Monographs Details: Eurhynchium
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants small to rather robust, in dull to lustrous, often stiff, bright- to dark-green, yellowish or golden-brown mats or wefts. Stems creeping, arched or ascending, irregularly to pinnately branched, the branches ascending; in cross-section with small thick-walled cells surrounding larger firm-walled cells, central strand well developed; paraphyllia none; pseudoparaphyllia broadly folióse; axillary hairs with a single short brown basal cell and 1-4 relatively short to elongate hyaline distal cells. Stem and branch leaves differentiated, stem leaves usually spreading, sometimes from an appressed base, broadly ovate to broadly triangular, with a wide insertion, gradually short-to long-acuminate, ± concave, often plicate, ± decurrent; margins serrulate throughout, usually more distantly so below, plane; costa single, bold, ± the same width throughout, i.e., not tapering distally, ending at or above midleaf, the apical cells projecting as a prominent spine; cells long-hexagonal to oblong-linear, smooth, thin- to firm-walled, not porose, not or only slightly shorter in the apex above the termination of the costa; alar cells gradually and slightly differentiated, rectangular in basal angles and ± across the insertion. Branch leaves erect to erect-spreading, smaller than the stem leaves, oblong-lanceolate to ovate-lanceolate, gradually to ± abruptly acute, ± concave, ± striate, scarcely or not decurrent; margins serrate to serrulate throughout, more strongly so than in stem leaves, plane; costa single, bold, not tapering distally, usually ending above midleaf, the apical cell and often several subapical ones projecting as prominent spines; cells at midleaf as in the stem leaves, those apically (above the termination of the costa) noticeably shorter, often short-rhombic; alar cells few, gradually differentiated, subquadrate to rectangular. Asexual propagula none. Dioicous, sometimes phyllodioicous, rarely autoicous or synoicous. Perichaetia inconspicuous; leaves numerous/perichaetium, sheathing at base, with wide-spreading to squarrose apices, broadly oblong, ± gradually to abruptly long-acuminate, ± concave, sometimes striate; margins serrulate throughout or subentire below, plane; costa single, ending near or just above base of acumen, not or only slightly projecting as a spine at apex; cells linear, smooth, ± thin-walled, not porose, becoming broader and long-rectangular toward the insertion; alar cells not differentiated. Setae elongate, sometimes stout, smooth or roughened throughout, reddish, mostly straight, not or scarcely twisted; capsules inclined to horizontal, ± arcuate, asymmetric, short-cylindric to cylindric; exothecial cells short-rectangular, firm- to thick-walled, not collenchymatous, stomata round-pored; annulus well developed, broad; operculum obliquely long-rostrate; exostome teeth reddish brown, triangular, shouldered, bordered, on the front surface cross-striolate below, sometimes with overlying papillae, coarsely papillose above, trabeculate at back; endostome with a high basal membrane, segments keeled, perforate to gaping, ca. as long as the teeth, cilia in groups of 1-3, nodose to short-appendiculate, shorter than the segments. Spores spherical, finely papillose. Calyptrae cucullate, naked, smooth.
Discussion:Eurhynchium Bruch & Schimp. in Bruch, Schimp. & W. Gümbel, Bryol. Eur. 5(fasc. 57-61, Monogr. 1): 217. 1854; Hypnum sect. Eurhynchium (Bruch & Schimp.) Sull. in A. Gray, Manual, ed. 2, 669. 1856; Hypnum subgen. Eurhynchium (Bruch & Schimp.) Hobk., Syn. Brit. Mosses 152. 1873; Rhynchostegium subgen. Eurhynchium (Bruch & Schimp.) Brizi, Malpighia 10: 233. 1896.
Eurhynchium sect. Oxyrrhynchium Bruch & Schimp. in Bruch, Schimp. & W. Giimbel, Bryol. Eur. 5(fasc. 57-61, Monogr. 1): 224. 1854; Oxyrrhynchium (Bruch & Schimp.) Warnst., Krypt.-Fl. Brandenburg 2: 764, 781. 1905.
Eurhynchium sect. Stokesiella Kindb., Eur. N. Amer. Bryin. 1: 93. 1896 ; Stokesiella (Kindb.) H. Rob., Bryologist 70: 39. 1967, hom, illeg., non Lemmerm., Krypt.-Fl. Brandenburg 3: 373. 1908 [Chrysophyceae]; Kindbergia Ochyra, Lindbergia 8: 53. 1982.
Discussion. Eurhynchium is distinguished from the other Brachytheciaceae by its differentiated branch and stem leaves, with acuminate stem leaves and acute branch leaves; the leaves, especially those of the branches, have a relatively broad costa that does not gradually narrow distally and projects prominently as a spine. In the branch leaves the apical cells are markedly shorter than the cells at midleaf.
I have carefully reviewed the generic problems of the Brachytheciaceae with rostrate opercula (Buck, 1988b). In short, Eurhynchium s.l. differs from Rhynchostegium and Platyhypnidium by a costa that does not taper distally. Kindbergia seems to be nothing more than an extreme expression of Eurhynchium with exaggerated branch and stem leaf differentiation and I think recognition of Kindbergia would leave Eurhynchium paraphyletic.
1. Plants of hydric habitats, synoicous; branch leaves lax, mostly ovate, >0.85 mm long; setae rough. 1. E. clinocarpum 1. Plants of mesic habitats, phyllodioicous; branch leaves crowded, mostly lanceolate, <0.8 mm long; setae