Frullania clarkii J.J. Atwood & Mamontov, 2018

Atwood, John J. & Mamontov, Yuriy S., 2018, The lectotypification of Frullania mexicana and the description of F. clarkii sp. nov. (Frullaniaceae, Marchantiophyta), Phytotaxa 383 (2), pp. 206-212 : 208-209

Frullania clarkii J.J. Atwood & Mamontov , sp. nov., Fig. 1 .

Type: — Mexico, without locality or collector. ( G (00114898), holotype).

Diagnosis:— Similar to F. laxiflora and F. planifolia in its distally inflated lobule with decurrent beak, but differs in its non-auriculate underleaves with repand margins, innermost bracteole not highly connate with the bract lobes on both sides, and in the terminal position of the gynoecia.

Description: —Plants medium-sized, dull, brown in herbaria, 1.3–1.6 mm wide. Stems 150–170 μm wide, irregularly pinnately to bi-pinnately branched; first branch appendage, 3-fid, consisting of a flattened, lanceolate-ovate, unequally 2-fid segment, and a flattened lobule; second branch appendage lateral and consisting of two inflated lobules and associated stylus. Lateral leaves imbricate when dry, widely spreading when moist, dorsal lobe oblong-ovate, 1.0–1.2 × 0.8–0.9 mm, concave, apex rounded to subacute, involute, antical margin base expanded and extending beyond distal edge of stem, base cordate; lobule contiguous to imbricate, subparallel with stem, distal portion galeate, 280–340 × 240–250 μm, slightly compressed at mouth, external margin rostrate, decurrent along slightly sinuous free margin for more than half the length of the proximal portion, proximal portion ligulate, 280–360 × 200–240 μm, keel 210–220 μm; styli subulate, composed of 3–6 cells long and 2–3 cells wide; marginal cells rectangular, 18–24 × 12–20 μm, median cells polygonal, 16–20 × 18–20 μm, basal cells polygonal to elliptical, 26–40 × 18–22 μm, sinuous with intermediate thickenings and large, nodular trigones. Underleaves contiguous to imbricate, broadly ovate, 0.4–0.5 × 0.5–0.6 mm, flat, bifid for about 50–120 μm, lobes subacute, sinus U- or V-shaped, inserted on an arcuate line, bases decurrent, margins entire, irregularly repand. Sexual condition autoicous. Androecia capitate, sessile on stem or main branch. Gynoecia terminal on stem or main branch, innermost gynoecial bract lobe ovate, 1.0 × 0.6 mm; apex acute to apiculate, margins with blunt teeth near the apex; lobule lanceolate, 1.0 × 0.3 mm, apex acute to acuminate, margins entire except for prominent stylar tooth; bracteole obovate, 0.9 × 0.6 mm, bifid to 140 μm, lobes and sinus rounded to bluntly acute, low connate on both sides with bracts. Perianth oblong, 1.6 × 0.8–0.9 mm, abruptly narrowed, with 4-keels, ornamentation smooth, beak 120 × 100 μm, mouth with papillae. Sporophyte absent.

Etymology:— The specific epithet honours the American hepaticologist Lois Clark (1884–1967) (see Howard 1968) whose type studies on numerous Central and South American Frullania are a source of detailed species descriptions and valuable illustrations.

Figures

FIGURE 1. Line drawing of Frullania clarkii sp. nov. 1, 2, 4: Underleaves. 3, 8: Median cells of leaf lobe. 5–7, 10: Leaf lobes, dorsal view. 9, 13: Shoots, ventral view. 11, 12, 14: Leaf lobes and lobules, ventral view. 15: Enlarged leaf lobule, ventral view. Scale bars: 750 μm for 1, 2, 4; 100 μm for 3; 50 μm for 8; 2 mm for 9; 850 μm for 5–7, 10–12, 14; 1.5 mm for 13; 500 μm for 15. All from holotype (G00114898), by Yuriy Mamontov.