Commelina mascarenica

Faden, Robert B., 2008, Commelina mascarenica (Commelinaceae): an overlooked Malagasy species in Africa, Adansonia (3) 30 (1), pp. 47-55 : 48-49

COMMELINA MASCARENICA IN AFRICA

The plant that would prove to be C. mascarenica was first recognized in Africa as a distinct species in Kenya ( Faden 1974). Because no name could be found for it, the species was designated as “ Commelina sp. D ”. No name had yet been discovered 20 years later, so the same designation was used in Faden (1994). This species was recognized from Somalia in Faden (1995), where it was called “ Commelina sp. #5”.

The identification of Commelina sp. D and Commelina sp. #5 as C. mascarenica happened as a result of a study that I began in 2000 of an apparently undescribed species of Commelina from coastal and subcoastal Kenya and Tanzania. That species (Faden in press) also has elongate, smooth seeds, so it became necessary to determine whether it might actually be C. mascarenica . I had not studied that species before, so in March 2002, in a loan from the Muséum national d’Histoire naturelle, Paris (P) to the Royal Botanic Gardens, Kew (K), I examined 14 of the 15 collections – all except Perrier de la Bâthie 9018, which was not sent – that were cited as C. mascarenica in Flore de Madagascar ( Perrier de la Bâthie 1938). Thirteen specimens appeared to belong to a species that significantly differed from my new East African species. The fourteenth specimen, Bojer s.n., was a mixed collection, one part of which – designated by Perrier de la Bâthie (1938) as “ Bojer B ” – was indeed my new East African Commelina species , and was not conspecific with the other 13 collections. The other part of the Bojer collection, “ Bojer A ”, belonged to an unrelated species, C. lyallii C.B.Clarke.

The 13 remaining collections from Madagascar and the Comoro Islands that were treated by Perrier de la Bâthie (1936, 1938) as C. mascarenica were recognized as conspecific with my Commelina sp. D and Commelina sp. #5 because some of them, e.g., Decary 791 (P) from the Comoro Islands, had mature seeds that were identical to those of the African plants. However, because I now had evidence that my putative new species also occurred in Madagascar, it became necessary to examine the type of C. mascarenica , in order to determine to which species the name should be applied.

In August 2002, I was able to study the type of C. mascarenica , sent on loan to Kew from G. Although the type specimen was rather scrappy,and the capsule and seeds in the packet were immature, I had no doubt that this was same species as the 13 collections examined from P that were cited as C. mascarenica in Flore de Madagascar and also matched African Commelina sp. D and Commelina sp. #5. Therefore the African plants were C. mascarenica too.

The first reference to C. mascarenica in Africa was by Faden (2006), in an appendix to the Flora of Somalia. The species name was applied to a previously unnamed species ( Commelina sp. #5) and the species was noted to also occur in Kenya, Tanzania, Mozambique, Comoro Islands and Madagascar.