Additions to the genus Lessingianthus ( Asteraceae , Vernonieae ) from South America

Two new species of Lessingianthus (Asteraceae: Vernonieae) are described and illustrated. One of these, L. foliosus Dematt., bears a resemblance to L. vepretorum, but can be separated from it by its linear leaves, that are lanate on the abaxial surface, and by its shorter internodes. The other new species, L. lapinhensis Dematt., can be easily separated from L. brevifolius and other taxa of the genus by the combination of stems 8-18 cm tall, glabrous linear leaves and campanulate involucres. Thirteen other taxa previously described as Vernonia are transferred to the genus Lessingianthus and two lectotypes are designated here.

This group can be distinguished from the remaining American members of the tribe by its eglandular anther appendages, lack of basal style node and quadrate raphids in the achene wall (Robinson 1999).The genus is distinguished also by the surface morphology of the pollen grains and the basic chromosome number.The pollen grains have been called type "B" by Keeley & Jones (1979) and they are tricolporate, echinolophate, with a discontinuous tectum, very long germinal furrows that converge at the poles and lacunae distributed in a regular pattern but lacking a polar lacuna (Dematteis & Pire 2008).The basic chromosome number of the genus is x=16, differing from the majority of the American Vernonieae with a base number of x=17 (Dematteis 2002).
Following the segregation of Lessingianthus (Robinson 1988), the only modification has been the transference of Lessingianthus subgen.Oligocephalus H. Rob. to the genus Chrysolaena H. Rob.(Dematteis 2007).Nevertheless, several species still included in Vernonia have not been examined and consequently their taxonomic Rodriguésia 61(2): 233-241.2010 position remains uncertain.In this paper, two new species are described and thirteen taxa previously placed in Vernonia are transferred to Lessingianthus.

Materials and Methods
This study was based on morphological analysis of specimens deposited at BA, BCN, BM, BR, C, CTES, CESJ, ESA, F, FCQ, G, G-DC, HBR, ICN, K, L, LIL, LP, LPB, MBM, MNES, NY, P, PACA, R, S, SI, SP, SPF, UEC, US, USZ and W (Holmgren et al. 1990).The terminology applied for the description of the species in general follows Robinson (1988) and Dematteis (2007).The line drawings were realized under camera lucida with a Leica MZ6 stereo microscope using herborized specimens.The abbreviations used for authors' names are those recommended by Brummit & Powell (1992).Journal abbreviations are from Botanico Periodicum Huntianum (Lawrence et al. 1968) and book abbreviations are from the many volumes of Taxonomic Literature, edition 2 (Stafleu & Cowan 1976-1988).
Pollen samples were obtained by removing one or two florets from herbarium specimens of the species.The pollen grains were acetolysed according to the procedure suggested by Erdtman (1966).For light microscopy (LM) the pollen samples were mounted in glycerine-jelly on glass slides and then examined with a Zeiss Axioplan microscope.Permanent slides were deposited at the Palynological Laboratory of the Universidad Nacional del Nordeste (PAL-CTES).For scanning electron microscopy (SEM), acetolysed pollen grains were firstly washed in 96º alcohol and absolute alcohol, next sputtered with gold-palladium and then observed in a JEOL 5800 LV scanning electron microscope.The terminology applied for pollen grain description in general follows Keeley & Jones (1979).Folia linearia,[15][16][17][18][19][20][21][22][23][24][25]coriacea,pedunculata,
This taxon was initially determined as a new species by Glaziou in herbarium specimens deposited at P, but it remained unknown until the author published (posthumously) the Plantae Brasiliae centralis a Glaziou lectae (Glaziou 1909(Glaziou -1910)).In this article, the author listed all the species of Asteraceae from central Brazil, including also Vernonia paulensis.This name was also included in the Supplement IV of Index Kewensis (Prain 1913), but the name was published without a validating description, according to the International Code of Nomenclature (McNeil et al. 2006).A detailed examination of the specimens collected by Glaziou showed that they constitute a hitherto undescribed species belonging to the genus Lessingianthus.
The new species appears to be closely related to Lessingianthus brevifolius (Less.)H. Rob. by the shape and distribution of the leaves, but it differs mainly in having hemispherical involucres, leaves lanate on the abaxial surface, 40-50 florets per capitulum and corollas 14-15 mm long, amongst others features.It is only known from southwestern Minas Gerais in the Serra do Cipó.It grows on the campo rupestre habitats, which possesses rocky and sandy soils occupied by shrubby savannas and grasslands.In Brazil, this habitat is especially represented in the Serra do Espinhaço and associated ranges in Minas Gerais, the Chapada Diamantina in Bahia, and the Serra Geral in Goiás (Oliviera-Filho & Ratter 2002).Among the species of the genus, it seems to be closely related to L. glabratus (Less.)H. Rob., from which it can be distinguished by the capitulum size and the phyllary shape.Lessingianthus constrictus possesses larger capitula and the phyllaries are notably caudate at the apex.Lessingianthus hystricosus (Cabrera & Dematt.) Dematt., comb. nov. Vernonia hystricosa Cabrera & Dematt., Candollea 54: 103. 1999 4.II.1994, fl., C. Saravia Toledo 12309 (CTES).Jones (1982) considered this species a subspecies of Vernonia asteriflora.However, both taxa have strong morphological differences and different geographic distribution.Lessingianthus kuntzei is distributed in southern Bolivia, between 1400 and 3500 m, while L. asteriflorus grows in eastern Paraguay and southern Brazil.The first taxon has lanceolate leaves, glabrous above and acute at the apex, while L. asteriflorus possesses oblanceolate to obovate leaves, lanate above and apically obtuse.This species resembles Lessingianthus niederleinii (Hieron.)H. Rob. with similar capitulum shape and inflorescence pattern, but it differs in the shape, distribution and size of the leaves, in addition to the plant being taller than the other species.This species is closely related to Lessingianthus glabratus, but can be separated by the shape of leaves and the outer phyllaries.Lessingianthus teyucuarensis possesses widely obovate leaf blades and ovate phyllaries, while L. glabratus has narrowly lanceolate leaves and lanceolate to ovate-lanceolate phyllaries.Lessingianthus constrictus differs in having constricted phyllaries and lanceolate leaves.

Lessingianthus laniferus
Thanks to Nicholas Hind (Royal Botanic Gardens, Kew).The line drawings were prepared by Mirtha Liliana Gómez from the Instituto de Botánica del Nordeste (Argentina).This work has been supported by grants from the Consejo Nacional de Investigaciones a b Científicas y Técnicas (CONICET) and the Secretaría General de Ciencia y Técnica of the Universidad Nacional del Nordeste, which are greatly appreciated.