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Phytotaxa 420 (2): 095–101
https://www.mapress.com/j/pt/
Copyright © 2019 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by William Baker: 3 Oct. 2019; published: 10 Oct. 2019
https://doi.org/10.11646/phytotaxa.420.2.1
95
Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0
Sabal lougheediana (Arecaceae), a critically endangered, endemic palm species
from Bonaire
M. PATRICK GRIFFITH1, QUIRIJN COOLEN2, MICHELLE BARROS1 & LARRY R. NOBLICK1
1Montgomery Botanical Center, Coral Gables, Florida, United States of America.
2 BonBèrdè, Tras ‘I Montaña 45, Bonaire. Dutch Caribbean.
Email: patrick@montgomerybotanical.org, bonberde@gmail.com, michelleb@montgomerybotanical.org, larryn@montgomerybotani-
cal.org.
Abstract
A new palm species, Sabal lougheediana, is described and illustrated. This critically endangered island endemic, native
solely to Bonaire, is characterized by a compact crown of leaves, erect leaf segments, distinctive leaf scars, and frequently
vascularized fiber bundles in leaflet transection. Detail on history, morphology, range, habitat, and conservation status is
presented, along with a diagnostic key.
Key words: anatomy, Coryphoideae, critically endangered, single-island endemic, Palmae, palms, Southern Caribbean
Introduction
Sabal Adans.—the palmetto—is a New World genus with 17 recognized species (Zona, 1990, Goldman et al. 2012,
Griffith et al. 2017). Boldingh’s Florae (1913, 1914) did not include any Sabal in the Leeward Antilles. The first
collection of Sabal on these islands (M. Arnoldo 1030, U!) was made in 1948 on Curaçao, and thereafter Stoffers (1956)
wrote of “an unidentified species of Sabal” on both Curaçao and Bonaire. More than two decades later, a dedicated
and detailed study of these palms on both islands (Winkelman, 1979) considered them endemic, but continued to list
them as “Sabal spec.”
Despite being a prominent, emergent feature of the Bonaire vegetation, review of herbaria suggests that the native
palm on Bonaire was not collected until 2017 (Griffith 392, NY!). Conservation concern over the native Bonaire palm
population—first mentioned by Winkelman (1979), and continued through de Freitas et al. (2005) and Griffith et al.
(2017)—prompted further study of these little-known plants. Following in the steps of Winkelman’s work, a detailed re-
assessment of the palms on both Bonaire and Curaçao was conducted, mapping and documenting every native palm on
both islands (de Freitas et al. 2019), comparing these data to the record from 40 years prior. Significant morphological,
anatomical, and ecological differences were noted during the course of both the 1979 and 2018 surveys: the palms
on Bonaire share a number of morphologically cohesive features not seen elsewhere, and are also distinct from Sabal
antillensis M.P.Griff. (2017:56) on Curacao. We therefore describe the Sabal on Bonaire as a new species.
Taxonomic Treatment
Sabal lougheediana M.P.Griff. & Coolen, sp. nov. (Figures 1, 2, 3A, 4A, 5A).
Type:—BONAIRE. Lima, limestone terrace pavement west of Lac Bay, north of the solar salt works, and south of Kaya Rudolph Statius
von Eps. 5 m elev., 12° 6’ 1.098” N, 68° 15’ 30.603” W, 11 January 2017, Griffith 392 (holotype NY!, isotype FTG!).
Diagnosis:—This new species is most similar to Sabal antillensis in leaf morphology and inflorescence structure, but
differs by the much taller overall height (7 m vs. 5 m) and more slender-trunked (less than 40 cm vs. greater than 40
cm) habit, the conspicuous, textured trunk scars, the uniformly erect leaf segments unlike the pendescent segments in
S. antillensis, and the more frequently vascularized fiber bundles.
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FIGURE 1. Sabal lougheediana (illustration: Barros). A. Habit. B. Detail of leaf scar. C. Leaf.
Habit as a solitary palm, overall height to 7 m, with a compact crown of leaves, mostly ascending from the
trunk axis, and inflorescences held within and mostly occluded by the crown of leaves.
