taxonID	type	description	language	source
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	description	urn: lsid: ipni. org: names: 77376847 - 1 Figs 2 – 3	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	diagnosis	Diagnosis Acianthera amazonica sp. nov. resembles A. saraca-taquerensis Campacci & J. B. F. Silva by the stem caespitose, erect, lamina linear-elliptic, with trilobed lip, but differs by the 4 or 5 flowers per inflorescence (vs 2 or 3 in A. saraca-taquerensis), lateral sepals with equal length of the dorsal (vs lateral sepals longer than the dorsal), apical lobe of the lip with margin fimbriate (vs margin slightly serrate), two callus in the lip (vs callus absent in the lip), and longer lip (3 mm vs 2.2 mm long).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	etymology	Etymology The name is in reference to the Amazon, where the species is apparently endemic.	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	materials_examined	Type material Holotype BRAZIL • Acre, Mâncio Lima, Parque Nacional da Serra do Divisor, trilha para a cachoeira da Formosa, cerca de 8 km do início; 07 ° 20 ′ 58 ″ S, 73 ° 41 ′ 25 ″ W; 370 m a. s. l.; 23 Nov. 2024; Marcusso, G. M., Demarchi, L. O., Biral, L., Zartman, C. E., Magalhães, J. 2801; holotype: RB [01578438].	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	description	Description Epiphytic herb, erect, ca 12 cm tall, caespitose, rhizome with internodes ca 0.5 mm long, 1.8 mm wide. Stem cylindrical, sulcate, 2.7 to 3 cm long, 0.9 mm wide, with a tubular sheath up to the middle, brownish with age. Leaf sessile, lamina carnose, 7.7 to 8.5 cm long, 1.2 mm wide, elliptical-lanceolate, base attenuate, apex acute, margin flat. Inflorescence multi-flowered, coflorescences with 4 or 5 - flowered, peduncle ca 5 mm long, enclosed by a conduplicate, lanceolate bract with 3.5 mm long, green, with apex acute, rachis ca 6 mm long, covered by the floral bracts, which are tubular, green, 1.4 mm long, ca 0.8 mm wide. Ovary ca 2 mm long, glabrous, cylindrical, slightly grooved. Flowers tubular, ca 4.5 mm long. Sepals densely lilac-dotted, glabrous, dorsal sepals oblong, with acuminate apices, 5.8 mm long, 2 mm wide, 3 - veined, lateral sepals connate to the upper third, ca 5 mm long, oblong, with apices slightly asymmetric, attenuate, 5.8 mm long, 2 mm wide, and adaxially with a central carina. Petals lilac-dotted, oblanceolate, with acute apex, 3.4 mm long, 1 mm wide, 1 - veined, margin in the apices slightly irregular. Lip lilac densely in spots, oblong, trilobed, slightly recurved, unguiculate, 3 mm long, 1 mm wide, apex obtuse, with the apical lobe densely fringed, two lateral lobes erect, slightly rounded, two parallel longitudinal callus ca 1 mm long, slightly fringed towards the apex, central lip slightly papillose distally. Column densely lilac-dotted to whitish, semi-terete, slightly recurved, ventrally channeled, winged, 3.6 mm long, 1 mm wide, apical margin slightly denticulate, foot 1.3 mm long, anther sub globose, glandular-papillose, surrounded by the clinandrium, ca 0.5 mm long, 0.4 mm wide, pollinarium with two ovoid pollinias, ca 0.3 mm long, attached to a caudicle. Capsule not seen.	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	distribution	Distribution, habitat and phenology Acianthera amazonica sp. nov. is currently known only from the State of Acre in the Serra do Divisor National Park (Fig. 1). It occurs as an epiphyte in low densities in Dense Lowland Ombrophilous Forests, locally known as terra firme, at 370 m of elevation. Collected with flowers in November.	