ALICE, LAWRENCE A.*, GERASSIMO G. BORNEO, AND KHIDIR W. HILU. Department of Biology, Western Kentucky University, Bowling Green, KY 42101 and Department of Biology, Virginia Tech University, Blacksburg, VA 24061. - Systematics of Chloris (Chloridoideae; Poaceae) and related genera: evidence from nuclear ITS and chloroplast matK sequences.
We used DNA sequences from the nuclear ribosomal internal transcribed
spacer (ITS) region and the chloroplast gene matK to examine
generic circumscriptions and infer phylogenetic relationships of the
grass genus Chloris (Chloridinae: Chlorideae: Chloridoideae)
and several related taxa. Our ITS and matK data sets include
36 and 29 species, respectively, and represent at least 13 genera plus
three outgroups from the tribe Eragrostideae. Independent and
combined analyses of both data sets firmly suggest that Chloris
is polyphyletic and should be redefined. However, a clade containing
7-11 Chloris species, Enteropogon dolichostachys, and
Lintonia nutans is strongly supported by bootstrap values of
99%. Thus, it appears that Lintonia nutans of subtribe
Pommereullinae and Enteropogon dolichostachys should be
included in Chloris. Species treated either as a separate
genus (Eustachys) or as a subgenus of Chloris (except
for C. retusa) form a monophyletic group that is distinct from
Chloris and weakly associated with a clade comprising
Cynodon + Brachyachne. The relationships among
Eustachys, Cynodon-Brachyachne, and
Chloris are not clear based on either data set alone or the
combined analysis due to an internal polytomy. Additional taxa that
have been treated in Chloris and as separate genera, such as
Trichloris and Oxychloris, are distinct in these
analyses and should be retained. This study forms the phylogenetic
foundation for a taxonomic revision of Chloris.
Key words: Chloridoideae, Chloris, ITS, matK, phylogeny, Poaceae