Diego L. Salariato

Phylogeny of the Paniceae (Poaceae: Panicoideae): integrating plastid DNA sequences and morphology into a new classification

Included in the PACMAD clade of the family Poaceae (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, Danthonioideae), the tribe Paniceae s.l. is one of the largest tribes of the subfamily Panicoideae, with more than 2000 species. This tribe comprises a huge morphological, cytological and physiological diversity represented by different inflorescence types, several basic chromosome numbers, and at least four major photosynthetic pathways. The tribe Paniceae has been the subject of molecular studies that have confirmed its paraphyly: two major clades were recognized based on their basic chromosome numbers (x = 9, x = 10). The x = 10 Paniceae clade is sister to the Andropogoneae–Arundinelleae s.s. clade (x = 10), while the combined x = 10 clade is sister to the x = 9 clade that contains the remaining genera of Paniceae. As a result of a recent realignment within the tribe in terms of the phylogenetic position of minor and major Paniceae genera, a reanalysis of the whole sampling is performed and new underrepresented taxa are discussed. A total of 155 genera, currently considered within subfamily Panicoideae, are represented here by almost all genera of Paniceae s.l., representatives of Andropogoneae and Arundinelleae s.s., and the endemic and small tribe Steyermarkochloeae; we also included specimens of subfamily Micrairoideae, tribes Isachneae and Eriachneae. The sampling includes as outgroups 18 genera of the PACMAD clade (excluding Panicoideae) and four genera from the BEP clade (Bambusoideae, Ehrhartoideae, Pooideae), rooting with Bromus inermis. A matrix with 265 taxa based on the combined evidence from ndhF plastid sequences (2074 bp) and 57 morphological characters was subjected to parsimony analyses. Jackknife resampling was used to calculate group support. Most clades are characterized by morphological, cytological, anatomical, and/or physiological characters. Major tribal changes are based on the basic chromosome number; the pantropical x = 9 clade is here recognized as Paniceae s.s., while the American x = 10 Paniceae s.l. is restricted to the reinstated tribe Paspaleae. The optimization of the photosynthetic pathway for the Paspaleae–Andropogoneae–Arundinelleae s.s. clade, including the monotypic Reynaudia, shows a plesiomorphic C4 state while the ancestral state for Paniceae s.s. is ambiguous. If Reynaudia were not included or placed elsewhere, the ancestral photosynthetic pathway for both the Paspaleae–Andropogoneae–Arundinelleae s.s. clade and the Paniceae s.s. would be unambiguously C3. In order to explore character evolution further, the morphological characters were mapped onto one of the most parsimonious trees. A relationship between photosynthetic pathways and inflorescence morphology is suggested here for the first time. Based on the optimization of morphological characters and additional data, we propose names for almost all inner clades at the rank of subtribe with a few groups as incertae sedis. With this extensive sampling, we resolved the phylogenetic relationships and the assignation of synapomorphies, and improved the support in subtribe sorting; consequently a robust circumscription of the tribe Paniceae s.l. is proposed.

Molecular phylogeny of the subtribe Melinidinae (Poaceae: Panicoideae: Paniceae) and evolutionary trends in the homogenization of inflorescences

The subtribe Melinidinae (Poaceae: Panicoideae: Paniceae) includes 14 genera that present the PCK photosynthetic subtype in addition to several other unique and also common characters. The purpose of this research was (1) to test the monophyly of the subtribe Melinidinae, including 331 ndhF sequences of Panicoids and related genera, (2) to analyze the phylogenetic relationships among genera of Melinidinae using four cpDNA regions, and (3) to study evolutionary trends in the homogenization of inflorescences. As a result, the monophyly of Melinidinae is supported if Urochloa venosa is excluded from the subtribe. Alloteropsis semialata subsp. semialata, an unusual PCK species, is here confirmed within the Forest shade clade. Within Melinidinae, Urochloa and Eriochloa appeared as paraphyletic and polyphyletic genera, respectively. Finally, the general trend in the evolution of the inflorescences in Melinidinae seems to be the reduction from non-homogenized to complete homogenized inflorescences.

