Inversodicraea cussetiana (Cheek & Ameka) Cheek, 2017

Tchouto, P. & Burgt, X. van der, 2017, A synoptic revision of Inversodicraea (Podostemaceae), Blumea 62 (2), pp. 125-156 : 148-149

27. Inversodicraea cussetiana (Cheek & Ameka) Cheek , comb. nov.

Basionym. Macropodiella cussetiana Cheek & Ameka (2016) 2. — Type: J. de Koning 5232 (holotype K; isotypes UCJ n.v. WAG), Côte d’Ivoire, Sassandra River , near Louga, N5°03'02.53" E6°12'32.55", fl., fr., 25 Jan. 1975.

Etymology. Named in honour of Colette Cusset of P, to whom all working on African Podostemaceae owe a great debt for establishing the taxonomic framework on which all current research is based.

Distribution — Côte d’Ivoire, Sassandra River (type collection only).

Habitat & Ecology — On rocks of rapids in river in evergreen forest zone; 17 m altitude.

Conservation — Rapids and waterfalls are often favoured sites for placing hydroelectric projects, which threaten Podostemaceae species present at such sites by construction of dams, turbine houses, canals, and other connected infrastructure on their habitat, by the permanent submergence and loss of aerated water in areas flooded by the dam, and by the change to the natural hydrological regime in areas downstream of the dam.

The only known locality for Macropodiella cussetiana is on the Sassandra river about 20 km N of the coastal town of Sassandra. Further upriver, about 92 km N of the type locality of M. cussetiana , is the town of Soubre, and the Naoua Falls where a new hydroelectric scheme managed by Sinohydro is planned (http://www.hydroworld.com/articles/2014/01/alstom-winscontract-to-outfit-ivory-coast-s-soubre-hydropower-project.html downloaded 26 June 2014). This project threatens the only known global locality for Macropodiella taylorii (J.J.de Wilde & Guillaumet) C.Cusset whereat multiple specimens have been made ( Cusset 1978). In June 2014 interest was being shown in developing hydropower sites downriver of Soubre, which threatens Macropodiella cussetiana (http://www.hydroworld. com/articles/2014/06/ivory-coast-seeks-hydropower-sitestudies-below-270-mw-soubre-hydro-project.html downloaded 26 June 2014). Since the latest Google Earth imagery for the area dates from 4 Oct. 2013 (downloaded 12 Jan. 2016) the exact location and state of development of the project cannot be viewed remotely through this means.

The only known site for this species lies just inside the ‘Parc Naturel de Gaoulou’ as demarcated on Google Earth (viewed 13 Jan. 2016). This area appears to be less heavily impacted by development than adjoining areas, although it still contains villages and palm oil plantations and is far from pristine.

Since there is a single location, with an EOO and AOO estimated (using current IUCN guidance for aquatic plants) of 1 km 2, and with the clear threat of a hydroelectric scheme being constructed in the vicinity of the only known location, we here assess I. cussetiana as Critically Endangered, CR B1+B2 ab(iii). This assessment follows that of Cheek & Ameka (2016). Should the project referred to go ahead, it is possible that this species will become extinct, given the evidence available at present.

Notes — Inversodicraea cussetiana is transferred here from Macropodiella since it has been established through molecular means (e.g., Thiv et al. 2009) that the possession of scale-leaves (indicating Inversodicraea ) has primacy over whether or not the ovary and fruit are laterally flattened (flattened ovaryfruits previously defining Macropodiella , e.g., Cusset 1983). Inversodicraea cussetiana may have a close affinity with I. feika of Sierra Leone since that species also has laterally flattened ovaries. However, this character may have arisen independently several times (see Cheek & Ameka 2016). Within Macropodiella we had placed I. cussetiana with M. garrettii and M. macrothyrsa (G.Taylor) Cusset , however, these last two species appear to lack the scale-leaves which indicate Inversodicraea so are not similarly transferred in this paper. However, it is possible that they may simply have lost scale-leaves entirely. If this can be shown as probable with molecular phylogenetic methods then consideration should be giving to transferring these two species also.

This is the only known species of the genus known for Cote D’Ivoire apart from a single record of I. ledermannii ( Aké Assi 2002) .