A synopsis of Galianthe ( Rubiaceae ) in Rio Grande do Sul , Southern Brazil , and a new endemic species from Serra Geral

irteen species of the genus Galianthe have been recorded for state of Rio Grande do Sul, Brazil. e species are distributed among seven biomes, one of which contains all thirteen taxa–Subtropical Seasonal Forest. Herein a new endemic species, G. riograndensis J. Florentín & E.L. Cabral, is described, illustrated and di erentiated from all other species of the genus by having 3-4 verticillate leaves and a long bi d style. In addition, the pollen grain morphology and the seed micromorphology of the new species are described and illustrated, and the conservation status assessed according to IUCN criteria. Moreover, G. chodatiana is recorded for the rst time from the state, and a lectotype for G. equisetoides is designated. Most of the species of Galianthe are described and illustrated with detailed photos of living specimens. A taxonomic key for species identi cation, as well as comments on distribution, overall phenology and habitat, are also presented. e distribution of the new species is discussed in the context of the biogeographic region of the state, and maps and a table of species by biome are also provided.


Introduction
Recent molecular phylogenetic studies have demonstrated that Galianthe (Rubiaceae) belongs to the Spermacoce clade (Kårehed et al. 2008;Salas et al. 2015), is monophyletic and is most closely relate to Carajasia and Schwendenera, with both sharing the presence of pollen grains with a double reticulum (Salas et al. 2015).e genus is Neotropical, with the exception of a single taxon living in Mesoamerica (G.brasiliensis subsp.angulata), is widespread in South America (Cabral & Bacigalupo 1997;Cabral 2009), with the majority of species occurring in Brazil (37 species).e species occur in campos rupestres (quartzitic rock outcrops), cerrado (savanna), low land grasslands, campos de altitude (highland grasslands), caatinga vegetation (seasonaly dry tropical forests) and savanna hillsides; in lateritic, sandy soils or with rock outcrops.Exceptionally, there are some shade-loving species, which occur in the understory of forests and woodlands, such as G. hispidula, G. brasiliensis, and G. laxa (Cabral & Bacigalupo 1997;Cabral 2009;Cabral & Salas 2015;Carmo et al. 2016).Galianthe comprises 50 species grouped in two subgenera: Galianthe subg.Galianthe, with 40 species, and Galianthe subg.Ebelia, with 10 species (Cabral & Bacigalupo 1997;Cabral 2009).In oristic surveys of Rio Grande do Sul, Rambo (1962) and Porto et al. (1977) recorded 10 and 7 species of Galianthe, respectively, for the state, under Borreria and Diodia, generic names linked to Galianthe based principally on fruit dehiscence.Galianthe di ers from the remaining genera of the Spermacoce clade by having an erect habit generally with xylopodium, distylous owers arranged in lax thyrsoid in orescences, plump or complanate seeds with wing-like margins, pollen with a double reticulum, and a basic chromosome number of x=8 (Cabral 2009).
Since new data regarding this genus has become available for Rio Grande do Sul, and because previous taxonomic revisions and regional checklists have become outdated (Rambo 1962;Porto et al. 1977;Cabral 2002), an updated taxonomy of Galianthe is needed.
As a result of taxonomic studies of the tribe Spermacoceae for the Flora do Brasil 2020, a new species, Galianthe riograndensis, was recognized.erefore, the aims of the present study are to: present an illustrated morphological description and a conservation assessment for the new taxa.
e new species is also included in an identi cation key for all species of Galianthe recorded in the state of Rio Grande do Sul, along with maps, tables, and comments about the geographic distribution and habitats of the species.

