Gymnosiphon, Blume

Cheek, Martin, Xander M. Van Der Burgt, Tchiengué, Barthélemy, Thiam, Aminata, Molmou, Denise, Doré, Tokpa Seny & Magassouba, Sékou, 2024, New discoveries of plants from Republic of Guinea, W. Africa, including Gymnosiphon fonensis Cheek, sp. nov. (Burmanniaceae), a new Critically Endangered species from Simandou, Adansonia (3) 46 (10), pp. 89-101 : 92

KEY TO THE SPECIES OF GYMNOSIPHON IN AFRICA, COMORO ISLANDS AND MADAGASCAR.

1. Stigmas with filiform extensions exserted from flower at anthesis ................................................................ 2

— Stigmas lacking filiform extensions .............................................................................................................. 5

2. Flowers zygomorphic, inflorescence capitate, Madagascar................................................... G. marieae Cheek

— Flowers actinomorphic, inflorescences cymose. Africa and Comoro Islands................................................. 3

3. Perianth tube 2-5 mm long ......................................................................................................................... 4

— Perianth tube 1-2 mm long. Gabon................................................................ G. constrictus Maas & H. Maas

4. Inflorescence bracts about as long as rhachis internodes, inner tepals absent; stigmas horizontal; tepals changing from white to translucent at anthesis ............................................................................. G. mayottensis Cheek

— Inflorescence bracts <1/4 as long as rhachis internodes, inner tepals present; stigmas pendulous; tepals white at anthesis. R. of Guinea to DRC......................................................................... G. longistylus (Benth.) Hutch.

5. Rootstock with numerous bulbils, ovary ribbed, inner tepals absent. Malawi, NE Zambia, S. Tanzania.......... .................................................................................................................................. G. afro-orientalis Cheek

— Rootstocks lacking bulbils, ovary smooth, inner tepals present. Guineo-Congolian Africa or Madagascar......... 6

6. Flowers sessile or subsessile, pedicel if present to 0.5 mm long .................................................................... 7

— Flowers with a distinct pedicel 1 mm long or more ..................................................................................... 8

7. Flowers white, perianth tube 10 mm or more long ...................................................................................... 9

— Flowers yellow or white, perianth tube <5 mm long. R. of Guinea & Liberia......... G. samoritoureanus Cheek

8. Plants commonly 15-35 cm tall; base of stem completely covered in many tens of brown leaf-scales. E. Africa ...................................................................................................................................... G. usambaricus Engl.

— Plants always <15 cm tall; base of stem sparsely covered, with only 3-4 leaf scales. Madagascar...................... .................................................................................................................................. G. danguyanus H.Perrier

9. Corolla diam. 12-15 mm, ≥ corolla tube length 12 mm. E. Cameroon to R. of Congo....... G. bekensis Letouzey

— Corolla diam. 10-11 mm, <corolla tube length (13-) 14-18 mm. R. of Guinea............ G. fonensis Cheek , sp. nov.