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Considering the progress of the Flora Vascular de la República Argentina project, we introduce the first interactive, multi-access key to the angiosperm families of the Argentinian Flora. The key is an open resource, built under Lucid ™ software, and available through the Flora Argentina site (https://clave.floraargentina.edu.ar/), with an on-line form for the user’s suggestions. We explain the advantages of multi-access keys versus dichotomous keys, briefly describe how the key was built, and how Lucid tools can be applied (Spanish version) for a better use of the key.

Tillandsia subgenera Diaphoranthema and Phytarrhiza s.s. are closely related epiphytic and epilithic plants adapted to xeric habitats in the Americas. Several studies suggested that subgenus Diaphoranthema and the xerophytic species of subgenus Phytarrhiza should not be segregated into different subgenera. In recent phylogenetic analyses of Tillandsioideae, subgenus Phytarrhiza s.l. is revealed as highly polyphyletic, showing a xerophytic lineage closely related to subgenus Diaphoranthema. Moreover, the evolution of neotenic traits, a selfing breeding system and polyembryony have yet to be fully investigated in a phylogenetic context. Infrageneric classifications and phylogenetic relationships were inferred using the plastid matK-trnK and nuclear ETS markers and morphology. Phylogenetic analyses of individual and combined molecular data sets were performed under parsimony and Bayesian inference. Our results confirm subgenus Diaphoranthema as monophyletic if three xeric species of subgenus Phytarrhiza are included. In subgenus Diaphoranthema, aggregates Loliacea and Rectangula were recovered as monophyletic, whereas Myosura was paraphyletic and Caliginosa, Capillaris and Recurvata were polyphyletic. Alternative groupings and morphological trends are discussed. Analysis of morphological characters associated with heterochrony indicates that neoteny may not be the only paedomorphic process in the evolution of this group. Furthermore, paedomorphosis would occur in some vegetative structures, inflorescences and flowers, whereas some fruit and seed traits could be modified by peramorphosis.

Fil: Brignone, Nicolas Fernando. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Botanica Darwinion. Academia Nacional de Ciencias Exactas, Fisicas y Naturales. Instituto de Botanica Darwinion; Argentina

Congruence among different sources of data is highly desirable in phylogenetic analyses. However, plastid and nuclear DNA may record different evolutionary processes such that incongruence among results from these sources can help unravel complex evolutionary histories. That is the case of Nassauvia subgenus Strongyloma (Asteraceae), a taxon with five putative species distributed in the southern Andes and Patagonian steppe. Morphometric and phylogeographic information cast doubt on the integrity of its species, and previous molecular data even questioned the monophyly of the subgenus. We tested those questions using plastid and nuclear DNA sequences by the application of different methods such as phylogenetic trees, networks, a test of genealogical sorting, an analysis of population structure, calibration of the trees, and hybridization test, assembling non-synchronous incongruent results at subgenus and species levels in a single reconstruction. The integration of our molecular analyses and previous taxonomic, morphological, and molecular studies support subgenus Strongyloma as a monophyletic group. However, the topology of the nuclear trees and the evidence of polyploids within subgenus Nassauvia, suggest a hypothetical origin and initial radiation of Nassauvia related to an ancient hybridization event that occurred around 17–6.3 Myr ago near the Andes in west-central Patagonia. Plastid data suggest a recent diversification within subgenus Strongyloma, at most 9.8 Myr ago, towards the Patagonian steppe east of the Andes. These processes cause phylogenies to deviate from the species tree since each putative species lack exclusive ancestry. The non-monophyly of its species using both plastid and nuclear data is caused mainly by incomplete lineage sorting occurred since the Miocene. The final uplift of the Andes and PliocenePleistocene glacial-interglacial and its consequences on the landscape and climate structured the genetic composition of this group of plants in the Patagonian steppe. The molecular data presented here agree with previous morphological studies, in that the five putative species typically accepted in this subgenus are not independent taxa. This study emphasizes that adding more than one sequence per species, not combining data with dissimilar inheritance patterns without first performed incongruence tests, exploring data through different methodologies, considering the timing of events, and searching for the causes of poorly resolved and/or incongruent phylogenies help to reveal complex biological underlying processes, which might otherwise remain hidden. Fil: Nicola, Marcela Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Johnson, Leigh. University Brigham Young; Estados Unidos Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

