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Hydrochorea gonggrijpii (Kleinhoonte) Barneby & J.W. Grimes A branch with inflorescences B, C extra-floral nectaries D peripheral flower bud E peripheral flower F terminal flower bud G terminal flower H leaflet. A–H from Fróes 28045. Illustration by Alex Pinheiro.
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Hydrochorea and Balizia were established to accommodate four and three species, respectively, that were previously included in different ingoid genera, based primarily on differences in fruit morphology. Both genera have Amazonia as their centre of diversity, extending to Central America and the Brazilian Atlantic Rainforest. Previous phylogenetic...
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... Arthrosamanea will be fundamentally characterized by 16-celled polyads. This seems likely for two reasons: (1) all taxa whose pollen has been studied in the genera Hydrochorea Barneby & J.W. Grimes (sensu Soares et al. 2022), Jupunba Britton & Rose and Punjuba Britton & Rose (i.e. the "Abarema alliance" of Barneby and Grimes 1996), that together form the sister-group of Albizia sect. Arthrosamanea in the Jupunba clade (sensu Koenen et al. 2020;Ringelberg et al. 2022), consistently have 16-celled polyads (Guinet and Grimes 1997); (2) all species included by Barneby and Grimes (1996) in Albizia sect. ...
Recent phylogenomic analyses placed Albiziacarbonaria Britton as the sister-group of the two currently known species of Pseudosamanea Harms, clearly outside AlbiziasectionArthrosamanea (Britton & Rose) Barneby & J.W. Grimes where it has until now been included. Its morphological similarities to Pseudosamanea are discussed, including characteristics of the polyad, and it is concluded that the species is compatible with the generic description of that genus except for its much more finely divided leaves with smaller leaflets, and its smaller flowers and fruits. Since these are merely quantitative differences, the species can readily be accommodated in Pseudosamanea. The new combination Pseudosamaneacarbonaria (Britton) E.J.M. Koenen is made, and a diagnosis distinguishing it from the other two species of Pseudosamanea is presented.
... Similarly, it also seems clear that septate lomentiform fruits with valves readily cracking between the seeds and breaking up into one-seeded articles have also evolved multiple times (Fig. 13), often within genera (e.g. Capuron 1970;Aviles et al. 2022;Koenen 2022a;Soares et al. 2022) associated with hydrochory in species adapted to grow in seasonally inundated habitats and this has impacted on generic delimitation. For example, Barneby and Grimes (1996) separated their newly-segregated genera Balizia and Hydrochorea Barneby & J.W. Grimes on fruit types, yet it is clear that Hydrochorea is nested within a paraphyletic Balizia ( Fig. 9; Soares et al. 2022) and that the distinctive lomentiform fruits of Hydrochorea are derived from non-lomentiform indehiscent or follicularly dehiscent pods within this clade (Aviles et al. 2022;Soares et al. 2022). ...
... Capuron 1970;Aviles et al. 2022;Koenen 2022a;Soares et al. 2022) associated with hydrochory in species adapted to grow in seasonally inundated habitats and this has impacted on generic delimitation. For example, Barneby and Grimes (1996) separated their newly-segregated genera Balizia and Hydrochorea Barneby & J.W. Grimes on fruit types, yet it is clear that Hydrochorea is nested within a paraphyletic Balizia ( Fig. 9; Soares et al. 2022) and that the distinctive lomentiform fruits of Hydrochorea are derived from non-lomentiform indehiscent or follicularly dehiscent pods within this clade (Aviles et al. 2022;Soares et al. 2022). This prevalence of homoplasy associated with fruit types across the mimosoid clade matches that seen across other legume clades (e.g. in subfamily Papilionoideae ;Geesink 1984;Hu et al. 2000;Lavin et al. 2001) suggesting that the late developmental stages of the legume pod and associated legume seed dispersal syndromes are prone to convergent evolution, as previously suggested (Geesink 1984;Hu et al. 2000). ...
