Type: CHINA. Schen-si [Shaanxi]: Prope In-kia-po, Sep 1896, /. Giraldi (det. Prof C. Muller sub no. 2100) (lectotype nov. H-BR).
Rhynchostegium longirameum C. Müll., Nuovo Giom. Bot. Ital. N. Ser. 5: 202. 1898, syn. nov.; Oxyrrhynchium longirameum (C. Müll.) Broth., Nat. Pflanzenfam. 1(3): 1155. 1909; Platyhypnidium longirameum (C. Müll.) Fleisch., Musci Fl. Buitenzorg 4: 1537. 1923. Type: CHINA. Schen-si [Shaanxi]: In monte Tui-kio-san, 17 Sep 1896,7. Giraldi (det. Prof C. Müller sub no. 2264) (lectotype nov. H-BR).
Eurhynchium serricuspis is a characteristic and easily recognized species. It resembles E. praelongum and E. arbuscula Broth, in having a richly branched or even tree-like growth habit, but it differs from both of them in having narrower leaf bases and gradually tapering leaves. The branches are attenuate as in E. praelongum and E. arbuscula and the costa is rather strong, ending in a dorsal spine. The whole costa is toothed or high papillose in its apical part, and there are scattered papillae or mammillae on laminal cells. Also the branch leaves are often characteristically bent upwards although the basal part ofthe leaf is spreading. Especially the stem leaves are more broadly decurrent than the leaves in E. praelongum.
Müller (1898) described Eurhynchium serricuspis and Rhynchostegium longirameum in the same paper and I select the former name to be used for this taxon at the specific level (Art. 57.2). In addition to the present specimens collected in Shaanxi (Shensi) province of China I have seen many specimens collected by Lou Jian-shin in Sichuan province (Koponen & Lou, unpubl.).