Trunk to 5.5 m high, 30–
37 cm diameter at widest point, gently narrowing near the crown, with prominent regular raised leaf scars (Figure
1B), holding up to 35 leaves. Leaf 120 to 200 cm long overall (longer in immature plants), strongly costapalmate,
grass-green, the palman strongly sinuous with more than one arch when viewed from the side, filiferous between the
leaflets. Petiole half or less of the total leaf length, less than 1 m, often 60–100 cm long, up to 6 cm wide, 2 cm thick,
the proximal portion split to nearly 35% of its length, with papyraceous ligules to 22 cm long and 5 cm wide, persistent
on newest leaves and rarely seen on older leaves. Hastula adaxial, acute, 10 to 17 cm long. Costa linear, 30–55 cm
long. Leaf segments up to 80, strongly induplicate at insertion to hastula and proximally undivided for up to 25% of
their length, with the apex divided for up to 35% of the segment length. Basal leaf segment 45–70 cm long hastula to
tip, up to 1.8 cm wide. Median leaf segment to 90 cm long, 5 cm wide, undivided up to 50% of its length. Apical leaf
segment to 70 cm long, 1.8 cm wide. Inflorescence arcuate, held within the crown of leaves and not pendant below it,
very rarely exserted beyond the leaf tips, mostly occluded by the foliage unless senescent, branched to three orders,
to 150 cm long. Peduncle proximally to 2 cm wide and 1 cm thick with an average of 5 sheathing bracts. First order
branches up to 15. Flowers sessile, 3–4.5 mm long, bisexual. Sepals 3, green, glabrous, tubular to cupulate, 2–3 mm
long, 2 mm wide. Petals 3, glabrous, white, obovate, 1.2–1.5 mm long, anthers 1–1.2 mm long, cream white to pale
SABAL LOUGHEEDIANA Phytotaxa 420 (2) © 2019 Magnolia Press • 97
yellow, style 1.4–1.5 mm long, 0.5 mm wide. Fruit glabrous, maturing to black, spherical, 9–12 mm high, 11–13 mm
wide. Seed oblate-spherical to slightly pyriform, brown to black, 5–8 mm high, 7–11 mm wide.
Distribution:—This species is currently limited to a very small range on the island of Bonaire (de Frietas et al.
2019) in the Southern Caribbean. The plants are found in the southern part of the island (Lima), west of Lac Bay and
north of the solar salt factory.
Habitat:—The plants are found in the Coccoloba–Melocactus Middle Terrace landscape type (de Freitas et
al. 2005), on flat limestone pavements, at elevations near 5 m. Vegetation cover in the range of S. lougheediana is very
sparse, and there is evidence that the current vegetation is greatly reduced from its potential density via introduced
herbivores (Coolen, 2015; Roberts et al. 2018).
Etymology:—The name honors Dr. Lin Lougheed, author, explorer, and patron of botanic gardens.
Common Names:—The plant is called Sabalpalm on Bonaire. We also propose an additional common name
“Bonaire Palm” to highlight its single-island endemism, and distinguish from its nearest geographic neighbor on
Curaçao also called Sabalpalm.
FIGURE 2. Sabal lougheediana, Bonaire, showing uniformly erect leaf segments and infructesence (white arrow) occluded by foliage
(photograph: Coolen).
Conservation Status:—Under the IUCN (2012) Red List criteria, Sabal lougheediana is considered Critically
Endangered (criteria B1ab(v), B2ab(v), C2a(ii), D), owing to its single, very restricted population of very few mature
individuals. Complete survey in 2018 located only 25 reproductively mature palms in the wild (de Freitas et al.,
2019), compared to 31 adults located during the Winkelman (1979) survey. Furthermore, the range of these palms
fell from near 5 km2 to less than 1 km2 over the same period. Winkelman detailed an extractive harvest of these palm
leaves with over a dozen individuals—at least 40% of the mature population—completely defoliated and showing
cuts on the trunks. Extant palms in 2018 still show these “steps” (Figure 4A) to facilitate climbing, which may date
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to Winkelman’s era. However, no palms in 2018 showed signs of cut leaves. A single dead palm was noted during
recent field survey, but the loss of this single plant represents 4% of the total reproductive population. Very limited
recruitment of seedlings into more mature palms—likely due to herbivore pressure—suggests that the population will
continue to decline without intervention (de Freitas et al. 2019).
De Freitas
et al. (2019) presented recommendations to improve the conservation status of this highly imperiled
island endemic, primarily dependent upon excluding herbivores from the very limited native range. Cultivation of
Bonaire Palm in offsite reserves and other managed landscapes on Bonaire and elsewhere is also essential to assure
against extinction, given the small number and tiny range of extant wild plants.
FIGURE 3. Comparison of habit and leaf segments of Sabal lougheediana and S. antillensis (photographs: Griffith). A. Sabal lougheediana
showing typical slender trunk and erect leaf segments, Bonaire; overall height of this plant is just over 7m. B. Sabal antillensis showing
pachycaulous trunks and pendescent leaf segments, Christoffelpark, Curaçao; overall heights of these plants are 4–5m.
Discussion:—The leaf, leaflet anatomy, inflorescence, flowers and seeds all place this species in Sabal, and
these plants were once considered close to Sabal causiarum Beccari (1907:71), as reviewed in Griffith et al. (2017).