The Calyceraceae (47 spp.) is a small family of plants that is sister to the Asteraceae (∼ 25,000 spp.), one of the largest families of angiosperms. Most members of Calyceraceae are endemic to the Andes and Patagonia, representing an excellent model within which to study diversification patterns in these regions. The single phylogenetic study of Calyceraceae conducted to date revealed that the boundaries of most genera and several species of this family require further analyses, especially the “Nastanthus–Gamocarpha” clade. In this study, we reconstructed the phylogeny of the “Nastanthus–Gamocarpha” clade using multispecies coalescent models under BPP and StarBeast2 programs, sampling 63 individuals from 13 of the 14 species recognized to date. We then used this phylogenetic framework to delimit species using BFD and the A11 method implemented in BPP. Species limits suggested through a coalescent approach were then re-evaluated in the light of morphology, geography, and phenology. Coalescent-based methods indicated that most putative lineages could be recognized as distinct species. Morphological, geographical, ecological, and phenological data further supported species delimitation. Necessary taxonomic changes are proposed. Namely, the paraphyletic Nastanthus is synonymized under Gamocarpha, while five species of Boopis are transferred into Gamocarpha. We used an integrative taxonomic approach to recognize 13 species and one subspecies within the newly circumscribed genus Gamocarpha. Fil: Denham, Silvia Suyai. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Brignone, Nicolás Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Johnson, Leigh. University Brigham Young; Estados Unidos Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

We describe and illustrate Mastigostyla coronata, a new species of Iridaceae from the high Andes of Jujuy (Argentina), morphologically similar to Mastigostyla vargasii. The inclusion of this new species in Mastigostyla is supported by a phylogenetic analysis based on plastid markers. We also present a morphological comparison among the sub-acaulescent species of Mastigostyla (including Cardenanthus), and a key to those species.

Valeriana serratifolia, a new species from the Andean region of northwestern Argentina, is described and illustrated. It can be distinguished from its closest morphological taxon, V. macrorhiza, by its entire, spathulate leaves with serrulate margin, and falcate fruits, 2–2.5 mm long, crowned by the reduced annular calyx shifted toward the ventral face. A phylogenetic analysis based on DNA sequences of plastid markers trnL-F and trnK intron supported V. macrorhiza as its closest related species. We also provide a key to differentiate V. serratifolia from the epappose species of Valeriana from Argentina.

Inflorescences in Cyperaceae are a source of characters with significant systematic value; however, the structure and primary homologies pose a challenge to their interpretation. The relationships among members of Abildgaardieae are not clear due to the absence of a phylogeny with strong support, comprising a representative number of species. Establishing correct primary homologies of inflorescences within Abildgaardieae might help to clarify the relationships among its members, as well as to find synapomorphies for the most important clades. Variations in the mature inflorescences within Abildgaardieae have been related to their ?shape? and ?structure?, and preliminary phylogenetic studies in species of Bulbostylis have shown that inflorescence structure traits are phylogenetically informative, but this is not true for the mere shape. While similar structures in the adult inflorescences of the members of different clades within Abildgaardieae might be considered homologous, it must be ascertained whether such similar structures share the same developmental process or have different developmental patterns. By studying the development of inflorescences in selected species of Abildgaardieae using SEM, we were able to show that inflorescences with homologous structures share a similar developmental process and, therefore, the adult structure of inflorescences may be relied on for establishing correct primary morphological homologies in this plant group. Most structural variations of inflorescences in Abildgaardieae depend on the degree of development of processes shared by the studied species. While phyllotaxis in the main axis of Cyperus may be modified during inflorescence development after primordial inception, variations in the phyllotactic patterns of leaves on vegetative shoots (=nomophylls) and of leaves on fertile shoots (=bracts or hypsophylls) within Abildgaardieae, might establish deeper differences in inflorescence structure, since they depend on changes in the shape of the apical meristem. Fil: Reutemann, Andrea G.. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Catedra de Morfologia Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Cs.agrarias. Catedra de Morfologia Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pozner, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion; Argentina

The Patagonian steppe is an immense, cold, arid region, yet phylogeographically understudied. Nassauvia subgen. Strongyloma is a characteristic element of the steppe, exhibiting a continuum of morphological variation. This taxon provides a relevant phylogeographical model not only to understand how past environmental changes shaped the genetic structure of its populations, but also to explore phylogeographical scenarios at the large geographical scale of the Patagonian steppe. Here, we (1) assess demographic processes and historical events that shaped current geographic patterns of haplotypic diversity; (2) analyze hypotheses of isolation in refugia, fragmentation of populations, and/or colonization of available areas during Pleistocene glaciations; and (3) model extant and palaeoclimatic distributions to support inferred phylogeographical patterns. Chloroplast intergenic spacers, rpl32–trnL and trnQ–5′rps16, were sequenced for 372 individuals from 63 populations. Nested clade analysis, analyses of molecular variance, and neutrality tests were performed to assess genetic structure and range expansion. The present potential distribution was modelled and projected onto a last glacial maximum (LGM) model. Of 41 haplotypes observed, ten were shared among populations associated with different morphological variants. Populations with highest haplotype diversity and private haplotypes were found in central-western and south-eastern Patagonia, consistent with long-term persistence in refugia during Pleistocene. Palaeomodelling suggested a shift toward the palaeoseashore during LGM; new available areas over the exposed Atlantic submarine platform were colonized during glaciations with postglacial retraction of populations. A scenario of fragmentation and posterior range expansion may explain the observed patterns in the center of the steppe, which is supported by palaeomodelling. Northern Patagonian populations were isolated from southern populations by the Chubut and the Deseado river basins during glaciations. Pleistocene glaciations indirectly impacted the distribution, demography, and diversification of subgen. Strongyloma through decreased winter temperatures and water availability in different areas of its range. Fil: Nicola, Marcela Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Nicola, Marcela Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Johnson, Leigh. University Brigham Young; Estados Unidos

