Research Article |
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Corresponding author: Bruno Francisco Sant’Anna-Santos ( bsantannaufmg@gmail.com ) Academic editor: Igor Kessous
© 2025 Bruno Francisco Sant’Anna-Santos, Elaine Lopes Pereira Nunes, Rafael Micheli, Dayana Maria Teodoro Francino.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Sant’Anna-Santos BF, Lopes Pereira Nunes E, Micheli R, Maria Teodoro Francino D (2025) Hidden in the mountain: a new rare Syagrus (Arecaceae) with morphological novelties. Plant Ecology and Evolution 158(1): 63-81. https://doi.org/10.5091/plecevo.140657
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Background and aims – The Serra do Ambrósio is a mountain with a unique vegetation called carrasco. The carrasco is characterised by sandy soils of high granulometry and is home to rare species. During the current research on the Arecaceae flora of the Diamantina Plateau, a new Syagrus species was discovered, which is described here.
Material and methods – The morphology and anatomy are described based on field collections. The pinnae anatomy was analysed using LM (free-hand cross sections). The new species belongs to the Syagrus glaucescens complex, and an identification key and a distribution map were created.
Key results – Syagrus harenae resembles S. glaucescens, but some characteristics easily differentiate it, such as the small size, lax pinnae, symmetric pinnae tips, ramenta scales, a scattered thin indumentum on the peduncle, inflorescences and fruits orangish-yellow, and pistil with indumentum. The new species also possesses flowers arranged in tetrads and pentads and is the first species of Syagrus showing two sepals, petals with imbricate tips, staminodes with anthers, and frequently lacks staminodial rings. The pinnae anatomy of the new species also resembles S. glaucescens, which indicates their relatedness. However, reliable differences in pinnae anatomy set the new species apart, such as the fibrous ring reaching the abaxial hypodermis and the large first adaxial fibre bundle near the margin. The new species is assessed as critically endangered.
Conclusion – Syagrus harenae is the first endemic species of the genus described for the Serra do Ambrósio and possesses striking characteristics, such as the re-greening of the pistillate flowers and flowers arranged in tetrads and pentads. The type population corroborates the Diamantina Plateau and its disjunctions as one of the centres of diversity for Syagrus. The discovery of this new species reinforces the uniqueness of the local flora and its classification as a priority area for conservation.
campo rupestre, carrasco, Espinhaço Range, Palmae, Serra do Ambrósio, taxonomy
The Espinhaço Range in eastern Brazil was designated a biosphere reserve by UNESCO (
Distribution map of the Syagrus glaucescens species complex, maps of Serra Negra Formation (SN), and 3D map of Serra do Ambrósio mountain (SA). A. Location of SN, Diamantina Plateau, Syagrus harenae, Syagrus aristeae, Syagrus duartei, Syagrus evansiana, and Syagrus glaucescens. B. Relief and outline of the SN and localisation of the SA. C. Municipalities embedded in the SN. D. Relief of the SA and collection points of Splett 875 and the holotype of S. harenae. E. An endocarp (en) of S. harenae on the sandy soil of the carrasco.
The carrasco is a more or less dense shrubland that grows in whitish and coarse sand (
The monophyletic genus Syagrus Mart. comprises thus far 70 species, with Central and Eastern Brazil being the centre of its distribution (
Initially, plant anatomy played a unifying role for Syagrus (
The Serra do Ambrósio mountain is one of these understudied areas, standing out by the record of two species from the Syagrus glaucescens complex: Syagrus evansiana Noblick and Syagrus glaucescens Glaz. ex Becc. (
In other disjunctions of the Diamantina Plateau, such as the Serra do Cabral massif, S. glaucescens and S. evansiana were also recorded (see
This study was based on field observations in carrasco areas at the base of the Serra do Ambrósio mountain, municipality of Itamarandiba, Minas Gerais State, Brazil. This study also includes information from the specific literature about the species of the Syagrus glaucescens complex (
Qualitative and quantitative morpho-biometric data and images were recorded in situ for the new species. Data were taken from 30 individuals of the new species randomly chosen. For the remaining species of the S. glaucescens complex (S. aristeae, S. duartei, S. evansiana, and S. glaucescens), the morphological and anatomical data were retrieved from the literature (
Differences in morphology between S. harenae and S. aristeae, S. duartei, S. evansiana, and S. glaucescens.
