Research Article |
Corresponding author: Bruno Francisco Sant'Anna-Santos ( bsantannaufmg@gmail.com ) Academic editor: Brecht Verstraete
© 2023 Bruno Francisco Sant'Anna-Santos, Rafael Micheli, Luiz Fernando Lima Carvalho, Patrícia Soffiatti.
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 B, Micheli R, Carvalho LFL, Soffiatti P (2023) A new bluish-leaved Syagrus (Arecaceae) from an overlooked OCBIL in the Espinhaço Range (Brazil). Plant Ecology and Evolution 156(2): 129-145. https://doi.org/10.5091/plecevo.101027
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Background and aims – This study is part of ongoing research on the Arecaceae Flora of the Serra do Cabral, an isolated massif in the southwest of the Espinhaço Range in Minas Gerais State. Because of the isolation of the massif, the area has a rich biodiversity and a high level of endemism. While searching for populations of the rare and critically endangered Syagrus cabraliensis, a new bluish-leaved palm species was discovered and it is described here.
Material and methods – The new species’ morphology is described based on field collections. The pinnae were analysed using SEM and LM cross- and longitudinal sections following default methodology. In addition, we compared the species to S. cabraliensis and provided ecological notes and a conservation status assessment.
Key results – Syagrus carvalhoi resembles S. cabraliensis but they can easily be distinguished by morphoanatomical characters. Both species occur non-sympatrically in the Serra do Cabral, in contrasting microhabitats: S. carvalhoi in the southern quartzitic campos rupestres and S. cabraliensis in the northern ferruginous campos rupestres. A key to the known grass-like Syagrus species from the massif is provided. Based on the restricted area of occurrence and the anthropogenic threats, Syagrus carvalhoi is assessed as critically endangered.
Conclusion – Syagrus carvalhoi is the second grass-like endemic Syagrus species from the Serra do Cabral and presents rare characters within the genus (grass-like aspect, colonial habit, flowers in tetrads, and the stem forking at or below the ground). This discovery corroborates that this isolated OCBIL is a home for endemic and rare palm species. The Serra do Cabral massif has proved a source of morphological and anatomical novelties in Arecaceae, affecting the taxonomy and understanding of the evolution and ecology of palms. Our results reinforce the notion that it is important to conserve this area with rich and rare biodiversity but under alarming and unprecedented threats.
campos rupestres, grass-like leaf, Minas Gerais State, new species, Palmae, plant anatomy, Serra do Cabral, taxonomy
Campos rupestres are considered an OCBIL (old, climatically-buffered, infertile landscape), ancient montane habitats with remarkable biodiversity, high degrees of endemism characterised by stable geology and relative modulated climate fluctuation existing across a timespan of millions of years (
Most of the campos rupestres occupy the highlands of the Espinhaço Range, forming rocky mountaintop archipelagos holding ca 15% of the Brazilian vascular flora in less than 1% of the territory (
In general, plant communities in campos rupestres possess very restricted distributions, being sometimes known from just a single population (
Syagrus carvalhoi. A. Straight leaves. B. Spicate inflorescences and infructescences. C. Close-up to a symmetrical pinnae tip. D. Branched inflorescence. E. Staminate flowers at anthesis. F. Tetrad. G. Triad. H. Staminate flower. I. Filaments connate. J. Petal. K. Stamens: ventral view. L. Pistillode. M. Stamens: dorsal view. N. Transversal-section: valvate petals. O. Pistillate flower. P. Sepal keeled. Q. Petal obscurely nerved. R. Petal: trichomes. S. Pistil. T. Infructescence. U. Endocarp pores. A, C–U from Sant’Anna-Santos 377 (UPCB, holotype), spicate inflorescences and infructescences of B added from habitat photographs. Illustration by Gustavo Surlo.
