Format: ORAL

Roy E. Gereau1, Fandey H. Mashimba2, Patricia Barber S.1, Alexander Linan1, Rebecca Sucher1, Andrew Wyatt1, Christine Edwards1

1 Missouri Botanical Garden, St. Louis, USA 2 Tanzania Forest Service Agency, Dodoma, TANZANIA

The tree species originally known as Holmskioldia gigas was first collected in a small patch of coastal forest on the coast of Kenya in 1977. Only one mature, fruiting tree and one sapling were observed, and by 1985, they were both found to have been cut down. Thus, when the species was formally described and named in 1988, it was considered Feared Extinct. The species was transferred from the genus Holmskioldia (Lamiaceae subfamily Scutellarioideae) to Karomia (subfamily Ajugoideae) in 1992 with the caution that its generic placement would have to be confirmed by its then-undocumented floral morphology. The rediscovery of Karomia gigas in 2003-2011 in two Tanzanian coastal forests more than 600 km south of its original Kenyan locality demonstrated that the species is not extinct, but its flowers remained unknown. A large number of mature fruit with seeds were collected in 2017, but initial attempts to germinate and propagate the species were unsuccessful due to fungal infection of most of the wild-collected seeds. In 2018, a second attempt at germination after treating the seeds with a fungicide was successful, resulting in 30 healthy seedlings that grew into young saplings that produced flowers in early 2021. Analysis of its floral morphology confirms the current placement of this species in Karomia, and DNA sequencing will further elucidate its subfamilial and generic position. With only 46 known individuals in the wild, Karomia gigas is assessed as Critically Endangered on the IUCN Red List of Threatened Species. Genomic analysis of an ex-situ population has provided important insights into the conservation of genetic diversity K. gigas. With many threats and low population numbers in its native habitat, continued protection and propagation of this species is required to enable future population recovery in Tanzania and eventually repatriation to Kenya.