Inversodicraea bosii (C.Cusset) Rutish. & Thiv

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

16. Inversodicraea bosii (C.Cusset) Rutish. & Thiv

Inversodicraea bosii (C.Cusset) Rutish. & Thiv ( Thiv et al. (2009) 72). — Ledermanniella bosii C. Cusset (1983) 385, f. 9; (1987) 78. — Type: Bos 3592 (holotype WAG n.v; isotypes K, P00179266 image, YA), Cameroon, S. Region, S. Kribi, Chûtes de la Lobé, fl., 8 Jan. 1969.

Etymology. Named for the collector of the type specimen, Dr Bos , of the Herbarium Vadense, University of Wageningen (now transferred to Leiden). He was a noted botanical collector in S. Region Cameroon,and specialist in Dracaena .

Distribution — Cameroon, Chûtes de la Lobé.

Habitat & Ecology — ‘In fast running shallow water on otherwise bare rockfaces’ ( Bos 3592); in evergreen forest zone; 5–10 m altitude.

Conservation — Inversodicraea bosii was listed on www. iucnredlist.org in 2007 as EN B2 ab(iii), i.e., Endangered ( Ghogue 2010b). Two locations are cited there, the first at Lobé, threatened by tourist trampling, and the second at Campo (no threats listed), with an area of occupancy of 2 km 2. The same assessment was made by Cheek (in Onana & Cheek 2011) additionally citing hydroelectric development as a threat at the Campo (Ntem) location.

In fact (see notes above), we now know that I. bosii is known from a single location, the Lobé Falls, at which we assess its area of occupancy (and so its extent of occurrence) as 1 km 2 using the IUCN-preferred cells of that size. Here it is threatened by trampling from the many tourists that visit what in Cameroon is a major tourist attraction (Cheek in Onana & Cheek 2011, Ghogue 2011). Therefore the species is here reassessed as Critically Endangered, CR B2 ab(iii).

Additional specimen. CAMEROON, S. Region, S. Kribi, Chûtes de la Lobé, fl., 8 Jan. 1969, Bos 3597 ( WAG spirit specimen n.v.) .

Note — The paratype of I. bosii, Letouzey 15333 (Chûtes du Ntem près de sa deviation sur le Bongola) is I. ntemensis (see under that species). Inversodicraea bosii is therefore only known from the type locality at Chûtes de la Lobé. The isotype at K is I. ledermannii suggesting that this number is a mixed collection. The large, entire, ovate scale-leaves described and depicted in the protologue are distinctive. Initially Cusset (in litt. 1975) had determined the type material at YA as Ledermanniella (Inversodicraea) kamerunensis . Elad 1482 and 1484 may be hybrids between I. bosii and I. ledermannii (see discussion under I. eladii ).