BRAZIL – Minas Gerais • Itacambira; 16°57’29.28”S, 43°25’4.98”W; 1240 m; 30 Jul. 2024; fl., fr.; Sant’Anna–Santos 425; holotype: DIAM; isotypes: UPCB, IBGE, HCF.

Syagrus montana is similar to Syagrus evansiana Noblick, from which it differs in leaf rachis length (21–57 vs 79–97 cm); leaf sheath length (12–20 vs 1.5–12 cm); apical pinnae length (3–8.5 vs 9–12 cm), middle pinnae length (12–18 vs 19–30 cm); inflorescence rachis length (0–2.5 vs 0–13 cm); apical rachillae length (10.5–11 vs 4.5–10 cm); flowers always arranged in triads (vs triads, tetrads, and pentads); basal staminate flowers pedicellate (vs sessile); anther bases cordate (vs sagittate); apical pistillate flower length (8–15 vs 15–18 mm), basal pistillate flower length (11–16 vs 17–20 mm); pistillate flowers with 3 sepals (vs 2 to 3); pistillate flowers with 3 petals or occasionally 4 (vs 3), with valvate tips reaching 2/3 of the petal length (vs 1/3–1/2); pistil length (6–8 vs 9–13 mm), pistil with indumentum (vs glabrous flowers in pre-anthesis), staminodes undulate (vs dentate); fruit nearly globose (vs ellipsoid); endocarp length (1.3–1.4 vs 1.6–2.0 mm).

Small palm, solitary palm, 37–80 cm tall. Apparently acaulescent. Leaves pinnate, 3–6(–10) in number; leaf sheath ca 12–20 cm long; pseudopetiole 10–23 cm long; true petiole absent to 39.5 × 0.6–1.1 cm and 0.3–0.6 cm thick, adaxially grooved and abaxially rounded; abaxial surface of the petiole and leaf rachis with white tomentum; leaf rachis 21–57 cm long; pinnae medium to dark-green, discolorous, abaxial surface glaucous, linear, rigid-coriaceous, with a more or less asymmetric apex and an elongated, tapering midrib, 18–43 pairs, arranged in 2–5(–6) along the leaf rachis and inserted in divergent planes; ramenta or tomentum absent at the insertion of pinnae on the leaf rachis and along the abaxial surface of the pinna midrib; apical pinnae 3–8.5 × 0.1–0.9 cm; median pinnae 12–18 × 1.3–2.0 cm; basal pinnae 11–18 × 0.5–0.9 cm; prophyll 5–14 × 1.0–1.8 cm; peduncle indumentum glabrous. Inflorescence erect, spicate or spirally branched, but usually spirally branched; prophyll 5–14 × 1.0–1.8 cm; peduncular bract ca 12–31 cm long, inflated portion 7–16.5 × 1.5–4.8 cm, including a beak 0.4–0.8 cm long, perimeter 2.5–6.2 cm, 1–2.5 mm thick, woody, striate, exterior glabrous; peduncle 8–16 cm long, 1.6–5 × 1.5–4 mm wide, elliptic in transverse section, glabrous; inflorescence axis 8–15 cm long; rachis 0–2.5 cm long; rachillae 1–6, 10.5–11 cm long at the apex, (2–)4–9.5 cm long at the base, glabrous. Staminate flowers 8–14 × 3–6 mm at the apex, 13–15 × 4–6 mm at the base, shortly pedicellate at the base of the inflorescence; pedicels ca 1 mm long, yellow; sepals 3, 0.5–4 × 0.5–2 mm, glabrous, without evident nerves, briefly connate at the base; petals 3, 7–13 × 2.0–5.0 mm, with acute apices, nerves inconspicuous; stamens 4–8 mm long, anthers 3.5–6 mm long; filaments 1–3 mm long, briefly connate at the base; pistillode trifid, ca 0.5–1.5(–3) mm long. Pistillate flowers elongate-pyramidal, 8–15 × 6–7 mm at the apex, 11–16 × 3–6 mm at the base, glabrous; sepals 3, 11–16 × 4–6.5 mm, yellow, without visible venation, imbricate; petals 3 or occasionally 4, 8–14 × 3.5–5 mm, with valvate apices reaching 2/3 of the petal length; pistil 6–8 × 2–4 mm, with lepidote indumentum from the base of the outer ovary wall to approximately the base of the stigmas; stigmas 3, 2–5 mm long; staminodial ring ca 1–1.5 mm tall; staminodes undulate. Fruits nearly globose, 1.4–1.6 × 1.1–1.4 cm, brown when mature; epicarp less than 1 mm thick, covered with dense brownish tomentum; mesocarp ca 0.5 mm thick, succulent and fibrous; endocarp ca 1.3–1.4 × 1.0–1.2 cm, ca 1 mm thick, with 3 pores in the basal portion. Seed nearly globose, endosperm homogeneous. Germination remote-tubular.

