The tribes Acacieae and Ingeae (Leguminosae: Caesalpinioideae) in the Environmental Protection Area Serra Branca, Raso da Catarina, Jeremoabo, Bahia, Brazil

Leguminosae includes six subfamilies, where the traditionally recognised subfamily Mimosoideae was accepted as a distinct clade included within the recircumscribed subfamily Caesalpinioideae, called informally as Mimosoid clade. The representatives of the tribes Acacieae and Ingeae can be differentiated principally in terms of the patterns of their stamens, being free in Acacieae and monadelphous in Ingeae. The floristic survey of Acacieae and Ingeae in the Environmental Protection Area Serra Branca included analysis of specimens collected from June 2011 to September 2012. The analyses were supplemented with dried collections from the following herbaria: ALCB, HRB and HUEFS. Ten species were cataloged, distributed among four genera of Ingeae: Calliandra Benth. (1 sp.), Chloroleucon (Benth.) Britton & Rose ex Record (1 sp.), Enterolobium Mart. (1 sp.), Pithecellobium Mart. (1 sp.); and one genus of Acacieae: Senegalia Raf. (6 spp.). The most representative species were Calliandra aeschynomenoides Benth. associated with sandy and stony soils and Chloroleucon foliolosum (Benth.) G.P.Lewis and Senegalia bahiensis (Benth.) Seigler & Ebinger growing on sandy-clay soils. The taxonomic treatment includes a key for the identification, descriptions, illustrations, photos, data of the geographical distribution phenological data and comments about the species.

Studies on taxa of Mimosoid clade in areas of Caatinga in Bahia are few. Given the significant rate of endemism and diversity for the Caatinga biome, and the limited number of surveys for the clade therein, this study aimed to contribute to a better understanding of the Mimosoid clade in the EPASB, in order to contribute to knowledge about the flora of the semiarid region of Bahia, as well as to support the development of the area's management plan.

Study area
The Evironmental Protection Area Serra Branca, Raso da Catarina (EPASB, Figure 1) comprises 67,237 ha., located in the municipality of Jeremoabo in Northeastern Bahia fully inserted into the "polígono das secas" (Fundação CTI/NE 2016), delimited by the coordinates 09º53 '15.5'' to 09º44'34.6''S and 38º49'36.1''to 38º52'20.4''W, limited to the South with the Vaza-Barris River and North to the Ecological Station Raso da Catarina (ESEC). The predominant vegetation is the sandy, very dense bushy Caatinga. The climate of the Ecoregion is semiarid, with average rainfalls of 500 mm/year and annual temperature is approximately 23ºC (Szabo et al. 2007). The soils are generally sandy deep and very fertile relief plan with sandstone formations (Velloso et al. 2002).

Taxonomic study
The study was based on fieldwork carried in the period from June 2011 to September 2012, besides information complemented by the analysis of specimens deposited in the following herbaria: ALCB, HRB, and HUEFS, acronyms according to Thiers 2018 (continuously updated; Appendix 1). The field collections and observations were performed during random walks exploring most of the study area. The herborization and material processing followed the methodology by Fosberg & Sachet (1965) and Mori et al. (1989), where fertile material was collected with flowers and/or fruit. Observations were made about the distribution of the species and the type of soil (Tricart 1972, Sampaio 1995. The specimens were deposited in the herbarium of the State University of Bahia (HUNEB -Paulo Afonso Collection) and the duplicates will be sent to the main herbaria in the state of Bahia (ALCB, HRB and HUEFS).
The identifications were made based mainly on specialized bibliographies, protologues, photos of type collections and comparison of the collections in the visited herbaria. For the taxonomic descriptions, the terminologies proposed by Mesquita (1990), Barneby & Grimes (1996), Barneby & Grimes (1997), Barneby (1998), Harris & Harris (2001), Seigler et al. (2006), and Melo et al. (2010) were adopted. The inflorescences were measured considering principally the stamens. The taxonomic treatment includes an identification key, descriptions, illustrations, photos, data of the geographical distribution, phenological data and comments about the species.  (Varjão et al. 2013).

