A new species of Eriotheca (Malvaceae, Bombacoideae) from coastal areas in northeastern Brazil

Abstract A new species of Eriotheca (Malvaceae, Bombacoideae) from coastal areas in the northeastern Brazilian states of Alagoas and Bahia is described and illustrated. Eriothecaalversonii inhabits Atlantic coastal forest and is found principally on sandy soils in restinga vegetation. It is most similar morphologically to E.parvifolia. Both species have 3-foliolate leaves and short petioles on fertile branches, but the new species has smaller flowers, truncate to crenulate calyces, and smaller globose to subglobose capsules. The affinities of E.alversonii to morphologically similar species and its phenology are discussed. A distribution map and preliminary assessment of its conservation status are provided.

Molecular phylogenetic analyses place Eriotheca and Pachira Aubl. in a clade characterized by striate seeds Carvalho-Sobrinho et al. 2016), alternate eophylls, lack of prickles on trunks and branches, leaflets with brochidodromous venation (Carvalho-Sobrinho et al. 2016), and only two rows of ovules in the ovary (Franca et al. 2018). These analyses, however, also suggest that Eriotheca and Pachira as currently circumscribed are not monophyletic, and further molecular and taxonomic sampling is necessary to resolve the relationships between these two genera (Carvalho-Sobrinho et al. 2016). Until such sampling is completed, it would be premature to place Eriotheca in synonymy with Pachira and as a consequence new species have been described in both genera while maintaining their traditional circumscriptions Carvalho-Sobrinho 2013;Carvalho-Sobrinho et al. 2014b, 2015Macedo et al. 2018).
Eriotheca is characterized by mostly medium to emergent trees, leaves that are palmately compound with leaflets articulate at the petiole apex, flowers with a persistent calyx that is accrescent in fruit, a receptacle often with external nectaries, an androecium with 18 to 170 stamens and dorsifixed anthers, capsules with copious brown kapok, and numerous, striate seeds usually up to 1 cm in diameter (Robyns 1963). An underground xylopodium-like structure was reported for E. saxicola Carv.-Sobr. (Carvalho-Sobrinho 2013). Eriotheca flowers are pollinated by bees, bats or hawkmoths (Oliveira et al. 1992;Sazima et al. 1999;MacFarlane et al. 2003).
The taxonomy of Eriotheca is challenging because type specimens are often phenologically incomplete (cf. Robyns 1963) and affect species circumscriptions because it is difficult to match leaves, flowers, and fruit characters from different specimens (Carvalho-Sobrinho andQueiroz 2008, 2010;Carvalho-Sobrinho et al. 2013a, b, 2014a. Identification of Eriotheca specimens traditionally has relied largely on floral characters, especially the length of pedicels, flower bud shape, calyx shape and indumentum, petal shape, and staminal tube shape (Robyns 1963). More recently, micromorphological characters from leaves have been used to circumscribe and diagnose species Carvalho-Sobrinho et al. 2015) and to elaborate identification keys , although this innovation has limited applicability in fieldwork or herbarium research.
Ongoing studies on the systematics of Neotropical Bombacoideae (Carvalho-Sobrinho and Queiroz 2008Carvalho-Sobrinho et al. 2009, 2013a, b, 2014a, b, 2015, 2016Carvalho-Sobrinho and Dorr 2017) have revealed herbarium specimens of Eriotheca from the coastal Atlantic states of Alagoas and Bahia in northeastern Brazil that are noteworthy because their leaves and fruits are smaller than others in the genus. Careful study of these specimens has led to the recognition of a new species, which is described and illustrated here. Notes on this species' distribution and phenology, comments on morphologically similar species, and a preliminary assessment of its conservation status are provided.
Phenology. Flower buds in June and July, open flowers in August and September and mature fruits in October and December to February.
Distribution and habitat. Eriotheca alversonii is known from coastal vegetation mainly over quaternary white sand (restinga forest) or less frequently on clay-sandy soils in transitional vegetation between restinga forest and wet dense forest ("floresta ombrófila densa"), in the northeastern states of Alagoas and Bahia, Brazil.
Conservation status. Eriotheca alversonii is known from 19 collections from six different localities (municipalities). The extent of occurrence (EOO) of this species has been calculated to be 18,466 km 2 , which qualifies the species for the Vulnerable (VU) category, and the area of occupancy (AOO) was estimated to be 28 km 2 , which qualifies it for the Endangered (EN) category (Bachman et al. 2011;IUCN 2019). Based on herbarium specimen labels, three collections of E. alversonii were made inside one state-level protected Reserve (APA de Santa Rita) as explicitly stated in collectors' descriptions, and an additional four collections probably were made inside state-(APA Pratigi and APA Marituba do Peixe) or federal-level (Reserva Extrativista de Canavieiras) protected areas; nevertheless, all these protected areas allow sustainable use of natural resources and none of them are of the highest level of protection (level I or II) described by the IUCN (Dudley 2008). Furthermore, restinga habitat currently is being lost at an accelerated rate due to anthropogenic pressures (Rocha et al. 2007;Pergentino and Landim 2014) and most collections of E. alversonii were made on

Discussion
Eriotheca alversonii is characterized by leaves on fertile branches 1-3-foliolate, petioles up to 8 mm long, leaflets coriaceous, elliptic to broadly-elliptic or narrowly obovate, proximal leaflets up to 27 mm wide, flower buds linear-oblong, and small capsules globose to subglobose up to 21 mm long with glabrous valves. On herbarium sheets, specimens are characterized by terminal vegetative buds with attenuate, falcate apices and by leaves on fertile branches often 1-2-foliolate and often reddish-brown on the abaxial surface.