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 .