BFNA Title: Pseudoleskea
Author: J. R. Spence
Date: November 11, 2010
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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XX. PSEUDOLESKEA Bruch & Schimper, Bryol. Eur. 5: 147 (fasc. 49--51. Monogr. 1). 1852 * (Latin pseudo, false and Leskea)

John R. Spence

 

Plants prostrate, in thin to thick mats, green, yellow-green, orange-green or gold-green, becoming brown with age. Stems slender to robust, not fragile, tips often ascending or hooked, irregularly branched, secondary branches appressed to ascending or erect, not flagelliform at tips, sometimes julaceous, older primary stems becoming stoloniferous; paraphyllia common, filamentous to foliose, not much branched, cells smooth or prorulose, becoming scarce on older stems; rhizoids in clusters arising from base of stem leaves. Leaves of stems and branches similar although branch leaves smaller, ovate to ovate-lanceolate, weakly to strongly concave, more or less symmetric, appressed to julaceous when dry, not catenulate, erect-spreading when wet, dull to lustrous, with or without distinct hair-point; lamina weakly to strongly plicate on either side of costa, abruptly acute to long-acuminate, margins smooth to serrulate distally, recurved proximally; costa moderately strong, 2/3 length of lamina to subpercurrent, green to yellow-green, not or weakly sinuose; mid-laminal cells quadrate to elongate-rhomboidal, 1--4(--5):1 firm walled to  thin-walled, 1-papillose to prorate, laminal cells in acumen similar to more proximal cells, strongly prorate, translucent or opaque due to dense chloroplasts; alar cells distinct in small to large groups, transversely elongate, quadrate to short-rectangular, smooth, juxtacostal cells similar to median cells but mostly shorter, walls pitted or not. Specialized asexual reproduction absent. Sexual condition dioicous; perichaetial leaves pale translucent, longer and more acuminate than the cauline, erect when wet, costa percurrent. Capsule red to red-brown, ovate to cylindric, inclined to erect, asymmetric or rarely nearly symmetric, operculum conic, rarely with small apiculus; annulus lacking; peristome double, well developed, exostome teeth lanceolate, striate to papillose, bordered, endostome of high basal membrane, segments slender lanceolate to filiform, keeled, cilia 1--3, well developed to short and rudimentary. Calyptra cucullate. Spores small, papillose.

 

Species ca. 12 (8 in the flora): Northern Hemisphere, mostly montane to alpine regions.

 

Pseudoleskea is a group of Northern Hemisphere species found on rock and soil, typically in cool to cold climates. Southern Hemisphere species of Pseudoleskea are not closely related to those of the Northern, with numerous morphological differences, and are probably closest to Lindbergia, according to recent molecular studies (M. S. Ignatov et al. 2007). Pseudoleskea differs from Lescuraea in the shorter and mostly thicker-walled laminal cells and in the mostly perfect hypnoid peristome, showing some reduction in a few species. J. R. Rohrer (1986) presented a useful comparison of differences between the genera. Pseudoleskea baileyi does not belong in the genus and appears to be closest morphologically to the East Asian Rigodiadelphus (M. U. Krieger, unpublished); it is included here for completeness.

 

SELCTED REFERENCES: Lawton, E. 1957. A revision of the genus Lescuraea in Europe and North America. Bull. Torrey Bot. Club 84: 281--307. Rohrer, J. R. 1986. Taxonomic notes on Rigodiadelphus, Ptychodium, and Okamuraea: three genera misplaced by Fleischer in the Rhytidiaceae. Lindbergia 12: 33--40. Ignatov, M. S., A. A. Gardiner, V. K. Bobrova, I. A. Milyutina, S. Huttunen and A. V. Troitsky. 2007. On the relationships of the mosses of the Order Hypnales, with special reference to taxa traditionally classified in the Leskeaceae. In Newton, A. E. and R.S. Tangney (eds). Pleurocarpous mosses: systematics and evolution. CRC Press, New York. Pp. 177--214.

 

1. Median laminal cells isodiametric to elongate, papillose over the lumen.

2. Leaves with long slender acuminate apex, median laminal cells elongate, 2--4:1, most papillae off-centered on distal cell lumens; bark and twigs of shrubs and trees ..........…… 7. Pseudoleskea stenophylla

2. Leaves ovate, short-acuminate to acute, median laminal cells short, predominantly isodiametric, papillae mostly centered over lumens, soil or rock, never corticolous.

