Asplenium kassneri Hieronymus (1911: 376)

Fischer, Eberhard & Lobin, Wolfram, 2023, Synoptic Revision of Aspleniaceae (Asplenium, Hymenasplenium) of Rwanda, Phytotaxa 608 (1), pp. 1-65 : 57

Asplenium kassneri Hieronymus (1911: 376) .

Holotype: —D.R. CONGO. Nord Kivu: Ruwenzori , October 1908, T.W.Kassner 3114 (B, not found).

Note: —The specimen Kassner 3114 at K (K000423913 [digital image!]) is Asplenium volkensii and has as such been correctly identified by Pichi Sermolli on a determinavit slip. Pichi Sermolli (1985: 124) did not see the holotype of A. kassneri , but saw a photo and a fragment, and maintained the taxon on the base of two specimens from Rwanda and D.R. Congo (Auquier 4520 BR0000024680196 and Auquier 2289 BR0000024680189), but they belong to A. uhligii (see above under A. uhligii ).

Unfortunately, the holotype of A. kassneri at B was lent to BM, and is now missing. According to Pichi Sermolli the collection Kassner 3114 was distributed before the description of A. kassneri and consists of two species.

Beentje (2008) reduced A. kassneri to synonymy of A. uhligii . He argued that the protologue already indicated that the two taxa were close, and with the amount of material available now, there were no remaining consistent differences between what is described in the protologue of A. kassneri and A. uhligii . This decision was also accepted by Roux (2009). However, there is a a character of the rhizome scales, that indicates that A. kassneri and A. uhligii may represent different taxa. In the protologue of A. kassneri, Hieronymus (1911) wrote “Die Spreuschuppen der Rhizome sind jedoch, obgleich äusserlich ähnlich von verschiedenem Bau und unterscheiden sich besonders dadurch, dass die Zellen mehrerer Reihen des Randes bei A. Kassneri kleiner sind als die in der Mitte der Schuppen befindlichen und entsprechend dünnere Innenwände zeigen, während bei A. uhligii die Zellen in dieser Beziehung ziemlich gleichartig sind und im allgemeinen auch viel dickere und dunklere Innenwände besitzen, so dass die Spreuschuppen dunkler gefärbt erscheinen und weniger durchsichtig sind.” ( Hieronymus 1911: 377–378) (“The rhizome scales, however, despite superficially similar, show a different structure and are distinct especially in several rows of the scale margin of A. kassneri , that are smaller than the cells in the scale center and show thinner walls, while in A. uhligii the cells are almost equal in this respect and the cell walls are much thicker and darker, so that the scales appear darker and less transparent”). We have not yet seen plants with this kind of scales, but they must be searched for.