Advances in Legume Systematics 14. Classification of Caesalpinioideae. Part 2: Higher-level classification.

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.

Distribución conocida y potencial de dos taxa del género Mimosa (Leguminosae) endémicos de México / Present and potential distribution of two Mimosa (Leguminosae) taxa endemic to Mexico

Resumen Mimosa aculeaticarpa var. aculeaticarpa y M. luisana son endémicas de México y consideradas plantas multipropósito, ya que ofrecen diversos servicios a los ecosistemas y pobladores en donde se establecen. Además, son valoradas por su potencial como restauradoras de ambientes tropicales, por lo que el objetivo de este estudio fue modelar su distribución conocida y potencial. En el año 2014, se obtuvieron registros de dos bases de datos (CONABIO y MEXU); cada resgistro fue validado taxonómica, geográfica y estadísticamente, una vez validados, se obtuvo la distribución conocida y potencial para M. aculeaticarpa var. aculeaticarpa (basada en 99 registros) y M. luisana (basada en 50 registros), utilizando el algoritmo MAXENT. La distribución conocida de ambos taxa se sobreposicionó en las capas de: elevación, clima, suelo, provincias biogeográficas y cuencas hidrológicas. Mimosa aculeaticarpa var. aculeaticarpa presenta amplia distribución en México (16 estados); mientras que M. luisana se encuentra restringida a los estados de Puebla y Oaxaca. M. aculeaticarpa var. aculeaticarpa se establece entre 1 900 y 2 700 msnm y M. luisana entre 500 y 1 760 msnm. Ambas se encuentran en climas áridos y semiáridos; sin embargo, M. aculeaticarpa var. aculeaticarpa también se puede encontrar en climas templados y mésicos. Asimismo, ambos taxa se distribuyen en suelos de tipo regosol calcárico; aunque, M. aculeaticarpa var. aculeaticarpatambién está en regosol éutrico, vertisol crómico y feozem háplico. La distribución de M. aculeaticarpa var. aculeaticarpa abarca ocho provincias biogeográficas y tres cuencas hidrológicas; mientras que M. luisana se localiza en tres provincias y dos cuencas; ambas coinciden en las provincias del Eje Volcánico y la Sierra Madre del Sur. Los modelos de distribución potencial se consideran excelentes, ya que poseen un AUC de 0.91 y 0.97, respectivamente. Los modelos indican que las condiciones de temperatura y precipitación son propicias para que ambos taxa pudieran ampliar su distribución. Igualmente, los modelos generados pueden considerarse como una aproximación al conocimiento de la distribución potencial de las mimosas mexicanas. Aunque, es importante considerar que los modelos son estáticos y no consideran a las interacciones bióticas, por lo que su relación con la realidad puede variar; por lo que se recomienda analizar los modelos mediante diferentes escenarios de cambio climático y de uso de suelo.

Abstract Mimosa aculeaticarpa var. aculeaticarpa and M. luisana are endemic to Mexico, and are considered as multipurpose plants, due to the diverse services they offer to ecosystems and to local people. Additionally, they are appreciated for their potential to restore tropical environments; hence, the objective of this study was to model the present and potential distribution of these taxa. In 2014, species registers were obtained from two databases (CONABIO and MEXU); each register was taxonomically, geographically and statistically validated. Once validated, the present and potential distribution of M. aculeaticarpa var. aculeaticarpa (based on 99 registers) and M. luisana (based on 50 registers) were obtained using the MAXENT algorithm. For both taxa, the present distribution was overlapped using the layers of: elevation, climate, soil, biogeographic provinces, and hydrologic basins. Mimosa aculeaticarpa var. aculeaticarpa showed a wide distribution in Mexico (16 states); whilst M. luisana was restricted to the states of Puebla and Oaxaca. M. aculeaticarpa var. aculeaticarpa establishes between 1 900 and 2 700 masl, and M. luisana between 500 and 1 760 masl. Both species were established in arid and semiarid climates; however, M. aculeaticarpa var. aculeaticarpa can also be found in temperate and mesic climates. Moreover, both taxa are distributed in calcareous regosol soils; although, M. aculeaticarpa var. aculeaticarpa is also found in eutric regosol, chromic vertisol and haplic phaeozem. The distribution of M. aculeaticarpa var. aculeaticarpa includes eight biogeographic provinces and three hydrologic basins; whilst M. luisana was only located in three provinces and two hydrologic basins; both are present in the Eje Volcánico and Sierra Madre del Sur provinces. The potential distribution models are considered as excellent ones due to an AUC of 0.91 and 0.97, respectively; these models indicated that the temperature and precipitation conditions would be suitable for the enlargement of their distribution. Likewise, these models can be considered an approach to the potential distribution knowlegment of the Mexican mimosas. Nevertheless, it is important to note that the models are static and do not take into account any biotic interaction; therefore, their relationship with reality can vary. Thus, it is recommended to analyze the models through different climate change and land use scenarios. Rev. Biol. Trop. 66(1): 321-335. Epub 2018 March 01.