Until 2012 it was thought that only one species could be found on the continent, 6 in Madagascar and1 in Australia.
Pettigrew in 2012 while examining baobabs in Iringa discovered that not all were tetraploid as Adansonia digitata. Some were found to be diploid. Therefore a new species Adansonia kilima has been described for Africa by Prof. Jack Pettigrew.
In Ruaha one may also find the Adansonia kilima. This species is found in the highlands of Tanzania although very similar to the A. digitata but has smaller flowers and lots of them. The digitata has fewer flowers but is nearly double in size.
Dr. Sarah Venter:
This is significant because worldwide there are only eight species of baobab, six of them are in Madagascar, one is in Australia and one in Africa (Adansonia digitata). But what has always intrigued taxonomists is that the species that occur in Madagascar and Australia are diploid (having 2 chromosomes in a set) and the one in Africa is tetraploid (having 4 chromosomes in a set).
Taxonomists have said that the 'original' baobab must have been diploid and spurred by this Pettigrew felt that diploid trees must still exist in Africa. He ventured from Australia, where he lives, to the Kenyan highlands where he found a population of diploid trees. Since then he has found other populations of diploid trees and by chance it seems that this new species even occurs in our back yard in Limpopo. I headed out a few weeks ago to see the tree he described as the new species.
This interesting article by Isla Grundy was published in March 2014:
A new baobab species Adansonia kilima, called the Kilima or Mountain Baobab, has recently been claimed to be co-existing with A. digitata in southern Africa by an Australian academic who co-authored a paper about it online in early 2013. The paper, authored by eight people, describes the difference between the two species. The proposed new species is said to be diploid (having 22 chromosomes) rather than being tetraploid (having 44 chromosomes, i.e. with twice the amount of genetic material) like its relative that we all know so well. The Kilima baobab is said to grow at higher elevations than A. digitata, between 650-1500m.
Dr Sarah Venter, who recently completed her PhD on baobabs in Venda (just south of the Limpopo River in South Africa), says that the distinction between flower size and fruit size is not as clear as described by Pettigrew et al. and therefore it may be difficult to tell the species apart. She also cautioned that the existence of the Kilima baobab is still a theory. It still needs to go through the rigors of scientific questioning and testing before it becomes established and accepted. So far it is a controversial finding and needs more investigation, but because the theory is based on chromosome number and DNA sequencing, it has more credibility.