Results
Ten taxa were recorded for the tribes Acacieae and Ingeae in the EPASB (Figure 2). For the Acacieae, six species of the genus Senegalia The species in the EPASB are distributed throughout the subshrub to arboreal caatinga vegetation in well-preserved areas and in anthropogenically modified zones growing on sandy, sandy-stony, or sandy-clayey soils. The most representative species were Calliandra aeschynomenoides, Chloroleucon foliolosum, and Senegalia bahiensis. Calliandra aeschynomenoides occurs in fragments of the EPASB, associated with shrub vegetation on sandy-stony soils. Chloroleucon foliolosum and S. bahiensis are associated with shrub to arboreal caatinga vegetation occurring on sandy-clayey soils. The diagnostic morphological characters used to identify these taxa in the area were: the presence or absence of prickles, spines, the shapes of the stipules, numbers of leaflet pairs; shapes and locations of the extrafloral nectaries, inflorescence patterns, and types of fruits.

Discussion
Calliandra aeschynomenoides is endemic to Brazil, Caatinga region, with records from the states of Pernambuco and Bahia (Queiroz 2009, Flora do Brasil 2020. It differs from the other species by having unarmed branches, extrafloral nectaries absent on the petiole and leaf rachis, leaves with one pair of pinna, red flowers with long stamen tubes exserted from the corolla. It was collected with flowers in June and July, with fruit in April and October. Chloroleucon foliolosum occurs in Argentina and Bolivia (Barneby & Grimes 1996) in all regions of Brazil, except the southern region (Souza 2018). It can be characterized by having flexuous branches, isolated spines or paired at the nodes, dormant buds scaly, heteromorphic glomerules, with differentiated central flowers, with long perianth, and stamen tubes exserted from the corolla. The fruit is characteristic of the species, generally dehiscent, linear, curved 90°-360°, with valves extending over the seeds. The flowers were observed in June, July and October the fruits were observed in July and October.
Enterolobium timbouva occurs in South America, with records from Brazil, Colombia, and Paraguay (Mesquita 1990); occurs in northern, northeastern, midwest, and southeastern Brazil in the phytogeographical domains of Caatinga, Atlantic Forest and Amazon Forest (Mesquita et al. 2018). It was collected in anthropized areas, growing on sandy soils in pastures and agricultural plots. It was collected with flowers in the month of December and fruits in March and May. The species can be distinguished from the other species occurring in EPASB by having an arboreal habit, 8-10 m tall, lenticular branches, leaves with 2-4 pairs of pinnae; oval petiole, and auriculate fruit, blackish when mature. It was collected with flowers in the month of December and fruits in March and May.
Pithecellobium diversifolium is endemic to Brazil and restricted to the areas of dryland caatinga of the Northeastern region (Iganci 2015). This species can be recognized by presence of leaves with 1-2 pairs of pinnae, elliptic to oval leaflets, spiny stipules (stipules transformed into spines), villous corolla, and sigmoidal fruits in spirals. The seeds of this species are also important in their identification as they are shiny and black with a red aril having a sweet taste. This species is easily recognized in the field due to the morphology of the leaflets, and the spiraled fruit when young are green and ripe are red. The flowers and fruits were observed in October.
Senegalia bahiensis is endemic to Brazil, distributed in the northeastern (Alagoas, Bahia, Paraíba, Pernambuco, Piauí, Rio Grande do Norte, and Sergipe) and southeastern (Minas Gerais and Rio de Janeiro) regions of that country (Ribeiro 2012, Flora do Brasil 2020. It can be recognized in the EPASB by having angular branches, prickle generally straight, stipules cordiform foliaceous to oval, and stipitate extrafloral nectaries cylindrical to calicioid. The specimens were collected with flowers in May and October, and with fruits in March. Senegalia globosa is endemic to Brazil and endemic from Bahia State in caatinga vegetation (Queiroz 2009, Flora do Brasil 2020. This species demonstrates morphological variability the numbers of pairs of leaflets and the shape of its extrafloral nectaries, globose or conical, distributed below the basal pina pair or in the median region of the petiole, with or without additional nectar distributed along the rach or between last pairs of leaflets. It is characterized by having slightly angular branches, recurved prickle, stipules linear to lanceolate, and relatively large glomerules (17-22 cm diameter). The flowers were observed in July.
