Amaioua longipedicellata (Rubiaceae, Gardenieae), a new species from the Brazilian Atlantic coast

Background – Ongoing studies of Brazilian Rubiaceae revealed an undescribed species of Amaioua endemic to Atlantic Forest (Restinga and Semideciduous forest) of the state of Bahia, which is here described and illustrated, and its morphological characters are discussed and compared with those of similar species. Methods – This study is based on examinations of herbarium specimens, samples preserved in 60% ethanol, field observations, and digital images. Herbarium specimens of the CAY, CEPEC, HBR, IBGE, K, MBM, NY, RB, U, UB, UFG, and US herbaria were directly studied. Additional images of herbarium specimens were studied online. Results – Amaioua longipedicellata Delprete & J.G.Jardim is here described, illustrated and compared with the two most similar species, i.e., A. glomerulata (Lam. ex Poir.) Delprete & C.H.Perss. and A. intermedia Mart. A table comparing the morphological characters of these three species, and an appendix with selected specimens studied of A. glomerulata and A. intermedia are included.


INTRODUCTION
According to several phylogenetic studies using morphological and molecular data (Persson 1996, 2000a, 2000b, Andreasen & Bremer 1996, Bremer & Eriksson 2009, Mouly et al. 2014) the tribe Gardenieae, as traditionally recognized, is paraphyletic, and its Neotropical genera are found in three groups: (1) Alibertia group, (2) Randia group, and (3) Genipa, positioned in a clade of mostly Paleotropical genera. Mouly et al. (2014), according to the molecular phylogenies obtained, described the new tribe Sherbournieae (where they included the Paleotropical genera Atractogyne Pierre, Mitriostigma Hochst., Oxyanthus DC., and Sherbournia G.Don), and resurrected the tribe Cordiereae, which corresponds to the Alibertia group. However, Persson & Delprete (2017) considered that in the phylogenies of Mouly et al. (2014) the resolution between the two groups is low, and treated the formal recognition as tribes as premature; therefore, they preferred to call the latter ensemble of genera the Alibertia group, a delimitation and a name that is here maintained.
The molecular phylogenetic analyses of Cortés-B. et al. (2009) and Mouly et al. (2014) showed that the Alibertia group includes 12 genera. Persson & Delprete (2017) confirmed the same number of genera, and esteemed that the group includes about 110 species. In their monographic treatment of the Alibertia group, they provided an expanded discussion of the morphological features, phenology and ecology of the taxa of the group, along with the first part of the taxonomic revision, namely the genera Agouticarpa C.H.Perss., Alibertia A.Rich., Cordiera A.Rich., Melanopsidium Colla, Riodocea Delprete, and Stenosepala C.H.Perss.
Delprete & Jardim, Amaioua longipedicellata (Rubiaceae), a new species from Brazil Amaioua Aubl. (Aublet 1775) and Duroia L.f. (Linnaeus 1782) are unique within the Alibertia group, in having stipules as a conical apical cap, readily caducous, or rarely remaining on the stem and splitting on one side; these two genera are quite similar to each other and are frequently confused. They have been traditionally separated by the number of flowers per female inflorescence, although with overlapping ranges, being with 1-3(-5) flowers in Duroia, and with (1-)2-7 flowers in Amaioua (e.g. Steyermark 1974Taylor et al. 2004, Delprete 2010, Persson & Delprete 2017. In the molecular phylogenies of Persson (2000aPersson ( , 2000b, Amaioua and Duroia were found on a strongly supported clade, the former, represented by a single species, nested within the latter. Since the name Amaioua has priority over Duroia, if the two genera will eventually be treated as synonymous, the previous name is the one to be adopted. For the purpose of this study, we maintain the two genera separated and as currently delimited. Ongoing studies of Brazilian Rubiaceae revealed an undescribed species of Amaioua, with fasciculate, 2-3-flowered, or rarely trichotomous, 3-9-flowered female inflorescences, and oblong-elliptic, 1.2-2.2 cm long berries, differing from similar species by the thin, long pedicels, among other characters. This new species is endemic to Restinga vegetation and semideciduous seasonal forest (Mun. Jequié) of the state of Bahia, coastal Brazil.
Restinga vegetation occurs on sandy deposits present along the Atlantic coast of Brazil, which accumulated during the Quaternary Period, when the sea level went through considerable fluctuations. Restinga is characterized by sandy or clay-sandy soils, poor in nutrients. Two main types are recognized: shrubby Restinga ("Restinga arbustiva") and arboreal Restinga ("Restinga arborea"). Arboreal Restinga, where the present new species is found, is a forest formation composed by dense small trees and with a closed canopy (Thomas & Barbosa 2008). It is an edaphic formation related to the sandy Quaternary lowlands located between the sandy beaches and the first slopes parallel to the coast (Vinha et al. 1976).
Semideciduous seasonal forest is a vegetation type occurring in the transitional zone present between the Atlantic Forest and the Caatinga Biome. It is characterized by a well-marked dry season (winter season) and an intense rainy season (summer season). During the drastic dry season, a considerable portion of the trees (between 20% and 50% of the species) lose their leaves (Veloso et al. 1991). It is characterized by sandy-clay soils. According to Vinha et al. (1976), this forest is composed by dense patches of small trees averaging 10-12 m in height. According to the latter authors, this vegetation is strongly threatened by aggressive cattle ranching, which represent the principal cause of the disappearance of its last remnants.