Materials and methods
Descriptions were made by analyzing live specimens and herbarium material from the collections deposited at the herbaria B, BR, CRI, CTBS, CTES, EAC, FLOR, FUEFS, FUEL, FURB, HAS, HBR, HDCF, HPL, HUCS, HVAT, IAC, IBGE, ICN, INPA, JOI, K, LIL, MBM, MO, MPUC, MVFA, NY, P, PACA, R, RB, SI, SP, UB, UEC [acronyms according to iers ( 2017)].Additionally, databases of Lista de Espécies da Flora do Brasil and Missouri Botanical Garden were consulted.Distribution, habitat, details of ower or fruits, and phenological data were recorded from specimen labels and eld observations.In order to illustrate features or structures not or poorly shown in previous literature, a detailed photographic record of diagnostic vegetative and oral features was made (except for Galianthe riograndensis J. Florentín & E.L. Cabral and G. verbenoides (Cham. & Schltdl.)Griseb.).Vegetative and reproductive characters were measured on living and pressed specimens using a digital caliper.To analyze the distribution of species by biome, specimens were georeferenced using Google Earth (2015) and plotted in DIVA-GIS (Hijmans 2013).We followed the classi cation of the vegetation of Southern Brazil proposed by Iganci et al. (2011), who modi ed the classi cation of Leite (2002).
Pollen grains of Galianthe riograndensis were acetolyzed according to Erdtman (1966) and mounted in glycerine jelly for analysis by light microscopy (LM).Conventional parameters (P = polar axis, E = equatorial axis) of at least 20 grains were measured under LM, and the exine was analyzed using scanning electron microscopy (SEM).Seeds were also analyzed using SEM.For SEM analyses, seeds and acetolyzed pollen grains were sputter-coated with gold, and then photographed with a Jeol 5800 LV SEM (scanning electron microscopy service of the SGCyT-UNNE, Corrientes, Argentina).Pollen terminology follows Punt et al. (2007) and seed terminology follows Stearn (1986).
Conservation status was assessed according to IUCN criteria (2001).e extent of occurrence (EOO) and the area of occupancy (AOO) were estimated using GeoCAT (Bachman et al. 2011).
Subshrubs, erect or decumbent, exceptionally scandent, with or without xylopodium; stems winged or not, glabrous or pubescent.Stipular sheath with 1-multi mbriate margin, covering part of the internode above the corresponding leaf pair or at the same level of the leaf pair.Leaves opposite, frequently pseudo-verticillate, sessile; leaf blades entire, chartaceous or coriaceous.Inflorescences thyrsoid, cymose or partial in orescences in dichasium more or less condensed, fascicles or heads; in the main and/or secondary branches.Flowers 4-merous, actinomorphic, distylous, the short-styled owers (SS owers) slightly larger than the long-styled owers (LS owers); calyx 4-lobated, rarely 2, with intercalary teeth between lobes, sometimes colletertipped; corolla infundibuliform or campanulate, white, exceptionally pale pink or lilac, internally with moniliform hairs with the same or di erent arrangement between both oral morphs; stamens 4, laments of variable length in SS owers and LS owers, anthers dorsi xed; nectariferous disk entire or 2-lobed; ovary 2-locular, each locule 1-ovulate; style with bi d stigma.Capsule septicidal with dehiscent or indehiscent valves.Seeds plump or dorsoventrally attened, winged, with strophiole on the ventral face, persistent or caducous.

