Flora of Espírito Santo, Brazil: Bixaceae

Abstract The present study is part of the Flora of Espírito Santo project and aimed to survey and describe the morphological diversity of species of Bixaceae from Espírito Santo state, Brazil, as well as to provide data on geographical distribution, biology, and habitat of these species. To do so, fieldwork was carried out in several areas of Espírito Santo and the most important herbaria collections in the state were examined. Bixaceae in Espírito Santo is represented by the genus Bixa, with two species. Bixa atlantica, recently described and repeatedly misidentified as Bixa arborea, is a forest tree up to 20 m tall (rarely appearing as treelet or shrub in savannah-like vegetation), with spine fruits and lacking nectaries in the pedicel apex. Bixa orellana, on the other hand, is recognized as a shrub or treelet up to 5-6 m tall, with conspicuous nectaries in the pedicel apex. The species origin is uncertain, though it occurs sub-spontaneously in Espírito Santo state, where it is widely cultivated due to its value as a spice. In this paper we provide taxonomic descriptions, an identification key, geographic distribution maps, photographic plates and comments on the ecology, conservation, and recognition of both species.


Introduction
The Bixaceae family comprises four genera and 20-26 species, has a pantropical distribution, and is especially diverse in the Neotropics.Amoreuxia Moç.& Sessé is composed of four species distributed in Mexico and South USA (Stevens 2022); Bixa L. is composed of five to seven species distributed in tropical America, especially in the Amazon (Dequigiovanni et al. 2018;Antar et al. 2022); Cochlospermum Kunth is composed of 12-15 species distributed in the Americas, Africa, Asia, and Oceania (Johnson-Fulton & Watson 2017;WCVP 2022); and Diegodendron Capuron is monotypic and endemic to Madagascar (Bayer 2002).The species of Bixaceae occur predominantly in seasonal climates, inhabiting deciduous or semi-deciduous forests, tropical forests, natural grasslands, savannahs, and sometimes, disturbed environments (Poppendieck 1981(Poppendieck , 2002a,b;,b;Stevens 2022).
Bixaceae has traditionally been recognized as monogeneric, composed exclusively of Bixa, while the other genera currently placed within Bixaceae have been treated in separated families: Amourexia and Cochlospermum in Cochlospermaceae, and Diegodendron in Diegodendraceae (Bayer 2002;Poppendieck 2002a,b).Phylogenies based on molecular characters supported the placement of all these members within Bixaceae (APG IV 2016;Fay et al. 1988).This hypothesis is currently widely accepted (Stevens 2022), although it is not a consensus, as a concurrent phylogenetic hypothesis (Johnson-Fulton & Watson 2017) advocated the separation of Cochlospermaceae.The lack of consensus indicates that further studies on these taxa are needed.
In Brazil, Bixaceae is represented by seven species and two genera, Bixa and Cochlospermum (Antar 2022;Antar et al. 2022).These taxa have been the subject of recent floristic studies, which resulted in the publication of some treatments (e.g.

Materials and Methods
This study is based 1) on the analysis of material collected in field expeditions carried out since 2010 in several areas of Espírito Santo, and 2) on the comparative analysis of herborized specimens deposited in the botanical collections ESA, MBM, MBML, RB, SAMES, SPF and VIES (acronyms according to Thiers, continuously updated).Additionally, virtual collections, accessed via SpeciesLink (2022) and Reflora Herbário Virtual (2022), were examined.To identify and describe the taxa, specialized bibliography was used (Baer 1976;Antar et al. 2022).Author names and species nomenclatures follow IPNI (2022).The morphological characters used in the descriptions follow the terminology of Hickey (1973) for leaf morphology, Harris & Harris (2004) for general terms, and Baer (1976) for terms unique to Bixaceae.The species occurrences were obtained by consulting herbarium data, and the distribution maps were produced using the QGIS software, version 3.10.0(QGIS Development Team 2019).Only non-cultivated individuals (natural or spontaneous) were considered.

Results and Discussion
The flora of Bixaceae in Espírito Santo state is represented by two species, Bixa atlantica and B. orellana.Bixa atlantica occurs in semideciduous forest, tabuleiro forest, and sometimes in disturbed secondary forest or along forest edges and modified lands in savannah-like physiognomies.The species is able to grow among rocks at the bottom of valleys.The species also occurs in the states of Bahia and Minas Gerais, but most gatherings are from Espírito Santo.Specimens of Bixa atlantica have often been referred to as Bixa arborea Huber, an Amazonian species that clearly differs from B. atlantica in having spineless fruits (Antar et al. 2022).This misidentification was reproduced in published articles (e.g., Vieira Neto et al. 2012;Klippel et al. 2015;Spadeto et al. 2017), and only recently resolved (Antar et al. 2022).The species was evaluated as Near Threatened due to its endemic distribution in the forest physiognomies of Espírito Santo, Bahia and Minas Gerais, a distribution pattern that links its conservation with the conservation of the Atlantic Forest, a domain under severe threats due to habitat loss by agriculture and urbanization (Rezende et al. 2018).In addition to several unprotected areas, Bixa atlantica occurs in three protected areas in Espírito Santo: Reserva Biológica de Sooretama, Reserva Biológica Córrego do Veado, and Reserva Natural Vale (Linhares).
Rodriguésia 74: e00792022.2023 Bixa orellana, on the other hand, is widely cultivated in tropical regions and its occurrence is documented for all Brazilian states.Although sometimes it can be hard to infer the proper origin of the individuals of Bixa orellana (i.e., whether cultivated or sub spontaneous), some collections -as Crepaldi 114 (RB 441580) -confirm the occurrence of the species in natural formations in Espírito Santo, mostly in areas of secondary forest.Thus, in view of its wide distribution and cultivation, there is little evidence of threats to its conservation.
Bixa comprises four to six species distributed in Tropical America, especially in the Amazon region (Baer 1976;Antar et al. 2020).Bixa orellana is widely cultivated and naturalized in some tropical localities (Poppendieck 2002b).From four to five species occur in Brazil, depending on whether Bixa urucurana Willd. is a valid name (Baer 1976;Steyermark & Holst 1997) or a synonym of B.
As a widely cultivated species, the origin of Bixa orellana remains controversial, although Bixa urucurana (sometimes treated as B. orellana var.urucurana) stands as a potential candidate for a non-domesticated species from which B. orellana was selected (Dequigiovanni et al. 2018).

Specimens examined :
Figure 2 -Geographic distribution of Bixa atlantica in the state of Espírito Santo, Brazil.