Fissidens strictidens Brugg., 2020

Bruggeman-Nannenga, Maria A. & Müller, Frank, 2020, A contribution to the Fissidens Hedw. (Musci, Fissidentaceae) of Myanmar, including F. strictidens sp. nov. and F. pseudoanomalus sp. nov., Cryptogamie, Bryologie 20 (18), pp. 229-238 : 230-233

Fissidens strictidens Brugg. -Nann. & Frank Müll., sp. nov.

( Figs 1 ; 2 )

DIAGNOSIS. — The species is characterized by pluripapillose cells and limbidia restricted to the vaginant lamina. It differs from it congeners by stiff, erect, almost completely divided peristome teeth.

HOLOTYPE. — Myanmar, Kachin State, Hponkan Razi, epiphytic in evergreen broadleaved forest, mixed with F. serratus Müll.Hal. and F. pokhrensis Nork. ex S.S. Kumar, 1565 m, 27.548702N, 97.032742E, 14.X.2014, J. Kluge & P. K. Kine 14-031-001b-B (holo-, DR; iso-, L).

DESCRIPTION

Growing scattered between other mosses and hepatics on bark.

Stems

3-4 × 1.5-2 mm, hardly heterocaulous, pinnately foliated, unbranched, some stems with perichaetial branches in axils of subperichaetial and perichaetial leaves of old perichaetia, without or with weak central strand.

Rhizoids

Brown, smooth.

Axillary nodules

Not differentiated.

Leaves

Close, up to 11 pairs,hardly crispate when dry, elliptic-lanceolate with acute-acuminate apex, (0.9-)1-1.2(-1.3) × (0.2-) 0.3 mm, 3.5-4.1(-5.2) times as long as wide, margin crenulate, limbate on the vaginant laminae of all well-developed leaves of perichaetial stems, limbidium reaching ± ½ the length of the vaginant lamina in perichaetial leaves, in mid leaves consisting of a few elongated cells only, marginal, reaching insertion of vaginant laminae, up to 19 µm wide, unistratose; vaginant laminae ± ½ the leaf length, at base less wide than the stem, rounded at insertion, ± decurrent, unistratose, slightly unequal; basal part of dorsal lamina rounded, reaching the insertion, not decurrent; dorsal and apical lamina unistratose.

Costa

Percurrent to excurrent, in cross-section bryoides-type.

Lumina

Of mid dorsal laminal cells (3-)3.5-5(-6) × (2-)3-4.5(-5.5) µm, 3-4 papillose. Of mid vaginant laminal cells oblong, (5-)5.5-8 (-9.5) × (2.5-)3-4.5(-5.0) µm, 3-4 papillose.

Gemmae

Not observed.

Fertile parts

Perigonia and perichaetia on the same stem, perigonia terminal on ± stemless, 0.4-0.5 mm long branches; antheridia 200 µm long; perichaetia terminal on main stems and short, circa 0.35-0.4 mm long branches, archegonia 250-265 µm long, perichaetial leaves 1.5 mm long; calyptra not observed. Sporophyte, seta 2 mm long, smooth, 1 per perichaetium; capsule erect, 0.6 × 0.3 mm, with ± 32 columns of quadraticoblong exothecial cells, with stomata; peristome anomalous, teeth erect, ± completely divided ( Fig. 1A ); operculum not observed; spores subglobose, (7.0-)7.5-9.5(-11.5) × (5.0-)6- 7.5(-10.5) µm, papillose.

DISCUSSION

The new species is characterized by its corticolous habitat, pluripapillose cells and limbidia restricted to the vaginant lamina. The limbidia are found in upper and mid leaves of perichaetial stems and extend about half the length of the vaginant laminae in perichaetial leaves. Its best diagnostic characters are the stiff, erect, almost completely divided peristome teeth ( Fig. 1A, B ).

Gametophytically it closely resembles F.linearis var. obscurirete , F.pokhrensis and F.kurzii . All three have pluripapillose cells, but differ from the new species in having scariosus-type peristomes. Species with pluripapillose cells and limbidia restricted to the vaginant laminae belong to the gametophytically heterogeneous subgenus Aloma (Pursell & Bruggeman-Nannenga 2004) . The sporophyte of this subgenus is characterized by ± 32 columns of exothecial cells on the capsule periphery, a scariosus-type of peristome (though anomalous peristomes frequently occur) and by, though this was not mentioned by Pursell & BruggemanNannenga (2004), long rostrate opercula (versus shortly and bluntly rostrate in subg. Fissidens ).

It is interesting to note that anomalous peristomes are frequently found in corticolous species, e.g. in the Indian F. macrosporus Mitt. , the Japanese F.neomagofukui Z.Iwats. & Tad.Suzuki , the pantropical F. lagenarius Mitt. and F.gardneri Mitt. and the African species F. macroglossus (Broth.) Brugg. - Nann. and F. cyatheicola Brugg. -Nann.

Figures

FIG. 1. — Fissidens strictidens sp. nov.: A, peristome teeth; B, capsule; C, leaf; D, stem cross section; E, sporophytic stems. All from the holotype J. Kluge & P.K. Kine 14-031-001b-B. Scale bars: A, 20 µm; B, C, 0.5 mm; D, 50 µm; E, 1 mm.

FIG. 2. — Fissidens strictidens sp. nov.: A, basal part of vaginant lamina showing the short, weak limbidium; B, mid leaf; C, trans sections of leaves; D, leaf apex; E, upper part of vaginant lamina; F, leaf insertion. All from the holotype J. Kluge & P.K. Kine 14-031-001b-B. Scale bars: A-C, E, 50 µm; D, F, 100 µm.