- Scientists have described three new species of plants closely related to the cacao tree, highlighting the importance of dried herbarium collections in uncovering hidden biodiversity.
- The newly described species, native to the Amazon Basin, are already facing conservation challenges, with two potentially qualifying as vulnerable to extinction.
- While these new species could potentially offer genetic resources for developing more climate-resilient cacao varieties, some say it’s too soon to predict practical impacts for chocolate production.
- The findings underscore the urgency of conservation efforts in the Amazon region, not only for these newly described species but for countless others still unknown to science.
Scientists have uncovered a surprising find from the Amazon Basin: three new species of plants closely related to Theobroma cacao, the tree that gives us chocolate. This finding, made by examining dried plant specimens in herbaria, reveals that even well-known plant groups can still hold secrets.
This research, published in the journal Kew Bulletin, highlights the importance of preserving both natural habitats and scientific collections of plants and animals, especially as more biodiversity hotspots like the Amazon face unprecedented threats from deforestation and climate change.
“That there were recently unknown species closely related to Theobroma cacao, which is of huge importance for the production of chocolate and other products, shows how much more work there is to be done to catalogue the vast amount of unknown biodiversity across our planet,” James Richardson, a plant evolutionary biologist at University College Cork in Ireland, told Mongabay.
The research team, comprising scientists and students from University College Cork; the University of São Paulo (including lead author Matheus Colli-Silva); the New York Botanical Garden; and the Royal Botanic Gardens, Kew, in the U.K., meticulously examined herbarium specimens to identify the new species: Theobroma globosum, T. nervosum, and T. schultesii. These species were originally collected from various locations across the western Amazon Basin, in Brazil, Peru, Ecuador and Colombia.
Theobroma schultesii, named after botanist Richard E. Schultes, is the tallest of the three new trees, reaching up to 8 meters (26 feet) in height, with crimson flowers and large, conical fruits. T. globosum, named for its distinctive round fruits, is a small tree with purple flowers. T. nervosum has leaves with prominent veins that extend beyond the leaf edge, forming small points.
This finding comes at a time when cacao production faces significant challenges due to climate change. According to the Intergovernmental Panel on Climate Change (IPCC), while rising temperatures alone may not harm cacao trees, increased evapotranspiration could make current cultivation areas, particularly in West Africa, less suitable for the crop by 2050.
The researchers say they hope these newly described Theobroma species could offer genetic resources for developing more resilient cacao varieties. “The identification of new species, in addition to those already known, expands the genetic resources that are available to us that might allow us to produce drought-tolerant or disease-resistant cacao trees,” Richardson said.
However, some caution it may be too soon to predict a practical impact for chocolate. “I don’t doubt that [new species] could potentially be used to modify cacao trees to adapt to climate change in the future, but I also don’t think that’s the super big news,” Jerry Toth, who runs a cacao-based conservation project in Ecuador and was not involved in the study, told Mongabay. “Finding three new Theobroma species is exciting in its own right.”
Richardson said that in addition to their potential use in improving cacao resilience, these new species could be sources for novel products from the fruit pulp. The pulp of Theobroma cacao is eaten on its own or used as a flavoring for ice cream and other desserts, while the pulp of Theobroma grandiflorum, another species in the genus, is used in Brazil to make a drink called cupuaçu. Richardson suggested that similar products could potentially be developed from the pulp of these newly identified species.
Richardson emphasized the crucial role of herbarium collections in this research. Herbaria, which house dried plant specimens collected over centuries, continue to yield new scientific insights, even in the age of modern genetic analysis and field research.
“These new species were identified as a result of studying specimens in herbaria, and demonstrate the importance of maintaining these natural history collections as many more species remain to be found within them,” he told Mongabay.
Richardson and his team say they have ambitious plans to build on this research. They plan to complete a taxonomic revision of the Theobroma genus, investigate drought tolerance in wild cacao relatives, and conduct genomic studies to identify traits that could improve cacao resilience. They also say they hope to advance conservation efforts by bringing rare species into cultivation and studying how climate change might affect their distribution.
The new species are already facing conservation challenges. Based on preliminary assessments using IUCN Red List criteria, T. globosum and T. nervosum may both qualify as vulnerable to extinction. T. schultesii, with its more extensive geographical range, is provisionally assessed as near threatened. This species has been found in several protected areas, which may offer some level of conservation. However, the general threats to Amazon habitats, including deforestation and climate change, pose potential risks to all three species.
These assessments highlight the urgency of conservation efforts in the Amazon region, Richardson said, not only for these newly described Theobroma species but also for the countless other species still unknown to science. These hidden treasures could offer keys to climate resilience and adaptation in a changing world.
“The motivation for all of this work,” Richardson said, “is conservation of biodiversity.”
Banner image.of a Theobroma pod in Peru (not one of the new species) by Rhett A. Butler.
Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in ecology and evolutionary biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.
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Citation:
Colli-Silva, M., Richardson, J. E., Michelangeli, F. A., & Pirani, J. R. (2024). Expanding the cacao group: three new species of Theobroma sect. Herrania (Malvaceae: Byttnerioideae) from the Western Amazon Basin. Kew Bulletin, 1-12. doi:10.1007/s12225-024-10171-x
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