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Larreoideae are one of the major representatives of Zygophyllaceae in South America. In this work, we analysed the phylogenetic relationships of species in the subfamily Larreoideae using morphological and molecular data in a total evidence context. We also evaluated the monophyly of Larreoideae considering both morphological and a combined set of data (morphological + molecular), providing a discussion of the phylogenetic position of its members. Finally, we constructed a molecular tree based on nuclear and plastid sequences, analysing them separately. The integration of morphological and molecular data reaffirms the monophyly of Larreoideae. The phylogenetic analysis supports the traditional genera as well-supported groups. Species in Bulnesia are clearly separated by molecular and morphological characters which reinforce the consolidation of the genus Gonopterodendron. Therefore, we recognize eight genera forming Larreoideae. We confirm the taxonomic position of Guaiacum angustifolium (Porlieria angustifolia) in Guaiacum supported by molecular and morphological data, and suggest the inclusion of Pintoa chilensis and Metharme lanata in Larreoideae based on morphological features shared with members of the subfamily. [ABSTRACT FROM AUTHOR]

Monosulcate pollen grains are an important component of the Mesozoic palynofloras around the world. These type of grains are produced by several groups of plants and because of the morphological similarities among them, their taxonomic determination is difficult. Currently, there is scarce information about morphological differences of monosulcate pollen grains and this makes their botanical affinity in fossil specimens challenging. In this work, we analyzed statistically the morphological features of monosulcate fossil pollen grains recovered from six palynological assemblages from the Lower Cretaceous Lagarcito Formation of central-western Argentina. We used our own fossil dataset and data from the description of monosulcate pollen grains published from Cretaceous cycadalean in situ male cones from Patagonia. Furthermore, morphological variables from selected living species were added to support the analysis. According to our results, two main groups with clear morphological features were characterized among fossils. The use of an extant dataset allowed us to support the exine sculpture as an important variable when characterizing fossil pollen grains. Finally, our fossil dataset showed similarities with the in-situ pollen grains from the cycadalean cone species Androstrobus munku and Androstrobus patagonicus. This work is the first attempt to identify different morphological types among fossil monosulcate pollen grains recovered from the Lagarcito Formation of central-western Argentina. Our results will contribute to elucidate morphological variations in fossil pollen grains and may improve future taxonomic studies. [ABSTRACT FROM AUTHOR]

A new monosulcate species, Shanbeipollenites lagarcitensis sp. nov. is described from the Lower Cretaceous Lagarcito Formation, Sierras de Guayaguas (north-western San Luis Basin), Argentina. Shanbeipollenites lagarcitensis shares with other species of this genus a broadly ellipsoidal outline and a diagonally disposed distal sulcus. However, the new species differs from the psilate type species Shanbeipollenites quadrangulatus and from S. quadratus by the presence of sculptural elements distributed at the equatorial region, close to the opposite ends of the sulcus. The thicker wall, exine separation, much more strongly diagonal offset of the sulcus and the rugulate-verrucate sculpture with an equatorial distribution close to the opposite ends of the sulcus, distinguish this new species and expands the concept of the genus Shanbeipollenites. The presence of two separate exine layers supports its gymnosperm affinity. Furthermore, the occurrence of Shanbeipollenites lagarcitensis in the Albian Lagarcito Formation from mid–latitudes, central–western Argentina constitutes the youngest record of the genus worldwide. This new record expands the biostratigraphical range of the taxon into the Albian. [ABSTRACT FROM AUTHOR]

Here we present a revision of the elaterate pollen species that belong to the genus Galeacornea. We also describe a new species, Galeacornea guayaguensis sp. nov., from the Early Cretaceous (Albian?) of central-western Argentina. The specimens from this species were retrieved from sediments of the Lagarcito Formation (San Luis Basin) located at the Sierra de Guayaguás ranges in the San Juan province. Galeacornea guayaguensis shares with the other Galeacornea species the shape of the grain and the presence of an annular rim and distal appendages. The ridge-like appendages of G. guayaguensis are similar to those of G. stoveri and G. tarimensis, although they never fuse with the annular rim or with each other at their ends as it respectively occurs in these species. This new pollen species provides further evidence on the morphological variation of elaterate grains and extends the geographical distribution of Galeacornea to southern South America, far beyond the palaeophytogeographic Albian–Cenomanian Elaterates Province of the equatorial region. Finally, we propose a new combination of the species Quantonenpollenites crassatus to Galeacornea crassatus, considering that the morphological features of the former perfectly fit the diagnosis of the genus Galeacornea. [ABSTRACT FROM AUTHOR]