Scapania sect. Americanae Vana , Hentschel, Joch. Muell . & Heinrichs, 2012

Vana, Jiri, Hentschel, Joern, Mueller, Jochen & Heinrichs, Jochen, 2012, Taxonomic novelties in Scapania, PhytoKeys 10, pp. 13-17 : 13

Scapania sect. Americanae Vana, Hentschel, Joch. Muell. & Heinrichs sect. nov.

Diagnosis.

The new section of Scapania subg. Scapania is characterized by its type, the dioicous Scapania americana Müll. Frib. Distinctive features of Scapania americana and Scapania sect. Americanae are thick-walled, pigmented stem epidermis cells with thinner-walled cells on the ventral side of the stem, closely and sharply ciliate-dentate leaf-margins, with largest teeth up to five cells long and terminal cells considerably longer than wide, leaf-lobes that are usually decurrent beyond the level of the keel, a verruculose or striate-verruculose cuticle, and two-celled gemmae at the margins of unmodified leaves. The dorsal leaf-lobes often develop an undulate or folded base and may even show minute lobules or auricles.

Type.

Scapania americana Müll. Frib., Bull. Herb. Boissier, sér. 2, 3: 44. 1902.

Note.

Scapania americana is placed sister to Scapania sect. Compactae ( Müll. Frib.) H. Buch with weak bootstrap support ( Heinrichs et al. 2012). It differs from members of Scapania sect. Compactae by its dioicous condition; hence we place it in a new section rather than in sect. Compactae . In our current circumscription, Scapania sect. Americanae is monospecific, however, extension of the taxon sampling in forthcoming molecular studies may disclose further representatives.