Dispersal assembly of rain forest tree communities across the Amazon basin

This is the author accepted manuscript. The final version is available from National Academy of Sciences via the DOI in this record.We investigate patterns of historical assembly of tree communities across Amazonia using a newly developed phylogeny for the species-rich neotropical tree genus Inga. We compare our results with those for three other ecologically important, diverse, and abundant Amazonian tree lineages, Swartzia, Protieae, and Guatteria. Our analyses using phylogenetic diversity metrics demonstrate a clear lack of geographic phylogenetic structure, and show that local communities of Inga and regional communities of all four lineages are assembled by dispersal across Amazonia. The importance of dispersal in the biogeography of Inga and other tree genera in Amazonian and Guianan rain forests suggests that speciation is not driven by vicariance, and that allopatric isolation following dispersal may be involved in the speciation process. A clear implication of these results is that over evolutionary timescales, the metacommunity for any local or regional tree community in the Amazon is the entire Amazon basin.We thank Terry Pennington for help with Inga species identification, and Paul Fine and Hans ter Steege for helpful comments and discussions. R.T.P. thanks the Leverhulme Trust for Study Abroad Fellowship RF/2/2006/0142, which supported DNA sequencing and the development of ideas in this paper in the M.L. laboratory. K.G.D., P.D.C., and T.A.K. thank the Peruvian Ministry of Agriculture for permission to conduct research in Peru, and the Nouragues Research Station for grants to fund fieldwork in French Guiana (2009 Call for Research at Nouragues). K.G.D. and R.T.P. acknowledge the Natural Environment Research Council for Support via NE/I028122/1. Field research by P.D.C. and T.A.K. was supported by National Science Foundation Grants DEB-0640630 and Dimensions 1125733. A.D.T. is supported by Natural Environment Research Council Fellowship NE/L011336/1

Unearthing a Forgotten Legacy of 20th Century Floristics: the Collection of Taiwanese Plant Specimens in the Herbarium of the Academy of Natural Sciences (PH)

The flora of Taiwan, comprising more than 4,400 vascular plant species, is one of the best studied of Asian floras. Herbarium collections of Taiwanese plants document the island's plant diversity and serve as important reference material for botanists and conservationists. Collections made during the Japanese colonial period in Taiwan (1895–1945) are of special interest in that they mark the first attempt at a truly comprehensive botanical inventory of the island. Unfortunately, these early collections are not widely distributed and are often in poor condition in Taiwanese herbaria. As such, the existence of a large, under-documented collection of Taiwanese plants in the Herbarium of the Academy of Natural Sciences-Philadelphia (PH), with many specimens collected during the Japanese colonial period, is likely to be of interest to the botanical and conservation communities in Taiwan and elsewhere. To determine the size and taxonomic scope of the collection, its historical and taxonomic importance, and the historical details of its assembly, a systematic survey was conducted in which all of the Taiwanese material was separated from the general collection at PH. Specimen label data were recorded from a phylogenetically diverse selection of plant families. The Academy’s collection was found to contain about 6,260 Taiwanese plant specimens, including representatives of 150 of the 198 seed plant families that occur in Taiwan. Within selected families, broad taxonomic representation of Taiwanese genera (33%–100%) and species (15%–100%) was encountered. Specimens in the collection were gathered between 1861 and 1977, with 90% the specimens dating to the periods 1905 (9%), 1929–1935 (28%), and 1955–1973 (53%). Over 60 collectors are represented. A preliminary search of the taxonomic literature indicates that significant type material is contained within the collection. Historical research revealed that most of the collection was assembled in Philadelphia by Hui-Lin Li (1911–2002), former professor of botany at the University of Pennsylvania and important figure in the history of floristic research in Taiwan

Alexa duckeana G. S. da Silva & Mansano. A. Flowering 2023, sp. nov.