| Syagrus harenae | Syagrus glaucescens | Syagrus duartei | Syagrus evansiana | Syagrus aristeae | |
| Plant size | Small to moderately-size | Moderately-sized | Small to moderately-sized | Small | Small |
| Stem size | 0.4–1.1(–1.4) m × 15–25 cm | 0.5–4 m × (8–)10–12 cm | 0–2 m × 8–12 cm | acaulescent | 0.1–0.15 m × 3–9 cm |
| Leaf vertical rows | Distinct | Distinct | Distinct | Indistinct | Indistinct |
| Subterranean stem | Prostrate | Erect | Prostrate | Subterranean | Subterranean |
| Pinnae | Lax | Congested | Congested | Lax | Lax |
| Leaf rachis | 95–167 cm | (55–)62–118 cm | 50–90 cm | 21–92 | 94–145 cm |
| Pinnae number | 63–79 | (38–)59–79 | 44–64 | 18–48 | 38–67 |
| Pinnae clusters | 2–5 | 3–5 | 2–3(–4) | 2–4(–5) | 2–3(–4) |
| Ramentas | Present | Absent | Present | Absent | Absent |
| Tomentum petiole and rachis | Present | Absent | Absent | Absent | Absent |
| Leaves | 8–15 | 5–15 | 6–12 | 3–11 | 3–6 |
| Sheathing leaf base ca | 10–28 cm long | 42–52 cm long | 20 cm long | 10–20 cm long | 13–23 cm long |
| Apical pinnae | 8–12 × 0.2–0.4 cm | 1.5–6 × 0.2–1.0 cm | 6–9 × 0.2–0.8 cm | 3–12 × 0.1–0.9 cm | 7–18 × 0.6–1.0 cm |
| Prophyll length | 11–16(–26) cm | 18 cm | 18–22 cm | 6–16 cm | 7–23 cm |
| Peduncle indumentum | Scattered thin indumentum | Glabrous | Glabrous | Glabrous | Glabrous |
| Inflorescence | Strongly pendulous | Erect or slightly pendulous | Erect or slightly pendulous | Erect | Erect |
| Inflorescence | Branched | Branched | Branched | Spicate or branched | Spicate or branched |
| Flower arrangement | Triads/Tetrads/Pentads | Triads | Triads | Triads | Triads |
| Staminate flower length at the apex | 9–10 mm | 8–12 mm | 10–15 mm | 8–10 mm | 10–12.5 mm |
| Staminate flower length at the base | 11.5–14 mm | 14–17 mm | 16–28 mm | 8–10 mm | 11.2–15.9 mm |
| Staminate flower colour | Yellow | Green to yellow | Green to yellow | Yellow | Yellow |
| Stamen length | 5.0–7.0 mm | 6.0–8.5 mm | 8–10.5 mm | 4–5 mm | 5.9–9.0 mm |
| Anther length | 4.0–7.0 mm | 5.0–7.5 mm | 6–9.5 mm | 3.5–4.0 mm | 4.4–7.7 mm |
| Filament length | 2.0–3.0 mm | 1.0–2.0 mm | 2.0 mm | 1.0 mm | 1.3–3.2 mm |
| Pistillode | 0.8–1.0 mm | Less than 1 mm | Less than 0.5 mm | Less than 1 mm | 0.5–1.5 mm |
| Pistillate flowers length | 13–17 mm | 10–17 mm | 17–25 mm | 8–19 mm | 12.1–16 mm |
| Number of sepals | 2–4 | 3 | 3 | 3 | 3 |
| Number of petals | 3–4 | 3 | 3 | 3 | 3 |
| Petals tips | Imbricate tips | Valvate tips, 1/3 to 4/5 the length of the petal | Valvate tips, 1/2 the length of the petal | Valvate tips, 2/5 to 1/2 the length of the petal | Valvate tips, 2/5 to 1/2 the length of the petal |
| Pistil size | 6–8 × 3–4 mm | 6–9 × 4.0–6.0 mm | 10 × 4.5 mm | 10–11 × 3.5–4 mm | 5.8–7.7 × 2.1–3.9 mm |
| Pistil indumentum | Whitish indumentum on lower 1/3 | Glabrous | Glabrous or fine wax indumentum | Lepidote indumentum from base to nearly the base of the stigmas | Glabrous |
| Stigmas | 3–4 mm | 3–4 mm | 6 mm | 3–5 mm | 2.8–3.4 mm |
| Staminodal ring | Less than 0.5 mm | 0.7–2 mm | ca 0.8 mm | 1–3 mm | 1 mm |
| Fruit | Ellipsoid to ovoid | Ellipsoid | Nearly globose | Globose | Nearly globose |
| Fruit sized | 2.1–3.0 × 1.6–2.0 cm | 2–3 × 1.6–2.5 cm | 3.0–3.8 × 2.5–3.2cm | 1.5–2.3 × 1.5–2.3 cm | 1.7–2.5 × 1.1–1.9 cm |