3. Stems and branches mostly julaceous to appressed, leaves large, typically more than 0.8 mm, margins recurved proximally, lamina cells opaque, papillae low to large, but not distinctly pointed-mammillose, costa ending in short projection, never morningstar-like  ..................................................................... 4. Pseudoleskea patens

3. Stems and branches mostly catenulate, leaves small, typically less than 0.8 mm, margins plane, lamina cells translucent, papillae large, distinctly pointed-mammillose, costa ending in strong morningstar-like extension of apical abaxial cells ........ 8. Pseudoleskea tribulosa

1. Median laminal cells mostly rhomboidal, 2--4:1, smooth to prorate over distal cell ends.

4. Leaves with distinct hair-point, paraphyllia absent, costa weak, reaching 2/3\x leaf length, stem lacking central strand ........... 2. Pseudoleskea baileyi

4. Leaves lacking hair-point, paraphyllia present although sometimes scarce, costa mostly percurrent, stem with central strand of small cells.

5. Lamina cells of stem leaves, except alar, distinctly and strongly pitted

.......................... 1. Pseudoleskea atricha

5. Lamina cells of stem leaves not pitted or weakly pitted only near leaf base.

6. Proximal laminal cells elongate rhomboidal, 3:1 or more, longer than more distal cells, median lamina cells strongly prorate, distal leaf margins strongly and broadly recurved, leaves long-acuminate .................................. 6. Pseudoleskea saviana

6. Proximal lamina cells quadrate to short-rectangular, 1--2:1, same length or shorter than distal cells, median lamina cells obscurely prorate to nearly smooth, distal leaf margins weakly recurved, leaves acute to short-acuminate.

7. Cells of distal leaf margins short, mostly less than 2:1, median-distal laminal cells mostly less than 8 \um wide, incrassate, often very heterogeneous in shape, alar cells mostly quadrate, paraphylla not branched ............................. 4. Pseudoleskea incurvata

7. Cells of distal leaf margin elongate, more than 2:1, median-distal laminal cells mostly more than 10 \um wide, thin-walled, mostly homogeneous, alar cells often longer than wide, paraphyllia often branched ............................. 5. Pseudoleskea radicosa

 

 

1. Pseudoleskea atricha (Kindberg in J. Macoun) Kindberg, Ottawa Nat. 7: 20. 1893

 

Pseudoleskea atrovirens var. atricha Kindberg in J. Macoun, Cat. Canad. Pl., Musci, 180. 1892; Lescuraea atricha (Kindberg) E. Lawton

 

Plants robust, in thick, stiff mats, green, yellow-green, orange-green or black-green, becoming brown with age. Stems prostrate, with central strand, branches robust, often julaceous, mostly prostrate, paraphyllia common, predominantly filamentous, not branched. Leaves ovate, asymmetric, appressed to julaceous when dry, erect spreading when wet, rarely somewhat falcate, dull, lacking hair-point, (0.5--)1--1.2 mm; gradually acute to rarely short acuminate, margins recurved proximally, costa percurrent, green to yellow-green, somewhat sinuose; median laminal cells opaque, elongate-rhomboidal, 3--4:1, mostly less than 40 \um, incrassate, distinctly prorate, strongly pitted, laminal cells in acumen similar to proximal cells, alar cells distinct in medium-sized groups, transversely elongate, quadrate to short-rectangular, smooth, juxtacostal cells similar to median cells but mostly shorter, walls pitted or not. Capsule cylindric, inclined to suberect, asymmetric, 0.5--1.2 mm, operculum smooth conic; basal membrane 1/3--1/2\x length of exostome, segments shorter than exostome, cilia well developed to occasionally rudimentary. Spores (10--)12--18(--20) \um.

 

Capsules mature summer (Jul--Aug). Local and uncommon on subalpine and alpine rock outcrops or rarely on mineral soil, 600--2300 m; B.C.; Alaska, Wash.

 

A local high elevation endemic, Pseudoleskea atricha is characterized by plants with ovate leaves having an acute but not acuminate apex, and incrassate laminal cells that are strongly pitted. Only P. baileyi also has strongly pitted cells, but it differs in leaves with long acumen and hair-point, and stems lacking paraphyllia.