Several endemics and rare species were recently discovered in the SC (
Syagrus has a high concentration of endemics in the campos rupestres, being commonly occurring dwarf species in these mountainous habitats (
One of the rarest and endangered species of the Syagrus – the grass-like Syagrus cabraliensis (Noblick & Lorenzi) B.F.Sant’Anna-Santos – is only known from a small ferruginous campo rupestre, occurring near the boundaries of the SC State Park, the only conservation unit located in the SC (
During the last eight years of unsuccessfully searching for S. cabraliensis within the borders of the SC State Park, a hitherto unknown species was discovered. Here, we describe and illustrate this new grass-like palm species and compare it with S. cabraliensis as an additional effort to quickly improve measures towards conserving the campos rupestres from the overlooked SC massif. The area under protection by the park is small, and the endemics and rare species are threatened by the proximity of exotic species cultivation, fires, and mining, among other threats (
This study is based on field observations across the Serra do Cabral State Park, Minas Gerais, Brazil. The literature review considered all publications on the taxonomy or anatomy of the genus (
Vegetative and reproductive parts were taken from 30 randomly chosen individuals of the new species. For S. cabraliensis, we retrieved information about vegetative and reproductive parts from the literature (
Distribution data were plotted on a map using QGIS v.3.16.2 (
For the anatomical study of the pinnae of the new species, 15 samples were analysed. The samples were collected from the middle of the central pinnae from herbarium specimens of our collections and specimens in the field, following
Syagrus carvalhoi is similar to Syagrus cabraliensis (Noblick & Lorenzi) B.F.Sant’Anna-Santos, from which it differs by larger, taller clumps (sometimes with colonial habit); taller plants; leaves bluish and straight (vs dark green and slightly arched); pinnae inserted at various angles near the base but otherwise regularly arranged on the upper part of the leaf towards the tip (vs inserted at various angles throughout the entire rachis); pinnae with symmetric tip (vs asymmetric tip); pinnae glaucous on adaxial surface (vs pinnae glossy on adaxial surface); the presence of inconspicuous ramenta (vs without ramenta); rachillae of different sizes throughout the rachis (vs similar-sized rachillae); staminate flowers briefly pedicellate and filaments briefly connate at the base (vs staminate flowers long pedicellate and stamens with free filaments).
Vegetative morphological aspects of Syagrus carvalhoi. A. Colonial habit near a rock outcrop (black arrowheads). B. Detail of A: straight and ascending leaves. C. Prostrated stem (white arrowhead). D. Roots (white arrowhead). E. Unbranched stem (white arrowhead). F. Forked stem (white arrowhead). G. Acaulescent specimen: without aerial stem (white arrowhead). Photographs by Bruno F. Sant’Anna-Santos.
BRAZIL – Minas Gerais • Buenópolis, Parque Estadual da Serra Cabral; 17°57’13.41”S, 44°15’2.46”W; 1044 m; 8 Jan. 2021; fl., fr.; Sant’Anna-Santos 377; holotype: UPCB; isotypes: DIAM, IBGE, MBM, UFG.
Reproductive morphological aspects of Syagrus carvalhoi. A. Dried inflorescence: inflorescence peduncle (pe) surrounded by prophyll (pr) and peduncular bract (pb). B. Bifurcate prophyll (white arrowhead). C. Base of a peduncle (pe) and peduncular bract (pb), tomentose (white arrowhead). D. Dorsal surface of the peduncular bract, deeply grooved (white arrowhead). E. Ventral surface of the peduncular bract, deeply grooved (white arrowhead). F. Tetrad after the fall of the staminate flower, bracteoles (br). G. Fruits (fr) with persistent perianth (pp), mostly covered by a brown lepidote indumentum (in) contrasting the green glabrous tip (gt). Photographs by Bruno F. Sant’Anna-Santos.