The nucellar beak is a proboscis-like outgrowth of the nucellus at the micropylar end, being the obliged path for the pollen tube entering the ovule. Among the few angiosperm families with nucellar beak, Cucurbitaceae is remarkable because the pollen tube may develop at least two types of growth within the nucelar beak: tubular, and ampulliform. Wondering about the possibility that Cucurbitaceae ovules may express some histological variation that could be related to pollen tube growth within the nucellar beak, we performed a compared anatomical, histochemical study of the nucellar beak and pollen tube growth of ten species of Cucurbitaceae. Results show that Cucurbitaceae ovules are diverse in size and proportions (of integuments, nucellar body, and nucellar beak), and they have at least four types of nucellar beak histology: pectic-tracked, secretory-like, amylaceous, and mixed. Amylaceous and mixed nucellar beaks are related to the ampulliform growth of the pollen tube, which could have appeared independently in most derived tribes of Cucurbitaceae, although information about nucellar beak structure in the basal tribes is still needed. In addition, the understanding of the relation between amylaceous nucellar beaks and the ampulliform growth of the pollen tube, whose function is still to be discovered, might open the possibility of a unique model of pollen tube - ovule co-evolution in angiosperms. Fil: Lizarazu, Mabel Angela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

Tillandsia subgenus Diaphoranthema (Tillandsioideae, Bromeliaceae) includes 29 epiphytic species distributed widely from southern North America to central Argentina and Chile. The species of Diaphoranthema are characterized by few small flowers, and most species are differentiated by phyllotaxy, leaf shape, flower number, and by the morphology and number of bracts. In addition to the highly variable vegetative characters, most species of subgenus Diaphoranthema possesses polyembryonic seeds (rare in Bromeliaceae) and an autogamous breeding system with a few number of species having cleistogamous flowers. In order to clarify relationships within Diaphoranthema and to understand the evolution of polyembryony, the breeding system, and diagnostic characters, a cladistic analysis of all known species using 85 morphological characters was conducted. Phylogenetic results suggest that Diaphoranthema is monophyletic if some species from the closely related subgenus Phytarrhiza are included. These two subgenera can only be distinguished from each other by the shape and size of their petals. A complete sampling of Phytarrhiza is still needed to test these hypotheses. None of the six informal groups as previously recognized are monophyletic. Vegetative characters such as phyllotaxy and the shape, length, and width of leaves were the most useful for distinguishing four major clades within Diaphoranthema. Flower number, scape development, exocarp and endocarp fusion at fruit ripening, and absence of endosperm in mature seeds were also used to distinguish some clades. Evolutionary trends favour a distichous phyllotaxy, linear shape leaf blades, and a reduction in flower number and bracts per inflorescence. In addition, capsules with disaggregating exocarp and endocarp at ripening, and polyembryonic seeds are also derived states within subgenus Diaphoranthema. Fil: Donadío, Sabina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Giussani, Liliana Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

Morphological variation among the five species of Nassauvia subgenus Strongyloma was assessed through statistical analyses of morphometric traits in populations throughout the southern Andean-Patagonian region. Uni- and multivariate analyses were used to identify patterns of morphological variation in relation to geography. Additionally, species distribution modeling was implemented to relate these patterns to climatic conditions. No well-defined groups could be recovered through multivariate analyses, although we observed some geographic structure. Latitudinal variation was found in leaves, phyllaries and cypselas, with a cline towards the south, where these structures become shorter and wider. Towards the east, the number of flowers per capitulum decreases, and abaxial corolla lips and cypselas become narrower and shorter. Distribution modeling showed several areas of contact and a large overlap of suitable conditions for more than one species, which is mainly related to the mean temperature of winter. Despite an association between morphological variation with geography and climate, actual geographic distributions of the putative species did not entirely match the clinal pattern of morphology, geography, and climate. Further genetic analyses are still needed to identify the probable processes that led to the complex patterns of observed variation.