Phylogeny of New World Stipeae (Poaceae): an evaluation of the monophyly of Aciachne and Amelichloa

© The Willi Hennig Society 2010.

Molecular phylogenetics of tribe Eudemeae (Brassicaceae) and implications for its morphology and distribution.

Tribe Eudemeae comprises a morphologically heterogeneous group of genera distributed along the Andes of South America from Colombia southward into southern Chile and Argentina. The tribe currently includes seven genera: Aschersoniodoxa, Brayopsis, Dactylocardamum, Delpinophytum, Eudema, Onuris, and Xerodraba, and exhibits a wide morphological diversification in growth habit, inflorescences, and fruits. However, little is known about the phylogenetic relationships and evolution of the tribe. We present here a molecular phylogeny of representative sampling of all genera, utilizing sequence data from the nuclear ribosomal ITS region and chloroplast regions trnL-F, trnH-psbA, and rps16. Additionally, climatic niches of the tribe and its main lineages, along with the evolution of diagnostic morphological characters, were studied. All analyses confirmed the monophyly of Eudemeae, with the exception of Delpinophytum that was included with genera of the lineage I of Brassicaceae. Eudemeae is divided into two main lineages differentiated by their geographical distribution and climatic niche: the primarily north-central Andean lineage included Aschersoniodoxa, Brayopsis, Dactylocardamum, and Eudema, and the Patagonian and southern Andean lineage included Onuris and Xerodraba. Finally, ancestral-state reconstructions in the tribe generally reveal multiple and independent gains or losses of diagnostic morphological characters, such as growth form, inflorescence reduction, and fruit type. Relevant taxonomic implications stemming from the results are also discussed.

Revision and tribal placement of the Argentinean genus Parodiodoxa (Brassicaceae)

Parodiodoxa is a monotypic genus of Brassicaceae endemic to northwestern Argentina. It is poorly known and until now remained the only South American genus of the family that had not been assigned to a particular tribe. Sequence data from the nuclear ribosomal ITS region and the chloroplast trnL intron/trnL-F spacer region were used in this study to determine the systematic position of Parodiodoxa. For this purpose, taxa were sampled both at the tribal and generic levels. Results from tribal-level sampling support the inclusion of Parodiodoxa in the tribe Thelypodieae, whereas those at the generic level reveal a relationship to Weberbauera (W. rosulans and W. herzogii). Topologies within the Thelypodieae were poorly resolved, in agreement with previous studies. Morphological characteristics of Parodiodoxa are also discussed in relation to other genera of the tribe.

Molecular Phylogeny and Morphological Analysis of Tetraglochin (Rosaceae: Rosoideae: Sanguisorbeae) and Recognition of the New Species T. andina

Abstract Tetraglochin is distributed along the Andes from Peru to southern Argentina and central Chile. In order to test its monophyly and analyze relationships among species of this genus and allied genera, we conducted morphological studies and phylogenetic analyses using both nuclear (ITS) and cpDNA (trnL-F) sequences. As a result, Tetraglochin is supported as monophyletic, with the genus Margyricarpus as its sister group. Tetraglochin acanthocarpa and T. caespitosa are sister to the rest of the genus, which is grouped in two clades. One clade grows primarily distributed along the Central Andes, includes T. cristata, T. inermis, plus some specimens of T. ameghinoi, and has a coriaceous or papery and non translucent hypanthium. The other clade is mainly in the Southern Andes, contains T. alata and some specimens of T. ameghinoi, and has a membranous translucent hypanthium. Based on results obtained from morphological studies, molecular phylogenies, and species delimitation analyses, a new species T. andina, is proposed, segregated from T. ameghinoi. A key to identify all species herein recognized, and a map containing geographical distribution of them are provided, together with a description and illustration of the new species.

