To better understand the taxonomy of Pulicaria,
the pollen wall architecture of the six Iberian species
were investigated using light (LM) and scanning electron
microscopy (SEM). The exine structure of Pulicaria odora
was also investigated using transmission electron microscopy
(TEM). Statistical analysis was performed to distinguish
taxonomically significant morphometric information
from all the measured parameters of pollen grains. It was
found that the exine sculpture characters, with special
importance paid to the spines, were the most useful of all
characters to define Pulicaria pollen types and separate the
species. Three pollen types distinguishable through the
spines morphology and the inter-spinular sculpture are
described: P. microcephala pollen type (incl. P. microcephala),
P. vulgaris pollen type (incl. P. vulgaris), and
P. dysenterica pollen type (incl. P. dysenterica, P. odora,
P. paludosa and P. sicula). A dichotomous key to these
Pulicaria pollen types is proposed. The distribution of
P. dysenterica, P. odora, P. paludosa and P. sicula in more
than one leaf node in the classification tree reveals that the
pollen grains of these species are difficult to segregate.
Therefore, the construction of a satisfactory dichotomous
key to the P. dysenterica pollen type species is not feasible.
Yet, the different spines apex morphology between
P. microcephala and P. paludosa and the existence of significant differences in five of the eight studied quantitative
pollen characters of these two taxa, supports the
opinion that the Berlengas Islands endemic P. microcephala
should be accepted as a separate species. In addition,
the differences among the spines morphology of P. vulgaris,
P. microcephala, and the other four Iberian (and
European) species, strengthen the conclusion that the section
Pulicaria is non-monophyletic.