| Fruit colour when mature | Orange | Brown | Brown | Yellowish brown | Yellowish brown |
| Mesocarp | 1–2 mm | 1–2 mm | 2–4 mm | 1–2 mm | 1.0–2.5 mm |
| Endocarp size | 1.8–2.0 × 1.2–1.9cm | 2–2.8 × 1.7–2.1 cm | 3.0–3.5 × 2.8–3.0 cm | 1.4–1.6 × 1.1–1.3 cm | 1.3–1.8 × 1.1–1.4 cm |
| Endocarp thickness on the sides | 2–3 mm | (2–)3–4 mm | 5–8 mm | 1 mm | 1 mm |
Differences in pinnae anatomy between S. harenae and S. aristeae, S. duartei, S. evansiana, and S. glaucescens.
| Syagrus harenae | Syagrus glaucescens | Syagrus duartei | Syagrus evansiana | Syagrus aristeae | |
| Number of accessory vascular bundles around the main vascular system of the midrib | 1 | 5 | 0 | 0 | 2 |
| Number of collateral bundles in the vascular system of the midrib | 4–5 | 4–5 | 4–5 | 1 | 3 |
| Fibrous ring reaching the abaxial hypodermis | Present | Absent | Absent | Absent | Present |
| Non-vascular fibre bundle rounded attached to the abaxial surface | Present | Absent | Absent | Absent | Absent |
| Midrib format | Triangular | Truncate | Truncate | Triangular | Truncate |
| Tiny fibres in the abaxial hypodermis | Present | Absent | Absent | Present | Present |
| One adaxial vascular bundle near the margin | Sometimes | Absent | Absent | Absent | Absent |
| Large first adaxial fibre bundle near the margin | Present | Absent | Present | Present | Absent |
| Abaxial tertiary vascular bundles | Present | Present | Present | Absent | Present |
| Hypodermal cells rounded | Absent | Absent | Present | Absent | Absent |
| Small group of fibres around the fibrous ring of the midrib | Present | Present | Absent | Present | Present |
The distribution map showing all species of the S. glaucescens complex was plotted using QGIS v.3.22.4 (
In order to create an identification key to distinguish the species of the S. glaucescens complex, the data obtained here were compared with
BRAZIL – Minas Gerais • Itamarandiba, Vilarejo de Penha da França; 18°2’44.76”S, 43°4’45.02”W; 1000 m; 15 Feb. 2024; fl., fr.; Sant’Anna-Santos & Francino 406; holotype: DIAM; isotypes: UPCB, IBGE, HCF.
Syagrus harenae. A. Prostrated stem. B. Sheathing leaf arranged in 5 nearly vertical or slightly spiralled rows. C. Flowers arranged in tetrads. D. Sepals connate at the base. E. Flowers arranged in pentads. F. Fruits. G. Endocarp pores. A–G from Sant’Anna-Santos & Francino 406 (DIAM, holotype). Illustration by Gustavo Surlo.
Syagrus harenae is similar to S. glaucescens Glaz. ex Beccari, from which it differs by lax pinnae on the leaf rachis (vs congested pinnae), apical pinnae size (8–12 × 0.2–0.4 vs 1.5–6 × 0.2–1.0), pinnae with symmetrical tip (vs asymmetrical); base of the stem not-angular (vs angular), brownish indumentum where pinnae are inserted on the lower leaf rachis (vs glabrous); prostrated stem (vs erect); sheathing leaf base length (10–28 cm vs 42–52 cm), lax sheathing leaf base (vs congested); inflorescence strongly pendulous (vs erect ou slightly pendulous); peduncle with scattered thin indumentum (vs glabrous); petal tips imbricate (vs valvate); pistil with whitish indumentum on lower 1/3 (vs glabrous), inconspicuous staminodial ring (vs conspicuous staminodal ring); fruit yellowish-orange when mature (vs brownish).