Senegalia limae is endemic to Brazil, essentially native from caatinga vegetation, and has been recorded in northeastern Brazil in the states of Pernambuco and Bahia, in the southeastern region of that country in Minas Gerais State (Queiroz 2009, Flora do Brasil 2020. Ribeiro (2012) noted that many collected specimens have been identified as S. limae, Acacia limae although analyses of the type specimen and additional material indicated them to be S. lasiophylla. (Benth.) Seigler & Ebinger (Flora do Brasil 2020). We prefer to maintain the older classification in this work as Ribeiro (2012) has not yet been formally published. This species demonstrates wide variations in the shapes and positions of its extrafloral nectaries, elevated, globose, concave, estipitate cylindrical, caliciform or conical. It can be recognized by its climbing habit, stipules lanceolate to oval, relatively large glomerules (25-30 mm in diameter), and flowers 16-18 mm long. The flowers were observed in July. Senegalia limae can sometimes be confused with S. globosa because both have leaves with similar numbers of pinnae. The two species can be easily distinguished, however, because S. limae is a climbing plant (vs. a shrub) with glomerules 25-30 mm in diameter (vs. glomerules 18-24 mm in diameter in S. globosa).
Senegalia piauhiensis endemic to Brazil, found in caatinga vegetation in northeastern Brazil, occurring in the states of Piauí, Ceará, Pernambuco, Bahia, Alagoas, and Sergipe (Queiroz 2009, Flora do Brasil 2020. This species is characterized by having leaves with 2-4 pairs of pinnae, elevated-concave to enclosed-concave nectaries along the petiole and, principally, by its inflorescence in spikes, 8.6-10.2 cm long. Senegalia piauhiensis differs from the other congeneric species occurring in the area by displaying its inflorescence in spikes (vs. glomerules). It was collected with flowers in March and April.
Senegalia polyphylla is widely distributed in the Americas (Rico-Arce 2007). It occurs in the northern, northeastern, and centralwestern regions of Brazil in caatinga, cerrado, amazon forest and atlantic forest, and in the seasonally flooded "pantanal" region (Morim & Barros 2012). It is characterized by having cylindrical branches, not lenticular, incurvate prickle, not in triplets in the nodal region, midrib with a tufted of trichomes at the base of the abaxial face, glomerules 8-11 mm in diameter, and cream-colored flowers. It was collected with flowers in May and June.
Senegalia tenuifolia is distributed in South America, with records for Argentina, Brazil, and Paraguay (Rico-Arce 2007). According to Ribeiro (2012), this species has been recorded to northern (in the states of Acre, Amazonas, and Pará), northeastern (Bahia, Paraíba and Pernambuco), central-western (Goiás and Mato Grosso), and southeastern (Minas Gerais, Rio de Janeiro and São Paulo) regions of Brazil. According to Queiroz (2009), this taxon occurs principally in seasonal forests and rainforests in northern Brazil, and occasionally in caatinga vegetation, especially arboreal caatinga. It was registered in arboreal shrub vegetation in the EPASB, growing on sandy soils. Senegalia tenuifolia can be recognized in the field by having branches cylindrical, lenticular, armed with recurved prickle in triplets in the nodal region, and by having small glomerules, 10-12 mm in diameter. It can be confused with S. polyphylla in the study area as both produce inflorescences in small glomerules with cream-colored flowers. However, S. tenuifolia can be easily distinguished by having lenticular branches (vs. branches not lenticular), recurved prickle, in triplets in the nodal region (vs. incurvate prickle not in triplets). Flowering was observed in May.
The morphological characters for recognition of the Acacieae and Ingeae tribes were: arrangement of prickles on the branches, presence or absence of spines or prickles, shape of stipules, shape and position of extrafloral nectars, number of leaflet pairs, inflorescence pattern and types of fruits.
With the study carried out at the EPASB, we can infer the environmental, taxonomic, and systematic relevance of the identified groups, mainly the degree of endemism of the Brazil for the species recorded. Among the species studied, six are registered as endemic to Brazil. The Acacieae Tribe is represented by S. bahiensis, S. globosa, S. limae, e S. piauhinesis. The Ingeae Tribe is represented by Calliandra aeschynomenoides and Pithecellobium diversifolium. These species also present distribution to the Caatinga domain (sensu stricto). Of these, only S. globosa was registered as endemic to the Bahia states. (CHESF) for their support during field work and Coordenação de aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the scholarship to the first author and postdoctoral grant to the third author (PNPD nº 02697/09-2). To Pétala Gomes Ribeiro by confirmation of the identities of part of the species. The first author thanks the curators and technicians of the herbaria that were visited for their readiness during the consultation of the collections and Natanael Santos for the botanical illustrations.

Author Contributions
Aline Franco Sampaio Brito: Contribution to the acquisition of data; analysis and interpretation of data; work of writing and conception and design work.
Élvia Rodrigues de Souza: Contribution to the interpretation of data and critical review adding intellectual content.
Adilva de Souza Conceição: Contribution to the acquisition of data; analysis and interpretation of data; work of writing; critical review adding intellectual content and conception and design work.