<i>Alexa duckeana</i> G.S. da Silva & Mansano, <i>sp</i>. <i>nov</i>. (Figs. 1–2) <p> <b>Type</b>:— BRAZIL. Pará, Marabá, São Felix, Estrada Brioflora, Entrocamento para igreja do Céu de Marabá. Área de mata de terra Firme fragmentada, 5°14’38’’S, 49°5’27’’W, 29 August 2022, <i>G.S. Silva 528</i> (Holotype: RB! [RB01472969], isotypes: UEC!, INPA!, IAN!).</p> <p> <b>Diagnosis:</b> — <i>Alexa duckeana</i> is distinguished from all other species in the genus by the following combination of characteristics: extrafloral glands absent; leaflets more than 10 cm long or rarely 8–10 cm long, pubescent on the abaxial side; inflorescences less than 14 cm long, bearing 30–40 flowers per raceme; actinomorphic, with all petals reflexed, pedicel less than 3 cm long, straight; nectariferous disc dark brown to red.</p> <p> <b>Trees</b> 6–20 m tall; trunk 20–30 cm in diameter; bark gray to blackish, coarse, peeling, displaying horizontal lines along the length of the trunk, inner bark yellowish to cream; sapwood yellow, with translucent watery exudate vaguely smelling of watermelon; branches terete, glabrous. <b>Leaves</b> imparipinnate, alternate, pulvinate, (20–) 25–30 cm long, lacking multicellular nectaries; <b>rachis</b> (12–) 14–16 cm long, terete, glabrous to pubescent; <b>petiole</b> 3.0–5.0(–6.0) cm long, terete, glabrous to pubescent; <b>Leaflets</b> (5–)7–9(–11), alternate to subopposite, rarely opposite, discolorous, (8–)9–12(–13) × (3.0–)3.5–5.2(–6.0) cm, the terminal leaflet and distal lateral leaflets larger than the basal ones, the petiolule 0.8–1.0 cm long, terete, glabrous, the blade elliptic to lanceolate, obtuse to acute at base, acute to shortacuminate at apex, entire-margined, the adaxial face glossy, glabrous, the abaxial face matte, pubescent, venation camptodromous, impressed adaxially, with the central and secondary veins prominent abaxially, the tertiary veins inconspicuous. <b>Inflorescence</b> a terminal raceme, rarely axillary and bifurcated at the base, 9–12(–13) cm long, with 30–40 flowers, disposed in a congested way; axis densely pubescent to velutinous, rarely lenticellate, terete, with the peduncle 5.0- 6.5 cm long; <b>bracts</b> ovate, rounded at apex, 0.2–0.3 cm long, pubescent to velutinous; pedicels terete 2.0–3.0 cm long, velutinous; <b>bracteoles</b> ovate to triangular, 0.2–0.3 cm long, pubescent to velutinous. <b>Flowers</b> 4.0– 4.5 cm long excluding the pedicel; hypanthium campanulate, coriaceous, 0.4–0.5 cm long, densely dark brown velutinous externally, glabrous internally with a brown to dark red hypanthial nectary; fragrance noticeable, similar to ripe melon or watermelon; <b>calyx</b> dark brown, campanulate, 4- or 5-lobed, coriaceous, 2.5–3.5 cm long, densely velutinous externally, glabrous internally, the lobes 0.1–0.2 cm long; <b>corolla</b> white, actinomorphic, with all petals reflexed, the vexillum obovate, chartaceous, slender, 3.0–3.5 × 1.5–2.5 cm, densely pubescent externally, glabrous internally, rounded at apex, smooth-margined, the wing petals narrowly obovate to oblong or spatulate, chartaceous, 3.0–3.5 × 1.0– 1.3 cm, densely pubescent externally, glabrous internally, acute to rounded at apex, smooth-margined; keel petals lanceolate, chartaceous, 2.5–2.8 × 0.8–1.0 cm, densely pubescent externally, glabrous internally, rounded at apex, smooth-margined; <b>androecium</b> more or less actinomorphic at anthesis, formed by 10 stamens, the stamens (3.0–)3.5–4.0 cm long, the anthers 0.8–1.0(–1.2) × 0.1–0.15 cm; <b>gynoecium</b> 5.0–6.0 cm long, the gynophore glabrous, 1.0– 1.5 cm long, the ovary proper densely yellowish-velutinous, 2.0–2.5 × 0.35–0.45 cm, the style glabrous, slightly curved distally, 0.6–1.2(–1.5) cm long. <b>Legume</b> dehiscent, woody, (14–)15–19 × 2.5–3.5 cm, with the calyx persistent, generally acute at base and apex, laterally compressed to slightly inflated, densely brown- or reddish-brown velutinous. <b>Seeds</b> three per fruit, ovoid or ellipsoid, 2.0–2.5 × 1.8–2.3 cm, glabrous, the seed coat smooth, dark brown. Figures 1–2.