Abstract—
The region of the Qinghai-Tibet Plateau hosts a remarkable biodiversity, including a plethora of endemics. There, the process of documenting biodiversity is still ongoing, and recently, an unusual plant of
Gentiana
section
Frigida
was discovered
at Cuopu Lakes (Sichuan, China). Although
Flora of China
identified these specimens as
G. algida
based upon unmistakable traits (e.g. corolla colour and length, sessile flowers), it was obvious that the Sichuanese plants strongly differed morphologically from
G. algida
specimens from Siberia and North America. In order to clarify their relationships, we used an integrative approach, investigating not only morphological traits, but also phylogenetic relationships (based upon plastome and rDNA-cistron), as well as chloroplast structure. Whereas the rDNA-cistron
phylogeny was poorly resolved, the plastome phylogeny was well supported in both Bayesian inference and maximum likelihood analyses. Our findings indicate that the samples of
G. algida
from Cuopu Lakes are morphologically and genetically distinct from those collected elsewhere, supporting
the recognition of a new species,
G. susanneae
. The new species differs from
G. purdomii
(another similar species) by having sessile flowers, and from
G. algida
by being a generally much taller plant with more and longer flowers, and by having a smaller calyx.
Gentiana
susanneae
clusters with other species from the region of the Qinghai-Tibet Plateau from which it differs morphologically, and is only distantly related to the
G. algida
/
G. frigida
clade, which stems from a dispersal event out of Tibet. Based upon these solid lines of
evidence,
G. susanneae
is described and illustrated (drawings and photographs). In addition, a conservation assessment and an identification key modified from
Flora of China
are provided.