... Capuron 1970;Aviles et al. 2022;Koenen 2022a;Soares et al. 2022) associated with hydrochory in species adapted to grow in seasonally inundated habitats and this has impacted on generic delimitation. For example, Barneby and Grimes (1996) separated their newly-segregated genera Balizia and Hydrochorea Barneby & J.W. Grimes on fruit types, yet it is clear that Hydrochorea is nested within a paraphyletic Balizia ( Fig. 9; Soares et al. 2022) and that the distinctive lomentiform fruits of Hydrochorea are derived from non-lomentiform indehiscent or follicularly dehiscent pods within this clade (Aviles et al. 2022;Soares et al. 2022). This prevalence of homoplasy associated with fruit types across the mimosoid clade matches that seen across other legume clades (e.g. in subfamily Papilionoideae ;Geesink 1984;Hu et al. 2000;Lavin et al. 2001) suggesting that the late developmental stages of the legume pod and associated legume seed dispersal syndromes are prone to convergent evolution, as previously suggested (Geesink 1984;Hu et al. 2000). ...
Subfamily Caesalpinioideae with ca. 4,600 species in 152 genera is the second-largest subfamily of legumes (Leguminosae) and forms an ecologically and economically important group of trees, shrubs and lianas with a pantropical distribution. Despite major advances in the last few decades towards aligning genera with clades across Caesalpinioideae, generic delimitation remains in a state of considerable flux, especially across the mimosoid clade. We test the monophyly of genera across Caesalpinioideae via phylogenomic analysis of 997 nuclear genes sequenced via targeted enrichment (Hybseq) for 420 species and 147 of the 152 genera currently recognised in the subfamily. We show that 22 genera are non-monophyletic or nested in other genera and that non-monophyly is concentrated in the mimosoid clade where ca. 25% of the 90 genera are found to be non-monophyletic. We suggest two main reasons for this pervasive generic non-monophyly: (i) extensive morphological homoplasy that we document here for a handful of important traits and, particularly, the repeated evolution of distinctive fruit types that were historically emphasised in delimiting genera and (ii) this is an artefact of the lack of pantropical taxonomic syntheses and sampling in previous phylogenies and the consequent failure to identify clades that span the Old World and New World or conversely amphi-Atlantic genera that are non-monophyletic, both of which are critical for delimiting genera across this large pantropical clade. Finally, we discuss taxon delimitation in the phylogenomic era and especially how assessing patterns of gene tree conflict can provide additional insights into generic delimitation. This new phylogenomic framework provides the foundations for a series of papers reclassifying genera that are presented here in Advances in Legume Systematics (ALS) 14 Part 1, for establishing a new higher-level phylogenetic tribal and clade-based classification of Caesalpinioideae that is the focus of ALS14 Part 2 and for downstream analyses of evolutionary diversification and biogeography of this important group of legumes which are presented elsewhere.
... However, subsequent phylogenetic analyses have confirmed that these genera were rightfully segregated as distinct evolutionary lineages, Hesperalbizia being more closely related to Lysiloma Benth. (Duno de Stefano et al. 2021), and the closely related Balizia and Hydrochorea (the former reduced to synonymy of the latter, Soares et al. 2022) being placed as the sister-group of Jupunba Britton & Rose (Iganci et al. 2015;Soares et al. 2021Soares et al. , 2022. Phylogenomic analysis of the mimosoid clade, based on DNA sequences of 964 targeted nuclear genes confirmed these findings and, furthermore, showed that the species from the Americas (i.e., sect. ...
... However, subsequent phylogenetic analyses have confirmed that these genera were rightfully segregated as distinct evolutionary lineages, Hesperalbizia being more closely related to Lysiloma Benth. (Duno de Stefano et al. 2021), and the closely related Balizia and Hydrochorea (the former reduced to synonymy of the latter, Soares et al. 2022) being placed as the sister-group of Jupunba Britton & Rose (Iganci et al. 2015;Soares et al. 2021Soares et al. , 2022. Phylogenomic analysis of the mimosoid clade, based on DNA sequences of 964 targeted nuclear genes confirmed these findings and, furthermore, showed that the species from the Americas (i.e., sect. ...