Small to moderate-sized palm, solitary, 110–160(–250) cm tall. Stem 40–110(–140) × 15–25 cm, prostrate, with persistent leaf bases arranged in rows with indistinct internodes near the crown, non-angular stem base. Leaves pinnate number 8–15; sheathing leaf base ca 10–28 cm long; pseudopetiole 15–37 cm long; petiole 9–27 × 0.5–1.6 cm and 0.2–0.7 cm thick, rachis 95–167 cm long; abaxial side of petiole and rachis with brownish tomentum; pinnae medium to dark-green, discolourous, abaxial surface glaucous, linear, rigid-coriaceous with apex more or less symmetrical and long tapering, pinnae numbering 63–79 pairs, in clusters of 2–5, lax on leaf rachis, inserted in divergent planes over the rachis; pinnae with inconspicuous ramenta scales along the abaxial midrib (near the rachis) on young leaves; basal pinnae 27–36 × 0.4–0.6 cm, middle pinnae 17.5–30.5 × 1.7–2.3 cm, apical pinnae 8–12 × 0.2–0.4 cm. Inflorescences pendulous, spirally branched, prophyll 11–16(–26) × 1.3–2.5 cm; peduncular bract 56–72 cm long, inflated portion 25–31 × 5.2–7.5 cm, including a 1.0–1.4 cm beak, 6.4–8.5 cm perimeter, 2–3 mm thick, woody, sulcate, exterior glabrous; peduncle 30–41.5 cm long, 8–10 × 4–7 mm wide, with brownish scarce indumentum; inflorescence axis 19.5–24 cm long; rachis 1.5–13.3 cm long; rachillae 3–15, glabrous, yellow, 8.5–20 cm long at the apex, 12–17 cm long at the base; flowers arranged in triads, tetrads (with two central pistillate flowers, each flanked by a staminate flower) or pentads (with three central pistillate flowers flanked by two staminate flowers), staminate flowers with three sepals and three petals, and pistillate flowers with three sepals and three petals, two sepals and four petals, three sepals and four petals. Staminate flowers 9–10 × 4–5 mm at the apex, 11.5–14 × 4–6 mm at the base, those at the apex sessile, sometimes pedicellate, pedicels 1–4 mm long, yellowish-orange, sepals 1.5–3.5 × 1.5–2.5 mm, glabrous, triangular, no visible nerves, keeled, connate at the base, petals 8–10 × 2.5–4.0 mm at the apex, 9–19 × 3.5–4.5 mm at the base, with acute tips, slightly nerved; ovate-triangular, valvate, stamens 5–7 mm long; anthers 4–7 mm long, basally sagittate; filaments 2–3 mm long, free at the base, dorsifixed at the base (basifixed); pistillode trifid, ca 0.8–1.0 mm. Pistillate flowers elongate-pyramidal, 13–17 × 6–7 mm, orangish-yellow when immature and green when mature, glabrous; sepals 13–16 × 5–7 mm, orangish-yellow when immature and green when mature, without visible venation, triangular, imbricate; petals 10–13.5 × 3–5 mm, orangish-yellow when immature and green when mature, imbricate, triangular; pistil 6–8 × 3–4 mm, with whitish indumentum from the base of the pistil to nearly the base of the stigmas, stigmas 3–3 mm long, glabrous; inconspicuous staminodial ring rarely present, less than 0.5 mm in height, staminodes arranged in pairs or isolated (sometimes with anthers), six in number, ca 1.0–1.8 mm in height. Fruits ellipsoid, 2.1–3.0 × 1.6–2.0 cm, orange when mature, scaly lepidote tomentum, epicarp less than 0.5 mm thick, mesocarp less than 0.5 mm thick, succulent, and fibrous; endocarp 1.8–2.0 × 1.2–1.9 cm, 2–3 mm thick on the sides, 4–5 mm thick on the tips, trivittate interior. Seeds more or less ellipsoid, endosperm homogeneous. Germination remote tubular.
