Schistidium squarrosum T.T. McIntosh, H.H. Blom, D.R. Toren & Shevock, 2015

Blom, Terry T. Mcintosh Hans H., Toren, David R. & Shevock, James R., 2015, Two new species of Schistidium (Grimmiaceae, Bryophyta) from western North America, Phytotaxa 213 (1), pp. 57-64 : 61-62

Schistidium squarrosum T.T. McIntosh, H.H. Blom, D.R. Toren & Shevock sp. nov. Fig. 2

Diagnosis: Schistidium squarrosum is readily distinguished from most species of Schistidium by often abruptly narrowed, ovate-lanceolate, often curved or falcate leaves, lacking or with very short awns, 2(–3) stratose upper leaf laminae, and large, tapering, broadly ovate-lanceolate or lanceolate perichaetial leaves. The perichaetial leaves are a useful field character as they tightly surround the capsule.

TYPE:— U.S.A. California: Tuolumne Co., Stanislaus National Forest. Along slopes just below ridge accessed from Mather Road west of Abernathy overlooking the Tuolumne River Canyon, R 19E, T1S, section 8, 37º52’32’’N 119º54’52’’W, 4550 ft., Shevock, Colwell & Haas 34866 (holotype CAS!; isotypes KRAM!, MO!, NY!, THR!, UBC!) .

Plants medium-sized to fairly large, olivaceous, sometimes brownish or blackish, somewhat shiny, forming loosely caespitose or flattish mats and tufts. Stems 1.0– 3.5 cm, frequently and irregularly branched, cortex relatively thick (~⅓ thickness of stem) with small central strand. Stem leaves (2.0–) 2.2–2.8 (–3.0) mm long, ovate-lanceolate, often abruptly narrowed to a rather narrow-lanceolate distal portion, sometimes lanceolate, usually curved or falcate, sometimes falcate-secund, occasionally straight, tips often slightly bent when dry, often curved and weakly spreading to patent when wet, obtusely folded distally, concave medially and proximally, usually 2-stratose distally and medially, occasionally 3-stratose (especially near apex, but also in striae along the leaf lamina), rarely with 4- stratose striae, mostly 1-stratose in the proximal ¼ of the lamina, with occasional 2-stratose striae almost reaching the base, not decurrent; margins plane distally, weakly recurved proximally, smooth, 2–3(–4) stratose near apex, usually 2-stratose medially, and 1-stratose proximally; apices rounded, rarely obtuse or acute, sometimes narrowly sub-cucullate; awns often absent, when present hyaline, terete, usually short, to 0.5 mm, sometimes composed of only a few cells, weakly to strongly spinulose with coarse and broad, short spinulae, not decurrent; costae percurrent, smooth, strongly bulging on abaxial surface in lower and central parts but almost confluent with lamina in distal and medial sections, in transverse section rounded near apex, broadened-elliptic medially and proximally, 2–3 cells thick distally, 5–6 cells thick medially and proximally, areolation more or less even; distal and medial laminal cells 8–12 μm, isodiametric or short-rectangular, often oblate, walls moderately thick often with small corner thickenings, luminae rounded or angular, sometimes weakly sinuose; basal cells rectangular to short-rectangular, often with small corner thickenings, sometimes weakly sinuose, marginal row of cells thinner walled than interior cells, often with small corner thickenings. Perichaetial leaves (2.4–) 2.8–3.4 mm, broadly ovate-lanceolate or lanceolate, sometimes abruptly narrowed distally, erect, sometimes slightly curved, often awned, similar to those on branch leaves although usually longer and often decurrent. Sexual condition gonioautoicous. Sporophytes common, shallowly immersed; Seta: (0.2–) 0.3 (–0.4) mm; Capsule reddish-brown, cylindrical or ovate-cylindrical, 1.8–2 (–2.2) mm; exothecial cells highly variable, ± isodiametric, short-elongate, or irregularly angular, rarely in lines, thin-walled, walls sometimes curved, often with corner thickenings; rim darker than capsule wall, reddish; peristome patent to recurved when dry, fragile and often broken, 220–260 μm, reddish-brown or reddish-orange, finely striolate-papillose proximally and medially, often slightly perforated proximally and medially, from lightly to strongly perforated distally, often cribrose, often with papillose terminal prongs, stomata absent. Operculum flat to slightly rounded, rostrate, rostrum straight or oblique. Spores (8–) 10–12 μm, finely papillose.

Etymology: —The epithet squarrosum refers to spreading position of the leaves from the stem when wetted.

Habitat and distribution: — Schistidium squarrosum is also viewed as a semi-rheophytic species occurring in habitats much like those described for S. splendens . However, some occurrences are in more exposed sites with less water flow such as sheet rock drainages or road banks. Elevation range is primarily between 1000–4000 ft. To date, S. squarrosum is restricted to western North America, reported from California, Nevada, Oregon, and Washington.

Comparison: — Schistidium cinclidodonteum appears closely related to S. squarrosum and is the species most likely to be confused with it. However, S. cinclidodonteum is usually a larger plant having longer leaves (up to 5.0 mm) whereas leaves of S. squarrosum usually range from 2.2–2.8 mm, rarely longer (to 3.0 mm). An efficient way to separate the two species is by examining leaf apices. The leaf apex of S. squarrosum is channeled apically, in contrast to that of S. cinclidodonteum which ends in a terete apiculus.