... That possibility was suggested by the occurrence of lomentiform fruits in some species of section Arthrosamanea as reflected in the classification into separate series by Barneby and Grimes (1996). Similar lomentiform fruits also occur in Hydrochorea (Barneby and Grimes 1996;Soares et al. 2022) and Albizia s.s. (Albizia dolichadena (Kosterm.) ...
Following recent mimosoid phylogenetic and phylogenomic studies demonstrating the non-monophyly of the genus Albizia, we present a new molecular phylogeny focused on the neotropical species in the genus, with much denser taxon sampling than previous studies. Our aims were to test the monophyly of the neotropical section Arthrosamanea, resolve species relationships, and gain insights into the evolution of fruit morphology. We perform a Bayesian phylogenetic analysis of sequences of nuclear internal and external transcribed spacer regions and trace the evolution of fruit dehiscence and lomentiform pods. Our results find further support for the non-monophyly of the genus Albizia, and confirm the previously proposed segregation of Hesperalbizia, Hydrochorea, Balizia and Pseudosamanea. All species that were sampled from section Arthrosamanea form a clade that is sister to a clade composed of Jupunba, Punjuba, Balizia and Hydrochorea. We find that lomentiform fruits are independently derived from indehiscent septate fruits in both Hydrochorea and section Arthrosamanea. Our results show that morphological adaptations to hydrochory, associated with shifts into seasonally flooded habitats, have occurred several times independently in different geographic areas and different lineages within the ingoid clade. This suggests that environmental conditions have likely played a key role in the evolution of fruit types in Albizia and related genera. We resurrect the name Pseudalbizzia to accommodate the species of section Arthrosamanea, except for two species that were not sampled here but have been shown in other studies to be more closely related to other ingoid genera and we restrict the name Albizia s.s. to the species from Africa, Madagascar, Asia, Australia, and the Pacific. Twenty-one new nomenclatural combinations in Pseudalbizzia are proposed, including 16 species and 5 infraspecific varietal names. In addition to the type species Pseudalbizzia berteroana, the genus has 17 species distributed across tropical regions of the Americas, including the Caribbean. Finally, a new infrageneric classification into five sections is proposed and a distribution map of the species of Pseudalbizzia is presented.
... G.C.C. Gilbert & Boutique and Cathormion rhombifolium (Benth.) Keay were shown to be closely related to South American Hydrochorea Barneby & J.W. Grimes and are transferred to that genus by Soares et al. (2022). This leaves us with three species, Cathormion altissimum (Hook. ...
... Much confusion about relationships and generic classification in mimosoids (especially ingoids) has been caused by homoplasious fruit characters and the lomentiform pod type is one of the most intriguing because it has apparently evolved multiple times associated with repeated adaptations to periodically inundated areas and/or riparian habitats to facilitate hydrochorous seed dispersal (Aviles Peraza et al. 2022;Ringelberg et al. 2022;Soares et al. 2022). Indeed, when comparing the pods of Osodendron spp. to those of some Albizia species (Fig. 1B) or Hydrochorea (Fig. 1F), one can understand why these have all been previously included in a broadly circumscribed Cathormion and why a close relationship between Osodendron and Robrichia was not suspected (Fig. 1G, H), even though Barneby and Grimes (1996: p. 247) noted that Robrichia schomburgkii (Benth.) ...