Calyceraceae is a small family with six traditionally recognized genera and 47 species from southern South America. Most species grow along the Andes (of both Argentina and Chile) and in arid regions of the Patagonian steppe. This family belongs to the well-supported MGCA clade within Asterales, which includes Menyanthaceae + Goodeniaceae + Calyceraceae + Asteraceae. Calyceraceae is monophyletic and sister to Asteraceae, one of the five largest families of angiosperms. Although Calyceraceae is clearly distinct as a family, its genera are not, and taxonomic revisionary effort has confirmed the lack of sharp boundaries among genera. We performed a phylogenetic analysis of Calyceraceae with a broad taxon sampling (41 of 47 species), and with sequence data from multiple regions from the nuclear (ITS) and plastid genomes (ycg6-psbM, psbM-trnD,trnS-trnG, trnH-psbA, trnD-trnT) using maximum parsimony and Bayesian approaches. We aimed at identifying monophylectic groups, their putative morphological synapomorphies and their geographical distribution; we also estimated divergence times and examined chromosomes numbers in an evolutionary context. We obtained well-resolved and strongly supported phylogenies that show Calyceraceae to be divided into two major clades with geographically structured subclades within each. Our results indicate that an early split within Calyceraceae occurred about 27.4 Ma, probably related to differential changes in chromosome numbers, which allowed the two lineages to evolve in sympatry. We found that major natural subgroups diverged 15?12 Ma, following the Early-Miocene South Andes construction stage. Finally, the diversification of the extant species is probably associated to Andean orogeny and climate changes in the last 5?4 Myr. We recovered Acicarpha as monophyletic, while the remaining traditionally recognized genera of Calyceraceae are para- or polyphyletic. Most species of Moschopis are included in the Glutinose group, but M. monocephala is more closely related to some Calycera species. Calycera is divided into two clades: the Calycera group and the Pilose group. All species of Nastanthus are placed in a well-supported main group with species of Gamocarpha and Boopis. Gamocarpha could be monophyletic after exclusion of G. dentata and G. angustifolia, but is nested within Nastanthus and Boopis species. Boopis is clearly polyphyletic with its species distributed in all main groups. Fil: Denham, Silvia Suyai. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina Fil: Zavala Gallo, Lucio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Johnson, LeighA.. Brigham Young University; Estados Unidos Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

The Abildgaardieae tribe within the family Cyperaceae comprises six or seven genera, among which Abildgaardia , Bulbostylis and Fimbristylis pose a challenge regarding their morphological delimitation. Molecular phylogenetic analyses including species of Abildgaardieae are rare, but in most of those studies, Abildgaardia and Fimbristylis appear as more closely related to each other than to the Bulbostylis genus. Duration of the style base has been one of the most widely used characters for delimiting these three genera. The style base is a persistent structure in most species of Bulbostylis and deciduous in Abildgaardia and Fimbristylis. The reasons why the style base may persist or fall off have been scarcely discussed. The assumption that abscission layers are present in the style base of all three genera and the fact that tracheids have been observed in the style base of Bulbostylis suggest that this structure might have histological complexity. In view of this, a complete ontogenetic and anatomical study of the gynoecium has been carried out for all these three genera. It turned out that the style base is histologically simple in Abildgaardia , Bulbostylis and Fimbristylis and shows similar structure and development in all three genera. The fact that the style base has a shorter duration in Abildgaardia and Fimbristylis than in Bulbostylis might be related to the lower number of sclerotised cells that make up such structures in the mature fruit of the former two genera. Abscission of the style and style base may be the result of much simpler reasons than the differentiation of an abscission layer, resulting merely from mechanical shear force effects. Differences among genera have been observed in the shape of the style base and the development of the style. The histological simplicity of the style base is consistent with the homoplastic appearance of this structure in genera that are not closely related (e.g. Rhynchospora ). Because of this, while the presence of the thickened style base seems to be a synapomorphy in species of Abildgaardieae, its persistence on or detachment from the fruit might have emerged repeatedly during this clade evolution and might not be a suitable character for genera delimitation.

Aim An integrative study of the endemic, yet ubiquitous, Patagonian shrub Mulinum spinosum (Apiaceae) was performed: (1) to assess the historical processes that influenced its geographical pattern of genetic variation; (2) to test hypotheses of its survival in situ or in glacial refugia during glacial cycles; and (3) to model its extant and palaeoclimatic distributions to assess support for the phylogeographical patterns recovered. Location Chilean and Argentinian Andean region and Patagonian steppe. Methods Chloroplast DNA sequences, trnH–psbA, trnS–trnG and 3′trnV–ndhC, were obtained for 314 individuals of M. spinosum from 71 populations. The haplotype data matrix was analysed using nested clade analysis (NCA) to construct a network. Analysis of molecular variance (AMOVA), spatial analysis of molecular variance (SAMOVA) and neutrality tests were also used to test for genetic structure and range expansion in the species. The present potential geographical distribution of M. spinosum was modelled and projected onto a Last Glacial Maximum (LGM) model. Results Amongst the 29 haplotypes observed, one was widely distributed, but most were restricted to either northern or southern regions. The populations with highest haplotype diversity were found in southern Patagonia, the high Andean region, and northern Patagonia. AMOVA and SAMOVA showed latitudinal structure for Argentinian populations. NCA implied patterns of restricted gene flow or dispersal but with some long-distance dispersal and also long-distance colonization and/or past fragmentation. Neutrality tests did not support range expansions. The current distribution model was a fairly good representation of the extant geographical distribution of the species, and the distribution model for the LGM did not show important shifts of the extant range to lower latitudes, except for a shift towards the palaeoseashore. Main conclusions Based on agreement amongst phylogeographical patterns, distribution of genetic variability, equivocal evidence of putative refugia and palaeodistribution modelling, it is probable that glaciations did not greatly affect the distribution of Mulinum spinosum. Our results are consistent with the in situ survival hypothesis, and not with the latitudinal migration of plant communities to avoid adverse climate conditions during Pleistocene glaciations. It is possible that populations of northern Patagonia may have been isolated from the southern ones by the Chubut and Deseado basins.

