Weissia francii Thouvenot 2021, comb. nov

Weissia francii (Thér.) Thouvenot, comb. nov. Hymenostomum francii Thér. Bulletin de l’Académie Internationale de Géographie Botanique 19: 21 (1909). Hymenostomum clausum Broth. & Paris Öfversigt af Finska Vetenskaps-Societetens Förhandlingar 51A(17): 11. 1909. — Type: New Caledonia. “Ad latera humida semitae ad Ouen Toro et ad Yahoué”, 17.VI.1908, A. Le Rat s.n. (isosyn-, PC[PC0735856, PC0735857]!). TYPE. — New Caledonia. Vallée de la Nondoué (Nouméa), 17.VIII.1908, Franc s.n. (lecto-, selected here: PC [PC 0697624!]). OTHER SPECIMENS EXAMINED. — New Caledonia. South Province, "au pied du Mont Mou, sur la terre du chemin, en plein soleil, 300 m ", 18.VII.1909, Franc s.n. PC [(PC 0735860)]; "Bois du Sud, sur la terre", IX.1915, Fran c s.n. PC [(PC 0735852)]; "Mt Coffin, près Nouméa, 50 m ", 20.IX.1910, Franc s.n. PC [(PCO 735855)]. DESCRIPTION FROM THE LECTOTYPE Habit Plant small, gametophyte 1 mm high, with sporophyte 3 mm high. When dry, leaves erect incurved, involute tubular; when wet, patent spreading, somewhat recurved. Stem Simple, shorter, 0.1 mm wide, cortical cells poorly defined, 1-3 layers of cells like the medullar but a little smaller and orange-brown tinged, central strand present. Leaves 0.9-1.1 mm long, 0.2-0.3 mm wide, narrowly lanceolate with lower parts sub-sheathing, hyaline, rectangular, margins plane, sharply narrowed by the inward winding of the margins in upper part, margins above strongly involuted, confluent in cucullate apices with acute mucrones. Costae strong, excurrent in acute mucrones, ovate-reniform in section, 40 µm wide, 30 µm high, ventral epidermis present, papillose, dorsal lacking, 2-3 guide cells, ventral stereid band weak, dorsal stereid band large. Cells Upper laminal cells opaque, 6-8 µm wide, quadrate-hexagonal, firm walled, strongly to slightly bulging or not, with many furcate papillae; basal ones smooth, translucent, wide rectangular, thin-walled, walls narrower and thicker toward margins, transitional cells smooth, progressively smaller and thick-walled, not ascending along the margins. Perichaetial leaves Similar to vegetative ones. Sporophyte Setae 1.5 mm long, twisted to the left, capsules rostrate, ovoid, cleistocarpous., urns 450 µm long, 300 µm wide, rostra 350 µm long; spores 20–25 µm, finely verrucose. COMMENTS Since genus Hymenostomum is now a synonym of Weissia (see above, under Trichostomum tonghoueensis), this species can be transferred to the genus Weissia, according to the following characters: dry habit crispate, margins strongly involute, capsules cleistocarpous. It differs from the other Weissia species in New Caledonia by the small size, the cleistocarpous capsules, the leaf costae with weakly developed ventral stereid bands.
Published as part of Thouvenot, Louis & Müller, Frank, 2021, Contribution to the bryophyte flora of New Caledonia IV. Species new to the country, new localities together with taxonomic notes, pp. 181-196 in Cryptogamie, Bryologie 20 (13) on pages 193-194, DOI: 10.5252/cryptogamie-bryologie2021v42a13, http://zenodo.org/record/7822275