Small palm, clustering to colonial, 100–140(–160) cm tall. Stem 30–60 × 7–9 cm, subterranean or prostrate, rarely erect, sometimes forking at or below the ground. Leaves pinnate number 6–13; sheathing leaf base ca 6–16 cm long; pseudopetiole 10–21 cm long; petiole 8–15 × 0.4–0.7 cm and 0.2–0.4 cm thick, abaxial side of petiole and rachis with scarce white tomentum; rachis 43–83 cm long; pinnae bluish-green on both surfaces, glaucous on both sides, pinnae narrow, single-folded and almost linear, fold quickly during drying, pinnae numbering 19–26 pairs, in clusters of 2–3, inserted at various angles near the base but otherwise regularly arranged on the upper part to the leaf towards the tip, inconspicuous ramenta scales along the abaxial midrib; basal pinnae 23–38 × 0.3–0.6 cm, middle pinnae 22–41 × 0.5–1.1 cm, apical pinnae 22.5–29.5 × 0.1–0.3 cm with an asymmetric tip. Inflorescences spicate or spirally branched, with prophyll 6.5–10 × 1.0–1.5 cm; peduncular bract 32–45 cm long, woody, narrow, sulcate, with whitish indument thicker at the base of the bract, inflated portion 19.5–35 × 1.3–2.5 cm, including a 0.8–1.5 cm beak, 1.8–3.1 cm perimeter, 0.8–2 mm thickness; peduncle ca 12.5–18 cm × 3.0–5.0 mm, with white indument; inflorescence axis 12–23 cm long; rachis 0–5.5 cm long; rachillae 1–4(–6), glabrous, 6–15 cm long at the apex, 9.5–18 cm long at the base; flowers arranged in triads or tetrads with two central pistillate flowers, each flanked by a staminate flower, both staminate and pistillate flowers with three sepals and three petals. Staminate flowers 6.4–10.8 × 2.5–4.1 mm at the apex, 8.3–16.8 × 2.6–4.3 mm at the base, those at the apex sessile, those at the base frequently pedicellate, pedicels ca 1 mm long, green to yellow, sepals 0.8–2.0 × 0.5–0.6 mm, glabrous, triangular, no visible nerves, briefly connate at the base, petals 5.5–7.2 × 2.0–2.8 mm at the apex, 8.2–10.2 × 1.5–2.8 mm at the base, with acute tips, nerves indistinct; ovate-triangular, valvate, stamens 3.9–9.5 mm long; anthers 2.7–3.5 mm long; filaments 2.1–6.8 mm long, very briefly connate at the base; pistillode trifid, ca 1.0–1.5 mm. Pistillate flowers elongate-pyramidal, 9.9–10.8 × 4.0–5.8 mm at the apex, 11.8–16.4 × 3.6–7.5 mm at the base, glabrous; sepals 9.9–12.9 × 2.3-2.6 mm, yellow, without visible venation, triangular, imbricate, with scarce hairs at the margin; petals 9.6–10.1 × 1.8–2.4 mm, obscurely nerved and slightly raised on the lower third of the petal, the lower third of margins with multiseriate hairs, imbricate at the base but valvate at the tips, triangular; pistil 5.4–10 × 2.5–4.0 mm, with lepidote indument from the base of the pistil to nearly the base of the stigmas, stigmas 2.7–3.7 mm long, glabrous; staminodial ring ca 0.4–1.2 mm in height, 6-dentate. Fruits ellipsoid, 1.8–2.7 × 1.0–1.6 cm, green tip when mature, tip glabrous, rest of the fruit brown, scaly lepidote tomentum, epicarp less than 0.5 mm thick, mesocarp less than 0.5 mm thick, succulent, and fibrous; endocarp 1.4–1.8 × 1.0–1.3 cm and ca 1 mm thick, trivittate interior. Seeds ellipsoid to nearly globose, endosperm homogeneous. Germination remote tubular.
Syagrus carvalhoi is endemic to the southern part of the Serra do Cabral State Park, municipality of Buenópolis, north-central Minas Gerais state, Brazil (Fig.
The Serra do Cabral is characterised by two well-defined seasons: rainy, with hot and humid summers and mean precipitation of 750 mm, from November to April, and a dry season, with winters occurring from May to October (
Habitat and morphoanatomical aspects of Syagrus carvalhoi with ecological implications. A. Specimens of Poaceae (3 black arrowheads) and Velloziaceae (2 white arrowheads) near S. carvalhoi (sc). B. Cyperus sp. C. Paepalanthus sp. D. Pinnae frequently folded during the dry season. E. pinna (pi) manually unfolded exposing the adaxial surface; the red dotted circle shows a diagram of the expansion tissue (et) on a midrib cross-section. F. pinna densely covered by epicuticular wax (ew) compared to an area where the wax was manually removed (re). G. Epicuticular wax, SEM. H. The white circle shows a snake (sn) revealed after removing old leaves. I. Hole (ho) caused by predation of fruits (fr) by rodents. J. Insect (in) on an old pseudopetiole. K. Ant (an) walking on a pinna. L. Larva of a beetle (la) feeding on the endocarp (en). Photographs by Bruno F. Sant’Anna-Santos.