Phylogeographical inferences, applied in a comparative framework across multiple species at a regional scale, provide the means for detecting regional and landscape-level patterns of biodiversity, which are important for understanding macroecology and evolution in a geographical mosaic against a backdrop broadly impacted by geological events. Although information on Patagonian phylogeographical patterns has accumulated for both aquatic and terrestrial organisms in recent years, no attempt has been made to compare patterns across major organismal groups. In this review, we compiled studies on the phylogeography of co-distributed plants and terrestrial vertebrates from Patagonia. From each study, we extracted information on levels of genetic diversity, and inferred demographic processes and phylogeographical breaks, as well as on putative refugia, to produce the first summary of emerging phylogeographical patterns for this region. This review reveals some congruent phylogeographical patterns within and among plants and terrestrial vertebrates, and suggests that Pre-Quaternary as well as Quaternary geological events would have been important driving forces in the evolutionary history of Patagonian lineages. Different processes and directional range shifts suggest a mosaic of phylogeographical patterns, far more complex than the several north–south common patterns traditionally proposed. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 475–494. Las inferencias filogeograficas, dentro de un marco comparativo cuando incluyen varias especies a escala regional, permiten detectar patrones de biodiversidad regional y de paisaje (fisonomicos), importantes para entender tanto la macroecologia como el impacto a gran escala de los eventos geologicos. En los ultimos anos, el conocimiento filogeografico de Patagonia se ha acumulado para organismos acuaticos y terrestres, y aunque se han propuesto pocos patrones demograficos o espaciales cualitativamente concordantes, no se ha hecho ningun intento de revisar comparativamente algunos de esos patrones considerando grandes grupos de organismos. En esta revision compilamos el conocimiento publicado sobre la filogeografia de plantas vasculares y vertebrados terrestres de Patagonia con el proposito de comparar niveles de diversidad genetica, procesos demograficos, quiebres filogeograficos y localizacion de posibles refugios, para producir el primer resumen de patrones filogeograficos emergentes para esta region. Esta revision revela algunos patrones filogeograficos congruentes dentro y entre plantas vasculares y vertebrados terrestres, y sugiere que tanto los eventos geologicos Cuaternarios como los pre-Cuaternarios pudieron haber jugado un papel importante en la historia evolutiva de los linajes patagonicos. Diferentes procesos y cambios direccionales en los rangos de distribucion, sugieren un mosaico de patrones filogeograficos mucho mas complejo que los patrones norte-sur tradicionalmente propuestos.

Spikelet structure and grouping are key characters to identify grasses. Here we tested the possibility that spikelet pairs, a distinctive morphological structure of many Andropogoneae and Paniceae, are the starting point for a secondary single spikelet condition that can also explain the change of spikelet orientation among Paniceae genera. As a first approach, we studied the inflorescence development of Paspalum simplex, P. stellatum, and Axonopus sufultus to clarify the origin of the spikelet orientation and other basic homologies. The results support that solitary spikelets of A. suffultus are homologous to the subsessile spikelets of P. simplex and that solitary spikelets of P. stellatum are homologous to the pedicellate spikelet of P. simplex. This last homology supports that spikelet orientation results from a differential reduction/abortion of either the pedicellate or the subsessile spikelet primordia. We also discuss the possibility that the RAMOSA and polar auxin pathways could play a role in the abortion of the lateral subsessile spikelets in P. stellatum. However, the apical meristem inhibition observed in A. suffultus and P. stellatum seems to depend on a very different genetic control, suggesting that the single spikelet condition is homoplasic within Paniceae and derived from at least two different genetic mechanisms.

Estudios moleculares recientes sugieren que Senecio sect. Senecio ser. Otopteri debería ser removido de Senecio para que este género extenso y taxonómicamente complicado sea monofilético. Con el propósito de evaluar la posición taxonómica de Senecio otites y la ubicación de la serie Otopteri, 13 especies, incluyendo S. otites, fueron examinadas en cuanto a los caracteres micromorfológicos de las ramas estigmáticas (superficie estigmática, ápice de las ramas estigmáticas) y de las anteras (collar del filamento, base de las anteras, apéndice de las anteras). Tres estados de estos caracteres micromorfológicos están presentes en todas las especies estudiadas de Senecio sect. Senecio ser. Otopteri: 1) ramas estilares apicalmente convexas o subconvexas, papilosas, rodeadas por una corona de pelos de distinta longitud; 2) superficies estigmáticas de configuración hendida (bandeada a hendida en S. attenuatus); y 3) anteras auriculadas. Estos resultados proveen apoyo morfológico nuevo para la ubicación de Senecio otites en Senecio sect. Senecio ser. Otopteri y la futura remoción de esta serie de Senecio L.

