Synopsis of Boraginaceae sensu lato in the Caatingas of the São Francisco River , Northeastern Brazil

Melo, J.I.M. 2015. Synopsis of Boraginaceae sensu lato in the Caatingas of the São Francisco River, Northeastern Brazil. Anales Jard. Bot. Madrid

The first formal taxonomic treatment was published by Candolle (1845) who recognized 17 genera to the family.Classic works that covered the family as a whole include Bentham andHooker (1873-1876), who distinguished 68 genera; Gürke (1893), who was the first author to divide the family into four subfamilies (Boraginoideae, Cordioideae, Ehretioideae and Heliotropioideae) and 21 genera; and Dalla Torre and Harms (1900) who followed the classification of Gürke (1893).Later on, the family was studied in different regions of the world, particularly in South America, and the works of Johnston (1928Johnston ( , 1930) ) amongst others expanded the knowledge of the taxonomy and geographical distribution of Boraginaceae s.l., especially of Cordia, Heliotropium and Tournefortia in this region.In Brazil, the most comprehensive treatment of Boraginaceae is still the monograph of the Flora Brasiliensis by Fresenius (1857Fresenius ( -1863)), which recognized nine genera.
According to Judd & al. (1999), Boraginaceae belongs to the order Solanales.However, according to Angiosperm Phylogeny Group (1998) and Angiosperm Phylogeny Group II (2003), Albach & al. (2001), Bremer & al. (2002) and Soltis & al. (2002), this family shows an uncertain position and therefore should not be included in an order with other families but rather constitute one on its own (Boraginales), as suggested by Böhle & Hilger (1997) and Gottschling & al. (2001).However based in molecular phylogenetic studies, according to the Angiosperm Phylogeny Group III (2009), Boraginaceae is placed in the core of Eudicotyledons, Euasterids I, within the Lamiids.
The current state of knowledge of the representativeness of Boraginaceae sensu lato, together with the biogeographic importance of the São Francisco River basin and the ecological interest of the Caatinga domain, suggests that a floristic update of that area may be useful.Thus a commented synopsis of the representatives of this family occurring in Northeastern Brazil, along the states of Pernambuco and Bahia, is presented, aiming to provide information on biogeographic aspects, and to a lesser extent in taxonomic aspects, including one new combination in the genus Myriopus Small.

Study Area
The São Francisco River source is in Serra da Canastra in the state of Minas Gerais, at an altitude of 1600 m.It runs some 2700 km to the northeast, covering a large part of this region, and has a great regional importance from an ecological, economical and social perspective.The hydrographical basin of the São Francisco River covers approximately 640,000 km 2 , extending over regions with humid, semiarid and arid climates.The basin is divided into four regions: Upper São Francisco, from the source to Pirapora, Minas Gerais state; Middle São Francisco, between Pirapora and Remanso, Bahia state; Lower-middle São Francisco, from Remanso to Cachoeira de Paulo Afonso and, Lower São Francisco, from Paulo Afonso, Bahia state, to the mouth, at the Atlantic Ocean.Many tributaries of the São Francisco River are permanent, as is the São Francisco itself (Fig. 1).The lower São Francisco basin is under a humid climate but it has tributaries that come from the semiarid and its vegetation is predominantly Cerrado and Atlantic Forest (Frigoletto, 2011).

