Cynodontium schisti (Web. & Mohr) Lindb.
Mowed Mosquito Moss
Grimmia schisti, Cnestrum schisti
Basis for Listing
Cynodontium schisti (mowed mosquito moss) has a nearly continuous northern-hemisphere distribution at high latitudes and also extends southward into mountains and coastal regions (Eckel 2007). It has been recorded regionally from Wisconsin, Ontario, and the Upper Peninsula of Michigan. In Minnesota, two historical records of C. schisti were collected by J.M. Holzinger and deposited at the University of Minnesota Herbarium, one in 1886 from Taylors Falls, Chisago County (Mille Lacs Uplands) and the other in 1902 from Rosebush Falls, Cook County (North Shore Highlands). Despite extensive surveys of suitable mesohabitat on the mainland along the North Shore of Lake Superior, no additional populations have been found. Given the species’ extreme rarity and limited geographic range in the state, its sterility and restrictive habitat requirements, the vulnerability of populations to degradation or destruction, and concerns over a range-wide decline, Cynodontium schisti was listed as a threatened species in 2013.
Cynodontium schisti is a small acrocarpous moss, similar in aspect to Ceratodon purpureus (ceratodon moss). The plants are less than 1 cm (0.4 in.) tall, and its leaves are distinctly crisped when dry. The 2- to multi-stratose and partially recurved margins are obvious, even with a hand lens. The small rounded to quadrate medial and upper cells are strongly mamillose-papillose, very distinctively so on the younger leaves. Sporophytes are used to differentiate the genus Cynodontium from other Dicranaceae genera without differentiated alar cells, such as Dichodontium, Oncophorus, and Rhabdoweisia (Ireland 2007). However, gametophores of C. schisti can be distinguished from D. pellucidum by the multi-stratose margins of their long, flexuose and narrowly lanceolate leaves; and from O. virens and R. crispata by the strongly mamillose-papillose cells. From papillose Pottiaceae species with narrowly lanceolate leaves and from Ceratodon purpureus, often with leaves with recurved margins, C. schisti is again most clearly differentiated by these distinctive mamillose cells. Cynodontium strumiferum (cynodontium moss), the only other member of the genus in Minnesota (Eckel 2007), is a larger plant (usually more than 1 cm (0.4 in.) tall; Crum and Anderson 1981), and the medial cells away from the multi-stratose margins are less obviously mamillose-papillose. Its capsules are distinctly strumose in contrast to those of C. schisti.
Cynodontium schisti grows in shaded crevices of cliffs and boulders and on soil over rock at moderate elevations (Eckel 2007; Crum and Anderson 1981). Although there is no specific habitat information given for the historical specimens, they were both collected at a falls along a creek or river. This habitat type is best described as bedrock/boulder shore (river).
Biology / Life History
This species is a colonist (During 1979, 1992), with spores less than 25 µm and capsules that mature in the spring. Its potential life span is only a few years.
Conservation / Management
Because C. schisti is now apparently part of the “Tundra Strip” flora (Schuster 1957) and has an arctic-montane habitat, its populations may be susceptible to local extinction due to climate change. The species’ biogeography is unique, and its habitat is susceptible to drying conditions and trampling. The long-term viability of C. schisti depends on the maintenance of cool and moist habitat conditions.
Best Time to Search
The best time to search for C. schisti is from May through September or essentially anytime the ground is not covered by snow.