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Fam. Gén. Musgos Andes Trop.
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Published In: Species Muscorum Frondosorum 104. 1801. (Sp. Musc. Frond.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 1/26/2013)
Acceptance : Accepted
Project Data     (Last Modified On 2/5/2019)
Plant Category: Mosses
General Reference:

Notes     (Last Modified On 2/5/2019)
Didymodon contains some 120 species exhibiting a worldwide distribution with primary diversification in the temperate regions and tropical highlands. More than 20 species in the Neotropics (many more names than taxa), at present 20 species recorded for the tropical Andes. Low to high open montane, páramo and puna, not uncommon in disturbed sites in the tropical Andes; on soil and rock. This genus, along with Barbula for which many species were previously associated (see discussion under Barbula for comparison between the two genera), are currently being revised by Juan Jiménez (MUB) for South America. The present concept includes Trichostomopsis, cf. Jiménez et al. (2005). The keys recently published by Jiménez and Cano (2008a) are useful for most of the tropical Andes.
Didymodon contiene unas 120 especies presentando una distribución mundial con divesificación primaria en tierras altas de regiones templadas y tropicales; mas de 20 especies en el Neotrópico (muchos más nombres que taxa).


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Plants medium sized to somewhat large, forming tufts or cushions, dark green to blackish-brown. Stems erect, few-branched; in cross-section outer 2-3 cell rows small, thick-walled, inner cells larger, ±thin-walled, central strand well developed. Leaves ovate- or triangular-short to -long lanceolate, apex acute to acuminate, base often subsheathing, channeled distally; margins plane distally, often recurved to reflexed below; costae single, subpercurrent to long-excurrent, adaxial and abaxial epidermal cells short or elongate, in cross-section stereids usually above and below guide cells, or absent above; laminal cells above lower sheath subquadrate, thin to thick-walled, bulging or with papillae, either simple or bifid; lower sheath and basal cells quadrate or rectangular, smooth or weakly papillose. Dioicous. Perichaetia terminal; leaves often enlarged, loosely sheathing. Setae elongate, twisted. Capsules erect, urn ovoid to long cylindrical; stomata few at base; annuli persistent; opercula conic or conic-rostrate; peristome single, teeth 16, usually divided into 32 filaments and often twisted, or reduced and short, papillose or spiculose, basal membrane absent or low. Calyptrae cucullate, smooth and naked. Sporesspherical, nearly smooth to papillose.
Plantas medianas hasta algo grandes, formando manojos o cojínes, verde oscuros hasta pardo-negruzcos. Tallos erectos, poco ramificados; en corte transversal 2-3 filas externas de células pequeñas, con paredes gruesas, células internas mayores, con paredes ± delgadas, cordón central bien desarrollada. Hojas ovado- o corto-triangulares hasta largo-lanceoladas, ápices agudos hasta acuminados, bases a menudo subamplectantes, acanaladas distalmente; márgenes planos distalmente, a menudo recurvados hasta reflexos abajo; costa simple, subpercurrente hasta largo-excurrente, células de la epidermis adaxial y abaxial cortas o alargadas, en corte transversal estereidas generalmente encima y debajo de las células guía, o ausente por encima; células de la lámina subcuadradas encima de la vaina inferior, paredes delgadas hasta gruesas, abultadas o con papilas, tanto simples o bífidas; células basales y de la vaina inferior cuadradas o rectangulares, lisas o débilmente papilosas. Dioicas. Periquecios terminales; hojas a menudo agrandadas, laxamente envainadoras. Setas alargadas y torcidas. Cápsulas erectas, urna ovoide hasta largo-cilíndrica; pocos estomas en la base; anillo persistente; opérculo cónico o cónico-rostrado; peristoma simple, con 16 dientes, generalmente partidos en 32 filamentos a menudo torcidos, o reducidos y cortos, papilosos o espiculados, membrana basal ausente o baja. Caliptra cuculada, lisa y desnuda. Esporas esféricas, casi lisas hasta papilosas.

