The latest phylogenetic tree for Malpighiaceae (Davis & Anderson, 2010) does not establish where the genus originated, but it is noteworthy that the sister genus
, Thryallis, is limited to southeastern Brazil and adjacent Paraguay and Bolivia (C.
Lempira and Pararhicnoderma, which are present from Southern Mexico south to Panama, plus the Panamanian endemic Panamacris, here resolved as the sister genus
Although the mating system has been experimentally examined in only six species or subspecies of Abronia, it is worthwhile to have information on mating systems from the probable sister genus
, Tripterocalyx, to aid in understanding the evolution of mating systems in Abronia specifically, and more generally, to increase confidence and resolution in phylogenetic reconstructions of the evolution of mating systems in Nyctaginaceae.
Grogan and Wirth (1979) reviewed Palpomyia in the Nearctic region and also discussed larval and adult biology, zoogeography, economic importance as well as phylogenetic relationships within the genus and to its sister genus
, Pachyhelea Wirth 1959.
The results indicate that the new genus does not belong to the Asteron complex but is the sister genus
Upon his erection of Heterochone, Ijima (1927) provided an extensive comparison of the new genus with its only sister genus
, Aphrocallistes, but did not provide a diagnosis.
This same study noted tori in wood of two of three subgenera of Wikstroemia, a sister genus
1) The number of species in a genus that contains at least one ornamented species will be larger than in a sister genus
The paramo endemic Aragoa is the sister genus
of Plantago (Plantaginaceae; Lamiales): evidence from plastid rbcL and nuclear ribosomal ITS sequence data.
The two genera are very similar and Descamps (1976) considered them to be vicariants; Rowell & Flook (2004) found them to be closely related, but placed Kritacris, rather than Balachowshyacris, as the sister genus