Trematodon brevicollis Hornsch.

Belkina, Olga A. & Vilnet, Anna A., 2019, Trematodon laetevirens Hakelier & J. - P. Frahm and T. brevicollis Hornsch. (Bruchiaceae, Bryophyta) in Russia, Cryptogamie, Bryologie 20 (19), pp. 247-258 : 251-252

Trematodon brevicollis Hornsch.

Flora 2: 88 (1819).

DESCRIPTION

The specimens from East Sayan differ significantly from those of Khibiny and are similar to Trematodon brevicollis samples from Mongolia, Alaska and West Greenland. Their characteristics are listed in description below.

Gametophytes

2-4 mm in height,

Leaves

Appressed or slightly contorted, 0.7-1.3 mm long and 0.4-0.6 mm wide, oblong or ovate suddenly or gradually narrowed into more or less long lanceolate upper part (apiculus), leaf margins flat, unistratose, leaf cells rectangular and shortrectangular (30-5 × 5 µm × 10-20 µm) in lower part and the same or shorter (16-40 µm long) in upper part of lamina, often irregular, thin walled.

Costa

100-175 µm wide, occupying about ¹�₃ of leaf width and filling the uppermost leaf apex, without stereids, in cross

section with ventral (adaxial) row of large cells, smaller cells on abaxial side and with equal or just smaller, central cells often with curved walls.

Perichaetial leaves

Differentiated: the largest one – obovate or almost spathulate, with distinct more or less long sharp apiculus (angle less than 90°), 1 or 2 innermost leaves linear-lanceolate and acute, other perichaetial leaves from wide-obovate or obovate base suddenly constricted into rather long subula.

Seta

4-5 mm in East Sayan and Mongolian Altai specimens, 5.5-6 mm in West Greenland, 6-8 mm in Gobi-Altai and Alaska.

Capsule

Curved (when dry at 90-120°, when moist at 120-150°), inclined or rarely almost erect, the capsule neck to urn ratio about 1:1, neck about 1 mm long, not strumose.

Exothecial cells

Thick walled, rectangular or near the mouth quadrate, on convex side of urn (i.e. on upper side of incline capsule) longer and more thick-walled than on concave.

Peristome teeth

Blunt, neither perforated nor split.

Annulus

Sometimes partly remaining, 1-2-rowed.

Spores

(30-) 40-50 (-55) µm in East Sayan specimen, 40-45 µm in others.

NOTES ON T. LONGICOLLIS SPECIMENS FROM RUSSIA

Four Trematodon longicollis specimens from Russian Far East are represented by few plants and have only single or few mature sporophytes. In addition, two samples are in a poor condition – plants (especially capsules) dead, or partially destroyed, or covered with black cyanobacteria and fungi. The plants from the Kunashir (Tyatya volcano)/ Kunashir (Zmeiniy stream)/ Kamchatka Peninsula ( Table 1 , Appendix 1 ) have the following features (based on one sporophyte only for the Kunashir and the Kamchatka specimens): seta 8.5/

8-19/ 11 mm, capsule neck 1.8/ 2.5-3.25/ 2.5 mm, urn 1.3/ 1.0-1.5/ 1.5 mm long, respectively. The length ratios of urn to capsule neck are 1:1.2/ 1:2 - 1:3/ 1:7. In all specimens, the leaf margins are more or less revolute or incurved above (at least on one side) and bistratose in the subula (one cell row along edge). Costa does not entirely fill the subula, and has a ventral (adaxial) row of large thin-walled cells, an abaxial row of smaller cells and well distinguishable stereids in the center. At some site, the large cells of the ventral row are replaced by 2-4 smaller cells with thickened walls, and at the point of transition, 2 or 3 large cells, resembling guide cells, occur below in a second row (under ventral). In Kunashir sample (Zmeiniy stream) having capsule in good mature condition, spores are 22-24 µm, peristome teeth are forked or perforated along middle line.

The specimen from Khabarovsk Territory is difficult to identify: it contains few plants and combines the features both T. longicollis and T. ambiguus in morphology. The neck to urn length ratio varies between 1:1.2 and 1:2, and in some leaves the costa fills the entire width of the subula width, and in others it completely occupies only the uppermost part of acumen. The latter leaves also have a margin that is bistratose above (in width of one row of cells).