Synopsis preparation
Comparative morphological analyses were conducted at the Botany Laboratory of the Department of Biology, Campus I, at the State University of Paraíba (UEPB) based on specimens deposited in the herbaria HVASF (Federal University of Vale do São Francisco foundation) and CPATSA (Brazilian Agricultural Research Corporation Semiarid), both located in the municipality of Petrolina, Pernambuco, Brazil.For the identification of the genera and species, local and regional flora and taxonomic revisions (Taroda & Gibbs, 1986a;1986b;1987;Förther, 1998) were consulted, in addition to the classic studies (Gürke, 1893;Johnston, 1928;1930).The studies of Melo & Sales (2004, 2005), Melo & Lyra-Lemos (2008), Melo & Semir (2008, 2010) and Cavalheiro & al. (2011) were also used.The vegetative and reproductive structures were characterized according to the works of Hickey (1973), Radford & al. (1974), Rizzini (1977) and Payne (1978).Author names of genera and species were verified in the Missouri Botanical Garden database (W 3 Tropicos, 2014) and in the Species List of Brazilian Flora online (Melo & al., 2014).Identification keys for separation of genera and species have been provided, and data on the distribution of the species are presented.The geographic distribution of the species was verified in Melo & al. (2010Melo & al. ( , 2014) ) and the ecological distribution was based on the specific literature cited above and specimens obtained in field works or examined in Brazilian herbaria (ASE, CPATSA, EAN, HST, HUEFS, HVASF, JPB, MOSS, PEUFR, UFC, UFG, UFP, UnB, R, RB).The herbaria abbreviations follow Thiers (2012).sometimes pyrenes or schizocarpous with 2 or 4 nutlets.1-2 seeds per locule; plane or curved embryo.
The genera Euploca and Myriopus were recently reestablished.Euploca includes the species belonging to Heliotropium sect.Orthostachys R. Br. and the genera Hilgeria Förther and Schleidenia Endl.and is defined by the following morphological and anatomical data: mericarpid or endocarpids structures with surface sculpturing described as "pits" (Diane & al., 2002a), kranz-chlorenchyma organization in leaves of almost all species, and the exclusive occurrence of characteristic trichomes that are on a pedestal of distinctly enlarged foliar epidermis cells (Diane & al., 2003).The recognition of the genus Myriopus is based on suggestions by Diane & al. (2002a) and includes the species circumscribed to Tournefortia sect.Cyphocyema I.M. Johnst.(Johnston, 1930).These are lianas with the following features: drupaceous deeply 4-lobed fruits with one seeded and 4-layered endocarpids, a thick tissue of transfer cells in the placenta region (Diane & al., 2002b), characteristic flowers with subulate corolla lobes and inflated bases of the corolla tubes, and involute corolla margins in the buds (Diane & al., 2003).

Representativeness and ecological distribution
In the studied area, five genera and 21 species were recorded: Cordia and Euploca, with five species each; Varronia, with four species and the genera Heliotropium and Myriopus represented by three species each.In the states of Bahia and Pernambuco, 13 and 14 species were found respectively, four of them occurring on both states (C.trichotoma, E. paradoxa, H. elongatum and V. leucocephala).Although these species have already been recorded for the flora of caatingas of the São Francisco River, comments on its geographical and ecological distribution are presented in this work.
However, some of these species have a wide ecological amplitude, e.g., E. polyphylla and E. procumbens are distributed in Brazil from the coastal line (Atlantic Ocean) to the semiarid region (Caatinga vegetation) and this same distribution pattern is found in Heliotropium angiospermum, H. elongatum and two Myriopus species (M.rubicundus and M. villosus).Myriopus salzmannii is found principally in areas of Caatinga vegetation.In Brazil, Cordia glazioviana, C. incognita and E. barbata are restricted to the Caatinga, C. incognita and E. barbata being endemic to this vegetation type.Regarding the Varronia species, V. curassavica, V. globosa and V. leucocephala are associated predominantly to open areas at the Caatinga vegetation while V. leucomalloides occurs also in open areas on Caatinga and Cerrado vegetation, only known to Brazil.
Distribution: Occuring in Cerrado and dry forests from the western part of Bahía to central Bolivia up to 500 m in elevation (Miller, 2013).In Brazil, it occurs in the Northeast and Central-West regions associated to Cerrado vegetation (Taroda, 1984).In the northeast region it can be found in areas of Caatinga in the states of Rio Grande do Norte (Taroda, 1984) and Alagoas and Sergipe (Melo & Sales, 2005).A. DC., Prodr. 9: 476 (1845).

Fig. 1 .
Fig. 1.Location of the São Francisco River and their tributaries, Brazil (map prepared by Jean P. Costa and Manoel Jeovani P. Costa).