''Cyclocephala castanea'' is a species of small

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

in the family Scarabaeidae which is native to the

Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. This beetle and certain others in the same

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

have a commensal relationship with the large water lily '' Victoria amazonica''. Visiting the flower for food, the beetles are trapped inside and emerge laden with pollen the following evening.

Ecology

''Cyclocephala castanea'', and the closely related '' Cyclocephala hardyi'', have co-evolved with the giant water lily '' Victoria amazonica'', found in shallow waters in the

. The flowers are nocturnal and float on the surface of the water. They are creamy-white and have a strong fragrance when they first open. The beetles are attracted to the flowers which have a high temperature, up to 10 °C (18 °F) warmer than their surroundings, and which contain starch-rich appendages called paracarpels. At the end of the night the flowers close and the beetles are trapped by the petals. When the flowers reopen the next night, they are pinkish-red or purple, no longer warmer than their surroundings, the fragrance has gone, and the stigmas are no longer receptive. However, the

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s are loaded with pollen and the beetles, well-dusted with pollen, fly off to find other, white flowers which are more attractive to them, and which they will pollinate. The plant benefits from this arrangement because it avoids self-fertilisation, each plant unfurling a new flower every alternate evening. The beetles also benefit; they have a period to feast on the specialised food tissues provided for them by the plant, and plenty of time in close proximity with one another for mating. Another water lily, '' Nymphaea rudgeana'', is similarly pollinated by ''C. castanea''.

References

{{Taxonbar, from=Q14868472 Dynastinae Beetles of South America Beetles described in 1789