</p> <p> <b>Etymology</b>: The specific epithet honors the botanist Adolpho Ducke (1876–1959), one of the foremost authorities on the Amazonian flora in general and Amazonian leguminous trees in particular during the first half of the twentieth century. Ducke published 133 papers, mainly on Leguminosae, and described 762 new species and 45 new genera (Archer, 1962).</p> <p> <b>Distribution and Habitat</b>: <i>Alexa duckeana</i> is known only from the middle drainages of the Xingu and Tocantins Rivers in the southeastern portion of the Brazilian state of Pará (Fig. 3), where it has been recorded in the municipalities of Marabá, Nova Ipixuna, and Altamira (89–205 m elevational range). It is unclear if an apparent disjunction between the westernmost record and those further east is meaningful since the intervening area has been little collected.Although it has not been recorded outside Pará, the species might be expected from parts of the states Maranhão and/or Tocantins adjacent to the easternmost records. The species has been found most often in fragments of well-drained Amazonian “terra firme” forest, sometimes in disturbed forest edges or along roadsides. A collection from the Flona de Carajás (<i>U.N. Maciel 808</i>) was made in a savanna on ferruginous substrates. The vegetation inhabited by <i>A. duckeana</i> typically has a canopy of 10–25 meters height, with the predominant tree species being <i>Bertholletia excelsa</i> Bonpland (1807: 122), <i>Manilkara elata</i> (Allemão ex Miquel 1863: 42) Monachino (1952: 101), <i>Lecythis pisonis</i> Cambessèdes (1833: 377) and <i>Carapa guianensis</i> Aublet (1775: 32). The most common cohabiting Leguminosae are trees of <i>Dipteryx</i> Schreber (1791: 485), <i>Inga</i> Miller (1754: without pagination), <i>Hymenaea</i> Linnaeus (1753: 1192), <i>Parkia</i> Brown (1826: 234) and <i>Tachigali</i> Aublet (1775: 372).</p> <p> The general region of occurrence in southeastern Amazonia falls within the transition zone between the rainforest and Cerrado biomes. The soils in the region where the species occurs are classified into red-yellow latosol, red-yellow podzolic, hydromorphic quartz sands, alluvial soils, and litholic soils, with a predominance of red podzolic soil (Miranda <i>et al</i>. 2021). According to Koppen & Geiger (1928) the climate is equatorial, hot, and humid, with average monthly temperatures between 22.9°C and 32°C, and an annual average of 26°C. Relative air humidity ranges from 73% to 93%, with annual precipitation around 1,976 mm (Miranda 2019). The wettest period begins in January and ends in March, and the driest period runs from July to September (Raiol 2010). The area of occurrence of <i>A. duckeana</i> is strongly influenced by the hydrographic region of Tocantins /Araguaia, constituted by the hydrographic basin of the Tocantins River to its mouth in the Atlantic Ocean, having as main rivers associated with the region the Itacaiunas, Sororó, Tocantins and Araguaia (Brazil 2012). A single record came from the drainage of the Xingu River, well to the southwest of the other records (<i>S.A. da M. Souza 371</i>).</p> <p> <b>Phenology</b>: <i>Alexa duckeana</i> has been collected with flowers from August to November, corresponding to the dry season in southeastern Amazonia, and fruits from September to April, corresponding to the end of the dry season and the beginning of the rainy season.