Hidden in plain sight: a new Cuscuta species from southwest Utah and northwest Arizona (section Californicae, subgenus Grammica, Convolvulaceae)

Cuscuta nuwuviana, a new species from southwest Utah and northwest Arizona
is described and illustrated. The phylogenetic analyses revealed that the
new species belongs to a subclade of sect. Californicae (subg. Grammica)
that also includes C. draconella and C. decipiens. Although not
statistically significant, a topological incongruence between the plastid
and nuclear data suggests that C. draconella most likely resulted from the
homoploid hybridization of C. nuwuviana and C. decipiens, accompanied by
plastid introgression.  Optical and scanning electron microscopy
were employed to morphologically distinguish C. nuwuviana from C.
draconella and C. decipiens, and an identification key was provided. Field
investigations allowed the description of the habitat and plant community
of the new species, which is currently known from only two populations in
which it parasitizes solely Gutierrezia microcephala (Asteraceae).
Evolutionary relationships, infrastaminal scales, and the presence of
floral stomatiferous protuberances in sect. Californicae are discussed.