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Keys from Jiménez & Cano 2008 for Peru
1. Leaf margins incurved in the upper part of the leaf … D. incurvus
1. Leaf margins plane, recurved or revolute in the upper part of the leaf … 2.
2. Ventral cells of the costa elongate in the upper part … 3.
2. Ventral cells of the costa quadrate to shortly rectangular in the upper part … 4.
3. Leaves ligulate to oblong-lanceolate, usually with an obtuse or rounded apex; costa generally ending several cells below the apex, very rarely percurrent … D. tophaceus
3. Leaves lanceolate, with apex acute; costa percurrent to shortly excurrent … D. laevigatus
4. Basal laminal cells clearly differentiated from the rest, hyaline … 5.
4. Basal laminal cells not differentiated, not hyaline … 6.
5. Stem with hyalodermis; leaves long-lanceolate; basal marginal cells clearly differentiated, long-rectangular to elongate, in 2-6 rows … D. umbrosus
5. Stem without hyalodermis or occasionally present in patches; leaves oblong-lanceolate to lanceolate, ovate or triangular; basal marginal cells not or weakly differentiated, quadrate to shortly rectangular … D. australasiae
6. Lamina entirely or mostly bistratose in the upper half … 7.
6. Lamina unistratose … 8.
7. Costa percurrent; laminal cells papillose … D. minusculus
7. Costa long-excurrent as a subula; laminal cells smooth … D. rigidulus var. subulatus
8. Lamina red or brown with KOH … 9.
8. Lamina green or yellow with KOH … 10.
9. Transverse section of the costa with 2-3 layers of ventral stereids, with a bulging layer of cells on the ventral surface … D. pruinosus
9. Transverse section of the costa without ventral stereids, without a bulging layer of cells on the ventral surface … D. vinealis
10. Leaf margins unistratose, apex sharp, not thickened, plants without gemmae in the axils of the leaves … D. rigidulus var. gracilis
10. Leaf margins bistratose in the upper part, apex blunt, thickened, plants generally with gemmae in the axils of the leaves … 11.
11. Leaves strongly incurved when dry, leaf margins plane or slightly recurved above midleaf, upper and middle laminal cells rounded to oval … D. humboltii
11. Leaves appressed when dry, leaf margins recurved from the base to ½ or ¾ of the leaf, upper and middle laminal cells quadrate … D. rigidulus var. rigidulus
1. Márgenes de la hoja incurvados en la parte superior de la hoja … D. incurvus
1. Márgenes de la hoja planos, recurvados o revolutos en la parte superior de la hoja … 2.
2. Células ventrales de la costa alargadas en la parte superior … 3.
2. Células ventrales de la costa cuadradas a brevemente rectangulares en la parte superior … 4.
3. Hojas ligulares a oblongo-lanceoladas, generalmente con un ápice obtuso o redondeado; costa generalmente terminando varias células debajo del ápice, muy rara vez percurrente … D. tophaceus
3. Hojas lanceoladas, con ápice agudo; costa percurrente a brevemente excurrente … D. laevigatus
4. Células basales de la lámina claramente diferenciadas del resto, hialinas … 5.
4. Células basales de la lámina no diferenciadas, no hialinas … 6.
5. Tallo con hialodermis; hojas largo-lanceoladas; células marginales basales claramente diferenciadas, largo-rectangulares a alargadas, en 2-6 filas … D. umbrosus
5. Tallo sin hialodermis o en ocasiones presente en parches; hojas oblongo-lanceoladas a lanceoladas, ovadas o triangulares; células marginales basales débilmente diferenciadas o no, cuadradas a brevemente rectangulares … D. australasiae
6. Lámina biestratificada completamente o generalmente en la mitad superior … 7.
6. Lámina uniestratificada … 8.
7. Costa percurrente; células de la lámina papilosas … D. minusculus
7. Costa largo-excurrente como una subula; células de la lámina lisas … D. rigidulus var. subulatus
8. Lámina roja o parda en reacción con KOH… 9.
8. Lámina verde o amarilla en reacción con KOH … 10.
9. Corte tranversal de la costa con 2-3 capas de estereidas ventrales, con una capa abultada de células en la superficie ventral … D. pruinosus
9. Corte tranversal de la costa sin estereidas ventrales, sin una capa abultada de células en la superficie ventral … D. vinealis
10. Márgenes de la hoja uniestratificados, ápices afilados, no engrosados, plantas sin yemas en las axilas de las hojas … D. rigidulus var. gracilis
10. Márgenes de la hoja biestratificados en la parte superior, ápice obtuso, engrosado, plantas generalmente con yemas en las axilas de las hojas … 11.
11. Hojas marcadamente incurvadas en seco, márgenes de la hoja planos o escasamente recurvados encima de la mitad de la hoja, células superiores y mediales de la lámina redondeadas a ovales … D. humboltii
11. Hojas adpresas en seco, márgenes de la hoja recurvados desde la base hasta ½ o ¾ de la hoja, células superiores y mediales de la lámina cuadradas … D. rigidulus var. rigidulus
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