Leguminosae: Biodiversity and Taxonomy for the Northeast Region of Brazil

The research aimed to know the diversity of Leguminosae in vegetational fragments of Cerrado in the state of Maranhão. Monthly expeditions were carried out in the period between September from 2016 and June 2017 for observation, collection, and identification of botanical material. A total of 68 specimens, 31 genera, and 45 species were cataloged. Of all the specimens collected, the subfamilies Papilionoideae and Caesalpinioideae were the most representative of 21 species each. As for the Life form, was observed that the prevailing growth habit was the bush type (20). Concerning to the physiognomies of the Cerrado, was observed the predominance of the species in the gallery forest environment (28). Taxonomic keys, descriptions and photo plates were elaborated with all the studied species, composing a taxonomic treatment. In this way, it can be established that the Cerrado of Maranhão possesses a diversity of species for the Leguminosae family and that the research carried out has provided a basis for later studies, since these are few for Maranhão. Keywords—Shrubs, Cerrado, Floristic, Papilionoideae, Vigna lasiocarpa .

taxonomic keys, and/or determined and confirmed by a family taxonomist. For the taxonomic treatment, all information and morphological characteristics of each species were observed and recorded. These characteristics formed a description of the plant along with the information of the author of the species, main work, geographical distribution and phytogeographical domains where the species occurs in the Brazilian territory. For the data of the author and main work of all species, was used the Tropicos (2019) (https://www.tropicos.org/); and SpeciesLink , CRIA (2019)( http://www.splink.org.br/ ). With the botanical description, dichotomous taxonomic keys of the described species were elaborated, using the taxonomic criteria already presented in the botanical description that better identifies the studied species.

III. RESULTS AND DISCUSSION
Taking into account floristic aspects, Leguminosae is one of the families among the angiosperms that have the richest species in the different phytogeographic domains of Brazil according to Queiroz (2009); Flora do Brazil 2020 (2019). From the obtained data were listed 68 specimens, distributed in 31, genera and 45 species. The representation of species of the Leguminosae subfamilies sampled in this research shows that of the 68 specimens studied, 21 species belong to the subfamily Papilionoideae, 21 belong to the subfamily Caesalpinioideae, 2 species belong to the subfamily Cercidoideae and 1 species belongs to the subfamily Detarioideae, as shown in table. As for species richness, the subfamilies Papilionoideae and Caesalpinioideae were the most representative, sampled 21 and 19 species respectively (table.1). Papilionoideae is a monophyletic subfamily, with high reliability of phylogenetic reconstruction. The subfamily includes many species of economic importance (TOZZI, 2016). Caesalpinioideae in its present circumscription contains 148 genera and 4.400 species. With pantropical distribution, being common in dewy and dry regions, with a handful of species that extend to the temperate zone (LPWG, 2017). In terms of Brazil distribution, is represented by about 52 genera and 810 species (FLORA DO BRASIL 2020. 2019).
In the physiognomy of occurrence, the specimens were collected, mainly in gallery forests, with 28 species, Clean Field 7 and Open field 6. Among the plant formations of the Cerrado, the gallery forest, also known as riparian forest or riparian forest by some researchers, is characterized by being associated with watercourses, and this formation, although small, possesses richness, genetic diversity, and acts in the protection of water resources (RIBEIRO, 1998). The two most representative genera in the survey were Aeschynomene and Mimosa with four species each.
The genus Aeschynomene L. has a pantropical distribution, with about 180 species (LEWIS et al., 2005). Mimosa L. comprises 540 species, being the second largest genus of the mimosoid clade (SIMON et al., 2011). It is distributed mainly in the neotropical region, counting on approximately 496 endemic taxa of the neotropics and 40 native species of the old world (SIMON et al., 2011;BARNEBY, 1991).
Regarding the life-form, was observed that the predominant habit of growth was the Shrub type with 18 species, after Tree 14 and herb 13. The life-formthis family is assorted, from trees, shrubs, sub-bushes to upright herbs, creeping or even climbing (JUDD et al., 1999). Shrubs are characterized by woody structures of varying size, but not more than 6 m in height, and stem with branches much close to the ground (ORMOND, 2006). The bushes are outreached of woody plants, in which the support and stem tissues form layers that are added year after year (BONONI; FIDALGO, 1989).
As for the number of specimens of each species, the species Phanera variegata (L.) Benth., Aeschymoneme histrix Poir., Libidibia ferrea (Mart. Ex Tul.) L.P Queiroz and Chamaecrista flexuosa (L.) Greene. were the most representative in the survey, being P. variegata the most representative with 5 specimens, and the other 3 specimens each. P. variegatais planted in the tropics and hot regions of the world (ISELY, 1990             Aeschynomene viscidula (Papilionoideae) and Vigna lasiocarpa (Papilionoideae), with V. lasiocarpa being a new ledger to the Northeast. This research is relevant for the Northeastern flora, through the increase of knowledge of the Leguminosae family characteristics and the expansion of the geographic distribution of the species in the region. proved to be very diverse in Cerrado Maranhense, making the work the largest survey in the family's geographical area for the State through a pioneering research for the area, building an important knowledge in the field of botanical study, thus offering taxonomic keys that will serve as recognition and identification of the species for the Cerrado of the state.
Producing taxonomic works on Leguminosae is of extreme importance, so it is pos sible to understand several characteristics wich are still unknown. The morphological and taxonomic diversity of Leguminosae is expressed in its high number of taxa that is distributed in almost all regions of the world.
Leguminosae proved to be very diverse in Cerrado Maranhense, making the work the largest survey in the family's geographical area for the State through a pioneering research for the area, building an important knowledge in the field of botanical study, where the taxonomic keys produced will serve as recognition and identification of the species for the State Cerrado.
The importance of the research is also evidenced by providing information for the conservation and management of these new occurrences from taxonomic data. It can be mentioned that the species indexed as a new occurrence will contribute to the construction of the Brazilian Flora, through the REFLORA 2020 Project, which intends to index all Brazilian plant species until the year 2020, fortifying the data of Maranhão and the Northeast region, thus guaranteeing greater representation of Brazilian biodiversity.