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BFNA | Family List | BFNA Vol. 1 | Grimmiaceae

Coscinodon Sprengel, Einl. Stud. Kryptog. Gew. 281. 1804.

Greek, a sieve-toothed peristome

Authors: Roxanne I. Hastings

Plants small, 4.5--15 mm, olive green to dark black-green. Stem leaves oval to ovate-lanceolate, keeled distally, usually long awned, basal cells usually rectangular and smooth walled. Seta straight. Capsule with poorly differentiated annulus. Calyptra large, covering 1/2 to all of capsule, erose, becoming cucullate with age, campanulate, plicate.

Species 10 (5 in the flora): temperate to Arctic-alpine.

Species in the genus Coscinodon are widespread across North America but are largely absent from the interior Great Plains and along the west coast. They all prefer dry acidic rocks. The largely calcareous regions of the continental interior do not provide suitable habitat for these species.

Historically, North American authors have often considered Coscinodon to be a subgenus of Grimmia. Not until the 1980's did they follow the European approach distinguishing these two genera. The separation of these two genera is largely sporophytic. Coscinodon have large, campanulate, plicate calyptra that commonly cover the capsule, whereas Grimmia have smaller, non-plicate calyptra that are not campanulate. It is often stated that Coscinodon have very long awns compared to most Grimmia. This is true for the widespread species, C. calyptratus and C. cribrosus, and also C. yukonensis. But C. arctolimnius is muticous to short awned and C. hartzii has awns not much longer than most Grimmia.


Churchill, S. P. 1981. A phylogenetic analysis, classification and synopsis of the genera of the Grimmiaceae (Musci). In: V. A. Funk and D.R. Brooks, eds. 1981. Advances in Cladistics. New York. Pp. 127--144. Hastings, R. I. 1999. Taxonomy and biogeography of the genus Coscinodon (Bryopsida, Grimmiaceae) in North America, including a new species. Bryologist 102: 265--286. Hastings, R. I. and H. Deguchi. 1997. Taxonomy of Coscinodon arctolimnius (Bryopsida, Grimmiaceae) including a new subspecies from Asia. Bryologist 100: 50--55. Ireland, R. R. and H. Crum. 1976. Distribution of Grimmia cribrosa in North America. Bryologist 79: 355--357. Muñoz, J. 1998. Amended description of Coscinodon calyptratus (Grimmiaceae) and major range extensions into Eurasia and New Zealand. Bryologist 101: 89--92. Murray, B. M. 1992. Bryophyte flora of Alaskan steppes. Brybrothera 1: 9--33. Steere, W. C. 1978. The Mosses of Arctic Alaska. Brophyt. Biblioth. 14: 1--508. Steere, W.C. 1974. Grimmia (Coscinodon) arctolimnia, a new species from Great Bear Lake, Northwest Territories, Canada. Bryologist 77: 230--234.

1 Leaves non-plicate; lamina distally 1-stratose; leaf margins plane or revolute on one side at midleaf.   (2)
+ Leaves plicate at least in distal lamina; lamina distally 2-stratose; leaf margins inrolled distally.   (3)
2 (1) Autoicous; capsule exserted; peristome solid; leaves 1.4--2.4 mm, narrowly ovate-lanceolate, margins plane or revolute on one side at midleaf; western North America.   Coscinodon calyptratus
+ Dioicous; capsule immersed; peristome scalloped; leaves 0.9--1.2 mm, broadly ovate-lanceolate, margins plane; northern British Columbia to Alaska.   Coscinodon yukonensis
3 (1) Capsule exserted; peristome present, xerocastique; leaf plications never to base; Arctic.   Coscinodon hartzii
+ Capsule immersed; peristome present and hygrocastique or absent; leaf plications variable; temperate to Arctic.   (4)
4 (3) Peristome present; leaf margins incurved distally, never cucullate, plications not always reaching base; apex frequently long-awned; plants dark olive green; temperate to Arctic.   Coscinodon cribrosus
+ Peristome absent; leaf margins incurved distally, apex often cucullate if muticous, inrolled if awned; plications extending to base; often muticous or with short awns; plants dark black-green; Arctic.   Coscinodon arctolimnius

Lower Taxa

Related Synonym(s):


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