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	description	Preliminary IUCN conservation assessment Acianthera amazonica sp. nov. was found in only one locality with few conspecific individuals. Although the number of known populations and individuals is very limited, similar environments are widely distributed throughout the region (Mendonça et al. 2020) suggesting that its possible that the global range is larger than the study area. The type locality of the species, the Formosa Waterfall Trail, is located within a protected area – the SDNP, this park is surrounded by other conservation areas including the Alto Juruá Extractive Reserve and the Nawa and Nukini Indigenous Lands in Brazil, as well as the Sierra del Divisor National Park in Peru. However, the region faces significant threats, such as the expansion of livestock farming and the proposed extension of the BR- 364 highway, which would cross the area (Koga et al. 2022). Given the lack of information on its distribution and population size, we suggest categorizing Acianthera amazonica sp. nov. as Data Deficient (DD) according to the IUCN Red List Categories (IUCN 2024).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6F6F0EED32FD36FAB9DB32.taxon	discussion	Remarks Acianthera amazonica sp. nov. is morphologically similar to A. saraca-taquerensis, which is known only by the type specimen from the Guyana Shield, in Pará State, near the border with Guyana (ca 2000 km from the type locality of A. amazonica), differing by several vegetative and floral features, as mentioned in the diagnosis. Furthermore, although the color is variable in orchids, A. amazonica has sepals and petals densely lilac-dotted, differing from A. saraca-taquerensis which have yellow sepals and lip with purple spots and white-green petals. Acianthera amazonica sp. nov. putatively belongs to the Acianthera subgenus Acianthera due to its stout habit, sulcate stem, fleshy flowers, and thick, papilose lip (Karremans et al. 2016). By the lateral sepals fused, and the lip with two longitudinal calluses, Acianthera amazonica fits with the Acianthera section Acianthera of Chiron & van den Berg (2012).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	description	urn: lsid: ipni. org: names: 77376848 - 1 Figs 4 – 5	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	diagnosis	Diagnosis Acianthera nukiniana sp. nov. resembles A. silvae (Luer & Toscano) Luer by the erect stem, lamina linear, 2 - flowered inflorescence, lateral sepals connate up to the upper third, and lip with two lateral lobes, but differs by the habit caespitose (vs the repent in A. silvae), petal margins pilose, mainly toward the apex (vs microscopically denticulate), densely papillose in the apex (vs smooth), and shorter lip (1.5 mm vs 2.75 mm long) with near equal length of the column (vs exceeding the column length).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	etymology	Etymology The name refers to the Nukini people, that historically lived in the high Rio Moa, in the Juruá basin (Oppenheim 1936), where P. nukiniana sp. nov. was recorded. Today, they still live in the region, along the border with the SDNP, in the Indigenous Land Nukini (Correia 2024).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	materials_examined	Type material Holotype BRAZIL • Acre, Mâncio Lima, Parque Nacional da Serra do Divisor, trilha para a cachoeira da Formosa, cerca de 8 km do início; 07 ° 20 ′ 58 ″ S, 73 ° 41 ′ 25 ″ W; 370 m a. s. l.; 23 Nov. 2024; Marcusso, G. M., Demarchi L. O., Biral, L., Zartman, C. E., Magalhães, J. 2799; holotype: RB [01578436].	