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!!Schistidium Bruch & Schimp.

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Project Name Data (Last Modified On 3/16/2009)

Acceptance : Accepted

Project Data (Last Modified On 3/16/2009)

General Reference:

Gao, C., M. R. Crosby & S. He. 2003. Grimmiaceae–Tetraphidaceae. 3: viii + 141 pp. In Moss Fl. China. Science Press & Missouri Botanical Garden, Beijing, New York & St. Louis.

Notes (Last Modified On 3/16/2009)

general taxon notes:

Bridel (1819) described the genus Schistidium with a confused concept based on a mixture of five species. Most of these species have later been transferred to different genera: S. caespiticium (Web. & Mohr) Brid. [= Blindia caespiticia (Web. & Mohr) C. Müll.], S. ciliatum (Hedw.) Brid. [= Hedwigia ciliata (Hedw.) P. de Beauv.], S. pulvinatum (Hedw.) Brid., S. strictum Brid., nom. illeg. [= Amphidium lapponicum (Hedw.) Schimp.], and S. subsessile (Brid.) Brid. [= Pterigoneurum subsessile (Brid.) Jur.]. It was in Bruch and Schimper (1845) that the natural and modern concept of Schistidium was established as generally accepted today. They included four species in the genus: S. pulvinatum, S. apocarpum (Hedw.) Bruch & Schimp., S. confertum (Funck) Bruch & Schimp., and S. maritimum (Turn.) Bruch & Schimp. Bruch and Schimper (1845) characterized these species as having short vaginulae, small calyptrae, and columella remaining attached to the opercula when falling. Schistidium has been classified at different ranks by different authors. Bremer (1980a, 1980b, 1981), T. Cao and Vitt (1986), Deguchi (1978), Limpricht (1890), Loeske (1930), and Nyholm (1956) accepted Schistidium as an independent genus, while Brotherus (1902, 1924b), P.-C. Chen et al. (1963), C. Gao (1977), Husnot (1884–1894), Jones (1933), Mitten (1859), Mueller (1849), and Schimper (1856, 1876) treated it as a subgenus or section in Grimmia. We accept it as a genus because the details of structural features in Schistidium provide enough evidence to support its recognition.

Defining features of Schistidium include: 1) columella remaining attached to operculum when falling; 2) calyptrae rather small, not reaching capsule urns; 3) annuli absent; 4) setae shorter than the urns; and 5) capsules immersed in large perichaetial leaves. In addition, Bremer (1980a) stated that stomata of Schistidium present at the base of capsule urns lack an air space and seem to have no function. The diminutive vaginulae were considered by Deguchi (1978) as one of the distinctive characters of Schistidium. There are about 55 species of Schistidium in the world, of which about 36 are better known (Crosby et al. 2000). Seven species are treated for China in this study.

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6. Schistidium Bruch & Schimp. in B.S.G. 连轴藓属 lian-zhou xian shu

Bryol. Eur. 3: 93 (fasc. 25–28). 1845, nom. cons. Lectotype species: Schistidium maritimum (Turn.) Bruch & Schimp. in B.S.G. (Grimmia maritima Turn., typ. cons.) [Homonym: Schistidium Brid., Muscol. Recent. Suppl. 20. 1819[1918], rejected against Schistidium Bruch & Schimp., proposed by Ochrya & Isoviita (1989), Taxon 38: 665–669. Type: Schistidium pulvinatum (Hedw.) Brid. (Gymnostomum pulvinatum Hedw.)]

Grimmia subgen. Schistidium (Brid.) Schimp., Coroll. Bryol. Eur. 45. 1856. Grimmia sect. Schistidium (Brid.) Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 43. 1859.

Plants slender to robust, green to yellowish green, reddish brown or black, in loose tufts. Stems erect to prostrate, frequently branched from innovations, with or without central strand in cross section. Leaves imbricate, erect when dry, erect-spreading to spreading when moist, lanceolate, ovate to ovate-lanceolate, keeled or obtusely keeled above, muticous or ending in short to long, hyaline hair-points; margins recurved on one or both sides, sometimes bistratose above; costa strong, single, percurrent or ending below the apex, terete, smooth or papillose on abaxial surface, consisting of nearly homogeneous cells in transverse section; upper cells quadrate to irregularly quadrate, unistratose or bistratose in places, with more or less thick, straight to sinouse walls, smooth; basal cells short, transversely rectangular to quadrate, occasionally short-rectangular to rectangular, with somewhat sinuose walls. Autoicous (except S. tenerum). Perichaetial leaves much larger than vegetative leaves, with broad base, loosely areolate. Setae straight, shorter than capsule urns, erect when dry; capsules erect, immersed in perichaetial leaves, subglobose to oblong-ovoid, smooth or nearly so; exothecial cells transversely rectangular to quadrate or rectangular, with thick or thin walls; stomata restricted to base of urns; annuli absent; opercula low-conic, with short, more or less oblique beaks; columella falling attached with opercula; peristome teeth 16, haplolepideous, well developed or vestigial, yellowish brown to reddish brown, erect, lanceolate to linear-lanceolate, entire or imperfectly perforate and split above, papillose on both outer and inner surfaces, sometimes nearly smooth in basal part of outer surface, outer plates thicker than inner plates. Calyptrae rather small, not extending to urns, cucullate to mitrate. Spores small or large, 9–19 µm in diameter, yellowish green, smooth or papillose.

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1. Leaves broadly ovate to ovate-lanceolate, muticous, without hyaline hair-points............................................. 2

1. Leaves narrowly ovate-lanceolate to lanceolate, with hyaline hair-points.......................................................... 3

2. Leaves broadly ovate, strongly concave, rounded-obtuse at apex; spores 11–13 µm................... 2. S. chenii

2. Leaves ovate-lanceolate, keeled above, acute at apex; spores 15–19 µm................................... 4. S. rivulare

3. Peristome teeth vestigial; basal marginal leaf cells short-rectangular to rectangular, more or less transparent......................6. S. subconfertum

3. Peristome teeth well developed; basal marginal leaf cells quadrate to subquadrate, obscure.......................... 4

4. Peristome teeth linear, elongate, entire, with papillae in rows; leaves muticous or with very short hyaline hair-points............7. S. trichodon

4. Peristome teeth lanceolate, short, perforate above, with papillae in irregular order; leaves with elongate, hyaline hair-points ..............................................................5

5. Plants less than 1 cm high; capsules deeply immersed in perichaetial leaves; basal marginal leaf cells with transverse walls thicker than longitudinal walls ...........................................3. S. liliputanum

5. Plants more than 2 cm high; capsules shallowly immersed in perichaetial leaves; basal marginal leaf cells with transverse walls nearly as thick as longitudinal walls............................................................6

6. Costa smooth on back; plants generally green to yellowish green, in compact tufts........... 1. S. apocarpum

6. Costa distinctly papillose on back; plants generally reddish brown, in loose tufts.................... 5. S. strictum