Acrocomia aculeata

The first classification of Acrocomia aculeata was made by Jacquin (Jacq.) in 1763 as Cocos aculeatus Jacq. It was included in the genus Acrocomia by Martius (Mart.) in 1824 and the scientific name transferred to A. sclerocarpa. In 1845, Loddiges (Lodd.) synonymized C. aculeatus and A. sclerocarpa under A. aculeata. In the scientific community, there is no consensus regarding its taxonomic determination and, therefore, many species are treated as synonymous (see Supplementary Material— Table S1).

The species is popularly known as macaw palm, due to its importance as a food source for the genus Anodorhynchus Spix (1824). In the Neotropics, it is known by several names such as the following: amolado, amolada, bocaíuva, chonta, corozo, chiclete-de-baiano, coco-de-catarro, coco-de-espinho, coco-baboso, coco-xodó, imbocaia, jabara, korondía, macaúba, macaúva, macaíba, macacauba, macajuba, macaibeira, macajá, marcová, mucajá, mucaia, macaiá, palma de corozo, tamaco, and tamaca (Smith 2015; Lorenzi et al. 2010; Galeano and Bernal 2010; Almeida et al. 1998). Indigenous names are shakána, ñala, yawalaboto, maka-djiup, roi, roy rak, and pinawa (Galeano and Bernal 2010; Smith 2015).

It has a wide distribution in the Neotropics, ranging from Caribbean islands and southern Mexico to Argentina (Dransfield et al. 2008). However, this and other descriptions of geographic distribution (Almeida et al. 1998; Henderson et al. 1995; Scariot et al. 1995) reflect the taxonomic disarray within the genus, since there is no consensus on the number of species, generating a bias in occurrence data. Vianna and Colombo (2013) conducted a survey on the geographical distribution of A. aculeata; however, for their database summary, they considered 29 species as synonyms, including A. media, which is recognized as a distinct species by the organizations cited in this work.

In Brazil, it occurs naturally in the following states: Bahia, Goiás, Mato Grosso, Mato Grosso do Sul, Maranhão, Minas Gerais, Piauí, Rio de Janeiro, São Paulo, and Tocantins. It is distributed in scattered areas of the Cerrado landscape such as cerradões and semi-deciduous forests (Almeida et al. 1998; Lorenzi et al. 2010).

Species studies are few, leaving doubts about its taxonomic classification. However, there are indications of high genetic diversity (Lanes et al. 2015; Oliveira et al. 2012) and natural populations with large phenotypic variability (Pires et al. 2013).

It is a diploid species (2n = 30), as described by (Röser et al. 1997), using microdensitometric of nuclei, and also by Abreu (Abreu et al. 2011), who detailed the karyotype with morphological characterization and determined the genome size as 2C = 5.81 pg, with base composition of AT = 58.3% and CG = 41.7%.

These palms are monoecious, with a mixed reproductive system, as verified in field experimentation (Scariot et al. 1995; Scariot et al. 1991) and by studies with microsatellite molecular markers (Abreu et al. 2012; Lanes et al. 2016). Flowering occurs between August and November and may extend until December. Usually, fruiting overlaps with this event and fruit drop occurs between June and March, with a peak in November (Scariot et al. 1995; Scariot et al. 1991).

Flowering follows the B multiple bang" model proposed by Gentry (1974), with isolated individual flowers blooming for a long period. At the population level, it follows the B cornucopia" model with a continuous offering of flowers throughout the flowering period (Scariot et al. 1991). The association of these two strategies with a long flowering peri- od in A. aculeata is beneficial in reproductive terms since it increases the potential number of individuals contributing to gene flow and it reduces selfing and decreases the risk of reproductive failure or absence of pollinators by adverse climatic conditions (Scariot et al. 1991).

