taxa of Plagiothecium (Plagiotheciaceae) from Pakistan, PhytoKeys 236, pp. 1-16 : 1

Plagiothecium higuchii var. brevicellum G.J.Wolski var. nov.

Type.

Pakistan, Mt. Nanga Parbat , Mazeno Base Camp, 4000 m alt, on soil, 15 September 1990, M. Higuchi 20460pp, holotype LOD 15017 , isotype PMNH .

Description.

Plants green-yellow to golden-gold, without metallic luster. Stems complanate-foliate, 3.0-4.0 cm long, in cross-section rounded, with a diameter of 310-388 μm, epidermal cells 10-16 × 21-33 (M 13 × 27) μm, the parenchyma thin-walled, 14-58 × 18-51 (M 34 × 35) μm; leaves quite loosely arranged on the stem, concave, symmetrical to gently asymmetrical, ovate, those leaves from the middle of the stem 2.9-3.2 × 1.0-1.2 (M 3.1 × 1.1) mm; the apex acute and apiculate, denticulate; costae two, thick and strong, usually to 1/2 of the leaf length, reaching 0.5-1.5 (M 1.0) mm; laminal cells symmetrical to slightly asymmetrical, the length and width very variable, but dependent on location: 70-170 × 10-19 (M 120 × 15) μm at apex, 100-200 × 14-26 (M 150 × 20) μm at mid-leaf and 100-200 × 19-36 (M 150 × 28) μm towards insertion, cell areolation loose; decurrency long, 390-650 (M 520) μm, composed of 4-6 rows of rectangular and spherically inflated cells, 36-116 × 18-67 (M 76 × 43) μm. Sporophytes unknown so far (Fig. 4 ). In these studies Plagiothecium higuchii var. brevicellum (M. Higuchi 20460) has been recorded on soil.

Etymology.

The variety name brevicellum refers to breve- [Lat.] short; -cellus [Lat.] cells and indicates the most distinctive features between varieties - leaves with short cells.

Figures

Figure 4. The most important taxonomic features of Plagiothecium higuchii var. brevicellum A apex serration B, C dimension of cells (B from the middle C basal part of the leaf) D decurrent cells E, F leaf shape (from M. Higuchi 20460).