The type population of Syagrus harenae was found in the village of Penha de França, in the Serra do Ambrósio mountain (Fig.
The Serra do Ambrósio mountain is characterised by forest formations at its base, which end abruptly at an altitude of around 900 meters, giving way to open vegetation types, such as the carrascos (
In areas with a gentle slope and sand deposition, at an altitude range of 800–1200 m, the vegetation is known as carrasco and is characterised by very ramified scrawny bushes, ranging from an open to dense physiognomy (
Vegetative morphological aspects of Syagrus harenae. A. Landscape photograph of the type locality: a group of individuals (white rectangles) growing on the sandy soils near rock outcrops (ro). B. The white arrowhead indicates the prostrated stem. C. Ramenta (black arrowheads) on the pinnae abaxial surface (ab) and leaf rachis with brownish tomentum (ra). D. Long tapering pinnae tips (white arrowheads). E. Pinnae: dark-green adaxial surface (ad) and glaucous abaxial surface (ab). F. Pinnae inserted in divergent planes over the rachis (rc). G. Fibres (white arrowheads) of the pseudopetiole. H. Leaf sheath (sh), peduncular bract (pb), and prophyll (pr). Photographs by Bruno F. Sant’Anna-Santos.
The climate of Serra do Ambrósio is Cwb according to the climatic classification of
The high floristic diversity in the carrasco includes species with large distribution (Pirani et al. 2014), such as Ananas ananassoides (Baker) L.B.Sm. (Fig.
After peduncular bract opening, the orangish-yellow flowers of S. harenae are prominent in the subshrub layer of the denser carrasco (Figs
Floral morphology of Syagrus harenae. A. Staminate flowers on rachillae upper 1/3 and triads on its lower 2/3: staminate flowers in pre-anthesis (two black arrowheads). B. Tetrads (two white circles): staminate flowers in anthesis (two black arrowheads). C. Inflorescence bearing only pistillate flowers (after staminate flowers’ senescence). D. Triad: sessile staminate flowers, yellow pistillate flowers. E. Pedicellate staminate flowers (two black arrowheads), green pistillate flowers. F. Tetrad: two central pistillate flowers flanked by two staminate flowers. G. Pentad on lateral view: three central pistillate flowers flanked by two staminate flowers (two black arrowheads). H. Pentad: top view. Staminate flowers (two black arrowheads). I. Apex and base staminate flowers. Three petals (pe). J. Staminate flower: petals (pe) longer than the sepals (se). K. Keeled sepals (white arrowhead). Petals (pe) slightly veined (black arrowhead). L. Valvate petals (pe). M. Six stamens (six white dots). N–O. The anther is dorsifixed at the filament base (fi). Anther (an) basally sagittate. Conective (white arrowhead). P. Stamen: anther (an) and filament (fi). Q. Longitudinal dehiscence (white arrowhead) and pistillode (white circle). R. Trifid pistillode (pi). Photographs by Bruno F. Sant’Anna-Santos.
Floral morphology of Syagrus harenae. A. Floral bracteole (black arrowhead). B. Perianths removed from four different pistillate flowers, bearing two sepals (se) and four petals (pe) or three sepals and four petals. C. Imbricate outer (ou) and inner sepals (in). D. Sepal (se): smooth margin (black arrowhead). E–F. Imbricate petal tips. G. Outer (ou) and inner (in) petals. H–I. Pistillate flower: ovary (ov), stigma (st) and staminodes with anther (an) and without (black arrowheads). J. Whitish indumentum (id). Staminode (st). Photographs by Bruno F. Sant’Anna-Santos.
Fruit morphology of Syagrus harenae. A. Infructescence. B. Immature fruit: epicarp green in colour and recovered by a scaly lepidote tomentum. C. Mature fruit: epicarp orange in colour and recovered by a scaly lepidote tomentum. D. Fibrous mesocarp (me). Epicarp (ep). Endocarp (en). E. Three apical endocarp pores: top view. F. Endocarp pore, lateral view. G. Longitudinal section: brownish endocarp (en) and whitish endosperm (ed). Photographs by Bruno F. Sant’Anna-Santos.
