Abrodictyum inexpectatum, an unexpected new fern species (Hymenophyllaceae, Polypodiidae) for Madagascar, as revealed by an integrative approach Author Dubuisson, Jean-Yves Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, MNHN, CNRS, EPHE, Université des Antilles, CP 48, 57 rue Cuvier, 75005 Paris, France. Author Bauret, Lucie Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, MNHN, CNRS, EPHE, Université des Antilles, CP 48, 57 rue Cuvier, 75005 Paris, France. & Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, SU, EPHE, Université des Antilles, CP 39, 57 rue Cuvier, 75005 Paris, France. Author Boucheron-Dubuisson, Elodie Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, MNHN, CNRS, EPHE, Université des Antilles, CP 48, 57 rue Cuvier, 75005 Paris, France. Author Rouhan, Germinal Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum national d’Histoire naturelle, CNRS, SU, EPHE, Université des Antilles, CP 39, 57 rue Cuvier, 75005 Paris, France. text Phytotaxa 2022 2022-10-11 568 1 83 91 http://dx.doi.org/10.11646/phytotaxa.568.1.6 journal article 163380 10.11646/phytotaxa.568.1.6 2b063b4f-7b73-4706-a4cb-0cd3d43366ae 1179-3163 7184304 New key to the Abrodictyum species in the Afro-Malagasy region (modified from Dubuisson et al. 2017 ) - Distal ultimate lobes or segment usually multi-veined and/or fused, often spatulate and appearing serrulate...... A. pachyphlebium 1. Distal ultimate lobes or segment usually single-veined, free, or sometimes fused by pair................................................................ 2 2. Lamina apparently absent or reduced to one row of cells on both sides of the veins ........................................................................ 3 - Lamina always developed .................................................................................................................................................................. 4 3. Fronds subsessile or with short stipes not exceeding 4–5 cm , narrowly oblong to linear on herbarium, always with a narrowly cylindrical brush-like shape when fresh ...................................................................................................................... A. cylindratum - Fronds with stipes usually longer than 4–5 cm , narrowly to widely lanceolate when dried, plane or with a lanceolate brush-like shape when fresh ......................................................................................................................................................... A. parviflorum 4. Lamina of ultimate segments usually not exceeding 3 cells on both sides of the veins..................................................................... 5 - Lamina of ultimate segments with usually more than 3 cells on both sides of the veins................................................................... 6 5. Lamina width often variable (1 to 3 rows of cells on both sides of the veins) within the same frond; fronds narrowly to widely lanceolate, plane or with a brush-like shape; usually more than 6 sori per pinna....................................................... A. parviflorum - Lamina width usually not variable within the same frond; fronds narrowly oblong to linear, sometimes narrowly lanceolate but never widely lanceolate, always plane; often a single sorus per pinna, rarely more than 6 sori per pinna.......................................... ........................................................................................................................................................................ A. angustimarginatum 6. Rhizomes erect; lamina without a clearly distinct marginal row of cells; plants usually terrestrial or saxicolous, rarely epiphytic... ............................................................................................................................................................................................................ 7 - Rhizomes short-creeping; lamina with a clearly distinct marginal row of cells; plants usually epiphytic, sometimes saxicolous ..... ................................................................................................................................................................................ A. tamarisciforme 7. Fronds bipinnate-pinnatifid or more divided, always plane in the wild, never crispate or curled ..................................................... 8 - Fronds rarely more than bipinnate-pinnatifid, usually with pinnules curled in the wild .................................................. A. franceae 8. Fronds often more divided than bipinnate-pinnatifid, broadly lanceolate to triangular, often exceeding 30 cm long; lamina dark green and opaque; sori cylindrical to slightly campanulate .................................................................................................. A. dregei - Fronds usually not more divided than bipinnate-pinnatifid, usually not exceeding 13.5 cm long, narrowly lanceolate; lamina light green and translucent; sori obconic (cup-shaped) ....................................................................................... A. inexpectatum sp. nov.