PHYLOGENY OF THE PANICEAE (POACEAE: PANICOIDEAE) INTEGRATING CHLOROPLAST DNA SEQUENCES AND MORPHOLOGY

OSVALDO MORRONE; LONE AAGESEN; M. AMALIA SCATAGLINI; DIEGO SALARIATO; SILVIA DENHAM; MARIA AMELIA CHEMISQUY; SILVANA M. SEDE; LILIANA M. GIUSSANI; ELIZABETH KELLOG; FERNANDO O. ZULOAGA

Tucumán, Argentina

Congreso; XXVII MEETING OF THE WILLI HENNIG SOCIETY AND VIII REUNIÓN ARGENTINA DE CLADÍSTICA Y BIOGEOGRAFÍA; 2008

The Willi Hennig Society

The tribe Paniceae currently includes approx. 110 genera and 2000 species worldwidedistributed. The Paniceae exhibits a great morphological and physiological variability that difficultsestablishing generic boundaries among its members; recent molecular studies lead to a newclassification of several genera of the tribe. The present study aims to analyze all genera of the tribecombining morphological and ndhF sequence data in order to delimit the tribe within the Poaceae,and to establish generic relationships within it. As found in earlier studies monophyly of thePaniceae was not supported. The Paniceae is divided in two major clades, recognized as the x=9 andx=10 clades. The ndhF sequences support a sister-group relationship between the x=10 clade andthe tribe Andropogoneae. The x=10 clade is defined by a 6 base pair long insertion in the ndhFsequences. The basal dichotomy divides the group into a small clade integrated by minor generafrom Australia, India, and Africa, and a major clade including American taxa only, some genera,such as Paspalum and Axonopus, with a high number of species. The distribution of the x=9 clade ismainly Pantropical. Within this clade the basal dichotomy separates a small clade including thegenus Digitaria and three small genera previously related to taxa of the ‘Bristle clade’: Anthephoraand related genera. This clade is well supported and defined by a 24 base pair long deletion withinthe ndhF sequences. Main clades within the x=9 clade are the ‘Bristle clade’ that among othergenera includes Setaria, Pennisetum and Cenchrus, the PEP-ck clade, with Urochloa and generawith a similar anatomic and photosynthetic syndrome, and the Panicum clade characterized byhaving a NAD-me photosynthetic subtype. Although the morphological characters werehomoplastic and lower the branch supports, they proved to be useful for placing several taxa forwhich DNA sequence data were not available.