A paleontologist from Oregon State University has found a new species of flower together with a new parasitic wasp species in a piece of amber excavated from a mine in the Dominican Republic.
Holotype of Plukenetia minima adjacent to the encyrtid wasp Hambletonia dominicana in Dominican amber. Scale bar – 0.6 mm. Image credit: Poinar Jr., doi: 10.1080/08912963.2022.2086053.
“Flowers in amber from the Dominican Republic reveal Neotropical plant groups that existed on the island of Hispaniola (home to Haiti and the Dominican Republic) during the mid-Cenozoic,” said Professor George Poinar Jr., a paleontologist in the Department of Integrative Biology at Oregon State University and an author of a paper published in the journal Historical Biology.
“Among these are representatives of the families Fabaceae, Arecaceae, Poaceae, Chrysobalanaceae, Lauraceae, Meliaceae, Burseraceae, Myristaceae, Rhamnaceae and Ticodendraceae.”
The newly-identified plant species, Plukenetia minima, belongs to the genus Plukenetia in the family Euphorbiaceae.
“The family Euphorbiaceae has a global distribution with some 300 genera, showing most diversity in tropical and subtropical regions of the world,” Professor Poinar said.
“In tropical America, there are some 105 genera with 1,800 species of which 65 are endemic.”
“One of these endemic genera is Plukenetia, a pantropical genus of twining vines and lianas.”
The mature female flower of Plukenetia minima is noteworthy for its small size but lengthy stalk, which at the tip has four distinct capsules.
It is the first record of Plukenetia on Hispaniola and also the first fossil record of the genus.
“Fossil flowers of Euphorbiaceae are quite rare. I could only find one previously known fossil, from sedimentary deposits in Tennessee,” Professor Poinar noted.
The fossil flower of Plukenetia minima originated from mines in the northern mountain range of the Dominican Republic between Puerto Plata and Santiago.
Amber from mines in this region was produced by an extinct leguminous tree species called Hymenaea protera and based on recovered biota in amber, the original habitat was characterized as a tropical moist forest.
The wasp from the same piece of amber was described by Professor Poinar as a new species in a separate paper published in the journal Biosis: Biological Systems.
Named named Hambletonia dominicana, it is an encyrtid, a group of wasps known for attacking a wide range of insects.
In the current study, the flower of Plukenetia minima has already bloomed and contains four maturing seed pods or capsules. One of the pods contains a developing fly larva.
“The wasp was likely attracted to the flower, either for obtaining nectar or in attempts to deposit an egg on the capsule that contains the fly larva,” Professor Poinar said.
“The wasp egg would then hatch, enter the pod and devour the fly larva, enabling the wasp to survive in the ecological niche created by the vegetation and flower heads of Plukenetia.”
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George Poinar Jr. Plukenetia minima sp. nov. (Euphorbiaceae) in Dominican Republic amber. Historical Biology, published online June 16, 2022; doi: 10.1080/08912963.2022.2086053
