Leptoscyphus incisus Gradst., F.R.

Oliveira-Da-Silva, Fúvio Rubens, Gradstein, S. Robbert, Viana, Pedro Lage, G., Carlos Ernesto, Schaefer, R. & Ilkiu-Borges, Anna Luiza, 2022, Bryophytes from Uei tepui (Serra do Sol), with liverworts new to Brazil and the description of Leptoscyphus incisus sp. nov., Cryptogamie, Bryologie 20 (4), pp. 51-64 : 60-62

Leptoscyphus incisus Gradst., F.R. Oliveira-da-Silva & Ilk.-Borg., sp. nov.

( Fig. 5 )

Autoicous. Plants prostrate with ascending branches, branching usually by innovations, sometimes with stoloniferous ventral branches with rhizoids and rudimentary leaves. Leaves succubous to almost transversally inserted, subopposite, subrectangular, bifid to trifid to ⅓-¼ of leaf length; leaf cells with nodulose and confluent trigones. Underleaves absent or rudimentary. Perianths long-ovoid to subcylindrical, mouth circular to broadly elliptic, entire, marginal cells little diferentiated, isodiametrical to subquadrate, outer cell walls thickened.

HOLOTYPE. — Brazil. Roraima state, Uei tepui, Bonnetia woodland, on tree trunk, 5°01’30”N, 60°36’45”W, alt. 2103 m, 8.IV.2019, Viana et al. 6264 (holo-, MG).

ETYMOLOGY. — The epithet refers to the incised leaves, an unusual character in neotropical Leptoscyphus .

DISTRIBUTION AND HABIT. — Leptoscyphus incisus Gradst., F.R. Oliveira-da-Silva & Ilk.-Borg., sp. nov. is only known from cloudy forest with dominance of Bonnetia sp. on Uei tepui, state of Roraima, northernmost Brazil, growing on the trunks of treelets at about 2100 m.

DESCRIPTION

Sexual system

Autoicous.

Habit

Plants prostrate with ascending branches, orange to red-brown, 1.3-2.6 mm wide on leafy ascending branches, considerably smaller in prostrate branches (to 0.5 mm wide), branched usually by innovations, innovations intercalary, originating ventro-laterally at the perianth base in the ventral axil of a bract, sometimes with intercalary, stoloniferous ventral branches with rhizoids and rudimentary leaves.

Stem

In cross section with epidermis weakly differentiated, one layer of c. 26 thick-walled epidermal cells surrounding c. 45 somewhat thin-walled medullary cells, the medullary cells little larger than epidermal cells.

Leaves

Succubous to almost transversally inserted, widely to obliquely spreading, contiguous to imbricate, subopposite, subrectangular, 1.5-2× longer than wide, (0.5-) 0.7-1.3 mm long, 0.35- 0.5 mm wide, apex bifid to trifid, incised ⅓-¼ of leaf length, uniseriate tips 2-4 cells long, margins entire, dorsal margin ± straight, ventral margin arched; leaf cells (sub)isodiametric in prostrate branches, 20-40 µm, elongate in ascending branches, 25-60 µm long, 15-25 mm wide, trigones nodulose, sometimes confluent, intermediate thickenings rare in elongate cells only, cuticle smooth.

Underleaves

Absent or rudimentary.

Rhizoids

Colorless, little ramified at the tip forming an adhesive patch.

Androecia

On innovations from axil of bracts or intercalary on the stem, with 4-5 pairs of bracts; bracts imbricate, subopposite, 0.5- 0.7 mm long, 0.3-0.5 mm wide, apex bifid to trifid, incised ⅓ of bract length, uniseriate tips 2-4 cells long, margins entire; bracteoles rudimentary (inconspicuous).

Gynoecia

Terminal on ascending branches and on innovations, usually repeatedly innovated, with one pair of bracts; bract subopposite, 0.7-1.3 mm long, 0.35-0.5 mm wide, apex bifid; bracteoles absent or rudimentary.

Perianths

Long-ovoid to subcylindrical, (1.0-) 1.6-2.2 mm long, 0.5- 1.1 mm wide, terete, narrowed to the mouth, the apex in profile truncate, mouth circular to broadly elliptic, entire, marginal cells little differentiated, isodiametrical to subquadrate, outer cell walls thickened.

REMARKS

The new species shares several features with Leptoscyphus autoicus (J.J. Engel & Gradst.) Vanderp. & Gradst. (basionym Physotheca autoica J.J.Engel & Gradst. ) from Ecuador, such as the autoicous sexuality, branching via innovations and perianths terete, inflated, bladder-like, with a narrow, fully entire mouth ( Engel & Gradstein 2003). The two species also have rather similar habitats, occurring as epiphytes in low woody vegetation on very mineralpoor soil. Leptoscyphus incisus sp. nov. clearly differs from L. autoicus , however, in the bifid to trifid leaves and reduced underleaves. In L. autoicus the leaves are undivided, suborbicular to oblate, and underleaves not reduced. Very small underleaves are otherwise also seen in Leptoscyphus subg. Anomylia (R.M.Schust.) R.M.Schust. , and 2-3-fid leaves occur in the African L. infuscatus (Mitt.) E.W.Jones (L. sect. Physoscyphus Grolle). The latter species, however, has dioicous sexuality, much larger underleaves and a flattened perianth with a wide, toothed mouth, similar as in most Leptoscyphus species.

Figures

FIG. 5. — Leptoscyphus incisus Gradst., F.R.Oliveira-da-Silva & Ilk.-Borg., sp. nov.: A, sector of a stem with gynoecia with perianth and male fertile innovation; B, cladographs of fertile plants, solid ellipse = androecia, open ellipse = gynoecia with perianth; C, sector of a stem with stoloniferous branch; D, apex of a leaf; E, sector of a stem with gynoecia with perianth and female fertile innovation;F, median cells of leaves of a prostrate branch; G, marginal cells of perianth mounth; H, apex of a leaf; I, median cells of leaves of an ascending branch; J, K, leaves. All from the holotype. Scale bars: A, C, E, 500 µm; D, F-I, 50 µm; J, K, 250 µm.