Habitat of Syagrus harenae. A. Landscape view of the carrasco: the small Syagrus harenae (sy), sandy soil (sa), and forest (fo). B. Open (op) and dense (de) carrasco vegetation. S. harenae (sy), forest (fo), and Kielmeyera regalis (ky). C. Ananas ananassoides. D. Rocks (ro). Pilosocereus aurisetus (pi). E. Fruits (fr) of Pilosocereus aurisetus (pi). F. Uebelmannia gummifera. Photographs by Bruno F. Sant’Anna-Santos.
Morphological aspects of Syagrus harenae with ecological implications. A. Fly on the peduncular bract. B. A bee visiting a pistillate flower. C. A bee visiting a staminate flower. D. Beetle. E–F. Larvae (two white arrowheads). G–H. Fruits and endocarps on the sandy soil. I. Mesocarp damaged (da) by fruit predation. J–K. Pendulous infructescences almost reaching the ground (three white circles), and young plants (two white arrowheads) near adult plants. Photographs by Bruno F. Sant’Anna-Santos.
Palms are well-known as hotspots for insect abundance and diversity, but so far for Syagrus, the evidence points to pollination both by beetles and bees (
In Syagrus, most species display flowers in shades ranging from green to yellow (see
Re-greening after anthesis, while rare in flowers, has been reported in some species (see
On the soil, next to the specimens of S. harenae, it is noticeable that many fruits from different reproductive periods are deposited just below the infructescences where they were produced (Fig.
For rare species such as S. harenae, natural selection would probably favour limited dispersal where drivers such as environmental conditions, surrounding vegetation and ineffective dispersal would be relevant causes of philomatry (
The new species was collected with flowers and fruits in February 2024.
The specific epithet, harenae, means sand and refers to the unique sandy soil where the new species grows in the Serra do Ambrósio mountain.
The population of the new species has only been recorded in the Serra do Ambrósio mountain, where there is no conservation unit. Close to the type population, there is a mining site for sand extraction, which has been closed. Sand extraction has also been recorded in other parts of Serra do Ambrósio (see
BRAZIL – Minas Gerais • Rio Vermelho, Pedra Menina, Serra do Ambrósio, Morro da Virada do Mato Virgem; 31 Jul. 1985; fl.; Mello-Silva et al. 7833; SPF • Penha da França, ca 100 km ao nordeste de Diamantina; 18°4’48”S, 43°4’48”O; 11 Mar. 1995; Splett 875; UB.
Stomata occur only on the abaxial surface (Fig.
Pinna anatomy of Syagrus harenae using LM with cross-sections. A. Bisseriate hypodermis (hy) between the adaxial non-vascular fibre bundles (fi). Adaxial epidermis (ad), cuticle (cu). B. Arciform subsidiary cells (two red dots) and guard cells (two black dots) are at the same level as the abaxial epidermis (ab). Cuticle (cu), hypodermis (hy), substomatal chamber (sc). C–D. Minor fibres (three white circles) and rounded groups with many fibres (three black circles). E. Primary (t1) vascular bundles connected to the adaxial hypodermis, secondary (t2) vascular bundles unconnected, and tertiary (t3) vascular bundles connected only to the abaxial hypodermis. F. Secondary (t2) vascular bundle abaxially surrounded by a sclerenchymatous sheath (ss). G. Tertiary (t3) vascular bundle abaxially surrounded by a sclerenchymatous sheath (ss). H. Primary vascular bundle: protoxylem (pr), metaxylem (me), two poles of phloem (ph) and sclerenchymatous sheath (ss) connected to hypodermis on both surfaces. I. Pinnae margin: large first (lf) adaxial non-vascular fibre bundles and adaxial tertiary vascular (t3) bundle. J. Midrib: fibrous (fr) ring reaching the abaxial hypodermis (black arrowhead) and interrupted expansion tissue (et). K. Detail of the expansion tissue: fibres (fi). L. Collateral fibre bundles (five black circles) and phloem poles (ph). M. Non-vascular (nv) fibre bundle. N. Accessory bundle (ab). Photographs by Bruno F. Sant’Anna-Santos.
