Re-establishment of the genus Pseudalbizzia (Leguminosae, Caesalpinioideae, mimosoid clade): the New World species formerly placed in Albizia

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

Filogenia de Lysiloma (Fabaceae), un género restringido a Megaméxico con especies atípicas en las Antillas y Florida

Background and Aims: Lysiloma is a Neotropical genus in the Fabaceae family that comprises eight species, six of which are widely distributed in Mexico, and two more that occur in the Antilles and Florida. Lysiloma is frequent in Megamexico’s dry forests. A previous phylogenetic study included three species of Lysiloma and Hesperalbizia occidentalis. Both genera are closely related, but their divergence has weak support. Our objectives were to test the monophyly of the genus, evaluate the sister relationships within the genus, and estimate the divergence times. Methods: A phylogenetic analysis based on morphological characters, molecular markers (ETS, matK, and trnK), as well as a combined analysis (morphology + molecules) was performed. The data matrices were analyzed both individually and concatenated (total evidence approach) with Bayesian inference and Maximum Parsimony. In addition, molecular divergence times were estimated from the ETS dataset with a Bayesian uncorrelated lognormal relaxed clock. Key results: The morphological analysis supports the monophyly of Lysiloma with Hesperalbizia as sister group. However, the individual and the combined molecular analyses do not provide resolution to clarify the relationships between Hesperalbizia occidentalis, Lysiloma sabicu, and core Lysiloma. The total evidence analysis (including morphology) supports the monophyly of Lysiloma, yet with low support. According to our molecular clock model, the clade Lysiloma+Hesperalbizia diverged from other members of the tribe Acacieae+Ingeae about 32 million years ago, and the diversification of the core of Lysiloma occurred during the Miocene. Conclusions: Lysiloma+Hesperalbizia is an early divergent clade of tribes Acacieae+Ingeae. There are enough morphological differences to recognize both linages. Morphological characters informally used for taxonomic delimitation seem to have evolved homoplasiously. The clade Lysiloma and Hesperalbizia separated from other members of the tribe Acacieae+Ingeae in the Oligocene, but the diversification of the core of the genus coincides with the expansion of the dry forest at the beginning of the Miocene.Antecedentes y Objetivos: Lysiloma es un género neotropical de la familia Fabaceae que comprende ocho especies, seis de las cuales se distribuyen ampliamente en México y dos más que ocurren en las Antillas y La Florida. Lysiloma es frecuente en los bosques secos de Megaméxico. Un estudio filogenético previo incluyó tres especies de Lysiloma y Hesperalbizia occidentalis. Ambos géneros están estrechamente relacionados, pero su divergencia tiene un apoyo débil. Nuestros objetivos fueron probar la monofilia del género, evaluar las relaciones de grupo hermano dentro del género y estimar los tiempos de divergencia. Métodos: Se realizó un análisis filogenético basado en caracteres morfológicos, marcadores moleculares (ETS, matK y trnK), así como un análisis combinado (morfología + moléculas). Las matrices de datos se analizaron tanto individualmente como concatenadas (enfoque de evidencia total) con inferencia Bayesiana y máxima parsimonia. Además, los tiempos de divergencia molecular se estimaron a partir del conjunto de datos ETS con un modelo de reloj bayesiano relajado lognormal no correlacionado. Resultados clave: El análisis morfológico respalda la monofilia del Lysiloma con Hesperalbizia como grupo hermano. Sin embargo, los análisis moleculares individuales y combinado no proporcionan resolución para aclarar las relaciones entre Hesperalbizia occidentalis, Lysiloma sabicu y el núcleo de Lysiloma. El análisis de evidencia total (incluida la morfología) respalda la monofilia de Lysiloma, pero con un bajo soporte. Según nuestro modelo de reloj molecular, el clado Lysiloma+Hesperalbizia se separó de otros miembros de la tribu Acacieae+Ingeae hace unos 32 millones de años y la diversificación del núcleo del Lysiloma se produjo a lo largo del Mioceno.Conclusiones: Lysiloma+Hesperalbizia es un clado de divergencia temprana de las tribus Acacieae+Ingeae. Existen suficientes diferencias morfológicas para reconocer ambos linajes. Los caracteres morfológicos utilizados informalmente para la delimitación taxonómica parecen haber evolucionado de manera homoplásica. El clado de Lysiloma y Hesperalbizia se separó de otros miembros de la tribu Acacieae+Ingeae en el Oligoceno, pero la diversificación del núcleo del género coincidió con la expansión del bosque seco a principios del Mioceno

Revisiting the phylogeny and taxonomy of the Pithecellobium clade (Leguminosae, Caesalpinioideae) with new generic circumscriptions

We present the most complete molecular phylogeny to date of the Pithecellobium clade of subfamily Caesalpinioideae. This neotropical group was informally recognised (as the Pithecellobium alliance) at the end of the 20th century by Barneby and Grimes (1996) and includes five genera and 33 species distributed from the southern United States and Caribbean Islands to north-eastern South America. Our aims were to further test the monophyly of the group and its genera and to identify sister group relationships within and amongst the genera. A phylogenetic analysis of nuclear ribosomal DNA sequences (ITS and ETS) was performed. The results provide further support for the monophyly of the Pithecellobium clade. The genera Ebenopsis, Pithecellobium and Sphinga were strongly supported as monophyletic. Havardia and Painteria were found to be non-monophyletic, prompting their re-circumscriptions and the description of two new genera: Gretheria and Ricoa. New combinations are made for the three species transferred to the new genera

Re-establishment of the genus Pseudalbizzia (Leguminosae, Caesalpinioideae, mimosoid clade): the New World species formerly placed in Albizia

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