Se describe e ilustra Cyclanthera oligoechinata (Cucurbitaceae, Sicyeae) una nueva especie del sur de Brasil (Paraná), noreste de Argentina (Misiones), y centro y sur de Paraguay (San Pedro). Esta nueva especie se asemeja a C. hystrix, C. eichleri y C. quinquelobata, pero difiere por sus frutos lisos o casi lisos, y por sus flores pistiladas y frutos con pedicelos largos y gráciles. Se incluye una clave para distinguir C. oligoechinata de sus taxones más afines.

We describe a new species of Sicydium endemic to Argentina. Relationships and differences with morphologically and geographically closest species are discussed, including a key for material with staminate flowers to all species of Sicydium, and an illustration of the new species. Fil: Nicola, Marcela Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Donadío, Sabina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

A developmental and anatomical study of the staminate flowers of Halophytum ameghinoi showed decussate tepal estivation; residual growth of the receptacle after stamen inception; monocotyledonous and basic types of anther wall development; secretory, binucleate tapetal cells; tetrahedral tetrads; and binucleate pollen grains. A vacuolate stage in the archesporial cells, the structure of endothecial thickenings, and a mechanism of anther dehiscence by connective contraction are new autapomorphies for this family. Anemophily is confirmed (Plantago‐type syndrome), and field studies of pollen release showed a subtle mechanism involving rigid anther wall structure, versatile anther insertion, and abaxial subterminal pores. In air currents, while anthers flutter with pores directed upwind, pollen is extracted presumably by a cavitation effect of the hooded anther tip. In a phylogenetic context, anemophily of Halophytum is of isolated occurrence within Caryophyllales, and uniovulate ovaries in sister clades probably represent a prerequisite for evolution of anemophily. Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Cocucci, Andrea Aristides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

A new species, Stillingia yungasensis, from the “Yungas Tucumano-Bolivianas” forest (northwestern Argentina and southern Bolivia) is described and illustrated, including data on habitat, distribution, phenology, and a key to the new species and closest taxa. Stillingia yungasensis may be one of the most basal taxa within Series Oppositifoliae. No other species of Stillingia is sympatric with S. yungasensis, and its distribution supports a recent subdivision of the Yungas forests into two distinct phytogeographical units. Unlike the remaining species of Series Oppositifoliae, S. yungasensis is relatively frequent within its habitat.

Echinopepon disjunctus, a new species of the Echinopepon torquatus species-group from the Yungas rainforest of Jujuy (Argentina), is described and illustrated. Echinopepon coulteri is here excluded from the E. torquatus group on inflorescence and floral characters; a key to the remaining species of the group is included. In addition, the floral structure of the monotypic genus Pseudocyclanthera and four species of Rytidostylis is reviewed. The aestivation of the corolla, invagination at the base of the hypanthium, nectar-secreting trichomes, synanther, and pollen morphology support a closer relationship between Pseudocyclanthera and Rytidostylis than between Pseudocyclanthera and Cyclanthera. The receptacular nature of the trichomatous base of the androecial column and style seems to be distinctive for Rytidostylis. A key to the genera Cyclanthera, Pseudocyclanthera, and Rytidostylis is also included.

This is the first integrative synopsis of the genus Atriplex L. for South America, based on the study of compared external morphology of extensive collections from South American herbaria, type material, digital images, original publications and field observations. The South American Atriplex flora includes 55 species, 45 of which are native species, mainly distributed in Argentina and Chile (a few of them growing in Bolivia, Ecuador, Paraguay, Peru, Uruguay and Venezuela), and 10 are adventive species. We accept two subspecies for Atriplex cordubensis Gand. & Stuck., namely, subsp. cordubensis and subsp. grandibracteata Múlgura, two varieties for A. imbricata D.Dietr., var. imbricata and var. foliolosa Rosas, proposed one new synonym for A. deserticola Phil., one nomenclatural change for A. mucronata Phil., and designate 19 lectotypes and one second-step lectotype for A. nummularia Lindl. This synopsis also includes a key to the 55 South American species, three new figures for A. asplundii Standl., A. oestophora S.F.Blake and A. rusbyi Britton, references for previous figures of the remaining species, illustrations of different positions of the radicle in the seeds, maps of distribution, taxonomic and morphological notes, and a complete list of material studied. Fil: Brignone, Nicolás Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Denham, Silvia Suyai. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