Distribution of species
Regions of greatest concentration, diversi cation and endemism of species of Galianthe are in Brazil, especially in the Brazilian cerrado, with 37 taxa, 21 of which are endemic (Cabral 2002;Flora do Brasil 2020).In the state of Rio Grande do Sul there are 13 species of which only one is endemic.e species described herein, G. riograndensis, is from the Reserve "Ibicuí-Mirim" in Santa Maria.Some species occur in restricted areas of the Southern Region of the country, such as G. latistipula (states of Rio Grande do Sul and Santa Catarina), and G. verbenoides and G. chodatiana (states of Rio Grande do Sul, Santa Catarina and Paraná), while the remaining species have wider distributions.
Distribution, habitat, and phenology: Galianthe riograndensis is known only from "Reserva Biológica do Ibicuí Mirim", located on the border between the municipalities of São Martinho da Serra and Itaara, in the southern region of Serra Geral, in the southern highlands of Brazil (state of Rio Grande do Sul).is species inhabits the geographic center of the state in an ecotonal region composed of hillsides with basaltic rocky elds and seasonal forest.Flowering occurs from October to February, and fruiting from March to June.
Etymology: e epithet "riograndensis" refers to the distribution of the species in the state of Rio Grande do Sul and to it being endemic to the state.
Conservation status: According to IUCN criteria (IUCN 2012) Galianthe riograndensis should be classified as endangered [EN B2ab(ii,iii)].e extent of occurrence (EOO) is calculated to be 15237 km 2 , and the area of Javier Elías Florentín, Mariela Nuñez Florentin and Elsa Leonor Cabral      4A-F (For synonymy and commentaries about the types see Cabral & Bacigalupo 1997).
Distribution, habitat, and phenology: Brazil (PR, SC, and RS).Frequently found in open grasslands between 700-900 m.Flowering from October and fruiting from January to February.
Observations: Recorded only for the states of Paraná and Santa Catarina, Brazil.From recent collections and study of additional herbarium material, this species is now reported for the rst time from the state of Rio Grande do Sul, extending its distribution to southern Brazil.Leaves pseudoverticillate, with leafy brachyblasts, leaf blades elliptic, 15-60 × 6-20 mm, pilose, scaberulous or subglabrous on both adaxial and abaxial surfaces, 3-5 pairs of secondary veins.In orescense cymose, dichasial to monochasial, with partial in orescences congested on main and secondary branches.Flowers with obconic, glabrous hypanthium; calyx 4-lobed; corolla externally micropapillate, internally with two rings of moniliform hairs, one in corolla tube and other with thick hairs on base of corolla lobes; SS ower with corolla 4-5.2 mm long; LS ower with corolla 3-7.5 mm long.Capsule 2.5-3.5 mm long, with indehiscent valves.Seeds 2 mm long, with strophiole partially covering the ventral surface.
Distribution, habitat, and phenology: Southern Brazil (PR, SC, and RS), Paraguay, Uruguay, and Argentina.is species grows in lowlands, marshy soils, and shore side of inland bodies of freshwater.Flowering from September to May.
Observations: We corroborate that the material recorded and analyzed as Diodia cymosa (Galianthe cymosa) in Rambo (1962) and Porto (1977)  Observations: Cabral (2009) designated a neotype for Borreria equisetoides, basonym of this species, assuming that the specimen of Sellow s.n, mentioned in the protologue was deposited in the herbarium B and was destroyed.However, currently the database of JSTOR possesses a digitalized specimen of Sellow s.n deposited in the HAL herbarium, which is here designated as lectotype.It should be noted that this specimen is sterile, nonetheless the stem possesses contractile nodes, linear leaves and inconspicuous secondary veins, all of which are diagnostic characters that diferentiate Galianthe equisetoides.
Distribution, habitat and phenology: Brazil (RS and SC), Argentina, eastern Paraguay and Uruguay.It is common in sandy and rocky soils, in palm groves of Butia and roadsides.Re-grow after burning.Flowering from October to February, fruiting from March to June.

Figure 6 :
Figure 6: A-E: G. equisetoides.A: Habit.B: Detail of the stipular sheath.C: Apical portion of the plant, with in orescences.D: Detail of a SS ower.E: Detail of a LS ower.F-K: G. fastigiata.F: Ambient.G: Habit.H: Detail of the stipular sheath.I: Detail of SS owers.J: Detail of LS owers.K: Detail of fruits.

Figure 7 :
Figure 7: A F: Galianthe hispidula.A: Ambient.B: Habit.C: Details of the stolons.D: Detail of a ower with a pollinator.E: Detail of a LS ower.F: Detail of the stipular sheath.G-J: G. latistipula.G: Ambient.H: Habit.I: Detail of the stipular sheath.J: Detail of an in orescence.

Figure 8 .
Figure 8. A-E: G. laxa.A: Ambient.B: Habit.C: Detail of the stipular sheath and the abaxial surface of the leaf.D: Detail of LS owers.E: Detail of SS owers F-K: G. thalictroides.F: Ambient.G: Habit.H: Detail of a portion of the stem and xylopodioum.I: Portion of a branch.J: Detail of the stipular sheath.K: Detail of the dehiscent fruits.

A
Figure 9. A-G: G. valerianoides.A: Ambient.B: Habit.C: Detail of the xylopodium.D: Detail of the abaxial surface of leaves.E: Detail of node, showing the leaves, brachyblasts, and stipular sheath.F: Detail of SS owers.G: Detail of LS owers.

synopsis of Galianthe (Rubiaceae) in Rio Grande do Sul, Southern Brazil, and a new endemic species from Serra Geral
recognized ten di erent phytoecological units and three transitional vegetation areas based on geology, terrain, climate, and soil.Iganci et al. (2011) modi ed the A

synopsis of Galianthe (Rubiaceae) in Rio Grande do Sul, Southern Brazil, and a new endemic species from Serra Geral
mbriae.