New Species of Paniceae (Poaceae, Panicoideae) from Brazil

Abstract Two new species of Paniceae are here described, one belonging to Dichanthelium (Dichanthelium barbadense) and the other to Panicum sect. Laxa (Panicum harleyi). Both taxa grow in open areas of Central Brazil are described, illustrated, and compared with putative related species.

Climatic niche evolution in the Andean genus Menonvillea (Cremolobeae: Brassicaceae)

The study of how climatic niches change over evolutionary time has recently attracted the interest of many researchers. Different methodologies have been employed principally to analyze the temporal dynamics of the niche and specially to test for the presence of phylogenetic niche conservatism. Menonvillea, a genus of Brassicaceae including 24 species, is distributed primarily along the Andes of Argentina and Chile, with some taxa growing in southern Patagonia and others in the Atacama Desert and the Chilean Matorral. The genus is highly diversified morphologically but also presents a remarkably wide ecological range, growing from the high Andean elevations, to the dry coastal deserts in Chile, or the Patagonia Steppe in Argentina. In this study, we used molecular phylogenies together with climatic data to study climatic niche evolution in the genus. The results show that the main climatic niche shifts in Menonvillea occurred between the sections Cuneata-Scapigera and sect. Menonvillea throughout the Mid-Late Miocene, and associated with the two main geographical distribution centers of the genus: the highlands of the central-southern Andes and the Atacama Desert-Chilean Matorral, respectively. Climatic niches in these lineages were mainly differentiated by the aridity and potential evapotranspiration, the minimum temperatures of the coldest month, and the temperature annual range and seasonality. Niche evolution in Menonvillea deviated from a Brownian motion process, with most of the climatic dimension best-fitting to an Ornstein-Uhlenbeck model of multiple adaptive peaks. Our results also indicated that higher aridity levels and lower annual temperature ranges were associated with the evolution of the annual habit, as exemplified by the distribution of sect. Menonvillea. Finally, the results suggested that climatic niche evolution in Menonvillea exhibited some degree of phylogenetic niche conservatism, fundamentally within the two main lineages (sect. Menonvillea and sects. Cuneata-Scapigera).

Taxonomic placement of Onuris hauthalii (Brassicaceae: Eudemeae), based on morphology and multilocus species tree analyses, and the recognition of the new genus Alshehbazia

SummaryOnuris hauthalii is a species distributed in Southern Argentina and Chile. Its generic assignment has been controversial, being included in Eudema, Brayopsis and Onuris. In order to clarify its generic affinities, we studied its morphology and phylogenetic relationships using multilocus/multispecies coalescent species-tree analyses based on four DNA regions (ITS, trnL-F, trnH-psbA, and rps16 intron). Results show that while O. hauthalii is related to Onuris s.s., it represents a well-differentiated lineage characterised primarily by having branched rhizomes, rosette flowering with ebracteate flowers, and latiseptate silicles. Based on the morphological and molecular evidence, we place this species in the new monospecific genus Alshehbazia. A description, morphological key, updated geographical distributions, map, and illustration are provided.

Mayariochloa, a New Monotypic Genus Segregated from Scutachne (Poaceae, Panicoideae, Paniceae)

Abstract The genus Scutachne (Poaceae, Paniceae) is revised. This American genus, which included two species from the Caribbean, was circumscribed on the basis of morphological and molecular characters. To analyze both species of the genus, S. amphistemon and S. dura, a detailed study of the micromorphology of the upper anthecium and leaf anatomy, together with exomorphological characters, was performed. Both species differ in vegetative and reproductive characters, including blade distribution, ligules, presence of axillary inflorescences, consistency of upper glume, lower lemma, and lower palea, presence of a lower flower, upper anthecium ornamentation, and presence of a rachilla extension. Anatomically, S. dura is a C4 PCK species, while S. amphistemon is a C3, non-Kranz taxon. The molecular phylogenetic analysis supports these morphological differences. As a result, we concluded that Scutachne, as presently circumscribed, is a polyphyletic genus. Therefore, the genus is here redefined and S. amphistemon is transferred to the new genus Mayariochloa . Affinities of the new genus with other genera of Paniceae are also discussed.