</p> <p> <b>Conservation Status</b>: Following the IUCN Standards and Petitions Committee (2019), this species can be classified as Endangered (EN), meeting criterion B2ab(i, ii, iii). GeoCAT analyses indicated an EOO of 17,640 km 2, placing the species in the category of Vulnerable (VU), and an AOO of 36 km 2, in the category Endangered (EN). When the result suggested by the EOO differs from that indicated by the AOO, the IUCN recommends the adoption of the highest threat category according to the precautionary principle (PP). Only four locations are known for the species, and we project a continuous decline in extent of occurrence, area of occupancy, and area and quality of habitat, due to observed frequent fire, cattle grazing, and agricultural activities. The species does not occur in any protected areas.</p> <p> Considering the territorial dynamics of the places where populations were recorded, deforestation is a growing problem due to integrationist development projects. Livestock and its tax incentives in the past are some of the main vectors that have provided the increase and permanence of deforestation, responsible for profound transformations in the landscape of the Mesoregion. This activity is characterized by the continuous expansion of deforested areas, being directly related to logging activity, burning to clear pasture, and the conversion of areas to mechanized agriculture in some places (Miranda 2019, Silva <i>et al</i>. 2019, Miranda <i>et al</i>. 2021).</p> <p> <b>Taxonomic notes</b>: Among the species of <i>Alexa</i>, <i>A. duckeana</i> is most similar to <i>A. grandiflora</i>. The two species share leaves with 5–9 elliptical leaflets, with the adaxial face glabrous, the base obtuse to acute, and the apex acute to short acuminate, a velutinous calyx, abaxially pubescent petals, and a velutinous ovary. Some collections of <i>A. duckeana</i> (<i>Maciel 808</i>, <i>de Cristo & Landim 33</i>, and <i>Ruschell 76</i> and <i>77</i>) were previously determined to be <i>A. grandiflora</i>. The new species differs from <i>A. grandiflora</i> in the absence of extrafloral glands on the pedicels and leaflets, the presence of pubescence on the leaflets, by a shorter, more congested inflorescence with more numerous flowers, shorter pedicels, a differently shaped calyx and apex of the vexillum, and longer stamens, which due to the more open calyx are less congested (Table1; compare Figs. 2 and 4).</p> <p> The petals of <i>A. duckeana</i> are thinner and less-fleshy compared to <i>A. grandiflora.</i> In mature forests, <i>A. grandiflora</i> may reach 40 m tall, whereas <i>A. duckeana</i> is not known to exceed 20 m tall. It’s worth noting that this difference might be influenced by environmental rather than genetic factors, given that the forest canopy tends to be lower in the rainforest/Cerrado transitional region where <i>A. duckeana</i> is found, as opposed to the usually wetter terra-firme forests occupied by <i>A. grandiflora</i>. The new species also resembles <i>A. wachenheimii</i>, a commonly encountered species in Guyana, French Guiana, and Suriname, with only one record in Brazil (<i>Fróes 25984</i>), from Amapá. The two species differ in pedicel length, floral symmetry, calyx and ovary length and in the shape of the apex of the vexillum (Table 1).