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ciliatus x P. fruticosus hybrids occurred. It is clear that acrocerid flies are important
pollinators of P. ciliatus over a large extent of its range. The different acrocerid species
that visited P. ciliatus have proboscides in a common range (8 – 12 mm), which matched
or were longer than the corolla tubes of P. ciliatus, but corresponded to the length of
the stamens and style, which facilitated pollen carry-over on the ventral head surface
and base of the proboscis of the fly.
The long-proboscid nemestrinid fly, Stenobasipteron wiedemanni, also visited P.
ciliatus populations in Stutterheim and at Oribi Gorge. The fly reached nectar without
contacting the sexual organs of the plant with its body. While some pollen may be
carried over on the proboscis, this is more a case of the fly exploiting the flowers for
nectar.
The apinid bee species Amegilla caelestina and A. bothai visited P. ciliatus at
Umtamvuna NR. No acrocerid flies were observed on P. ciliatus at this a site, but
Psilodera aff. confusa did occur at this site and may also pollinate the species.
Likewise, species of Amegilla bees occur at the other study sites and may also visit P.
ciliatus there.
At Magwa both the apinid bees and acrocerid flies were seen visiting flowers of the
same population of the tentative hybrid P. ciliatus x P. fruticosus. The bees were
Amegilla mimadvena and Zebramegilla sp. These bees may function as effectively as
pollinators as acrocerid flies, since they are similar in body shape and size and the
proboscis lengths match that of the P. ciliatus corolla tube. In most of the cases where
Amegilla bees and Psilodera flies visited the same species, they fulfilled a similar role
in terms of body sizes and proboscis lengths.
Other visitors to this tentative hybrid included a medium-proboscid nemestrinid fly
(Prosoeca sp.) and three lepidopterans: the hummingbird hawkmoth Macroglossus
trochilus, the papilionoid butterfly Papilio dardanus and a species of hesperid butterfly.
These Lepidoptera were unlikely to be major pollinators, since the proboscides were
much longer than the floral parts, which prevented bodily contact. Syrphid flies visited
flowers at Oribi Gorge and Pietermaritzburg, and the short-proboscid halictinid bee,
Lasioglossum sp., was observed at Pietermaritzburg. These species collected pollen,
but are unlikely to reach nectar from the corolla base.
Appendix/ 131
P. ciliatus