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13. Dicranella (C. Müll.) Schimp., Coroll. Bryol. Eur. 13. 1856; Aongstroemia sect. Dicranella C. Müll., Syn. Musc. Frond. 1: 430. 1848.
小曲尾藓属
Plants small, green, yellowish to brownish, gregarious or in loose tufts. Stems erect, simple or branched, sparsely radiculose below. Leaves often small and distant below, larger and more crowded above, erect-appressed to flexuose or secund above, erect or sheathing at base, narrowly lanceolate, often gradually tapered from a narrow, nonsheathing base to a subulate apex, sometimes abruptly narrowed and squarrose from a rather broad, obovate, sheathing base; margins plane or recurved, entire below, serrulate above, or sometimes serrulate nearly throughout; costa rather narrow to broad, subpercurrent to excurrent; upper cells subquadrate to linear, smooth; lower cells larger and oblong toward the insertion, sometimes short, quadrate to short-rectangular; alar cells not differentiated. Dioicous or rarely monoicous. Perichaetial leaves differentiated or similar to the upper stem leaves, usually sheathing at base. Setae single, elongate, straight or flexuose; capsules erect or curved, subglobose to cylindric, symmetric or asymmetric, sometimes strumose, smooth or ribbed when dry; stomata absent or present; opercula long-rostrate, oblique or curved; annuli absent or present with compound, revoluble cells; peristome teeth 16, often reddish, short or elongate, undivided or divided to the middle, papillose and vertically pitted-striolate below. Calyptrae cucullate, entire at base. Spores spherical, smooth or minutely papillose to densely papillose or warty.
Twenty species and two varieties of Dicranella have been reported from China (Redfearn et al. 1996). Sixteen species and one variety, including two new records, are recognized in this study.
Gametophytically, Dicranella is similar in appearance to some small species of Dicranum. The relationships between Microdus and Dicranella are also very close. Microdus has been treated as a synonym of Dicranella by numerous authors (Crum & Anderson 1981; Allen 1994). Microdus is, however, different from
Dicranella by having globose capsules with short, simple or irregularly split, papillose peristome teeth.
Doubtful taxa:
1. Dicranella divaricata (Mitt.) Jaeg., fide P.-C. Wu 1992. Yunnan: Xishuangbanna, W.-X. Xu (W.-S. Hsu) 6130 (PE, YUKU).
2. Dicranella setifera (Mitt.) Jaeg., fide P.-C. Wu 1992. Yunnan: Xishuangbanna, W.-X. Xu (W.-S. Hsu) 6578, 11171 (PE, YUKU).
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| 1 |
Stem leaves usually squarrose-recurved |
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(2) |
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Stem leaves erect, erect-flexuose or secund |
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(8) |
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| 2 (1) |
Costa slender, subpercurrent |
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(3) |
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Costa stout, percurrent to short- or long-excurrent |
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(4) |
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| 3 (2) |
Leaf margins entire; setae dark reddish |
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11 Dicranella palustris |
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Leaf margins serrulate; setae yellowish green |
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12 Dicranella rotundata |
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| 4 (2) |
Perichaetial leaves distinctly differentiated, broadly sheathing at base |
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(5) |
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Perichaetial leaves not differentiated, only slightly larger than stem leaves |
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(7) |
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| 5 (4) |
Capsules ovoid, curved, strumose at base, without a neck; basal leaf cells long-rectangular |
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9 Dicranella liliputana |
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Capsules cylindric, erect, without struma, with an indistinctly short neck; basal leaf cells short, quadrate to short-rectangular |
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(6) |
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| 6 (5) |
Plants 5-10 mm high, in loose tufts, often simple; upper leaves larger, up to 5 mm long, abruptly narrowed from a clasping base; capsules smooth or scarcely plicate when dry |
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4a var. coarctata |
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Plants 3-5 mm high, in dense tufts, often branched; upper leaves smaller, up to 2 mm long, gradually narrowed from a slightly wider base; capsules usually plicate when dry |
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4b var. torrentium |
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| 7 (4) |
Basal leaf cells subquadrate or rhombic; setae yellowish |
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10 Dicranella micro-divaricata |
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Basal leaf cells rectangular; setae reddish |
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14 Dicranella schreberiana |
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| 8 (1) |
Costa stout, shortly excurrent, or forming a long awn |
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(9) |
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Costa slender, percurrent, ending in the apex |
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(14) |
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| 9 (8) |
Leaf margins irregularly serrulate near the apex; setae yellowish |
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(10) |
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Leaf margins entire near the apex; setae reddish or yellowish |
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(11) |
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| 10 (9) |
Leaves ca. 5 mm long, sheathing at base, abruptly subulate; basal leaf cells rectangular; costa excurrent ending in a long awn |
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6 Dicranella fukienensis |
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Leaves 2-3 mm long, gradually tapered from a nonsheathing base; basal leaf cells quadrate to short-rectangular; costa slightly short-excurrent |
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8 Dicranella heteromalla |
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| 11 (9) |
Setae reddish |
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15 Dicranella subulata |
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Setae yellowish |
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(12) |
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| 12 (11) |
Leaf margins often incurved; capsules ribbed or plicate when dry; annuli in 1 row of cells |
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3 Dicranella cerviculata |
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Leaf margins plane; capsules smooth when dry; annuli in (1-)2-3 rows of cells |
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(13) |
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| 13 (12) |
Upper leaves gradually narrowed from a triangular base to a short acumen; capsules ovoid to short-cylindric; annuli in 2-3 rows of cells |
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7 Dicranella gonoi |
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Upper leaves abruptly narrowed from an oblong-ovate base to a long, subulate acumen; capsules cylindric; annuli in 1-2 rows of cells |
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2 Dicranella austro-sinensis |
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| 14 (8) |
Setae reddish; annuli absent |
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(15) |
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Setae yellowish; annuli present |
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(16) |
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| 15 (14) |
Leaf margins often incurved, entire except at the tips |
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16 Dicranella varia |
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Leaf margins plane, crenulate to serrulate above the shoulder |
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13 Dicranella rufescens |
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| 16 (14) |
Plants soft, yellowish; leaf cells thin-walled |
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1 Dicranella amplexans |
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Plants rigid, yellowish brown; leaf cells rather thick-walled |
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5 Dicranella divaricatula |
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List of lower taxa
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