Chromosome number and karyotype of Phaenospermateae and Duthieeae (Poaceae), with reference to their systematic implications

Abstract

Recent molecular phylogenetic studies indicate that Phaenospermateae and Duthieeae are among the early diverging lineages of Pooideae and that they are closely related to each other. Here, we test this with cytotaxonomical data. The monotypic tribe Phaenospermateae, represented by Phaenosperma globosum, has a chromosome number of 2n = 2x = 24 and a fairly symmetric karyotype consisting of 22 median (m) and 2 submedian (sm) chromosomes varying in length between 1.8–3 μm. Duthieeae, represented by Duthiea brachypodium, Sinochasea trigyna, Stephanachne monandra and Stephanachne pappophorea, also share the chromosome number 2n = 2x = 24 and similar symmetric karyotypes with the chromosomes varying in length between 1.4–5 μm. Thus, the close relationship of Phaenospermateae and Duthieeae is corroborated.

Molecular Phylogenetics and Micromorphology of Australasian Stipeae (Poaceae, Subfamily Pooideae), and the Interrelation of Whole-Genome Duplication and Evolutionary Radiations in This Grass Tribe

“…Presumably close relatives of grass tribe Stipeae, which likewise belong to the rather early diverging lineages of grass subfamily Pooideae (Schneider et al, 2009(Schneider et al, , 2011Romaschenko et al, 2012;Saarela et al, 2015), seem to share the chromosome base number of x = 12 with Stipeae (see above), even though only comparatively few counts are available: (1) monospecific Ampelodesmos Link [A. mauritanicus (Poir.) T.Durand & Schinz], regarded as either sole member of tribe Ampelodesmeae (GPWG (Grass Phylogeny Working Group), 2001; Soreng et al, 2017) or as morphologically anomalous genus of Stipeae (Decker, 1964;Barkworth, 2007;Schneider et al, 2009Schneider et al, , 2011Winterfeld et al, 2015) has 2n = 4x = 48 (Nilsson and Lassen, 1971;Schneider et al, 2011) or 2n = 8x = 96 (Myers, 1947 (Fedorov, 1969, p. 565 citing an unpublished count of L.A. Alexandrova; Winterfeld, 2006;Schneider et al, 2011;Zhang et al, 2018; with a discussion of a seemingly wrong previous chromosome counts of 2n = 14 in Danthoniastrum compactum of Kožuharov and Petrova, 1991), while n = 14 in was reported for Duthiea bromoides Hack. Sharma, 1975, 1977); and (3) monospecific Phaenosperma Munro ex Benth.…”

“…(P. globosum Munro ex Benth.) of monogeneric tribe Phaenospermateae has 2n = 2x = 24 (Avdulov, 1931, p. 92;Tateoka, 1954Tateoka, , 1955Tateoka, , 1956Schneider et al, 2011;Winterfeld et al, 2015;Zhang et al, 2018).…”