Silvia S. Denham

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.

Parodiophyllochloa, a New Genus Segregated from Panicum (Paniceae, Poaceae) Based on Morphological and Molecular Data

Abstract Taxonomic features of species of Panicum, previously classified in section Cordovensia, subgenus Dichanthelium, of Panicum, are reviewed and compared with those of other taxa in the Paniceae. The new genus Parodiophyllochloa is proposed on the basis of ecological and morphological features (i.e. plants growing at the edge of forests, with membranous ligules, lower glume more than 1/2 the spikelet length, lower palea and lower flower absent, and upper anthecium indurate with simple papillae all over its surface) and chloroplast ndhF sequences to include six species ranging from Mexico to Argentina. The new combinations: Parodiophyllochloa cordovensis, P. missiona, P. ovulifera, P. pantricha, P. penicillata, and P. rhizogona are proposed. The new genus is compared with other genera of the Paniceae.

Phylogeny of New World Paspalum (Poaceae, Panicoideae, Paspaleae) based on plastid and nuclear markers

Phylogenetic analyses of 131 terminals of Paspalum and related genera, based on both plastid and nuclear markers, were performed under maximum parsimony and Bayesian methods. The total evidence analyses generated a hypothesis showing that Paspalum would be monophyletic if Spheneria, Thrasyopsis and Reimarochloa are included within the genus. Paspalum inaequivalve and P. microstachyum, two species of the Inaequivalvia group were related to genus Anthaenantiopsis, excluded from Paspalum, or nested within it by plastid and nuclear markers, respectively. Subgenera Anachyris and Harpostachys were partially recovered as monophyletic assemblages, while subg. Ceresia and Paspalum resolved as polyphyletic. Within subgenus Paspalum, some informal groups were recovered as monophyletic, while others were resolved as paraphyletic or polyphyletic. Phylogenetic relationships among species of Paspalum were partially recovered possibly due to reticulation events among species, autopolyploidization and apomixis; all these processes being common in Paspalum, thus obscuring the infrageneric classification.

Estudios en el género Paspalum (Poaceae, Panicoideae, Paniceae): Paspalum denticulatum y especies afines1

Abstract Species related to Paspalum denticulatum Trin. are studied systematically, including taxa traditionally placed in the informal group Livida of Paspalum L. The analysis demonstrates Livida to be an artificial group, without characters that delimit it from remaining groups within Paspalum; for this reason, its species are treated as ungrouped within subgenus Paspalum. A total of 11 species are herein described, compared, and analyzed. Paspalum hieronymii Hack., P. jujuyense Zuloaga, P. lividum Trin. ex Schltdl., and P. proliferum Arechav. are maintained as synonyms of P. denticulatum. Paspalum tinctum Chase is here reduced to synonymy under P. hartwegianum E. Fourn. and P. arsenei Chase under P. pubiflorum Rupr. ex E. Fourn. Paspalum pisinnum Swallen and P. trinii Swallen are here treated under the synonymy of P. trichophyllum Henrard. Distribution maps, plates of species not previously illustrated, and SEM microphotographs of the upper anthecia are included, as well as a taxonomic key to differentiate the accepted species.

Synopsis of the genus Atriplex (Amaranthaceae, Chenopodioideae) for South America

Abstract. 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.