</p> <p> Identification Key to the species of the <i>Alexa</i> that occur in Brazil</p> <p>1. Bracteoles linear, 0.5–1.5 cm long; vexillum 5–7 cm long, 0.5–1.0 cm wide...................................................................................2</p> <p>- Bracteoles ovate to triangular, 0.1–0.4 cm long, vexillum 2–4.5 cm long, 1.5–2.5 cm wide............................................................3</p> <p> 2. Abaxial surface of the leaflets pubescent to velutinous; bracteoles lacking glands on the adaxial surface; vexillum velutinous on the abaxial surface........................................................................................................................................... <i>A. bauhiniiflora</i> Ducke</p> <p> - Abaxial surface of the leaflets glabrous to hirsute; bracteoles with glands on the adaxial surface; vexillum glabrous on the abaxial surface.......................................................................................................................................................... <i>A. canaracunensis</i> Pittier</p> <p> 3. Leaflets velutinous on the abaxial surface, the tertiary venation clearly evident; flowers with more than 10 stamens..................................................................................................................................................................... <i>A. confusa</i> Pittier</p> <p>- Leaflets glabrous to pubescent on the abaxial surface; tertiary venation inconspicuous; flowers with only 10 stamens..................4</p> <p> 4. Calyx 1.5–2.5 cm long, ovary 0.8–1.0 cm long; predominantly in extra-Brazilian Amazonia (Guyana, French Guiana, Suriname)....................................................................................................................................................................... <i>A. wachenheimii</i> Benoist</p> <p>- Calyx 2.5–3.5 cm long, ovary 2.0– 2.5 cm long, predominantly in the Brazilian Amazon................................................................5</p> <p> 5. Leaflets glabrous on the abaxial surface; extrafloral glands present at the base of pedicels and on the leaflet blades; flowers scattered on the inflorescence axis.................................................................................................................... <i>A. grandiflora</i> Ducke</p> <p> - Leaflets pubescent on the abaxial surface, extrafloral glands absent; flowers congested on the inflorescence axis........................................................................................................................................................................... <i>A. duckeana</i> G.S. da Silva & Mansano</p> <p> <b> <i>Additional Specimens Examined (Paratypes)</i>:— Brazil</b> . <b>Pará</b>: Marabá, São Felix, Loteamento Novo Progresso, 5°16´34.493´´S, 49°5´44.567´´W, 90 m, 6 Set 2022 (fl.), <i>G.S. Silva, C. Anjos & J. Neves 536</i> (RB), <i>G.S. Silva, C. Anjos & J. Neves 538</i> (RB); Parque Zoobotânico, 500 m após a entrada do Parque, 5°23´24.750´´S, 49°4´32.510´´W, 91 m, 2 Sep 2022 (fl.), <i>G.S. Silva, C. Anjos & J. Neves 530</i> (RB); São Felix, Chácara do seu Zé, 5°13´48.379´´S, 49°6´5.464´´W, 97 m, 4 Sep 2022 (fl.), <i>G.S. Silva, C. Anjos & J. Neves 533</i> (RB, INPA); Carajás, Serra Norte, Km 70 da Estrada de Ferro Carajás, 5°45´51.813´´S, 49°42´24.661´´W, 143 m, 13 Aug 1982 (fl.), <i>U.N. Maciel 808</i> (MG, INPA, NY); Fundação Zoobotânica de Marabá, Trilha Ecológica Hiram Bichara Júnior, 5°22´6.996´´S, 49°7´4.086´´W, 92 m, 28 Sep 2010 (fr.), <i>S.C. de Cristo & A. Landim 33</i> (INPA); Nova Ipixuna, Núcleo Maçaramduba 2, Projeto Agroextrativista, Praia Alta Pinheira, 4°55´15.997´´S, 49°4´36.842´´W, 109 m, 26 Oct 2022 (fr.), <i>A.R. Ruschell 76, 77</i> (IAN); Altamira, Rio Xingu. Picada da Topografia no largo do murici, à margem esquerda subindo o rio, 7°12´14.413´´S, 52°35´7.652´´W, 205 m, 18 Oct 1986 (fr.), <i>S.A. da M. Souza 371</i> (NY).</p>Published as part of <i>Silva, Guilherme Sousa Da, Torke, Benjamin M. & Mansano, Vidal De Freitas, 2023, Alexa duckeana (Leguminosae-Papilionoideae): a new species from the Brazilian Amazon, pp. 255-265 in Phytotaxa 629 (3)</i> on pages 257-262, DOI: 10.11646/phytotaxa.629.3.7, <a href="http://zenodo.org/record/10281745">http://zenodo.org/record/10281745</a&gt

