Phylogeny of sections Clavelligerae and Pectinatae of Panicum (Poaceae, Panicoideae, Paniceae): establishment of the new subtribe Dichantheliinae and the genus Adenochloa

Abstract

Taxonomic features of African species of Panicum sections Clavelligerae and Pectinatae are reviewed and compared with Dichanthelium and other taxa in tribe Paniceae. The new subtribe Dichantheliinae is proposed on the basis of molecular and morphological characters: it includes non-Kranz species, growing at forests edges or in mountain grasslands with membranous-ciliate ligules, lax and open inflorescences, ellipsoid to oblongoid spikelets, and an indurate upper anthecium. Within the Dichantheliinae, the new genus Adenochloa is also established on the basis of chloroplast ndhF sequences and morphological characters, i.e., plants with clavellate multicellular, and glandular hairs present on blades, main axis, branches, and pedicels of inflorescences; ellipsoid to oblongoid, glabrous spikelets, with a lower glume 1/3 to more than 1/2 the length of the spikelet; a 7–13-nerved upper glume and a 5–9-nerved lower lemma; the upper anthecium is indurate, pilose or glabrous. Adenochloa includes 14 species from Africa and Madagascar. The new combinations: Adenochloa adenophylla, A. adenophora, A. bullockii, A. claytonii, A. ecklonii, A. flacciflora, A. habrothrix, A. hymeniochila, A. lukwangulense, A. nigromarginata, A. pectinella, A. pole-evansii, A. sadinii, and A. squarrosa are proposed and the new genus is compared with other genera of the tribe Paniceae. Also, lectotypes are designated for Brachiaria sadinii, Panicum adenophorum, P. adenophyllum, P. ecklonii, P. katentaniense, P. kisantuense, P. hymeniochilum, P. hymeniochilum var. glandulosum, P. snowdenii, and P. scandens; Panicum glanduliferum and P. omega are treated as new synonyms of Adenochloa hymeniochila and A. pectinella, respectively. Finally, new illustrations are provided for 6 species of the new genus.