Morphological differences between Syagrus harenae (A, C, E, G, I) and Syagrus glaucescens (B, D, F, H, J). A. Prostrated stem (pr), lax (la) pinnae, and symmetrical (sy) pinnae tip. B. Erect stem (er), congested (co) pinnae, and asymmetrical (as) pinnae tip. C. Lax sheathing leaf base. D. Congested sheathing leaf base. E. Inconspicuous leaf scars on the stem base (st). F. Conspicuous leaf scars on the stem base (st). G. Strongly pendulous inflorescence. H. Erect inflorescence. I. Peduncle of the inflorescence with scattered thin indumentum. J. Peduncle of the inflorescence glabrous. Photographs by Bruno F. Sant’Anna-Santos.
All the known species in the Syagrus glaucescens complex occur in neighbouring regions of the Espinhaço Range in the state of Minas Gerais (Fig.
The third species in the complex, the dwarf Syagrus evansiana Noblick, is more easily differentiated from S. duartei and S. glaucescens by characteristics such as acaulescence, leaves not arranged in vertical rows, spiciform inflorescences (not just branched) and the rare variation of 3 to 5 pores in the endocarp (
The first record in the Serra do Ambrósio dates back to 1985, viz. Mello-Silva et al. 7833 (
| 1 | Plants with aerial above-ground stems; leaf bases in rows, inflorescences always branched; endocarp 1.8–3.5 mm long, only three endocarp pores, 2–8 mm thick on the sides | 2 |
| – | Plants with very short or subterranean stems (acaulescents); leaf bases not in rows on the stem, unbranched to branched inflorescences; endocarp 1.4–1.8 mm long, three to five endocarp pores, 1 mm thick on the sides | 3 |
| 2 | Stem base round in appearance, with inconspicuous leaf scars; lax pinnae on the leaf rachis; abaxial side of the petiole and leaf rachis with tomentum; peduncle with scattered indumentum; inflorescences strongly pendulous, pistillate flowers with imbricate petal tips; number of sepals 2–4; number of petals 3–4; inconspicuous staminodial ring | Syagrus harenae |
| – | Stem base angular in appearance, with conspicuous leaf scars; congested pinnae on the leaf rachis; abaxial side of the petiole and leaf rachis glabrous; peduncle glabrous; inflorescences slightly pendulous or erect; pistillate flowers with valvate petal tips; number of sepals 3; number of petals 3; conspicuous staminodial ring | 4 |
| 3 | Leaf rachis 94–145 cm long; middle pinnae tip usually asymmetrical; abaxial side of leaf rachis and petiole with tomentum; inflorescence axis 18–29.5 cm long; basal and apical rachillae of similar length; epicarp covered with crackled plates | Syagrus aristeae |
| – | Leaf rachis 21–92 cm long; middle pinnae tip usually symmetrical; abaxial side of leaf rachis and petiole glabrous; inflorescence axis 4.5–17 cm long; basal and apical rachillae of different length; epicarp covered by a thick brown indumentum | Syagrus evansiana |
| 4 | Stem usually erect; pistillate flowers 10–17 mm long; fruit ellipsoid, 2–3 cm long; endocarp ellipsoid to ovoid, 2–2.8 cm long, 2–4 mm thick on its sides | Syagrus glaucescens |
| – | Stem usually prostrate (occasionally erect); pistillate flowers 17–25 mm long; fruit globose, 2.8–3.5 cm long; endocarp nearly globose, 2.8–3.5 cm long, 5–8 mm thick on its sides | Syagrus duartei |
Our results show that, despite its short stem, the population from Serra do Ambrósio is not acaulescent like S. evansiana, and more closely resembles S. glaucescens due to the vertically arranged leaves. However, we were confident it was a new and undescribed species on our first encounter with the plant. Of course, although the Serra do Ambrósio is a disjunct area, S. harenae is geographically closer to S. glaucescens, reinforcing their relationship. However, the presence of flowers in tetrads in practically all the specimens evaluated and the first record of flowers in pentads for Syagrus also pointed to a striking species. Other characters, such as the re-greening of pistillate flowers, the imbricate petal tips in pistillate flowers, the variation in the number of sepals, and the basifixed anthers, also make S. harenae an impressive species that sets it apart from all other species of Syagrus in the region. According to
Our results here confirm what
We thank Dr Patrícia Soffiatti for the valuable suggestions and the anonymous reviewers for the valuable comments and correction made to the manuscript.