 

2. Pseudoleskea baileyi Best & Grout, N. Amer. Musc. Pl., 474. 1917

 

Lescuraea baileyi (Best & Grout) E. Lawton

 

Plants robust, in thick stiff mats, green, yellow-green, becoming orange-green, orange-brown to brown with age. Stems prostrate, lacking central strand, branches slender to robust, often julaceous, mostly prostrate but with upcurved tips, paraphyllia absent. Leaves ovate-lanceolate, mostly symmetric, appressed when dry, erect spreading when wet, strongly falcate-secund, dull, 1.5--2.5 mm, acumen ending in a short to long more or less hyaline hair-point, margins recurved proximally, costa ending in acumen, not percurrent, green to yellow-green, not usually sinuose; median laminal cells translucent, elongate-rhomboidal, 2--3:1, mostly less than 30 \um, incrassate, prorate, often somewhat pitted, laminal cells in acumen similar to proximal cells, alar cells distinct in medium-sized groups, quadrate to short-rectangular, smooth, juxtacostal cells similar to median cells but longer and narrower, to 60 \um, walls usually pitted. Capsule broadly cylindric, erect to suberect, symmetric, 0.8--1.7 mm, operculum conic-apiculate; basal membrane 1/3--1/2 length of exostome, endostome segments often longer than exostome teeth, cilia slender, 1--2 or often rudimentary to absent. Spores (14--)20--28 \um.

 

Capsules mature spring--summer (May--Jul). Locally common on bark of branches and twigs of trees and shrubs at moderately high elevations, descending to near sea level in northern portion of range, occasional on rock, rarely soil; 85--1400 m; B.C.; Alaska, Oreg., Wash.

 

Pseudoleskea baileyi is a distinctive endemic species, extending into the Aleutians, but does not belong in the genus (M. U. Krieger, unpublished).  The combination of long acumen ending in a hair-point, elongate proximal lamina cells, and lack of paraphyllia ally it with the East Asian Rigodiadelphus.  However, the peristome is different from that genus, which is strongly reduced, and lacks segments and cilia. If future studies indicate that the species does not belong in Rigodiadelphus, the subgenus name Tricholeskea is available.

 

3. Pseudoleskea incurvata (Hedwig) Loeske, Hedwigia 50: 313. 1911

 

Leskea incurvata Hedwig, Sp. Musc. Frond., 216, plate 53, figs. 8--14. 1801; Lescuraea incurvata (Hedwig) E. Lawton

 

Plants medium to large, in thick mats, green or yellow-green, orange-green or rarely black-green, becoming brown with age. Stems prostrate, with central strand, branches robust, often julaceous, apices mostly turned up, paraphyllia common, filamentous to foliose, branched. Leaves ovate to ovate-lanceolate, asymmetric, appressed to somewhat erect when dry, mostly falcate to falcate-secund, erect spreading when wet, glossy or dull, lacking hair-point, 0.8--2(--2.5) mm; gradually to abruptly acute to short or rarely long-acuminate into a short to moderately long acumen, margins strongly and narrowly recurved to near acumen, costa sub-percurrent to percurrent, orange-green, sometimes sinuose; median laminal cells mostly opaque, heterogeneous, mixed isodiametric to short-rhomboidal or elliptic, rarely fusiform, 1--2(--3):1, mostly less than 25 \um, firm-walled to strongly incrassate with narrow lumens usually less than 8 \um, pellucid to opaque, prorate to near base, not pitted, laminal cells in acumen similar to proximal cells but shorter, mostly 1--2:1, alar cells distinct in large groups, transversely elongate to quadrate, smooth, juxtacostal cells similar to median cells but somewhat shorter than cells above, walls not pitted. Capsule cylindric, erect to suberect, symmetric, 1--2.5 mm, operculum smooth, conic; basal membrane low, 1/4 to 1/3 length of exostome, segments shorter than exostome, cilia present, 1--2. Spores 10--20 \um.

 

Pseudoleskea incurvata is a complex and highly variable species. Most plants can be told from P. radicosa by the variably shaped thick-walled median laminal and proximal cells that are overall mostly short, and by the relatively short cells in the acumen.  Three varieties are recognized here. Although there are intermediate specimens, the three varieties are often quite distinct. Combined ecological, molecular and morphological studies of the varieties are needed to determine their distinctiveness.