FIGURE 3 in Alexa duckeana (Leguminosae-Papilionoideae): a new species from the Brazilian Amazon

FIGURE 3. Geographical distribution and habitat of Alexa duckeana. A. Map of geographic distribution of Alexa duckeana, Alexa grandiflora and Alexa wachenheimii in the Amazon. B–C. Habitat of Alexa duckeana. Photos: Jone Carlos Ferreira Neves Junior.Published as part of <i>Silva, Guilherme Sousa Da, Torke, Benjamin M. & Mansano, Vidal De Freitas, 2023, Alexa duckeana (Leguminosae-Papilionoideae): a new species from the Brazilian Amazon, pp. 255-265 in Phytotaxa 629 (3)</i> on page 260, DOI: 10.11646/phytotaxa.629.3.7, <a href="http://zenodo.org/record/10281745">http://zenodo.org/record/10281745</a&gt

FIGURE 1. Alexa duckeana G.S in Alexa duckeana (Leguminosae-Papilionoideae): a new species from the Brazilian Amazon

FIGURE 1. Alexa duckeana G.S. da Silva & Mansano. A. Flowering branch. B. Detail of leaflet blade base. C. Inflorescence with flowers in anthesis. D. Calyx with lobe details. E. Flower with the petals and stamens removed, showing the gynoecium. F. The external face of a petal. G. Stamen with detail of the filament insertion on the anther (dorsifixed). H. Gynoecium showing the indumentum of the ovary. I. Fruit demonstrating the persistent calyx. (A–E and I drawn from: Silva G.S. 528; F-H and J from: Silva G.S. 533). Illustrated by Marcus Falcão.Published as part of <i>Silva, Guilherme Sousa Da, Torke, Benjamin M. & Mansano, Vidal De Freitas, 2023, Alexa duckeana (Leguminosae-Papilionoideae): a new species from the Brazilian Amazon, pp. 255-265 in Phytotaxa 629 (3)</i> on page 258, DOI: 10.11646/phytotaxa.629.3.7, <a href="http://zenodo.org/record/10281745">http://zenodo.org/record/10281745</a&gt

On the “Cangaço” route: a new species of hymenaea (leguminosae) from the brazilian caatinga

A new species of Hymenaea from the Caatinga of northeastern Brazil is described and illustrated. H. cangaceira is morphologically similar to H. martiana and H. longifolia, and its geographical distribution overlaps those of both species; however, it differs in the combination of glabrous, ovate to broadly-elliptic leaflets, a glabrous ovary, and relatively short, cylindrical fruit. The new species is well represented in the herbaria of northeastern Brazil. An identification key is provided to distinguish it from other species of Hymenaea that occur in the Caatinga region723CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP563550/2010-4; 312766/2009-2E-26/111.581/20142010/52488-9Uma nova espécie de Hymenaea da Caatinga do Nordeste brasileiro é aqui descrita e ilustrada. H. cangaceira é morfologicamente similar às espécies H. martiana e H. longifolia e sua distribuição geográfica está sobrepostas as mesmas; contudo, difere na combinação dos folíolos glabros, ovados a largo-elípticos, ovário glabro e um fruto relativamente pequeno e cilíndrico. Esta nova espécie é bem representada nos herbários do nordeste do Brasil. Uma chave de identificação é fornecida para distinguir a presente espécie das demais que ocorrem na região da Caating

FIGURE 4 in A Taxonomic Revision of the Neotropical Genus Martiodendron (Fabaceae: Dialioideae)

FIGURE 4. Martiodendron elatum (Ducke) Gleason var. elatum. A. Trunk; B. Canopy tree over 40 meters tall; C. Trunk base with detail of buttresses; D. Detail of the bark; E. Detail of leaflets; F. Detail of the exsiccatae showing the standard number of 9 leaflets per leaf; G. Detail of flower buds; H. Detail of part of the inflorescence with flowers in anthesis; I. Branches with leaves and four terminal compound thyrsoids; J. Flower; K. Detail of the flower in lateral view without the perianth, showing the gynoecium and heteromorphic stamens, note the reduced size of the filaments; L. Large typical fruit with at least one strongly curved side. Image authors: A–E, G–H: Marcus Falcão; I–K: Cássio Toledo: Falcão, M.J. 212; F. Reflora: Ducke, A. 16479; L. Reflora: Ducke, A. 17062. Scale bar. A–C: 50 cm; D, I: 10 cm; E, G–H: 2 cm; F, L: 5 cm; J–K: 1 cm.Published as part of Falcão, Marcus José De Azevedo, Torke, Benjamin M., Garcia, Gabriel Santos, Silva, Guilherme Sousa Da & Mansano, Vidal De Freitas, 2023, A Taxonomic Revision of the Neotropical Genus Martiodendron (Fabaceae: Dialioideae), pp. 11-56 in Phytotaxa 578 (1) on page 28, DOI: 10.11646/phytotaxa.578.1.2, http://zenodo.org/record/751768