Syagrus montana is endemic to Minas Gerais State, Brazil, in a region known as the “Northern Mountains Complex”, in the southern portion of the Espinhaço Range (Fig. 1). The species occurs in campos rupestres, where it may be locally dominant, forming part of the graminoid stratum on high-elevation plateausat around 1240 m altitude, in the municipality of Itacambira and adjacent areas (Noblick 2017a). Campos rupestres are characterized by shallow, stony, nutrient-poor soils and are subject to severe fires (Almada et al. 2016; Fernandes 2016).

Syagrus montana was observed with flowers and fruits from November to December and from June to July in 2019 and 2024.

The specific epithet, montana, means “mountain” and refers to the high-elevation plateau where the species occurs.

The population of the new species is known only from the municipality of Itacambira, where no protected areas exist. Near the type population, there is a highway and Eucalyptus plantations. Considering the area of occupancy (AOO = 32 km²) and extent of occurrence (EOO = 42.998 km²) and following the IUCN Categories and Criteria (IUCN 2022), S. montana should be considered Critically Endangered: CR B1ab(i,iii).

BRAZIL – Minas Gerais • Itacambira, à beira da rodovia Montes Claros-Itacambira (MG-308); 19 Nov. 2013; fl.; Medeiros & Fonseca 84; SPF • same data as for preceding; Medeiros & Fonseca 86; SPF • Itacambira, estrada para Montes Claros; 9 Jan. 1986; fl.; Mello-Silva et al. 9158; SPF • Itacambira, fazenda da plantar siderúrgica, em área de plantação de eucalipto, na rodovia entre Juramento e Itacambira; 13 Dec. 2019; fl., fr.; Sant’Anna-Santos & Firmo 184; UPCB • same data as for preceding; Sant’Anna-Santos & Firmo 185; UPCB • same data as for preceding; Sant’Anna-Santos & Firmo 189; UPCB • same data as for preceding; Sant’Anna-Santos & Firmo 195; UPCB • same data as for preceding; Sant’Anna-Santos & Firmo 196; UPCB • same data as for preceding; Sant’Anna-Santos & Firmo 197; UPCB.

In S. montana, stomata occur only on the abaxial surface, whereas in S. evansiana stomata are present on both surfaces (Fig. 6D–E, H–I). In both species, subsidiary cells are arcuate and located entirely below the level of the cuticle (Fig. 6D, H–I). Adaxial non-vascular fibre bundles are narrower in S. montana than in S. evansiana (Fig. 6A and 6E, respectively). On the abaxial surface, groups of fibres and isolated fibres are rarer in S. montana than in S. evansiana (Fig. 6A–D, E–J). In S. montana, raphide-containing idioblasts are frequent and occur both at the margin and in the intermediate region of the pinnae (Fig. 6A–B). In S. evansiana, raphides are rare and restricted to the marginal region (Fig. 6E–F).

Adaxial fibre bundles are connected to the adaxial hypodermis and reach nearly half of the mesophyll in both species (Fig. 6A–E). Only primary vascular bundles are connected to the hypodermis on both surfaces and are always completely surrounded by fibres in both species (Fig. 6A–E). In both species, primary vascular bundles always have a larger diameter, distinct phloem poles, and conspicuous protoxylem and metaxylem elements (Fig. 6A–E). Secondary and tertiary vascular bundles are surrounded abaxially only by a sclerenchymatous sheath (Fig. 6A–E). Whereas secondary vascular bundles are connected only to the abaxial hypodermis, tertiary vascular bundles may or may not be connected to the abaxial hypodermis (Fig. 6A–E). The mesophyll is homogeneous in S. montana (Fig. 6A) and dorsiventral in S. evansiana (Fig. 6E). At the margin, a large first adaxial non-vascular fibre bundle is present in the new species, whereas in S. evansiana this bundle is not always present (Fig. 6A, E).