The pollination of A. aculeata is mainly by beetles, particularly Andranthobius sp., Phyllotrox tatianae Voeks (1985) (Curculionidae), Mystrops sp. Erichson (1843), M. dalmasi Grouvelle (1902), M. debilis Erichson (1843) (Nitidulidae), and Cyclocephala forsteri Endrodi (1963) (Scarabaeidae) (Brito 2013; Scariot et al. 1991). According to Brito (2013), these beetles remain on the same inflorescence, from the moment of its opening until night. Furthermore, Apis mellifera Linnaeus (1758) and Trigona spinipes Fabricius (1793) are considered occasional pollinators because they collect pollen but rarely visit female flowers.

The second major pollinator is the wind, probably due to the palm’ s occurrence in open environments and in groups, coupled with their capacity of releasing a large number of pollen grains at once (Scariot et al. 1991). Xenogamy is the main reproductive system, but as the species is self-compatible, geitonogamy accounts for a significant percentage of fruit production (Brito 2013; Scariot et al. 1995; Scariot et al. 1991). There are also records of apomixis (Brito 2013).

Macaw palm has a high fruit productivity, approximately 62 kg per plant (Scariot et al. 1991) and generating over 25 tons per hectare (Motoike and Kuki 2009). Usually, there is one seed per fruit; however, sometimes two or even three seeds can be found (Scariot 1998).

In a survey for dispersers and predators of A. aculeata seeds (A. O. Scariot 1998), the following species were captured: Didelphis albiventris Lund (1840) (white-eared opossum), Nectomys squamipes Brants (1827) (water rat), Cebus apela Linnaeus (1758) (capuchin monkey), and Turdus sp. Linnaeus (1758). As these wild animals are small and not all of them consume the fruits, they were considered as possible dispersers. In South America, the fruits are consumed and the seeds dispersed by Tapirus terrestris Linnaeus (1758) (tapir) (Rumiz 2001) and Tapirus bairdii Gill (1865) (Mesoamerican tapir) (Cortez and Pérez 2010; Olmos 1997), but not always in areas favored for germination.

It is reported, although without a proper confirmation, that fruits are an important food source for Mazama americana Erxleben (1777) (red brocket deer) and M. gouazoubira G. Fischer (von Waldheim) (1814) (brocket deer) (Rivero et al. 2005). Anodorhynchus hyacinthinus Latham (1790) (hyacinth macaw) consumes the nut of the fruit (Silva 2015). Even though it does not effectively contribute to dispersal because it damages the seed, the hyacinth macaw can drop undamaged fruit as it transports them during its flight (Scariot 1998).

Some animals consume the fleshy fruit without eating the seed, such as Artibeus jamaicensis (bat) (Ortega and Castro-Arellano 2001), Ara ararauna (canindé macaw) (Santos and Ragusa-Netto 2014), Pecari tajacu, and Tayassu pecari (jawbone pecari) (Beck 2006). Wild groups of Cebus libidinosus (capuchin monkey) break the seeds and consume the nuts (Waga et al. 2006).

Local communities modestly commercialize products derived from this species, although they are progressively gaining greater prominence by organizing into cooperatives, among them are the following: Central do Cerrado Produtos Ecossociais, Cooperativa Grande Sertão, and Unidade de Beneficiamento do Coco Macaúba. Cosmetic utilization has developed on an industrial scale, e.g., by manufacture of hair products by companies such as Macaúba Brasil, Lola Cosmetics, and Biodivér.

Fruit of A. aculeata is emerging as promising for biodiesel production and the secondary production of charcoal used in filters for the steel industry. The interest in this species for biodiesel production is justified by its high fruit production, concentration, and quality of oil derived from pulp and nut (Evaristo et al. 2016; Lanes et al. 2016; Lopes et al. 2013; Motoike et al. 2013; Pires et al. 2013).

The palm species is still exploited in an extractive way from the wild, and the collecting of fruits is inefficient. There are also few industries operating, which leads to low productivity of products (Pires et al. 2013). In economic terms, a wide range of applications is described in Supplementary Material—Table S2.