Background and aims – In a treatment of Serpocaulon for Colombia, a new species was found with pinnatisect laminae, patent rhizome scales and long creeping rhizome. The aim of this paper is to describe this new species and distinguish it from the most morphologically similar one, S. eleutherophlebium . Methods – Specimens and digital images from CAUP, CHOCO, COL, CUVC, MO, NY, P and PSO herbaria were studied. From the literature 59 morphological characters were selected (41 were qualitative and eighteen quantitative). The minimum, medium and maximum values were calculated for the quantitative characters, them along with the qualitative characters were used for the description and the key. Its conservation status was assessed using the IUCN Red List Categories and Criteria. Key results – Serpocaulon obscurinervium D. Sanín sp. nov. is described and illustrated. It resembles S. eleutherophlebium, by pinnatisect laminae, long creeping rhizome, and patent rhizome scales, but it differs by rhizome scales linear-lanceolate (versus subulate), dark orange (versus dark brown), larger size (5.2–(6.3)–8.5 mm) (versus 3.5–(5.1)–7.1 × 0.5–(1.1)–1.7 mm), more areolae per segment, the fertile veinlets are inconspicuous (versus conspicuous), and have trichomes in the blade and rachis (versus trichomes absent). The new species is known from three localities at the western Andes of Colombia and one from the eastern Andes of Ecuador. A key to the Colombian and Ecuadorian species of Serpocaulon with pinnatisect lamina and patent scales is provided. The species is considered as Endangered (EN).

CONSERVATION STATUS; EUPOLYPODS I; NEW SPECIES; PINNATISECT LAMINA; PTERIDOPHYTE; SERPOCAULON