Inversodicraea kamerunensis (Engl.) Engl.

Tchouto, P. & Burgt, X. van der, 2017, A synoptic revision of Inversodicraea (Podostemaceae), Blumea 62 (2), pp. 125-156 : 140-141

17. Inversodicraea kamerunensis (Engl.) Engl.

Inversodicraea kamerunensis (Engl.) Engl. (1915) 274, f. 180N–R; (1926) 463; (1930) 58, f. 47A–D. — Dicraea kamerunensis Engl. (1909) 380, f. 2A–D. — Ledermanniella kamerunensis (Engl.) C. Cusset (1974) 274; (1983) 387; (1987) 76. — Type: Ledermann 440a (holotype B destroyed; lectotype BM selected here), Cameroon,S.Region,‘Schnellen des Campo- Flusses, bei Dipika’ (falls of the Campo River near Dipika), fr., Aug. 1908.

Etymology. Named for Cameroon ( Kamerun is the German spelling) to which country it remains endemic.

Distribution — Cameroon. Only the type gathering is known.

Habitat & Ecology — Waterfalls at low altitude.

Conservation — Apparently not seen for over 100 years, this species is vulnerable to proposed hydroelectric projects on the Campo (Ntem) River, its only known location. Inversodicraea kamerunensis (as Ledermanniella ) was assessed as Vulnerable in 2007 ( Ghogue 2010e) but in view of imminent construction of the hydroelectric dams upstream of the only known location of this species (see under I. ntemensis ) we feel that the threat to the species has risen. Multiple surveys for Podostemaceae along the length of the Campo (Ntem) River in the last 10 years have not succeeded in rediscovering this species suggesting that the 20 km 2 area of occupancy estimated in Ghogue (2010e) may be an overestimate, and that 1 km 2 is the more realistic estimate and in keeping with IUCN guidance. Accordingly the species is here assessed as Critically Endangered, CR B2 ab(iii). In Cheek (in Onana & Cheek 2011) the same assessment was given. It is potentially Extinct.

Notes — According to a note on the type cover at BM: ‘ Holotype destroyed in Berlin’. On the sheet itself is written in pencil ‘Portion returned to B. June 1984. J. Laundon’. The specimen packet is marked ‘ Dicraea kamerunensis Engl. (portion of type)’. Therefore, with the destruction of the holotype at B in 1943, the BM material is here selected as lectotype being the largest remaining portion of the only original specimen mentioned and illustrated in the protologue of the basionym ( Engler 1909).

Ledermann 440 is the type of Ledermanniella linearifolia Engl. , and also the type of Ledermanniella Engl. The specimen details are identical with those of Ledermann 440a. The number- ing suggests that since they are numbered together the two specimens were growing together, and that the suffix ‘a’ was added later to separate them – a standard convention in this circumstance.

Cusset based her description and illustration (1983) of the species purely on the protologue and its illustration which is misleading in some respects. She was unaware of the BM material it seems, having failed to find the type at B ( Cusset 1983). No leaf stipules were seen on the lectotype by us although Cusset states that they are present ( Cusset 1983).

The illustration in the protologue is misleading, showing scale-leaves which are linear-oblong, whereas the type specimen has scale-leaves about as long as wide. The scale-leaves broaden slightly from base to apex. The apex is semicircular, and either entire, or minutely and irregularly laciniate.

The affinities of I. kamerunensis appear to be with I. thollonii (see notes there) and I. adamesii .