Additional specimens examined: — U.S.A. California. Fresno County: Highway 180 near Vista Point overlook, Sequoia National Forest , T13S, R28E, section 2, 36º50’00’’N, 118º53’45’’W, 4500 ft., 3 May 1996, Shevock, Norris & York 13306 ( CAS, THR) ; Kern County: east face of Spanish Needle Peak, southern Sierra Nevada, T25S, R37E, section 5, 35º47’00’’N, 118º00’15’’W, 7400 ft., 8 October 1995, Shevock & York 12393 ( CAS, THR) ; Lake County: BLM Cow Mountain Recreation Area, Mayacmas Mountains along Mendo Rock Road , 39º10’00’’N, 123º04’30’’W, 2800 ft., Shevock , Bourell & Toren 16894 ( CAS, THR) and Toren , Bourell & Shevock 6971 ( CAS), east of Crockett Peak , Mendocino National Forest , T 18N, R8W, section 10, 39º26’00’’N, 122º45’25’’W, 5400 ft., 12 July 2012, Toren & Dearing 9925 ( CAS), forest road M1 bridge over Eel River , Mendocino National Forest , T 18N, R10W, section 19, 39º24’N, 122º58’W, 1720 ft., 19 October 1998, Harpel & Toren 18525 ( CAS) ; Hull Mountain, headwaters of Rattlesnake Creek , 5525 ft., 21 September 2014, Shevock et al. 45880 ( CAS, NY) and Shevock et al. 45891 ( CAS, KRAM) ; Mendocino County: county road 338 at road marker 17.14 west of Mendocino Pass , Mendocino National Forest, T 22N, R10W, section 4, 39º46’00’’N, 122º58’30’’W, 4650 ft., 4 July 1997, Shevock 15886 ( CAS, THR) ; Napa County: Mayacmas Mountains, Robert Louis Stevenson State Park , Kimball Canyon near Red Hill, T 9N, R9W, section 10, 38º38’47’’N, 122º37’19’’W, 2450 ft., 15 Mar 2014 Shevock, Burge & Penneys 44635 ( CAS, F, MO, NY, UBC) ; Tulare County: Kern Plateau, Salmon Creek , Sequoia National Forest , T 23S, R34E, section 32, 35º53’20’’N, 118º20’45’’W, 7800 ft., Shevock 17515 ( CAS, THR), North Fork Kern River about 1.5 miles above Forks of the Kern , Sequoia National Forest , T 20S, R33E, section 32, 36º08’30’’N, 118º25’15’’W, 4800 ft., 21 September 1997, Shevock 16520 ( CAS, THR), South Fork of the Middle Fork Tule River at bridge crossing of road 21S94 below Camp Nelson toward Coy Flat, Sequoia National Forest , T 20S, R31E, section 33, 36º08’08’’N, 118º36’40’’W, 4575 ft., 14 Aug 2008, Shevock & Laeger 31848 ( CAS), along county road M-99 near Brin Canyon, Sequoia National Forest , T 23S, R32E, section 1, 35º57’30’’N, 118º28’45’’W, 3000 ft., 24 April 1998, Shevock 17055 ( CAS, MO, THR, UBC) and at Brush Creek , 35º58’00’’N, 118º30’00’’W, 3300 ft., 28 March 2000, Toren 7938 ( CAS) ; Squirrel Creek off of county road 372 below Oriole Lake , Sequoia National Park , T 17S, R30E, section 7, 36º27’50’’N, 118º45’10’’W, 5050 ft., Shevock 17643 ( CAS, THR, UBC), Marble Fork Kaweah River at Junction with Little Deer Creek , Sequoia National Park , T 15S, R29E, section 36, 36º34’45’’N, 118º47’05’’W, 5200 ft., 29 May 1997, Shevock 15641 ( CAS, THR) Tuolumne County: South Fork Tuolumne River at Rainbow Pool off highway 120, Stanislaus National Forest , T 1S, R18E, section 29, 37º49’15’’N, 120º00’15’’W, 2750 ft., 13 Aug 1999, Shevock 18460 ( CAS, MO, THR, UBC), along Hetch Hetchy Road 0.5 mile from O’Shaughnessy Dam, Yosemite National Park , T 1N, R20E, section 17, 37º56’25’’N, 119º47’21’’W, 3950 ft., 17 April 2011, Shevock & Hutten 37696 ( CAS) and Hetch Hetchy Road, UTM zone 11N, 252862, 4198731, 1465 m, 17 April 2011, Hutten 15395 ( CAS) ; Nevada: Humboldt County: Humboldt National Forest, Santa Rosa Range , 2.2 mi. NE of Hinkey Summit Road from Junction of Lye Creek Campground , 8 Aug 1979, Lavin & Rust s.n. ( WTU) and 28 Oct 1979, Lavin & Mozingo s.n. ( WTU) ; Oregon: Klamath County: Klamath Basin, Gerber Reservoir area , slopes above Barnes Valley Creek , downstream from road crossing, east side of Gerber Reservoir , 19 July 2010, Björk 20819 ( CAS, UBC) ; Washington: Chelan County: Icicle Creek near trail to Eight Mile Creek , Lawton 3962 ( WTU) ; Whitman County: near Palouse, Pullman , April 1919, Picket 597a–c ( NY) ; Yakima County: Yakima region , 1883, Brandegee s.n. ( NY) .

Figures

FIGURE 2. Schistidium squarrosum. A. Habit. B. Sterile plant. C. Stem section. D–F. Cauline leaves. G–I. Distal leaf sections. J–K. Cauline leaf apices. L. Median marginal laminal cells. M. Basal laminal cells. N. Medial leaf section. O. Capsule in perichaetium. P. Perichaetial leaf. Q. Capsule. R. Operculum and calyptra. S. Peristome tooth. Scale bar: 4 mm for A; 3 mm for B; 1 mm for O, Q; 100 μm for C, G–N, S; 0.5 mm for D–F, P–R.