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recognize only two species in this complex, one
from the “northern” part of the distribution area
( Solanum candolleanum from central and southern
Peru and north-western Bolivia), the other from
the “southern” part ( S. brevicaule from northern
Bolivia to central Argentina). However, even
these two species are extremely similar, differing
primarily in their geography, and are difficult to
key out. A key is announced, but although based
on the insights from the replicated field trials (Van
den Berg et al ., 1998; Alvarez et al ., 2008) and a
thorough study of herbarium specimens, the au-
thors themselves warn that determinations will
often fail. The extensive synonymy proposed on
the Solanaceae Source website is based on the im-
practicality of morphological data to distinguish
these species and the low support they receive in
molecular phylogenetic studies.
This solution to the problem of the brevi-
caule complex, already envisaged by Ugent
(1970), who reduced the whole complex to one
species, S. brevicaule , was anticipated by several
studies (Van den Berg et al ., 1996, 1998; Miller
and Spooner, 1999). Although a certain infra-
structure of the complex can be recognized,
leading to a series of geographically restricted
“species” from north to south, the morphomet-
ric studies mentioned above clearly showed that
many of the taxa involved could not be separ-
ated from each other reliably, and extensive syn-
onymy was unavoidable. The Solanaceae Source
website provides a workable taxonomic solution
and it would be wise to heed their warning:
and Solanum astleyi and enlarged terminal leaflet
in most other species). Giannattasio and Spooner
(1994a,b) reduced Solanum toralapanum to a sub-
species of Solanum megistracrolobum , and Spooner
et al . (1997) reduced S. astleyi to a subspecies of
S. boliviense . The treatment on the Solanaceae
Source website reduces most of the former spe-
cies names to synonyms of S. boliviense , accepts
Solanum sogarandinum as a separate species,
but notes that it is extremely difficult to dis-
tinguish it from S. boliviense and indicates
that the status of other species still has to be des-
ignated.
Our own AFLP data (Van den Berg and
Groendijk-Wilders, 2007) and the CBSG data (Ja-
cobs et al ., 2011) more or less clearly distinguish
a complex consisting of S. boliviense and S. astleyi
(which are indistinguishable from each other)
from the rest of the species of series Megistacroloba .
The synonymizing of S. astleyi as subspecies of
S. boliviense is not in line with the results of Jacobs
et al . (2011), who in their Structure analysis
found no support for a subspecies level within
S. boliviense . Reducing S. astleyi to a synonym of
S. boliviense seems more logical. The AFLP data
also show an unexpected closer relationship between
S. megistacrolobum and Solanum sanctae- rosae , with
S. toralapanum sister to both, which would be in
line with the Solanaceae Source treatment. Jacobs
et al . (2011) found only weak evidence for species
status for the combination of S. megistacrolobum
and S. toralapanum , and for S. sanctae-rosae , but
the material with these species names clustered
separately from that of an astleyi / boliviense cluster.
All this leaves some doubt whether the synonymy
arrived at on the Solanaceae Source website is
too extreme.
We suspect that our synonymy will be
questioned by those using molecular marker
data, but we suggest that such workers wishing
to resurrect our synonymized names do so only
with morphological data needed to support the
identification of these species in realistic and
practical ways. Without such data, we envision
the perpetuation of alternative taxonomies,
variant identifications by different workers, and
the maintenance of unstable names and
taxonomic confusion in these important but
taxonomically confusing species related to the
cultivated potato.
The gene bank predicament
As the cultivated potato is an important crop and
its wild relatives are valuable potential sources
of useful traits to improve the crop, much energy
and time have been invested to collect, maintain,
and evaluate germplasm of the wild species. These
collections are maintained in gene banks, with
the most important collections at CIP (Inter-
national Potato Center, Lima, Peru), NRSP- 6 (Potato
Introduction Station, US Potato Genebank,
Sturgeon Bay, USA), and CGN (Centre for Gen-
etic Resources, Wageningen, the Netherlands).
( http://solanaceaesource.org/ )
Series Megistacroloba
Hawkes (1990) recognized 11 species in series Meg-
istacroloba , mostly relying on leaf dissection char-
acters (e.g. simple leaves in Solanum boliviense
 
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