Hymenophyllum kuhnii C.Chr.

Ahamada H. Saïd, Sabine Hennequin, Germinal Rouhan & Jean-Yves Dubuisson, 2017, Disentangling the diversity and taxonomy of Hymenophyllaceae (Hymenophyllales, Polypodiidae) in the Comoros, European Journal of Taxonomy 313, pp. 1-53 : 27-28

Hymenophyllum kuhnii C.Chr.

Hymenophyllum kuhnii C.Chr. , Index filicum : 363 (1905), nom. nov. for H. meyeri Kuhn (in Engler 1892: 94) , non C.Presl (1843: 31, 50). – Type: As for H. meyeri Kuhn in Engler , Über die Hochgebirgsflora des tropischen Afrika: 94 (1892), nom. superfl., non C.Presl (1843: 31, 50), ‘am Ruabach 1900–2300 m’, H. Meyer 310 (lecto-: B200092787!; isolecto-: B200092783!, B200092784!designated by Beentje 2008); ‘Kilimandscharo, im Urwald am Südabhang massenhaft von 1930–2800 m’, R.F.X.R. von Höhnel 146 (syn-: B200092785), R.F.X.R. von Höhnel 147 (syn-: B200092782, B200092786!), O. Ehlers 66 (syn-: B200092790); ‘im oberen Urwald um 2500 m, Aug. 1881’, H. Meyer s.n. (syn-: not located); ‘am Ruabach 1900–2300 m, Nov. 1889’, H.Meyer s.n. (B200092788!).

Hymenophyllum henkelii Sim , South African Journal of Science 20: 309, pl. 9 (1923). – Type: Rhodesia, I.S. Henkel sub. F. Eyles 2559 (holo-: K0004356000!).

Mecodium kuhnii (C.Chr.) Copel., The Philippine Journal of Science 67 (1): 19 (1938).

Hymenophyllum polyanthos (Sw.) Sw. var. kuhnii (C.Chr.) Schelpe, Boletim da Sociedade Broteriana , sér. 2, 40: 156 (1966).

Short description

Epiphytic; long-creeping filiform rhizomes, bearing sparsely distributed roots and long reddish brown trichomes, and widely separated pending fronds; fronds stipitate, and stipes and rachises fully winged, with stipe wing usually well-developed (> 3 cells wide), up to 20 cm long (in Comoros), glabrous, quite variable in shape, lanceolate to oblong, sometimes widely ovate, pinnate-pinnatifid to bipinnatepinnatifid, with lamina apices attenuate to obtuse or rounded; pinnae often overlapping especially in widely ovate fronds; numerous sori, paratactic, bilabiate without a developed base.

Global distribution

Central Africa, East and South-Africa, Madagascar, Comoros, La Réunion?, Mauritius?

Distribution in Comoros

Grande Comore, Mohéli.

Additional specimens examined

COMOROS: GRANDE COMORE, Changani, Forêt de Changani, 16 Nov. 1999, J.­N.Labat et al. 3146 (P00184014); La Convalescence, 24 Nov. 2002, F.Rakotondrainibe et al. 6791 (P00312067); Massif du Karthala (versant sud), 2 Dec. 2002, F.Rakotondrainibe et al. 6864 (P00312328); Hantsangoma, sur les pentes autour du lac, 19 Oct. 2008, G.Rouhan et al. 742 (P02439802); Massif de La Grille, bord de la piste menant au pylône, 9 Nov. 2008, M.Pignal et al. 3512 (P02433494); Nfudo ya Mdrunda, au-dessus du village de Tsinimwapanga, en chemin vers le second point de récolte, 29 Nov. 2009, C.Loup et al. 550 (P02439779). MOHÉLI, Piste entre Miringoni et le Chalet St Antoine, 4 Nov. 2008, G.Rouhan et al. 897 (P02439807).

Note

All the specimens we examined were most often identified as H. polyanthos . Hennequin et al. (2006) nevertheless demonstrated that paleotropical H. polyanthos populations are molecularly clearly distinct from neotropical H. polyanthos which might rather be restricted to the Neotropics (type from Jamaica). Specimens known as H. polyanthos in Comoros and Madagascar (in addition to some African specimens) do not significantly differ from African H. kuhnii (which was also considered as a variety of H. polyanthos by Schelpe in 1966), agreeing with the detailed treatment given by Kornaś (1993), and the identifications of Malagasy specimens as H. polyanthos var. kuhnii by F. Rakotondrainibe (e.g., F.Rakotondrainibe 2569 - P00059741, 1356 - P00064677, 2542 - P00046641). Hymenophyllum kuhnii initially considered as distributed from South Africa to Tanzania is quite variable in size, shape and frond division. The frond can reach 50 cm long and be pinnate-pinnatifid to bipinnate-pinnatifid, lanceolate to linear with short to long pinnae (<6 cm) and often oblong (especially after specimens at B, including the types; Fig. 5C ). Hymenophyllum capense and specimens usually named H. polyanthos in the western Indian Ocean share the same gross morphology as continental H. kuhnii (see Fig. 5A–B ). They would differ in the frond length, shape and division. Fronds of H. capense exceptionally exceed 15 cm long and are linear to oblong and usually not more than pinnate-pinnatifid ( Fig. 5B ) while most H. ‘ polyanthos ’ can reach 20 cm long with lamina lanceolate to ovate, less often oblong, pinnatepinnatifid to bipinnate-pinnatifid ( Fig. 5A ). Because of morphologically intermediate specimens for which identifications are necessarily uncertain (e.g., F.Rakotondrainibe 6791 - P00312067), we suspect that the three supposed distinct morpho-species could cover the whole high variability of a single taxon (here H. capense according to anteriority), according to lamina division and shape. We propose thus here to name H. kuhnii the Comorian specimens usually identified as H. polyanthos , a treatment that could also be applied to Malagasy specimens. Additional investigations including molecular data are requested to precise the specific status of these taxa (including H. capense ). In absence of these studies, we nevertheless consider here H. capense as distinct, but not ruling out that such specimens could be dwarf forms of H. kuhnii (see Fig. 5A–C ). If further additional studies confirm that H. capense specimens are dwarf forms of H. kuhnii , all populations identified as H. kuhnii should thus be named H. capense .

Figures

Fig. 5. Western Indian Ocean Hymenophyllum subg. Mecodium, illustrating morphological resemblance of taxa which are difficult to distinguish (see text). A. Hymenophyllum kuhnii C. Chr. from Comoros, firstly identified as H. polyanthos (Sw.) Sw. (F. Rakotondrainibe et al. 6864, P 00312328). B. Hymenophyllum capense Schrad. from Madagascar, initially identified as H. fumarioides Bory ex Willd. (F. Rakotondrainibe et al. 6121, P 00212664). C. Syntype of Hymenophyllum kuhnii C. Chr. from Tanzania (B 200092782). D. Hymenophyllum inaequale (Poir.) Desv., representative specimen from La Réunion (L. Bauret 190, P).