Grimmia reflexidens
Grimmia nevadensis
1–2 cm, central strand absent.
0.5–0.7(–1) cm, central strand weak.
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.
ovate-lanceolate, 1.5–2 mm, both margins plane, incurved distally, intermarginal bands absent, awn 0.4–0.8 mm, costal transverse section prominent, semicircular;
basal juxtacostal laminal cells short-rectangular, straight, thin-walled;
basal marginal laminal cells short-rectangular, straight, with thick transverse and thin lateral walls, not hyaline;
medial laminal cells quadrate to rounded, straight, thin-walled;
distal laminal cells 2-stratose.
straight, 0.9–1.1 mm.
dioicous, perichaetial leaves enlarged.
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.]
commonly present, emergent, chestnut brown, ovate with distinct constriction below rim, exothecial cells rectangular, thick-walled, stomata absent, annulus of 1 row of quadrate, thick-walled cells, operculum conic, peristome absent.
cucullate.
leaves not enlarged.
dioicous.
Grimmia reflexidens
Grimmia nevadensis
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 nevadensis is a rare but locally abundant endemic, known only from the Sierra Nevada Mountains. Fertile specimens of it can be separated from G. mariniana by the absence of peristome teeth and by the chestnut brown capsules. Gametophytically, specimens of G. nevadensis contrast with those of G. mariniana by having a uniform basal areolation of short-rectangular cells with thin lateral walls, and margins not hyaline. If fertile, the immersed, eperistomate capsules will separate G. nevadensis from G. ovalis, G. alpestris, and G. montana. Sterile specimens can be separated from G. alpestris by the absence of bulging cells, and the uniformly short-rectangular, thin-walled basal laminal cells. While both G. nevadensis and G. montana have plane to incurved distal margins and both lack bulging laminal cells, the uniformly short-rectangular, thin-walled basal laminal cells and concave leaves will identify G. nevadensis. The latter is easily separated from G. arizonae and G. pilifera, in contrast with which it lacks stomata and peristome teeth, and its concave leaves with plane to incurved margins differ markedly from the keeled leaves with recurved leaf margins of the others.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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