Grimmia reflexidens
Grimmia moxleyi
moxley's dry rock moss
1–2 cm, central strand absent.
1–1.5 mm high, small central strand present.
absent.
ovate to oblong-lanceolate, 0.1–1.15 × 0.3–0.5 mm, keeled, not plicate, margins plane, awns 1–2 mm, very long, smooth to slightly denticulate, flattened basally, long-decurrent, costal transverse section prominent, semi-circular;
basal juxtacostal laminal cells rectangular, sometimes nodulose, thin- to thick-walled;
basal marginal laminal cells rectangular with thickened transverse walls, pellucid in 2–4 rows;
medial laminal cells rounded-quadrate, slightly sinuose, thick-walled;
distal laminal cells yellowish green, 1-stratose with 2-stratose ridges, not bulging, marginal cells 2-stratose, not bulging.
erect with slightly incurved tips when dry, erect-spreading when moist, oblong, broadly rounded and muticous at apex, 1.5–2 × 0.4–0.6 mm, keeled, margins plane to recurved, awns absent, only present in perichaetial leaves, costa weak proximally, projecting at abaxial side, perichaetial leaves longer and with awns;
basal juxacostal laminal cells short- to long-rectangular, straight, thin-walled;
basal marginal laminal cells short- to long-rectangular, thin-walled;
medial laminal cells rounded-quadrate, ± sinuose, thin- or thick-walled;
distal laminal cells 2-stratose.
flexuose to arcuate, 1–1.5 mm.
dioicous, perichaetial leaves enlarged.
autoicous.
absent in northern hemisphere material, emergent to shortly exserted, yellowish brown, oblate, exothecial cells irregularly short-rectangular, thin-walled, stomata absent, annulus of 1 row of quadrate, thick-walled cells, operculum mammillate to rostrate, peristome present, nearly fully-developed, split and perforated only in apex, papillose.]
usually present, exserted, chestnut brown, oblong-ovoid, wrinkled-plicate when dry, exothecial cells thin- to thick-walled, annulus present, operculum conical, peristome teeth yellowish, split and perforated, papillose.
cucullate.
Grimmia reflexidens
Grimmia moxleyi
Of conservation concern.
Previous to its discovery in Iceland, as Grimmia grisea (H. C. Greven 1998), G. reflexidens was known from only the Southern Hemisphere. It had previously been collected east of East Bay, Newfoundland, now the only known locality in North America, but was not recognized as G. reflexidens. The latter is similar to G. asperitricha Dixon & Sainsbury of New Zealand, and the two species have been confused by G. O. K. Sainsbury (1945) as well as by R. Ochyra (1993). J. Muñoz (1998b) synonymized G. reflexidens with G. sessitana. However, the former is readily separated from the latter by: (1) enlarged perichaetial leaves, (2) decurrent awns, (3) non-bulging laminal cells, and (4) dioicous sexual condition. Capsules are unknown from Northern Hemisphere material, but G. reflexidens lacks stomata while they are present for G. sessitana. Although G. reflexidens and G. teretinervis both have decurrent awns they are easily separated by a number of characters: G. reflexidens grows in compact cushions, has long awns, and a semicircular costa; G. teretinervis grows in loose clumps, is hyaline-tipped to short-awned, and has a unique costa that is distally almost completely circular in transverse section.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Grimmia moxleyi is endemic to the southwestern United States and northwestern Mexico. A thermophilous species from acidic rock, it is autoicous and usually richly provided with capsules. The species is characterized by growing in flat, easily disintegrating patches with short, keeled, muticous stem leaves that contrast with its much larger awned perichaetial leaves. J. Muñoz (2000) synonymized G. moxleyi with G. orbicularis. Although there are some similarities, G. orbicularis is much larger, grows in dense cushions on basic rock, has setae 2–3 mm, shiny, spherical capsules, and a mammilate operculum. Only the most proximal stem leaves of G. orbicularis are muticous and the basal juxtacostal cells have thick, nodulose walls.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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