Prodromus of a fern flora of Bolivia. XLII. Update I. Author Kessler, Michael Systematic and Evolutionary 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 Øllgaard, Benjamin Department of Biology - Ecoinformatics and Biodiversity, Ny Munkegade 116, building 1137, 8000 Aarhus C, Denmark. Author Matos, Fernando B. Centro de Referência em Informação Ambiental (CRIA), Rua João Carlos do Amaral 500, 13070 - 111, Campinas, SP, Brasil. Author Moran, Robbin C. New York Botanical Garden, 2900 Southern Blvd., Bronx, New York, 10458 - 5126, USA. text Phytotaxa 2023 2023-12-20 630 3 183 210 https://phytotaxa.mapress.com/pt/article/download/phytotaxa.630.3.2/51376 journal article 10.11646/phytotaxa.630.3.2 1179-3163 10409920 Serpocaulon australe D.Sanín, J.C.Ospina, I.O.Moura & Salino, Syst. Bot. 44(1): 95. 2019 . Range:— Southeast Bolivia (SC, TA), nw Argentina ( Sanín et al. 2019a ). Ecology:— Epiphytic in montane rain forests; 2500–3000 m . Notes:— Serpocaulon australe most resembles S. lasiopus , which also has short-creeping rhizomes with patent scales and pinnatisect laminae and occurs sympatrically in Bolivia and Argentina . However, S. australe differs from S. lasiopus by its rhizome apex scales acute to acuminate to rarely long-acuminate (vs. curved apex), glabrous fronds with a few scales in the axils of the segments (vs. fronds with dense hairs and sparse or caducous scales), ascending segments (vs. patent), and sori absent at segment apices (vs. present). This species was segregated from S. gilliesii , which Sanín et al. (2019a) regard as a synonym of S. lasiopus . Intermediates between S. australe and S. lasiopus are known, suggesting the possibility of hybridization, especially in northwestern Argentina ( Sanín et al . 2019a ). Sanín et al. (2019a) listed the following specimens for Bolivia : Santa Cruz : Prov. Caballero , Comarapa 32 km hacia Cochabamba, 2500 m , 24 March 1981 , Beck 6826 ( F ). Tarija : Prov. Mendez, Stelle, an der die Strasse von Tarija nach Iscayachi erstmals über 3000 m ansteigt [spot where the road Tarija-Iscayachi surpasses 3000 m the first time; ca. 21°27’38”S , 64°52’00”W ], 2 January1980 , Krach & Feuerer 7603a ( F ) . Serpocaulon caceresii (Sodiro) A.R.Sm. , Taxon 55(4): 928. 2006 – Polypodium caceresii Sodiro, Crypt. Vasc. Quit. 360. 1893. = Serpocaulon articulatum (C.Presl) Schwartsb. & A.R.Sm., J.Bot. Res. Inst. Texas 7(1): 85. 2013 . Range:— Costa Rica to Guyana , Bolivia (CO, LP, SC), and Brazil . Ecology:— Uncommon; terrestrial, rarely epiphytic, in humid forests; 1250–2450 m . Notes:— According to Sanín et al . (2021 , 2023 ), this species is synonymous with S. articulatum , previously recognized for Bolivia by Smith et al . (2018) but now with a somewhat expanded range. We agree with this broader interpretation of S. articulatum and its placement within S. caceresii .