The midrib is triangular in S. montana and the expansion tissue is continuous (Fig. 7A–B). In S. evansiana, the midrib is truncate and the expansion tissue is interrupted (Fig. 7F). In both species, the midrib is adaxially projected, and the expansion tissue contains immersed fibre groups arranged in a line in the new species (Fig. 7A–B) and dispersed in S. evansiana (Fig. 7F–G). The main vascular system of the midrib consists of a single collateral bundle in S. montana (Fig. 7A–E) and 2–4 in S. evansiana (Fig. 7F–J). In both species, the collateral bundles are surrounded by a fibrous ring with a reinforced sheath that does not connect to the adaxial or abaxial hypodermis (Fig. 7B–G). There are 0–5 and 10–14 non-vascular fibre bundles around the fibrous ring in S. montana and S. evansiana, respectively (Fig. 7A, F). The presence of a small accessory vascular bundle within the expansion-tissue caps is observed only in S. evansiana (Fig. 7G), representing the first record for the genus. The midrib hypodermis is biseriate in S. montana (Fig. 7D) and uniseriate in S. evansiana (Fig. 7I). Table 2 compares the leaf anatomy of S. evansiana, S. montana, and S. aristeae.

When described, Syagrus evansiana was characterized as a miniature of Syagrus glaucescens Becc. and Syagrus duartei Glassman due to strong similarity in leaf morphology (Noblick 2009). However, the acaulescent habit and other important morphological characters, such as the occurrence of both branched and unbranched inflorescences, strongly supported its recognition as a distinct species (Noblick 2009). In the following year, additional acaulescent Syagrus species were revealed as the result of an extensive effort to study these palms in their natural habitats combined with leaflet anatomy data (Noblick and Lorenzi 2010).

Since then, it has become clear that most dwarf Syagrus species do not occur over large geographic ranges and/or occupy different, geographically isolated areas (Noblick 2017a; Firmo et al. 2021; Sant’Anna-Santos et al. 2023a, 2023b, 2023c). However, some acaulescent Syagrus still show broader geographic distributions, such as S. evansiana (Noblick 2017a; Reflora 2026; SpeciesLink Network 2026), because they represent unresolved species complexes (Sant’Anna-Santos et al. 2025). In Noblick (2009), populations from two distinct regions were used in the characterization of the species: a cerrado sensu stricto population in the municipality of Jequitaí and a campo rupestre population in the municipality of Itacambira and adjacent areas. These two regions are more than 100 km apart in a straight line (Fig. 1), are geographically isolated, and occupy habitats with distinct conditions. Over subsequent years, additional areas were added to the distribution map of the species, such as Serra do Cabral and Serra do Ambrósio mountains (Noblick et al. 2014; Noblick 2017a).

Firmo et. al. (2021) provided the first step towards disentangling the Syagrus evansiana complex. The population treated as Syagrus evansiana from Serra do Cabral mountain, a disjunction in the southern portion of the Espinhaço Range, was formally described by Sant’Anna-Santos et al. (2023a) as Syagrus aristeae. In Noblick (2017a), another disjunction in the Espinhaço Range was indicated for the occurrence of S. evansiana: Serra do Ambrósio mountain. Recognized as an area of high endemism, Serra do Ambrósio harbours unique high-elevation environments known as carrascos, characterized by coarse sandy substrates and rare, microendemic species (Meguro et al. 1994; Pirani et al. 1994; Oliveira et al. 2014; Costa et al. 2016, 2018; Sant’Anna-Santos et al. 2025). Accordingly, Sant’Anna-Santos et al. (2025) described Syagrus harenae, representing yet another step in resolving the complex.