 

1. Plants large, leaves 1.5--2.5 mm, distinctly falcate-secund, long-acuminate, laminal cell prorae indistinct ………………………3a. Pseudoleskea invurvata var. gigantea

1. Plants small to medium, leaves mostly less than 1.5 mm, straight, falcate or falcate-secund, predominantly short acuminate to acute, laminal cell prorae distinct.

            2. Leaves 1--1.5 mm, short to sometimes moderately long-acuminate,

median laminal cells elliptic with rounded corners, mostly longer than wide

……………………………………..3b. Pseudoleskea incurvata var. incurvata

            2. Leaves smaller, mostly 0.8--1.1 mm, acute to short-acuminate, median laminal

cells predominantly isodiametric and angular

…………………3c. Pseudoleskea invurvata var. tenuiretis

           

 

3a. Pseudoleskea incurvata var. gigantea (E. Lawton) H. A. Crum, Steere & L. E. Anderson, Bryologist 67: 163. 1964

 

Lescuraea incurvata var. gigantea E. Lawton, Bull. Torrey Bot. Club 84: 294, figs. 21--25. 1957

 

Plants large. Stems long, with branches few or none. Leaves 1.5--2.5 mm, distinctly falcate-secund, long-acuminate, acumen as long or longer than rest of leaf, laminal cell prorae indistinct.

 

Capsules rare, mature summer (June-Aug). Uncommon to locally common on mineral soil and soil over boulders and outcrops, 600--2100 m; B.C.; Calif., Idaho, Oreg., Wash.

 

The var. gigantea is endemic to western North America.

 

3b. Pseudoleskea incurvata var. incurvata

 

Plants medium-sized. Stems long, with branches few to common, sometimes julaceous. Leaves 1--1.4(--1.5) mm, falcate to falcate-secund, abruptly acute to short to modernately acuminate, acumen shorter than rest of leaf, median laminal cells elliptic with rounded corners, mostly longer than wide, prorae distinct.

 

Capsules mature summer (June-August). Locally common on dry siliceous boulders, rare on calcareous rock and mineral soil, often along streams; 900--3300 m; Greenland; Alta., B.C., Nfld. & Labr., N.W.T., ; Alaska, Calif., Colo., Idaho, Mich., Mont., Nev., N.H., Oreg., Utah, Wash.; Eurasia.

 

3c. Pseudoleskea incurvata var. tenuiretis (Culmann) Podpĕra, Consp. Musc. Eur., 531. 1954

 

Pseudoleskea filamentosa var. tenuiretis Culmann, Rev. Bryol. 37: 94. 1910

 

Plants small, compact. Stems relatively short, with numerous julaceous side branches. Leaves 0.8--1(--1.1) mm, not falcate-secund, ovate with abruptly acute to short-acuminate apex, acumen short, median laminal cells predominantly isodiametric and angular, prorae distinct.

 

Capsules rare, mature summer (June-August). Uncommon on dry calcareous to rarely siliceous boulders and outcrops, rarely on exposed mineral soil; 1400--2400 m; Alta., B.C.; Calif., Mont., Utah; w Eurasia.

 

4. Pseudoleskea patens (Lindberg) Kindberg, Canad. Rec. Sc. 6: 20. 1894

 

Lescuraea patens  Lindberg, Meddeland. Soc. Fauna Fl. Fenn. 14: 75. 1888; Lescuraea patens (Lindberg) Arnell & C. Jensen

 

Plants small to medium, in slender mats, dark green or olive-green to black-green, rarely  yellow-green, becoming brown with age. Stems prostrate, with central strand, branches slender to robust, often julaceous, mostly prostrate, tips sometimes curved up, paraphyllia common, filamentous to foliose, not branched. Leaves ovate, asymmetric, appressed to julaceous when dry, erect-spreading to patent when wet, not or rarely falcate, dull, lacking hair-point, (0.6--)0.7--1 mm; abruptly acute to rarely short-acuminate, margins recurved proximally; costa not reaching acumen, green to orange-green, somewhat sinuose, abaxial cells at  tip not or only weakly projecting, not morning-star like; median laminal cells opaque, predominantly quadrate 1(--2):1, mostly less than 18 \um, incrassate, moderately to strongly low rounded papillose over lumen or sometimes papillae off-centered; laminal cell walls not pitted, cells in acumen similar to proximal cells, alar cells distinct in large groups, quadrate to transversely elongate, proximal juxtacostal cells similar to median cells but mostly shorter, walls pitted or not. Capsule curved, inclined, asymmetric, 0.5--2 mm, operculum smooth conic; basal membrane 1/3--1/2 length of exostome, segments shorter than exostome, cilia well developed. Spores 10--14 \um.