As detailed above, a record of the indigenous Bonaire Palm exists in the literature for over sixty years, yet apparently
no specimen was collected before 2017. Sabal lougheediana appears most similar to S. antillensis, also described in
2017; until now S. antillensis applied to palms from both Curaçao and Bonaire. Winkelman (1979) first noted the much
taller height of the Bonaire palms (Figure 3). The pronounced stem thickening seen in S. antillensisis is also not present
in S. lougheediana (Figure 3). S. lougheediana shows distinctive persistent raised leaf scars that do not appear on S.
antillensis (Figure 4). Both species show a characteristicly dense crown resulting from short petiole length relative
to lamina length, but also show a difference in foliage, with sharply erect “spiky” leaf segments distinctive for
S.
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lougheediana, and a more pendulous, flexible leaf segment habit in S. antillensis (Figure 3). Separating Bonaire’s S.
lougheediana from the previous broader circumscription of S. antillensis also tightens the concept of S. antillensis to
solely comprise the short, stout palms of western Christoffelberg.
Anatomical differences also support distinction between Sabal lougheediana and S. antillensis. (Figure 5). In leaflet
transection, S. antillensis shows a characteristic alternation between vascularized fiber bundles and unvascularized
fiber strands (Griffith et al. 2017). S. lougheediana instead shows more frequent large vascularized fiber bundles
without consistent intercalary, smaller unvascularized fiber bundles. This results in a greater density of vascularized
fiber bundles per width of lamina in S. lougheediana than in S. antillensis, and perhaps this anatomy supports the more
rigid leaflet habit in S. lougheediana.
FIGURE 4. Comparison of trunk leaf scars of Sabal lougheediana and S. antillensis (photographs: Griffith) A. Sabal lougheediana
showing typical conspicuous regular leaf scars (black arrows), presenting as linear rows of small (< 10mm) protuberances, Bonaire. This
distinctive character is observed on all trunked plants on Bonaire. Note also the carved “steps” (white arrows) originally observed by
Winkleman (1979). B. Sabal antillensis showing typical annular leaf scars with no raised texture, Christoffelpark, Curaçao.
Beyond the structural differences that separate these two species, they are also separated by 100 km of open water
and a mountain ridge, and occur in very different habitats. As noted above, Sabal lougheediana grows on limestone
flats near sea level, while S. antillensis grows on cherty mudstone hills only above 140m elevation. Overall vegetation
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100 • Phytotaxa 420 (2) © 2019 Magnolia Press
type differs sharply between these habitats (Beers et al. 1997, de Freitas et al. 2005). Conservation status also differs
between these two taxa. The S. antillensis population is trending upward as a result of conservation management, while
S. lougheediana is declining (de Freitas et al. 2019).
Given the very significant differences in morphology, anatomy, habitat, ecology, and geography detailed above,
recognizing Sabal lougheediana as separate from S. antillensis best characterizes both the distinctiveness of each
taxon, as well as the morphological cohesiveness of each. In addition to improved taxonomic clarity, recognition of
two separate taxa may further galvanize conservation action for these iconic plants.
Diagnostic key to the Sabal of the Leeward Antilles
1 Plants to 7 m overall height; trunk diameters 40 cm or less, showing prominent leaf scars of raised protuberances; with uniformly
erect leaf segments; Bonaire .................................................................................................................................Sabal lougheediana
1* Plants to 5 m overall height; mature trunk diameters above 40 cm at widest point, showing faint annular leaf scars with no texture,
or no leaf scars, with pendescent leaf segments; Curaçao .........................................................................................Sabal antillensis
FIGURE 5. Leaf segment lamina transections of Sabal lougheediana and S. antillensis, methods follow Noblick (2013), scale bar = 0.25
mm (micrographs: Noblick). A. Sabal lougheediana (Griffith 392, NY!). B. Sabal antillensis (Griffith 385, NY!). A shows secondary
minor veins with few intercalary fiber bundles, while B shows adaxial fiber bundles intercalated between all secondary minor veins.
Acknowledgements
The authors thank: Directorate of Spatial Planning and Development, Section Environment and Nature, Government
of the Public Entity of Bonaire for permission to study, collect and export specimens on Bonaire; USDA for permission
to import specimens (Permits PCIP-16-00418 and P37-16-00941); Johan van Blerk, Caren Eckrich, Peter Montanus,
Lauren Schmalz and Frank van Slobbe for information, advice, guidance, and discussion; Curators of FTG, NY, and U
for access; two anonymous reviewers and Editor William Baker for very constructive edits; and the Plant Exploration
Fund for supporting this project.
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