Therefore, targeting previously known localities of S. evansiana for fieldwork is an effective strategy to document Arecaceae diversity in the southern Espinhaço Range and adjacent areas (Firmo et al. 2021; Sant’Anna-Santos et al. 2023a, 2025). Many of these areas have experienced increased anthropogenic pressure in recent years, and localities formerly considered less suitable for agriculture—such as rocky outcrops along the Espinhaço Range—have become strongly impacted by mining, cattle raising, and silviculture (Costa et al. 2018; Carvalho et al. 2024), increasing the likelihood that new species will go extinct before being documented.

However, an obstacle impedes studies of the Syagrus evansiana complex: it is necessary to take a step back and reassess the different populations used in the species’ original circumscription, as they may represent distinct species. Therefore, establishing the true morphological spectrum of S. evansiana is crucial for further work on the complex. To date, populations treated as S. evansiana in the Espinhaço Range and adjacent areas still lack field-based study and detailed morphological and anatomical analyses (Reflora 2026; SpeciesLink Network 2026).

In Syagrus species delimitation, the size of leaf parts is an important diagnostic aspect (Glassman 1987; Henderson et al. 1995; Noblick 2009, 2017a; Firmo et al. 2021; Sant’Anna-Santos et al. 2023a, 2023b, 2023c, 2025). In S. montana, the length of the leaf rachis and sheath, as well as the length of apical and middle pinnae, are useful to distinguish it from S. evansiana (Table 1). Regarding reproductive traits, both inflorescence architectures (unbranched and branched) occur in both species (Figs 2C, 3C–D, 5A–B, 5D–E). However, branched inflorescences are more common in S. montana, whereas unbranched inflorescences are more common in S. evansiana (Table 1). In S. montana, flowers are always arranged in triads (Fig. 5G), whereas in S. evansiana we observed triads, tetrads, and pentads at similar frequencies (Fig. 5I–J). Pentads were first described for S. harenae (Sant’Anna-Santos et al. 2025); therefore, this is the second record for the genus. We also observed differences in the length of apical rachillae (Table 1). The length of pistillate flowers, as well as the number of sepals and petals, are also useful for distinguishing the two species, in addition to the valvate petal apices, which reach 2/3 of the petal length in S. montana (Fig. 3K) and 1/3–1/2 in S. evansiana (Fig. 2K). The pistil is smaller in S. montana (Table 1), bears indumentum and has an undulate staminodial ring (Fig. 3L), in contrast to S. evansiana, where the pistil is glabrous and the staminodial ring is dentate (Fig. 2L). The fruit is smaller and nearly globose in S. montana (Fig. 3M, 5K) and ellipsoid in S. evansiana (Fig. 2M, 5L).

Anatomically, S. montana is surprisingly different from S. evansiana (Table 2; Figs 6, 7). Notable differences include the frequency and location of raphides, the alignment of fibre groups in the expansion tissue, stomatal position, mesophyll differentiation, and an exclusive feature in S. evansiana: the presence of a small accessory vascular bundle within the expansion tissue. Our results confirm that knowledge of the plant in its natural habitat, combined with leaf anatomical studies, is essential for circumscribing these dwarf palms. In Noblick and Lorenzi (2010), these two factors supported the reinstatement of species previously synonymized and revealed multiple dwarf species that were unknown or treated as a single species. Since Glassman (1972), pinnae anatomy has been known to be useful not only for distinguishing morphologically very distinct species, but also morphologically very similar species, and distinct populations treated as a single species (Glassman 1972, 1987; Noblick and Lorenzi 2010; Noblick 2013, 2017a, 2017b; Noblick and Sant’Anna-Santos 2021; Sant’Anna-Santos 2021, 2023; Sant’Anna-Santos et al. 2015, 2018), as in the case of S. montana.

Syagrus montana shows marked morphological and anatomical differences from S. evansiana; together with geographic isolation and significant habitat differences, these data support its recognition as a distinct species. Syagrus evansiana exhibits rare characters for the genus, such as flowers arranged in tetrads and pentads, and an exclusive trait: an accessory vascular bundle within the expansion tissue. These results reinforce the need to revise poorly studied populations of acaulescent Syagrus that are still treated as S. evansiana. In addition, the data presented here corroborate the southern Espinhaço Range and its disjunctions as one of the centres of diversity of Syagrus. The discovery of this new species highlights the singularity of the local flora and supports its classification as a priority area for conservation.