13. Oxyrrhynchium (Schimper) Warnstorf, Krypt.-Fl. Brandenburg. 2: 781. 1905. • [Greek oxys, acute, and rhynchos, nose, alluding to beaked operculum].
Michael S. Ignatov
Eurhynchium subg. Oxyrrhynchium Schimper in P. Bruch and W. P. Schimper, Bryol. Europ. 5: 224. 1854
Plants medium-sized, in loose tufts, light green to whitish or brownish. Stems creeping to arching, loosely, occasionally more densely terete-foliate, julaceous or not, irregularly or sometimes regularly branched, branches terete-, subcomplanate-, or sometimes distinctly complanate-foliate, especially when leaves remote; central strand present; pseudoparaphyllia acute; axillary hairs of 2 or 3 cells. Stem leaves erectopatent to patent, loosely arranged to occasionally loosely imbricate, broadly ovate to ovate-lanceolate, slightly to moderately strongly concave, not plicate; base narrowly short-decurrent; margins serrate to serrulate; apex gradually tapered to acute, long- or short-acuminate; costa to 50-70% leaf length, broad throughout, terminal spine present, sometimes with additional teeth abaxially; alar cells enlarged; laminal cells elongate, walls moderately thick; basal juxtacostal cells shorter, slightly broader. Branch leaves slightly to strongly differentiated, if strongly differentiated then more elliptic, broadest at 1/3 -1/2 leaf length, twisted mid leaf; base often asymmetric; apex more shortly acuminate to acute; costa more strongly toothed distally, terminal spine more stout; . Sexual condition dioicous; perichaetial leaf acumen long, reflexed. Seta red-brown, rough. Capsule inclined to horizontal, red-brown, elongate, curved; annulus separating in fragments; operculum short-conic, narrowly long-rostrate; peristome xerocastique, perfect. Calyptra naked. Spores 10-13 µm.
Species 10-15 (1 in the flora): nearly worldwide; absent in cold boreal regions.
The segregation of Oxyrrhynchium from Eurhynchium was initially accepted by many authors, including V. F. Brotherus (1924-1925). However, the species were later placed back into Eurhynchium (for example, H. Robinson 1962; H. A. Crum and L. E. Anderson 1981). The phylogenetic analysis by M. S. Ignatov and S. Huttunen (2002) demonstrated that Eurhynchium in the broad sense is polyphyletic, and Oxyrrhynchium belongs to a subfamily different from Eurhynchium in the strict sense. Oxyrrhynchium is distinct in having a rough seta (smooth in Eurhynchium), and a tendency for subcomplanate foliage, but this is not observed in Eurhynchium. Aquatic species closely related to Oxyrrhynchium are treated as Donrichardsia (Huttunen et al. 2006).