Plagiothecium talbotii G.J.Wolski & W.R.Buck, 2022

Wolski, Grzegorz J., Nowicka-Krawczyk, Paulina & Buck, William R., 2022, Plagiothecium talbotii, a new species from the Aleutian Islands (Alaska, U. S. A.), PhytoKeys 194, pp. 63-73 : 63

Plagiothecium talbotii G.J.Wolski & W.R.Buck sp. nov.

Type.

U.S.A. Alaska, Attu Island, Lake Elwood area , under tall herbs on slope, 52°51'N, 173°10'E, 14 Sep 2002, W.B. Schofield and S.S. Talbot 120206, holotype MO 5925637, isotype UBC B193528 .

Description.

Plants large, dark green, without metallic luster, forming loose mats. Stems erect, julaceous in the lower part, more complanate above, 3.0-5.0 cm long (Fig. 3 ), very thick, in cross-section rounded, with a diameter of 500-700 μm, the central strand very well developed, epidermal cells 16-43 (M 25) × 12-39 (M 25) μm, the parenchyma thin-walled, 25-50 (M 36) × 18-60 (M 37) μm; leaves large, concave, symmetrical, ovate, imbricate, in wet condition, rather closely arranged on the stem, shrunken and sticking out when dry, those leaves from the middle of the stem 3.8-5.0 (M 4.4) mm long and the width measured at the widest point 1.9-3.1 mm (M 2.4); the apex obtuse and apiculate, entire, not denticulate; costae two, thick, strong and very large, extending usually more than ½ of the leaf length, reaching 1.0-3.0 mm (M 2.0); laminal cells rather symmetrical, in unregulated transverse rows, the length and width very variable, but dependent on location: 83-137 (M 101) × 17-22 (M 19) μm at apex, 100-175 (M 139) × 18-32 (M 24) μm at mid-leaf and 88-197 (M 132) × 22-35 (M 28) μm towards insertion, cell areolation loose; decurrencies very long, 700-1000 μm, composed of 3-4 rows of rectangular, at least some gently inflated cells, 90-216 (M 143) × 24-34 (M 28) μm. Sporophytes unknown so far.

Etymology.

The present species is named in honour of Stephen S. Talbot who spent decades studying the northern regions of North America, including the Aleutian Islands and who, with Wilfred B. Schofield on 14 September 2002, collected the specimen (No. 120206), chosen here as the holotype of Plagiothecium talbotii .

Distribution and ecology.

Plagiothecium talbotii so far has only been recorded from Attu Island in Alaska. In this area, it has been recorded in a non-forested area, on a slope, under tall herbs.

Figures

Figure 3. The most important taxonomic features of Plagiothecium talbotii. Stem (A) in dry condition; leaves from the middle of the stem (B), dimensions of cells from the apex (C), the middle (D) and basal part of the leaf (E). Drawing by G. J. Wolski from the holotype (W. B. Schofield and S. S. Talbot 120206, MO 5925637 [dupl. UBC B 193528]). Scale bars: 1 cm (A); 1000 µm (B); 100 µm (C-E).