Nomenclatural Changes in Leptochloa P. Beauvois Sensu Lato (Poaceae, Chloridoideae)

Abstract

Recent revisionary and cladistic studies in Leptochloa P. Beauvois (Snow, 1997a), along with preparation of the grass treatment for Flora Zambesiaca (Cope, in press), support nomenclatural changes for this nearly worldwide grass genus. The changes are necessary given the consistent lack of cladistic support for Diplachne P. Beau¬ vois as a taxon distinct from Leptochloa (Snow, 1997a) and the need to reduce in rank several species (Snow, 1997a(Snow, , 1997b.The synonymy of Leptochloa is extensive and only recently has been assessed from a global perspective (Snow, 1997a). However, since the primary purpose of this article is to make these new names available, complete synonymy will be withheld for a later publication (or see Snow, 1997a). In addition to these changes, descrip¬ tions of two new species are forthcoming (Snow, 1998; Snow & Simon, 1997).

Monograph of Diplachne (Poaceae, Chloridoideae, Cynodonteae)

“…The elongate, broadly to narrowly acute membranous ligule of Diplachne and numerous, dorsally rounded or flattened florets (before seed development), most consistently diagnose the genus from species formerly placed in Leptochloa sensu lato (Snow 1997a, 2003). As reported previously (Peterson et al 2012), banding patterns from chloroplast DNA restriction site analysis of populations of D. fusca subsp. fascicularis and uninervia were virtually identical, but consistently different from other North American members of Leptochloa s.l.…”

“…Descriptive terminology for leaf anatomy largely follows Ellis (1976) and includes information from Snow (1997a). This includes keel to refer to the proliferation of parenchyma (abaxially, but usually more prominent adaxially) that surrounds the central-most (median) vascular bundle, which typically extends laterally to at least the first vascular bundle on either side of the median bundle.…”

“…sensu lato (Parodi 1927; Hitchcock 1951; McNeill 1979; Phillips 1974, 1982; Clayton and Renvoize 1986; Nicora 1995, 2006; Snow 1997a, 2003, 2012). In-depth sampling within and among genera by Peterson et al (2010, 2012, 2014, 2015) recovered five strongly supported clades among members of Leptochloa s.l.…”

“…Beauv., the latter of which has been reduced to synonymy (e.g. Snow 1997a; Peterson et al 2001; Soreng et al 2012). Gray (1848), who first reduced Diplachne to synonymy under Leptochloa , initially did not indicate a taxonomic rank, but later specified its rank as subgenus (Gray 1857).…”

“…also once was applied to a species now placed in Verticordia DC., an Australian genus of Myrtaceae (Snow 1997a). After Hackel, the generic boundaries of Diplachne remained highly unstable (Parodi 1927; McNeill 1979; Phillips 1974, 1982; Clayton and Renvoize 1986; Watson and Dallwitz 1992; Jacobs 1987; Snow 1997a). Synonymy within Diplachne fusca is complex and summarised mostly under the subspecies of D. fusca .…”