BOHS, LYNN. Department of Biology, University of Utah, Salt Lake City, UT 84112. - Slicing up the Solanums: major lineages and morphological synapomorphies.
Analyses of molecular data from chloroplast ndhF and nuclear ITS
sequences have identified six to seven major clades within the genus
Solanum (Solanaceae). For the most part, these clades do not conform
to the traditional Solanum subgenera. Exceptions to this pattern are
the aneuploid Australasian subgenus Archaesolanum and the majority of
species in the spiny subgenus Leptostemonum, each of which appear to
form monophyletic groups. Closely related to subgenus Leptostemonum
are the non-spiny sections Brevantherum, Extensum, Lepidotum, Geminata
(including Holophylla pro parte), Gonatotrichum, Pachyphylla, and
Cyphomandropsis. Solanum allophyllum and the spiny species S.
wendlandii form a clade within this group which may either be basal in
Leptostemonum or placed outside the spiny Solanums. Woodiness and
branched hairs are commonly found in members of this larger clade.
Solanum sections Solanum, Parasolanum, Dulcamara, Jasminosolanum and
Holophylla pro parte form another discrete clade composed of taxa
placed by D’Arcy (1991) in subgenera Minon, Potatoe, and Solanum. The
potatoes (section Petota) comprise a clade with the tomatoes (section
Lycopersicum) and members of sections Anarrichomenum, Basarthrum,
Etuberosum, Juglandifolium, Regmandra, Pteroidea, and Herpystichum,
uniting taxa of subgenera Potatoe and Bassovia. The African non-spiny
taxa represented by S. terminale, S. quadrangulare, and S. aggregatum
in this analysis form an isolated clade within the genus. The genera
Normania and Triguera, notable for their unusual morphology and
distribution, are nested within Solanum and constitute a
well-supported clade with no clear relationship to other Solanum
groups. These data allow Solanum to be cleaved into several
well-supported subgeneric units, some of which are diagnosable by
morphological synapomorphies.
Key words: ITS, ndhF, Solanaceae, Solanum