 

Capsules mature in summer, July-Aug. Common on shaded to exposed rocks and outcrops, rarely on mineral soil, often near streams; mostly 900--3500 m; Alta., B.C., Nfld. & Labr., N.S., N.W.T.; Alaska, Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo; w Eurasia (including Siberia).

 

Pseudoleskea patens is a relatively small species that is usually dull dark green or olive, with short laminal cells with rounded centrally located papillae. It differs from P. tribulosa by recurved margins, weaker and lower lamina cell papillae lacking projecting apical salient, larger leaves with stronger plicae, and lack of the morningstar-shaped tips of the abaxial apex cells of the costa.

 

5. Pseudoleskea radicosa (Mitten) Macoun & Kindberg, Cat. Can. Pl., Musci, 181. 1892

 

Hypnum radicosum Mitten. J. Proc. Linn. Soc., Bot. 8: 31. 1865; Lescuraea radicosa (Mitten) Mönkemeyer

 

Plants medium to large, in thick mats, green or yellow-green, orange-green, becoming brown with age. Stems prostrate, with central strand, branches robust, often julaceous, apices mostly turned up, paraphyllia common, filamentous to foliose, branched. Leaves ovate to ovate-lanceolate, asymmetric, appressed to somewhat erect when dry, mostly falcate to falcate-secund, erect spreading when wet, glossy or dull, lacking hair-point, 0.6--2(--2.4) mm; gradually to abruptly acute to short- or rarely long-acuminate into short to moderately long acumen, margins narrowly recurved to midleaf or to near acumen, costa sub-percurrent to percurrent, yellow-green, sometimes sinuose; median laminal cells pellucid to opaque, homogeneous, short-rhomboidal, elliptic or fusiform, 2--3(--4):1, mostly less than 40 \um, thin or rarely firm-walled with lumens more than 10 \um, pellucid to opaque, prorate to near base, not pitted, laminal cells in acumen similar to proximal cells, mostly 2--3:1, alar cells distinct in small to medium-sized groups, transversely elongate to quadrate, smooth, juxtacostal cells similar to median cells but somewhat shorter than more distal cells, walls not pitted. Capsule cylindric, erect to suberect, symmetric, 1--2 mm, operculum smooth conic; basal membrane low, 1/4--1/3\x length of exostome, segments shorter than exostome, cilia usually present, 1--2, sometimes reduced. Spores 16--22 \um.

 

Varieties 3 (3 in the flora): North America, Eurasia, Atlantic Islands.

 

Pseudoleskea radicosa is a common and variable species, with three varieties, two of them quite distinctive.  Pseudoleskea radicosa is closely related to P. incurvata, but differs in its longer more homogeneous thin-walled and wider laminal cells. Combined ecological, molecular and morphological studies of the varieties are needed to determine their distinctiveness.

 

1. Plants large, stem tips hooked, branches few or lacking, leaves 1.6--2.3 mm, distinctly

falcate-secund, long-acuminate, often multi-plicate

………………………5b. Pseudoleskea radicosa var. denudata

1. Plants small to medium, stem tips not distinctly hooked, branches usually numerous, leaves mostly less than 1.6 mm, straight, falcate or falcate-secund, predominantly short acuminate to acute, mostly 2-plicate.

 

            2. Leaves small, distinctly concave, sometimes incurved, mostly 0.8--1.3 mm,

acute to short-acuminate; branches often julaceous, median laminal cells pellucid

………………………..………………5a. Pseudoleskea radicosa var. compacta

            2. Leaves medium, somewhat concave, not incurved, 1.2--1.7 mm, long-

acuminate, branches not usually julaceous; median laminal cells opaque

………………………………...…..……5c. Pseudoleskea radicosa var. radicosa

 

 

5a. Pseudoleskea radicosa var. compacta (Best) E. Lawton, Bull. Torrey Bot. Club 27: 231. 1900

 

Lescuraea radicosa var. compacta (Best) E. Lawton, Bull. Torrey Bot. Club 84: 305, figs. 45--49. 1957; Pseudoleskea pallida Best

 

Plants small, bright green. Stems short, branched, branches usually julaceous. Leaves small, mostly 0.8--1.3 mm, strongly concave, often somewhat incurved, abruptly acute to short-acuminate, appressed, not falcate-secund; median laminal cells pellucid, alar cells smooth.

