9. Dicranodontium Bruch & Schimper, Bryol. Europ. 1: 157. 1847.
[Greek dicranon, pitchfork, and odon, tooth, alluding to forked peristome teeth]
Robert R. Ireland Jr.
Plants medium-sized to large, in loose to dense tufts, yellowish brown to dark green. Stems erect, simple or sparingly branched; rhizoids smooth, scattered along stems or present on branch bases. Leaves gradually or abruptly narrowed, tubulose to subtubulose proximally, weakly concave to subtubulose distally, lamina 1-stratose, acute, erect-flexuose to falcate-secund, occasionally somewhat spreading, sometimes somewhat auriculate at base; margins incurved, serrulate to nearly entire near apex; leaf apex setaceous; costa single, excurrent, broad, filling 1/5-1/2 of leaf base and most of subula, sometimes indistinct, rough distally on abaxial surface, rhizoids at base occasionally on adaxial and commonly on abaxial surfaces, with a median row of guide cells, two stereid bands, epidermal cells differentiated on both surfaces; cells incrassate nearly throughout, distal rectangular to linear, smooth or prorate on abaxial surface, becoming broader toward base, often pitted, alar cells thin-walled, inflated, hyaline or sometimes reddish. Specialized asexual reproduction by deciduous leaves. Sexual condition dioicous. Perigonial leaves broad at base, more abruptly narrowed to a shorter setaceous apex than stem leaves, paraphyses filamentous, antheridia few. Perichaetial leaves often with broader and longer bases more abruptly narrowed distally than stem leaves, paraphyses absent, archegonia few. Seta solitary, smooth, elongate, curved to cygneous, erect-sinuous when dry. Capsule erect and symmetric, oblong-cylindric, smooth; annulus and stomata absent; operculum long-rostrate; peristome single, teeth 16, inserted below mouth, divided nearly to base, vertically striolate nearly to tips. Calyptra cucullate, smooth, entire at base, naked. Spores spherical, smooth.
Species 7 (3 in the flora): North America, Mexico, Central America, South America, Europe, Asia, Africa, Australia.
Dicranodontium can be confused with Campylopus but difffers primarily in two features: (1) the rhizoids, in addition to being on both surfaces of the costa in the two genera, are scattered along the stems or present at branch bases in Dicranodontium while they are only at the branch bases and branch primordia in Campylopus; and (2) Campylopus usually has ridges or low lamellae on the abaxial surface of the costa near the leaf middle while the costa in the mid-leaf region of Dicranodontium is smooth. Dicranodontium rarely produces perichaetia and perigonia so sporophytes are extremely rare in North America.
Species added in edit:
Dicranodontium subporodictyon Brotherus, Symb. Sin. 4, fig. 20. 1929
Known in North America only from cliff faces, outcrops, or boulders near waterfalls, or rarely damp boggy places at low elevations in western British Columbia, this species has recently been transferred to Campylopus by B. H. Allen & Ireland. The costa of Dicranodontium subporodictyon has ridges or small lamellae on the abaxial surface, as well as a number of other morphological features characteristic of Campylopus. It differs from other species of Dicranodontium in the flora area by leaves gradually tapering from base to subula, and laminal cells elongate, incrassate, and pitted through most of the lamina.
SELECTED REFERENCES
Frahm, J.-P. 1997. A taxonomic revision of Dicranodontium (Musci). Ann. Bot. Fenn. 34: 179-204. Ireland, R. R. 1989. The moss genus Dicranodontium (Dicranaceae) in Canada. Canad. J. Bot. 67: 640-649.