Amphitropical disjunct distributions between western North America and western South America have intrigued botanists for over a century. Here, specific examples of migration and speciation are investigated using herbaceous species from the phlox family (Polemoniaceae) as a model for considering the timing of dispersal relative to speciation. Comparative DNA sequencing reveals that, in Collomia and Navarretia, the South American species are allopolyploids, suggesting either two dispersals prior to the allopolyploidization event for each species with subsequent extirpation of the diploid progenitors from South America, or allopolyploid formation prior to dispersal with extirpation of these polyploids from North America. Divergence time estimates support a Pliestocene dispersal hypothesis and sequence data indicate that, at least in Collomia, hybridization of the diploid progenitors occurred in South America. Fil: Johnson, Leigh. University Brigham Young; Estados Unidos Fil: Chan, Lauren M.. University Brigham Young; Estados Unidos. University of Duke; Estados Unidos Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Glazier, Lisa D.. University Brigham Young; Estados Unidos

Premise of the study: The understanding of homoplasic structures becomes more relevant when they are complex and define large angiosperm taxa. Inflorescence architecture usually fulfills both features, as happens with Cyperus, a genus with two taxonomical subdivisions characterized either by alternative expressions of Kranz anatomy (C3or C4) or inflorescence shape (condensed or lax). Those subdivisions are not completely congruent because at least one of these presumed characters has evolved several times. We focused a SEM study on the inflorescence development in species with condensed inflorescences and different photosynthetic anatomy to test the possibility that condensed inflorescences of subgen. Anosporum (C3anatomy) have evolved independently from those of subgen. Cyperus (C4anatomy). Methods: Freshly collected inflorescences of C. entrerianus, C. eragrostis, C. oxylepis, and C. incomtus were studied using stereoscopic and scanning electron microscopy. Key results: Condensed inflorescences of Cyperus species with C3and C4anatomy had differences in structure and development: (1) mature structure, (2) position of second-order branching initiation in the first developmental stage of the inflorescence, (3) main axis development and elongation, and branching development, (4) types of ramifications, (5) phyllotaxis and symmetry. Conclusions: Results support multiple origins of condensed inflorescences in Cyperus, based especially on differences in timing during development and elongation of the main axis and branches, branching pattern and phyllotaxis. Structure and development may be the key to using inflorescence morphology as an external feature to distinguish large natural groups within Cyperus based on vegetative anatomy. © 2012 Botanical Society of America. Fil: Guarise, Nicolas Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

 Premise of the study: Phylogenies based on molecular data are revealing that generalizations about complex morphological structures often obscure variation and developmental patterns important for understanding the evolution of forms, as is the case for infl orescence morphology within the well-supported MGCA clade (Menyanthaceae + Goodeniaceae + Calyceraceae + Asteraceae). While the basal families share a basic thyrsic/thyrsoid structure of their infl orescences, Asteraceae possesses a capitulum that is widely interpreted as a racemose, condensed infl orescence. Elucidating the poorly known infl orescence structure of Calyceraceae, sister to Asteraceae, should help clarify how the Asteraceae capitulum evolved from thyrsic/thyrsoid infl orescences.  Methods: The early development and structure of the infl orescence of eight species (fi ve genera) of Calyceraceae were studied by SEM, and patterns of evolutionary change were interpreted via phylogenetic character mapping.  Key results: The basic infl orescence structure of Calyceraceae is a cephalioid (a very condensed botryoid/thyrsoid). Optimization of infl orescence characters on a DNA sequence-derived tree suggests that the Asteraceae capitulum derives from a simple cephalioid through two morphological changes: loss of the terminal fl ower and suppression of the cymose branching pattern in the peripheral branches.  Conclusions: Widely understood as a condensed raceme, the Asteraceae capitulum is the evolutionary result of a very reduced, condensed thyrsoid. Starting from that point, evolution worked separately only on the racemose developmental control/pattern within Asteraceae and mainly on the cymose developmental control/pattern within Calyceraceae, producing head-like infl orescences in both groups but with very different diversifi cation potential. We also discuss possible remnants of the ancestral cephalioid structure in some Asteraceae.

Inflorescence development in Panicum maximum and Urochloa plantaginea was comparatively studied with scanning electron and light microscopy to test the transfer of P. maximum to Urochloa and to look for developmental features applicable to future cladistic studies of the phosphoenol pyruvate carboxykinase (PCK) subtype of C4 photosynthesis clade (P. maximum and some species of Brachiaria, Chaetium, Eriochloa, Melinis, and Urochloa). Eleven developmental features not discernable in the mature inflorescence were found: direction of branch differentiation; origins of primary branches; apical vs. intercalary development of the main axis; direction of spikelet differentiation; direction of glume, lemma and palea differentiation; position of the lower glume (in some cases); size of the floret meristem; pattern of distal floret development; pattern of gynoecium abortion; differential pollen development between proximal and distal floret; and glume elongation. Inflorescence homologies between P. maximum and U. plantaginea are also clarified. Panicum maximum and U. plantaginea differ not only in their mature inflorescence structure but also in eight fundamental developmental features that exclude P. maximum from Urochloa. The following developmental events are related to sex expression: size of floret meristem, gynoecium abortion, pollen development delay in the proximal floret, glume elongation and basipetal floret maturation at anthesis. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina

In grasses, inflorescence diversification and its correlation with species evolution are intriguing and not well understood. Part of this problem lies in our lack of comprehension about the inflorescence morphological complexity of grasses. We focused our study on the PCK clade (named for phosphoenol pyruvate carboxykinase), a well‐supported monophyletic group for which the relationships among its taxa are not well resolved. Interestingly, the PCK clade has an extensive diversity of adult inflorescence forms. A comparative developmental approach can help us to understand the basis of such morphological differences as well as provide characters that can be used in phylogenetic studies of the group. Using SEM studies, we demonstrate that inflorescence morphology in this clade is even more complex than what is typically observed in adult forms. We describe a number of new characters, and some classical features previously used for taxonomic purposes are redefined on the basis of development. We also define four morphological groups combining adult inflorescence form and development, and we discuss some of the evolutionary aspects of inflorescence diversification in the PCK clade. Taxonomic delimitation among genera in the PCK clade remains confusing and unclear where molecular and morphological studies support different classifications. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Zuloaga, Fernando Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

We describe and illustrate two new species of Boopis from Argentina: Boopis pterocalyx (Mendoza province) and Boopis necronensis (Catamarca and La Rioja provinces). Both species are easily distinguished from the remaining species of Boopis (sensu lato, including Nastanthus) by the foliose, imbricate sepals, which become foliose and orbicular in the fruit of B. pterocalyx, or navicular, obtuse-mucronate and corky in the fruit of B. necronensis. A geographical distribution map, complete descriptions, and illustrations are also included. Fil: Zavala Gallo, Lucio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Denham, Silvia Suyai. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

The nomenclatural revision of 51 names previously published, combined or synonymyzed under the genus Nastanthus (Calyceraceae) is presented. Six species are recognized with correct names and new synonyms established. The nomenclature of Nastanthus ventosus , Nastanthus scapigerus and Nastanthus compactus is updated, giving a total of 45 synonyms. Lectotypes for Boopis caespitosa , Boopis scapigera , Boopis spathulata , Nastanthus laciniatus , Boopis araucana , Calycera ventosa , Nastanthus pinnatifidus and Boopis breviflora are here designated. A map with the geographic distributions, complete species descriptions, corrected illustrations, and a new key to accepted species of Nastanthus , are included. K eywords : Calyceraceae, Nastanthus , taxonomy. RESUMEN Se presenta la revision nomenclatural de 51 nombres publicados, combinados o sinonimizados bajo el genero Nastanthus (Calyceraceae). Se reconocen seis especies, estableciendo los nombres correctos y sinonimos nuevos. Se actualizo la nomenclatura de

De Gennaro, D., R. Pozner & O. Morrone (2010). Foliar anatomy of Sacciolepsis Nash (Poaceae). Candollea 65: 197–210. In Spanish, English and French abstracts. Leaf anatomy study of the genus Sacciolepis Nash (Poaceae, Panicoideae, Paniceae) is presented and discussed. It is based on the analysis of epidermis in paradermal view and blade sections of 18 species of this genus. It is concluded that the leaf anatomy does not support previous proposals of subdivisions of Sacciolepis, nor correlates with the geographical distribution of species, and it has a very limited predictive value of the environment where these species grow. An identification key, for the species of the genus Sacciolepis based on the leaf anatomy, is provided.

We investigated changes in floral developmental patterns and sex determination in the PCK (phosphoenolpyruvate carboxykinase) clade using a comparative approach and SEM. We identified variation in patterns of floral development that may be correlated with sex determination. Nine different patterns of floret development were identified, based on sex of the lower floret, sequence of stamen development, and rate of glume and lemma differentiation. Although staminate florets are always formed by the abortion of the gynoecium, the timing of abortion differs among species. Similarly, the formation of sterile lower florets showed different pathways that may operate at the level of floral meristem or organ identity. Finally, we discuss several reasons why patterns described for maize and closely related species may not be easily extrapolated to other grasses. Fil: Reinheimer, Renata. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Zuloaga, Fernando Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Vegetti, Abelardo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

The chromosome number and karyotype of Halophytum ameghinoi (Speg.) Speg. was found to be 2n = 24 and 12 m+ 10 sm+ 2t, respectively. Meiosis was regular and 12 bivalents were observed. The relationships of this monotypic family are briefly discussed. Fil: Hunziker, Juan Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raúl Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Escobar, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

10.11646/phytotaxa.130.1.6 Fil: Ospina Gonzalez, Juan Camilo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina Fil: Pozner, Raul Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina

A new apetalous species of Minuartia from the high Andes of northwestern Argentina, M. altoandina, is here described and illustrated. At first sight, M. altoandina is morphologically very similar to the European M. sedoides because of the absence of petals and ciliate leaf margin with narrow hyaline teeth; however, from a biogeographical point of view, it will probably be related to the North American M. rossii complex through the morphology of M. austromontana.