MATERIAL AND METHODS
This study is based on examinations of herbarium specimens, samples preserved in 60% ethanol, field observations, and digital images. Herbarium specimens were studied either by visiting and/or through loans from the CAY, CEPEC, HBR, IBGE, K, MBM, NY, RB, U, UB, UFG, and US herbaria.

A. glomerulata A. intermedia A. longipedicellata
Leaf secondary veins on each side of midrib 6-10 (4-)5-7(-9) 5-8    Habitat, ecology and phenology -This species grows in semideciduous seasonal forest and Restinga forest ("Restinga arborea-arbustiva"), commonly on white sand or sometimes on clay-sandy soil, or in transitional vegetation between Restinga forest and wet dense forest ("Floresta Ombrófila densa"), or in disturbed vegetation with selective logging and/or for the extraction of piassava palm (Attalea funifera Mart.); at 10-560 m altitude. Flowering specimens were collected in January, April, November and December. Specimens with immature fruits were collected in January, February, May, September and November, and with mature fruits in February, April and May. Etymology -The specific epithet refers to the long, thin flower pedicels, which further elongate in the fruiting stage. Conservation assessment -Vunerable (VU), B1 a, b(i, ii, iii). The extent of occurrence (EOO) of this species has been calculated to be 13 318 km 2 , which qualifies the species for the Vulnerable (VU) category, and the area of occupancy (AOO) was estimated to be 48 km 2 , which qualifies it for the Endangered (EN) category (Bachman et al. 2011;IUCN 2012IUCN , 2017. Although three collections of Amaioua longipedicellata were made inside the Mico-Leão Biological Reserve, which is part of the Una Reserve, most collections were made in disturbed vegetation or inside large farms, within the Restinga vegetation domain, along the Atlantic coats of the state of Bahia, Brazil. The species is known by 19 collections, but only from 10 localities (municipalities). It is extremely rare to find intact Restinga forest, and the few remnants are extremely scattered, as this vegetation is strongly impacted by numerous human activities, as selective logging, agriculture, housing construction, and extraction of piassava palm (Attalea funifera Mart.) for the production of fiber. Piassava extraction is commonly believed to be a non-timber forest product that could provide a commercial product with a minimum impact of the surrounding vegetation. However, this extraction is instead often accompanied by the almost complete obliteration of the surrounding vegetation, resulting in large areas where the natural vegetation has almost completely been destroyed and with sparse individuals of this palm on nearly denudated slopes of the Restinga biome. Therefore, due to the scattered areas still preserved in the region, and the rapid rate of deforestation of the much fragmented Restinga vegetation and semi-deciduous seasonal forests in the state of Bahia, we consider this species as Vulnerable [VU B1 a, b(i, ii, iii)] according to IUCN criteria (IUCN 2012(IUCN , 2017. Notes -Amaioua longipedicellata is also similar to A. intermedia Mart. by the subcoriaceous leaf blades, trichotomous male inflorescences, fasciculate female inflorescences (rarely trichotomous in A. longipedicellata), pedicellate male and female flowers, and pedicellate fruits; the former differs from the latter by the inflorescences with a thin rachis (vs. stout), male inflorescences commonly 3-9-flowered, each branch ending with a 1-3-flowered cymules (vs. 10-35-flowered, each branch ending with a 3-15-flowered cymule), female inflorescences fasciculate, 2-3-flowered, or rarely trichotomous, 3-9-flowered, each branch ending with a 1-3-flowered cymule (vs. fasciculate, 5-9-flowered), calyx with linear lobes (vs. truncate or undulate), male corollas 11-12.5 mm long, tube 6.5-7 mm long, lobes 4-5.5 mm long (vs. 16-22 mm long, tube 8-10 mm long, lobes 8-12 mm long), female corollas 10.5-13.5 mm long, tube 5.5-7 mm long, lobes 5-7 mm long (vs. 17-23 mm long; tube 8-9 mm long; lobes oblong-lanceolate, 9-14 mm long), fruits oblong-ellipsoid, 1.2-2.2 × 0.7-1 cm, with pedicels thin, 25-40 mm long (vs. oblong to ellipsoid, 2.5-3.5 × 0.8-1.1 cm, with pedicels stout, (2.5-)3-22 mm long). A comparison of morphological characters of Amaioua glomerulata, A. intermedia and A. longipedicellata is pre-sented in table 1. Characters and measurements of these three species are based on observations of specimens from throughout their ranges. Selected herbarium specimens of Amaioua intermedia and A. glomerulata analyzed for this study are reported in appendix 1.