 

Capsules mature summer (June-Aug). Locally common on dry siliceous boulders, rare on calcareous rock and mineral soil, subalpine-alpine; 900--4000 m; Alta., B.C., Nfld. & Labr., Que., Yukon; Ariz., Calif., Colo., Idaho, Oreg., Utah, Wyo.; Europe (Norway).

 

The var. compacta is a distinctive variety that may be a good species, distinguished by its bright green color, small size, ovate concave leaves that often incurve when dry, and clear laminal cells. The Norway plants require confirmation.

 

5b. Pseudoleskea radicosa var. denudata (Kindberg in Macoun) Wijk & Margadant, Taxon 9: 191. 1960

 

Pseudoleskea sciuroides var. denudata Kindberg in J. Macoun, Cat. Canad. Pl.. Musci, 181. 1892

 

Plants large, yellow-green to green to orange-green. Stems with hooked tips, branches few or lacking. Leaves large, 1.6--2.3 mm, weakly concave, not incurved, mostly strongly falcate-secund, long-acuminate; median laminal cells mostly opaque, alar cells often prorate.

 

Capsules very rare, mature summer (July-Aug). Locally common on mesic soil under shrubs or on boulders, often associated with snow banks, subalpine-alpine; 950--3000 m; Greenland; Alta., B.C.; Alaska, Mont. Wash., Wyo.; w Eurasia; Atlantic Islands (Iceland).

 

The var. denudata is distinctive by its large size, long unbranched stems with hooked tips, strongly falcate-secund leaves, and often multi-plicate lamina.

 

5c. Pseudoleskea radicosa var. radicosa

 

Plants medium-sized, yellow-green, green to orange-green. Stems freely and loosely branched, branches julaceous or not. Leaves medium-sized, weakly to moderately concave, not incurved, appressed to somewhat falcate, 1.2--1.7 mm, short to predominantly long-acuminate; median laminal cells mostly opaque; alar cells smooth.

 

Capsules mature summer (July-August). Widespread and common on shaded rocks and outcrops or tree bases, rare on humic soil in forests, subalpine to alpine, 680--3500 m; Greenland; Alta., B.C., Nfld. & Labr., Que., Yukon; Alaska, Calif., Colo., Idaho, Mich., Mont., Nev., N.H., N.M., Oreg., Utah, Wash. Wyo.; Eurasia; Atlantic Islands (Iceland).

 

6. Pseudoleskea saviana (De Notaris) Latzel, Beih. Bot. Centralblatt 48(2): 499. 1931

 

Leskea saviana De Notaris, Musc. Ital. Spic., 8. 1837; Lescuraea saviana (De Notaris) E. Lawton

 

Plants small to medium, in thin open to thick mats, green or yellow-green, becoming brown with age. Stems prostrate, with central strand, branches robust, often julaceous, apices mostly turned up, paraphyllia common, filamentous to foliose, not branched. Leaves ovate-lanceolate to lanceolate, asymmetric, appressed to somewhat erect when dry, more or less falcate, erect spreading when wet, glossy or dull, lacking hair-point, 0.9--1.2 mm; abruptly long-acuminate into slender acumen, margins strongly and broadly recurved to acumen, costa sub-percurrent to percurrent, green to yellow-green, sometimes sinuose; median laminal cells opaque, elongate-rhomboidal to fusiform or somewhat vermicular, 3--4:1, mostly less than 25 \um long, firm-walled to incrassate, strongly prorate to near base, not pitted, laminal cells in acumen similar to proximal cells, alar cells distinct in large groups, transversely elongate to quadrate, smooth, juxtacostal cells similar to median cells but somewhat longer than cells above, walls not pitted. Capsule cylindric, erect to suberect, symmetric, 1--1.5 mm, operculum smooth conic; basal membrane low, 1/3\x length of exostome, segments shorter than exostome, cilia lacking or rudimentary. Spores 12--17 \um.