The phenology was monitored between December 2019 and November 2022, and the species flowers and bears fruits throughout the year.
Characters | S. carvalhoi | S. cabraliensis |
Site of occurrence | Southern part of Serra do Cabral | Northern part of Serra do Cabral |
Habitat | Quartizitic campo rupestre | Ferruginous campo rupestre |
Size (cm) | 100–140(–160) | 37–80(–95) |
Pinnae colour | Bluish | Dark green |
Pinnae number | 19–26 | 9–19 |
Pinnae tip | Symmetrical | Asymmetrical |
Ramenta scales | Present | Absent |
Leaves | Straight | Slightly arched |
Pinnae arrangement on the upper part of the rachis | Regular | Various angles |
Leaf rachis length (cm) | 43–83 | 25–39 |
Peduncular bract length (cm) | 32–45 | 12.2–31 |
Length of the inflated portion of the peduncular bract (cm) | 19.5–35 | 8.5–19 |
Rachis length (cm) | 0–5.5 | 0–2.0 |
Size of the rachillae throughout the rachis | Different size | Similar size |
Pedicel length of the basal staminate flowers (mm) | ca 1 | 1–4.5(–5.0) |
Filaments | Very briefly connate at the base | Distinct |
Length of the basal pistillate flowers (mm) | 11.8–16.4 | 10.0–11.8 |
Indumentum of the petals of pistillate flowers | Margins with hairs | Glabrous |
Number of endocarp pores | 3 | 3 or 6 |
Endocarp pore position | Only subbasal | Subbasal or subbasal and subapical |
The specific epithet carvalhoi is named in honour of Wellington Geraldo Oliveira Carvalho Júnior, a palm enthusiast who discovered this species. Mr Carvalho and his family have provided financial and logistical support to our research in recent years. So, our team’s discoveries were only possible thanks to his support and motivation.
Syagrus carvalhoi is known only within the boundaries of the Serra do Cabral State Park. Near the park, there are small farms where livestock is raised, roads, Pinus sp. and Eucalyptus sp. plantations, and mining gravel extraction (
BRAZIL – Minas Gerais • Buenópolis, Parque Estadual da Serra do Cabral; 17°56’08.85”S, 44°16’28.21”W; 1206 m; 6 Jan. 2020; fl.; Sant’Anna-Santos & Firmo 236; MBM • Buenópolis, Parque Estadual da Serra do Cabral; 17°56’08.85”S, 44°16’28.21”W; 1206 m; 6 Jan. 2020; fr.; Sant’Anna-Santos & Firmo 237; MBM • Buenópolis, Parque Estadual da Serra do Cabral; 17°56’08.85”S, 44°16’28.21”W; 1206 m; 6 Jan. 2020; fr.; Sant’Anna-Santos & Firmo 238; MBM • Buenópolis, Parque Estadual da Serra do Cabral; 17°56’20.50”S, 44°15’11.29”W; 1100 m; 7 Jan. 2020; fl.; Sant’Anna-Santos & Firmo 242; MBM • Buenópolis, Parque Estadual da Serra do Cabral; 17°56’20.50”S, 44°15’11.29”W; 1100 m; 7 Jan. 2020; fl., fr.; Sant’Anna-Santos & Firmo 244; MBM.