Martiodendron elatum var. elatum Gleason var. elatum

<i>Martiodendron elatum</i> (Ducke) Gleason var. <i>elatum</i> <p> <b>Diagnosis:</b> — <i>Martiodendron elatum</i> var. <i>elatum</i> differs from <i>M. elatum</i> var. <i>occidentale</i> by its (8–)9(–10), generally larger and wider leaflets, the terminal ones (6.5–)9–15(–17) × (2.2–) 3.5–5 cm, 2.4–3.2(–3.6) times longer than wide; sometimes unstable number of stamens, ranging from 5(–7), 0–5 staminodes; wider fruits [(4–) 6–8 cm wide and 1.8–2.6 times longer than wide], and more strongly curved fruits, with one or both sides generally curved, sometimes fruits weakly falcate (Figures 3–4).</p> <p> <b>Distribution, Habitat and Ecology:</b> —The variety is distributed in two areas, with an apparent significant disjunction between them, although parts of the intervening area remain poorly collected. The first area is in the south-central Brazilian Amazon, mainly in the mid to upper basin of the Tapajós River in southwestern Pará, but also in adjacent parts of southeastern Amazonas, in the municipality of Borba. Ducke (1948) indicated that it also occurs in the Serra do Parintins, near the town of Santa Julia in western Pará, just south of the Amazon River, but there are no specimens from this area. The second area of distribution is in the upper drainage of the Rio Negro in extreme northwestern Amazonas, Brazil, and southern Venezuela (Figure 15).</p> <p> Although Ducke (1922) indicated that this taxon was common on the banks of the upper Tapajós River, very few collections from the region exist, probably reflecting low collecting effort in the area. However, during a recent expedition in and around the Parque Nacional da Amazônia, we located only one individual along the Tapajós River. Moreover, the variety also seems uncommon in the northern distribution area; we have located only 14 specimens from Venezuela and northwestern Amazonas, Brazil, and only seven specimens from Pará and southeastern Amazonas. Before our expedition in 2020, the taxon had not been collected in Pará since 1952. Besides the two populations of <i>M. elatum</i> var. <i>elatum</i> appears to be geographically isolated, the southeastern population of <i>M. elatum</i> var. <i>elatum</i> and <i>M. elatum</i> var. <i>occidentale</i> have an almost continuous distribution south of the Amazon basin, with possible gene exchange still taking place between them (Figure 15).</p> <p> <b>Taxonomic Comments:</b> —Although the two populations of <i>M. elatum</i> var. <i>elatum</i> are apparently geographically isolated, one in Upper Rio Negro another in the southwest of Pará, no morphological variation was found between the two populations. Zimmerman <i>et al</i>. (2017) indicated that <i>M. elatum</i> has partial conation of stamens. However, we observed completely free stamens in almost all specimens; only rare anomalous flowers in two specimens of the variety <i>elatum</i> had two of the six or seven stamens deformed and fused. Koeppen & Iltis (1962) also stated the variable number of stamens in this variety. Although anomalous quantities of stamens (reaching sometimes seven and with a variable number of staminodes) are, indeed, only found in this taxon among all others in the genus, we could observe here, with a greater number of specimens analyzed, that even within <i>M. elatum</i> var. <i>elatum</i>, this character is rare and the majority of specimens and the majority of flowers in each specimen present five stamens.