Prodromus of a fern flora for Bolivia. XXVII. Pteridaceae Author Kessler, Michael Systematic Botany, University of Zurich, Zollikerstrasse 107, CH- 8008 Zurich, Switzerland Author Smith, Alan R. University Herbarium, 1001 Valley Life Sciences Bldg. # 2465, University of California, Berkeley, CA 94720 - 2465 Author Prado, Jefferson Instituto de Botânica, Av. Miguel Estéfano, 3687, CEP 04301 - 902, São Paulo, SP, Brasil text Phytotaxa 2017 2017-12-22 332 3 201 250 http://dx.doi.org/10.11646/phytotaxa.332.3.1 journal article 10.11646/phytotaxa.332.3.1 1179-3163 Adiantum villosissimum Mett. ex Kuhn, Linnaea 36: 73. 1869 . Range: — Ecuador to Bolivia (BE, CO, LP, SC). Ecology: —Uncommon, terrestrial in lowland evergreen forests; 250–1450 m . Notes: —Related to A. scalare , which see. Distinguished by the 2-pinnate blades (rarely 1-pinnate) with only 2 or 3 pairs of lateral pinnae and pinnules 4–5 times longer than wide, 30–35 pairs per pinna. Rhizomes, stout, short-creeping, nodose; rachises scaly, scales with ciliate margins and pectinate bases; margins of sterile pinnules sparingly serrate; both surfaces with hairs 1–1.5 mm long, articulate, appressed, on and between veins; sori 1–3 per pinnule on acroscopic margins; indusia oblong, arcuate, bearing articulate hairs.