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	description	Description Epiphytic herb, erect, ca 10 cm tall, caespitose, rhizome with internodes ca 1 mm long, 1.4 mm wide. Stem cylindrical, sulcate, 3.1 to 3.8 cm long, 1 mm wide, with a tubular sheath up to the middle, brownish, apex acute. Leaf sessile, lamina carnose, 5.5 to 6.5 cm long, 5.6 to 6.3 mm wide, linear to oblanceolate, base attenuate, apex acute, margin revolute. Inflorescence multi-flowered, coflorescences 2 - flowered, peduncle ca 8 mm long, enclosed by a conduplicate, lanceolate bract with 3 mm long, ca 0.3 mm wide, green, with apex attenuate, rachis abbreviated ca 0.5 mm long, floral bract tubular, 1.4 mm long, ca 0.3 mm wide. Ovary ca 2 mm long, glabrous, cylindrical, slightly grooved. Flowers tubular, ca 5 mm long. Sepals pink, glabrous, dorsal sepal oblong, with acute apex, 5 mm long, 2 mm wide, 3 - veined, lateral sepals connate up to the middle, at ca 3 mm long, elliptic, apex acute, 6.2 mm long, 2 mm wide. Petals pink-whitish, oblong, with acute apex, 2.6 mm long, 0.8 mm wide, 1 - veined, margin ciliate, mainly towards the apex, surface in the apex densely papillose. Lip pink-whitish, sessile, oblong, trilobed, recurved, 1.5 mm long, 0.8 mm wide, apex rounded, two lateral lobes erect, recurved, apex papillose. Column pink-white, semi-terete, recurved, ventrally channeled, winged, 1.6 mm long, 0.8 mm wide, apical margin slightly denticulate, foot ca 0.8 mm long, anther oblong, glandular-papillose, surrounded by the clinandrium, ca 0.3 mm long, 0.5 mm wide, pollinarium with two ovoid pollinias, ca 0.3 mm long, attached to a caudicle, apical margin slightly irregular. Capsule not seen.	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	distribution	Distribution, habitat and phenology Acianthera nukiniana sp. nov. is known only from the SDNP, in Acre State (Fig. 1). This species occurs as an epiphyte in low densities in lowland dense ombrophilous forests, locally known as terra firme, at an elevation of 370 m. Collected with flowers in November.	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	description	Preliminary IUCN conservation assessment Acianthera nukiniana sp. nov. has been identified in only one location, where few mature individuals were observed, but similar habitats are found extensively throughout the region (Mendonça et al. 2020), suggesting that new populations can be found. The trail to Formosa Waterfall, lies within the SDNP, a protected area surrounded by several conservation areas, including the Alto Juruá Extractive Reserve and the Nawa and Nukini Indigenous Lands in Brazil, as well as the Sierra del Divisor National Park in Peru. Nevertheless, the region faces serious threats, including the growth of livestock farming and the proposed extension of the BR- 364 highway, which would intersect the area (Koga et al. 2022). Due to insufficient data on its distribution and population size, we suggest classifying Acianthera nukiniana as Data Deficient (DD) under the IUCN Red List Categories (IUCN 2024).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
038D878CCC6C6F03ED35FC70FD93DCA1.taxon	discussion	Remarks Acianthera nukiniana sp. nov. is morphologically similar to A. silvae, which is known only by the type from Japura River, in the State of Amazonas (Luer & Toscano de Brito 2002), with several floral differences (see diagnosis). Also resembles A. punicea (Luer) Pridgeon & M. W. Chase, from Ecuador, differing by the sessile lip (vs unguiculate in A. punicea), trilobate (vs not trilobate) and shorter (1.5 mm vs 3 mm long); and A. carinata (C. Schweinf.) Luer, from Peru, differing by the caespitose habit (vs repent), shorter sepals (5 to 6.2 mm vs ca 10 mm long), lip shorter (1.5 mm vs ca 5 mm long), and apical lobe of the lip rounded (vs acute). Acianthera nukiniana sp. nov. putatively belongs to the Acianthera subgenus Acianthera by the stout habit, sulcate stem, fleshy flowers, lateral sepals fused, concave, margin slightly denticulate, and lip thick (Karremans et al. 2016), and to the Acianthera section Acianthera (sensu Chiron & van den Berg 2012).	en	Marcusso, Gabriel Mendes, Biral, Leonardo, Demarchi, Layon Oreste, Zartman, Charles E. (2026): Two new species of Acianthera (Orchidaceae) from the Brazilian Amazon. European Journal of Taxonomy 1043: 103-117, DOI: 10.5852/ejt.2026.1043.3211, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3211/14243