Both adaxial and abaxial surfaces of the pinnae are coated by epicuticular wax in the form of hook-shaped filaments (Figs
Pinnae anatomy of Syagrus carvalhoi using SEM (A) and LM with cross- (B–H, J–M) and longitudinal (I) sections. A. Adaxial surface: epicuticular waxes (ew) and stomata (st). B. Adaxial surface: guard cells (gc) at the same level of the epidermis (ep); subsidiary cells (sc) at the same level of hypodermis (hy). Cell wall (cw), cuticle (cu). C. Stomata on both surfaces (white arrowheads); palisade parenchyma (pa) throughout the mesophyll; tertiary vascular bundles (t3) connected to the adaxial hypodermis (grey arrowhead) and not connected to the abaxial hypodermis (black arrowhead). D. Secondary vascular bundles (t2) connected to hypodermis (black arrowheads) on both surfaces. E. Primary vascular bundles (t1) connected to the hypodermis (black arrowheads), conspicuous metaxylem (me), protoxylem (white arrowhead) and phloem (ph). F. Adaxial surface: non-vascular fibre bundle (fi) and tertiary vascular bundle (t3) connected to the adaxial hypodermis (black arrowheads). Palisade parenchyma (pa). G. Silica bodies (white arrowheads) associated with primary vascular bundle (t1). Palisade parenchyma (pa). H. Tertiary vascular bundles (t3) and a raphide-containing idioblast (id). I. Idioblast (id) containing raphides (ra). J. Expansion tissue interrupted (surrounded by the dotted white line); fibres in the expansion tissue (white arrowhead); two collateral bundles (white circles); group of fibres (black arrowhead) and accessory bundle (white rectangle). K. Trichome (tr). L. Fibre (black arrowhead) in the expansion tissue (et). M. Silica bodies (white arrowheads) associated with the fibres (black arrowheads) in the expansion tissue (et).
Differences in leaf anatomy between Syagrus carvalhoi and S. cabraliensis.
Characters | S. carvalhoi | S. cabraliensis |
Adaxial veins | Present | Sometimes |
Expansion tissue | Interrupted | Continuous |
Number of small groups of fibres around the main vascular bundle | 0–3 | 5–12 |
Trichomes | Present | Absent |
Mesophyll symmetry | Isolateral | Dorsiventral |
Guard cells level | At the same level of the epidermis | At the same level of the hypodermis |
1 | Plants with straight leaves; pinnae glaucous on adaxial surface; pinnae with symmetrical tips; 19–26 pairs of pinnae along the rachis; pinnae regularly inserted on the upper part of the rachis; peduncular bract 32–45 cm long; basal and apical rachillae of different length | S. carvalhoi |
– | Plants with slightly arched leaves; pinnae glossy on adaxial surface; pinnae with asymmetrical tips; 9–19 pairs of pinnae along the rachis; pinnae inserted at various angles on the upper part of the rachis; peduncular bract 12.2–31 cm long; basal and apical rachillae of similar length | S. cabraliensis |
Syagrus carvalhoi has a grass-like aspect – typically attributed to dwarf palms with narrow pinnae and slender inflorescences according to
3D map of the Serra do Cabral massif (A) and some morphological differences between the grass-like Syagrus carvalhoi (B, D, F) and Syagrus cabraliensis (C, E, G). A. Relief of the SC and the location of S. carvalhoi and S. cabraliensis. B. Bluish, straight and ascending leaves. C. Dark green and slightly arched leaves. D. Symmetrical pinna tip. E. Asymmetrical pinna tip. F. Staminate flower with short pedicel (black arrowhead). G. Staminate flower with long pedicel (black arrowhead). Photographs B–G by Bruno F. Sant’Anna-Santos.
We thank Jarbas J. de Alcantara, and the staff of the Serra do Cabral State Park (licence 091/2018 IEF-MG), Ricardo A. dos Santos, and Deivison Henrique Teixeira Firmo for the assistance during part of the fieldwork activities; the CME/UFPR for the scanning electron microscopy analyses; and Dr Elaine Lopes Pereira Nunes for the valuable suggestions and language corrections. We thank Dr Brecht Verstraete, one anonymous editor, and two reviewers for the valuable comments and corrections made to the manuscript. Bruno Francisco Sant’Anna-Santos received financial support from Pró-Reitoria de Pesquisa da Universidade Federal do Paraná (Edital 04/2019).