Habenaria decaptera Reichenbach 1882

Habenaria decaptera Reichenbach (1882: 531) (Fig. 4) Painting number 45 in notebook 5 immediately drew my attention. Unfortunately, there is no herbarium specimen associated with this painting. Nevertheless, the painting is detailed and shows all aspects of the plants including the habit, front and side view of the flower, and the leaves (Fig. 4A). I was pretty sure that it belongs to the genus Habenaria, which is one of the genera I am actively working on, but I had never seen this species before. White flowers are rather unusual in African Habenaria and the trilobed lip with the side lobes starting in the middle of the lip is even more unusual. Despite this, I was not immediately able to name this taxon. It did not key out in Flora Zambesiaca, which, in the absence of a flora treatment for Angola, is the best tool to identify plants occurring in Angola. Then, recently, I was sent a photograph (Fig. 4B) by António Martins, an Angolan naturalist. The image was made in the Kuvango River floodplain near Capelongo (Huíla Province) in October 2020 and was clearly the same plant as the one painted by Mrs Faulkner. Since I was sure that this was not one of the species occurring in the Flora Zambesiaca area, I went through the species descriptions of Habenaria endemic to Angola. One description was a good match, namely that of Habenaria decaptera. This species was described by Reichenbach fil. in 1882 on the basis of a specimen collected by Alexander von Mechow (von Mechow 438, collected in January/ February 1880 around Malange [Malanje] in Malanje Province). There are duplicates of this collection in the Reichenbach Herbarium in Vienna (W-R), as well as in Munich (M) and Zurich (Z). There is also a trace drawing of the type at Kew. As far as I’m aware, Helen Faulkner was only the second person to see this species, which she found on a grassy mound in the Alto Catumbela swamp on 26 January 1938 and again on 3 February 1941. Her painting remained unnamed until now. Together with the record from Martins, it significantly expands the known range of this species by about 500 km southwards and can now be assumed to occur in the Benguela, Huíla, and Malanje Provinces of Angola.