The genus Osodendron is here newly described to accommodate three species and one subspecies of African mimosoid legumes. These taxa have previously been included by several authors in Albizia, Cathormion and/or Samanea, but they have been shown to be phylogenetically unrelated to any of these, being instead the sister-group of the recently described Neotropical genus Robrichia, which is similar in vegetative morphology and especially its very similar indumentum, but is decidedly different in pod morphology. A taxonomic treatment of the three species in the genus is presented, with species descriptions, photographs, distribution maps and an identification key. The type species Osodendronaltissimum (Hook. f.) E.J.M. Koenen occurs in swamp and riverine rainforest and gallery forests, with the typical subsp. altissimum widespread across tropical Africa, while Osodendronaltissimumsubsp.busiraensis (G.C.C. Gilbert) E.J.M. Koenen is only known from the Busira river catchment in the western part of the Democratic Republic of Congo. Of the other two species, Osodendrondinklagei (Harms) E.J.M. Koenen is a common tree of rainforest and the forest-savannah transition including semi-deciduous and secondary forest as well as gallery forest and is restricted to Upper Guinea and the similar, but vegetatively more variable Osodendronleptophyllum (Harms) E.J.M. Koenen occupies comparable vegetation types in Lower Guinea and extends marginally into the Sudanian and Zambezian savannahs in gallery forest.
Caesalpinioideae is the second largest subfamily of legumes (Leguminosae) with ca. 4680 species and 163 genera. It is an ecologically and economically important group formed of mostly woody perennials that range from large canopy emergent trees to functionally herbaceous geoxyles, lianas and shrubs, and which has a global distribution, occurring on every continent except Antarctica. Following the recent re-circumscription of 15 Caesalpinioideae genera as presented in Advances in Legume Systematics 14, Part 1, and using as a basis a phylogenomic analysis of 997 nuclear gene sequences for 420 species and all but five of the genera currently recognised in the subfamily, we present a new higher-level classification for the subfamily. The new classification of Caesalpinioideae comprises eleven tribes, all of which are either new, reinstated or re-circumscribed at this rank: Caesalpinieae Rchb. (27 genera / ca. 223 species), Campsiandreae LPWG (2 / 5–22), Cassieae Bronn (7 / 695), Ceratonieae Rchb. (4 / 6), Dimorphandreae Benth. (4 / 35), Erythrophleeae LPWG (2 /13), Gleditsieae Nakai (3 / 20), Mimoseae Bronn (100 / ca. 3510), Pterogyneae LPWG (1 / 1), Schizolobieae Nakai (8 / 42–43), Sclerolobieae Benth. & Hook. f. (5 / ca. 113). Although many of these lineages have been recognised and named in the past, either as tribes or informal generic groups, their circumscriptions have varied widely and changed over the past decades, such that all the tribes described here differ in generic membership from those previously recognised. Importantly, the approximately 3500 species and 100 genera of the former subfamily Mimosoideae are now placed in the reinstated, but newly circumscribed, tribe Mimoseae. Because of the large size and ecological importance of the tribe, we also provide a clade-based classification system for Mimoseae that includes 17 named lower-level clades. Fourteen of the 100 Mimoseae genera remain unplaced in these lower-level clades: eight are resolved in two grades and six are phylogenetically isolated monogeneric lineages. In addition to the new classification, we provide a key to genera, morphological descriptions and notes for all 163 genera, all tribes, and all named clades. The diversity of growth forms, foliage, flowers and fruits are illustrated for all genera, and for each genus we also provide a distribution map, based on quality-controlled herbarium specimen localities. A glossary for specialised terms used in legume morphology is provided. This new phylogenetically based classification of Caesalpinioideae provides a solid system for communication and a framework for downstream analyses of biogeography, trait evolution and diversification, as well as for taxonomic revision of still understudied genera.
Early natural historians-Comte de Buffon, von Humboldt, and De Candolle-established environment and geography as two principal axes determining the distribution of groups of organisms, laying the foundations for biogeography over the subsequent 200 years, yet the relative importance of these two axes remains unresolved. Leveraging phylogenomic and global species distribution data for Mimosoid legumes, a pantropical plant clade of c. 3500 species, we show that the water availability gradient from deserts to rain forests dictates turnover of lineages within continents across the tropics. We demonstrate that 95% of speciation occurs within a precipitation niche, showing profound phylogenetic niche conservatism, and that lineage turnover boundaries coincide with isohyets of precipitation. We reveal similar patterns on different continents, implying that evolution and dispersal follow universal processes.