 

Sporophytes mature spring-summer (May-Aug). Locally uncommon on bases of tree trunks, or boulders and outcrops, rarely on soil at moderately high elevations, descending to somewhat lower elevations in northern portion of range; (600--)1000--2500 m; Alaska (Aleutian Islands), Calif., Idaho, Wash.; w Eurasia.

 

Pseudoleskea saviana is characterized by its strongly recurved margins to near the acumen, the relatively long, slender median leaf cells, the somewhat longer proximal  juxtacostal cells, and a long-acuminate acumen that is often as long as the rest of the lamina.

 

7. Pseudoleskea stenophylla Renauld & Cardot in Röll, Bot. Centralblatt 44: 21. 1890

 

Lescuraea stenophylla (Renauld & Cardot) Kindberg

 

Plants small in thin open to thick mats, green or yellow-green, becoming brown with age. Stems prostrate, with central strand, branches slender, not or rarely julaceous, apices mostly straight to rarely turned up, paraphyllia common, filamentous to foliose, not branched. Leaves ovate-lanceolate to lanceolate, symmetric, appressed to somewhat erect when dry, erect spreading when wet, not or rarely falcate except at tips, glossy, lacking hair-point, 0.9--2 mm; gradually long-acuminate into slender acumen, margins recurved proximally to just before acumen, costa percurrent, green to yellow-green, not sinuose; median laminal cells pellucid, elongate-rhomboidal to fusiform or somewhat vermicular, 2--3 (4):1, mostly less than 30 \um, firm-walled to incrassate, strongly papillose over lumen, papillae usually off-centered to distal edge, rarely some cells prorate; not pitted, laminal cells in acumen similar to proximal cells, alar cells distinct in small groups, transversely elongate to quadrate, smooth, juxtacostal cells similar to median cells but somewhat shorter than more distal cells, walls not pitted. Capsule cylindric, erect, symmetric, 1--3 mm, operculum smooth conic; basal membrane low, 1/4\x length of exostome, segments shorter than exostome, cilia lacking or rudimentary. Spores 16--20 \um.

 

Sporophytes mature spring-summer (May-Aug). Locally uncommon on twigs and branches of shrubs or small trees including tree bases, primarily of Alnus or Acer along streams; 500-2100 m; Alta, B.C., N.S., Nfld. & Labr., Que.; Alaska, Calif., Idaho, Oreg., Mont., Utah, Wash.; w Eurasia.

 

Pseudoleskea stenophylla is distinguished as small plants growing on bark and twigs of shrubs and trees, leaves with a long, slender acumen comprising up to half the leaf length, and elongate laminal cells with papillae over the lumen but usually off-centered.

 

8. Pseudoleskea tribulosa Shevock & W. R. Buck, Bryol. 112: 184. 2009

 

Plants small, in slender mats, dark green or olive-green. Stems prostrate, with central strand, branches slender, not julaceous, mostly prostrate, tips rarely curved up, paraphyllia common, foliose, not branched. Leaves oblong-ovate, more or less symmetric, catenulate, weakly incurved dry, erect spreading when wet, not falcate, dull, lacking hair-point, 0.6--0.9 mm; gradually acute to broadly acuminate, margins plane; costa not reaching acumen to subpercurrent, green to orange-green, not sinuose, abaxial cells at apex projecting in a morningstar-like pattern; median laminal cells pellucid, predominantly quadrate to isodiametric, 1:1, mostly less than 10 \um, incrassate, strongly mammillose-papillose over lumen or rarely off-centered, papillae often with apical cell pointed, covering most of lumen; laminal cell walls not pitted, cells in acumen similar to proximal cells, alar cells distinct in large groups, quadrate to transversely elongate, proximal juxtacostal cells similar to median cells but mostly shorter, walls pitted or not. Capsule unknown.

 

Rare on shaded metamorphosed limestone overhangs and boulders, 2600--2900 m; Calif. Endemic. Of conservation concern.

 

Pseudoleskea tribulosa is a distinctive endemic species only known from a few sites in the subalpine zone of Yosemite National Park.  It seems to favor deeply shaded sites such as the mouths of caves or deep overhangs.  The combination of small catenulate leaves with weak plicae or these absent, plane margins, large central papilla of laminal cells with projecting apical salient, and odd extended apical cell walls of the abaxial costa are diagnostic.  It seems to be closest to P. patens (see the differences under that species).  Only male plants are known.