</p> <p> <b>Additional Specimens Examined (23 specimens:)</b> — BRAZIL: <b>Amazonas:</b> Borba: BR230, estrada Transamazonica, 1–5 km upstream from Sucunduri, 6°50’S 59°0’W. Tree, 5 m, 9-V-1985, <i>Henderson, A</i>. 418 (F; INPA; K; MG; NY; US); Santa Isabel do Rio Negro: acampamento da cachoeira do rio Tucano. Árvore 12 m × 15 cm, 23-VIII-2002, <i>Silva, J. B. F.</i> 1123 (IAN); Barcelos: environs of the Yanomami village of Watoriketheri, 62°49’W 1°31’N. Árvore, 40 m + × 80 cm, VIII-1994, <i>Milliken, W.</i> 2054 (K); Árvore, 20 m × 25 cm VIII-1994, <i>Milliken, W.</i> 2076 (K); Cuiufite, rio Demeni. Árvore, 18 m, 17-X-1952, <i>Fróes, R. L.</i> 28977 (IAN; NY); <b>Pará:</b> Alto Rio Tapajós, Itaituba, Parque Nacional da Amazônia. Árvore, 35-40 m, 27-I-2020, <i>Falcão, M. J</i>. 212 (RB; NY; HSTM); <i>Falcão, M. J</i>. 214 (RB; NY; HSTM); Vila Nova, perto da cachoeira do “Chacor ã o”. Árvore, 25 m × 30 cm, 22-I-1952, <i>Pires, J. M.</i> 4003 (IAN; INPA; NY; P); margem do Tapajoz, region des cataractis inferiores. 11-IX-1915, <i>Ducke, A. s.n</i>. MG16479 (MG; US); 5-II-1917, <i>Ducke, A</i>. <i>s.n</i>. MG16724 (MG; US); 25-VI-1918, <i>Ducke, A. s.n</i>. MG17062 (MG; P; R; US); “Boa Vista”. Tree, VIII-1932, <i>Capucho</i> 477 (F; IAN); Boa Vista on the Tapajós River. V-VI-1929, <i>Dahlgren, B. E.</i> 121 (F; US); VENEZUELA: <b>Amazonas:</b> rio Ugueto. 12-X-1951, <i>Croizat, L</i>. 826 (F; NY); 2°N 64°30’W. 10-X-1951, <i>Croizat, L</i>. 820 (NY); selvas pluviales del rio Pamoni, afluente del alto Casiquiare, 2°48’N 65°57’W. Arbol, 30 m, 24-IX-- 5- X-1987, <i>Stergios, B</i>. 11434 (MO; NY); Atabapo: caño Jayuwapuey, afluente del rio Ocano, 3°4’N 64°40’W. Arbol, 20 m, I-1990, <i>Fernandez, A.</i> 6770 (MO; NY); en la base de cuerpo circular en alto Orinoco, 2°17’N 63°47’ W. Arbol, 40 m × 160 cm CAP, X-1991, <i>Marin, E.</i> 1771 (MO; NY); 5 km al norte de la desembocadura del Rio Orinoquito en el Rio Orinoco, 2°24’N 64°24’W. Arbol de 36 m x 140 cm CAP. <i>Marin, E.</i> 1635 (NY); Tayari. 4-X-1975, <i>Lissot, J. s.n</i>. US 2775339 (US); rio Ocamo, entre los Yanomami. 1978, <i>Fuentes, E.</i> 1083 (US); Rio Metacuni, frente N °5 Pica N °4. Selvas riberenas y de banco, abajo del Salto “Wâniti ma”. Arbol de 25-30 m, 23-I-1990. <i>Stergios, B.</i> 14132 (NY); Rio Negro, 2°16’N 63° 31’W. Arbol 30 m, 120 cm CAP, X-1991, <i>Chaviel, A</i>. 43 (NY).</p>Published as part of <i>Falcão, Marcus José De Azevedo, Torke, Benjamin M., Garcia, Gabriel Santos, Silva, Guilherme Sousa Da & Mansano, Vidal De Freitas, 2023, A Taxonomic Revision of the Neotropical Genus Martiodendron (Fabaceae: Dialioideae), pp. 11-56 in Phytotaxa 578 (1)</i> on page 31, DOI: 10.11646/phytotaxa.578.1.2, <a href="http://zenodo.org/record/7517688">http://zenodo.org/record/7517688</a&gt