Ancient Beetle Discovery Gives Clue To Gymnosperm Pollination

Credit: NIGPAS

Phylogenetic analyses of the beetle and associated pollen grains conducted by Dr. CAI Chenyang from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and his colleagues indicated that it was probably a pollinator of early cycads.

Unlike modern wind-pollinated conifers and Ginkgo, cycads are unusual in that they are an ancient group of gymnosperms pollinated by insects, such as beetles and rarely thrips. Little is known about the early evolution of their pollination mode before the rise of angiosperms, or flowering plants, although cycads are well documented from the mid-Mesozoic.

The researchers discovered a new genus and species of boganiid beetle, named Cretoparacucujus cycadophilus Cai and Escalona, 2018, preserved with many tiny cycad pollen grains and possessing specialized mandibular patches for the transport of cycad pollen.

Most importantly, morphology-based phylogenetic placement of the species reveals it belongs to a clade of relict genera with a disjunct distribution encompassing southeastern Africa and southwestern Australia. The species are also specialist pollinators of the same clade of modern cycads. Thus, both morphological and phylogenetic evidence support the determination of the fossil as a cycad-associated insect species.

Credit: NIGPAS

The fossil represents the earliest definitive fossil evidence for cycad-insect interactions, and illuminates the ancient history of the establishment of complex entomophily in cycads. It also indicates a probable ancient origin of beetle pollination of cycads at least in the early stage of the Jurassic, some 176 million years ago, long before flowering-plant dominance and the radiation of their pollinators such as bees and butterflies later in the Cretaceous.

Contacts and sources:
Chen Xiaozheng

Chinese Academy Of Sciences

Citation:  Beetle Pollination of Cycads in the Mesozoic
Chenyang Cai 10 Hermes E. Escalona Liqin Li Ziwei Yin Diying Huang Michael S. Engel
Published:August 16, 2018DOI :https://doi.org/10.1016/j.cub.2018.06.036
http://dx.doi.org/10.1016/j.cub.2018.06.036