TAXONOMIC SECTION

                                                                                 

                                                               Family POTTIACEAE

                                                                                 

Pottiaceae Schimp., Coroll. Bryol. Eur. 24, 1855 [1856], nom. fam. cons.

 

The family name is based on Pottia, which was named by Friedrich Ehrhart in his Beiträge zur Naturkunde (1787) for “Cel. Joh. Frid. Pott,” a physician and professor of botany at Brunswick (mistakenly Braunschweig according to Müller 1853), author of an unpublished “Flora Brunswickensis.”

 

Plants usually turf-forming or loosely caespitose, green above and brown below, irregularly branching. Stems short or to several cm in length, mostly pentagonal in transverse section, central strand usually present, hyalodermis usually absent; axillary hairs several cells in length, sometimes the basal 1–3 cells brownish. Leaves usually appressed and often contorted when dry, spreading when wet, ovoid to lanceolate or lingulate, ca. 1.5 to 3.5 mm in length, margins usually recurved below, occasionally plane, entire or sometimes dentate above, occasionally bordered by thick-walled or elongate cells or cells in layers; apex rounded-obtuse to more commonly narrowly acute; base usually ovate to oblong, occasionally sheathing the stem; costa ending a few cells below the apex to short-excurrent or awned, in medial transverse section usually with a differentiated epidermis ventrally or on both sides, one or two stereid bands, guide cells in one or seldom more than one layer, hydroid strand occasionally present (sometimes multiple); upper laminal cells usually subquadrate, occasionally hexagonal or rarely short-rectangular, mostly ca. 9–16 µm wide, 1(–2):1, usually in one layer, walls mostly evenly thickened, superficially flat to bulging, sometimes bulging only ventrally; papillae usually present over the upper laminal cells, solid or occasionally hollow, usually bifid but occasionally simple, sometimes flattened or compound; basal cells usually differentiated, usually clear, smooth or lightly papillose above, rectangular, generally filling the base medially, sometimes rising marginally in a vee-shape, occasionally bulging. Asexual reproduction not uncommon, by multicellular (rarely unicellular) propagula borne on stalks in the leaf axils or more seldom on leaves, or obovoid brood bodies borne on rhizoids in the soil. Perichaetia and perigonia terminal or occasionally lateral on short branchlets. Dioicous or monoicous, occasionally apparently rhizautoicous. Perichaetial leaves often sheathing in the lower part and then with elongate-rhomboidal cells in lower portion, usually larger than the stem leaves, long-oval to long-lanceolate. Perigoniate plants occasionally smaller than the perichaetiate, seldom nearly stemless and bud-like. Sporophyte often in transformation series of apparent peristome reduction and seta shortening. Seta usually elongate, often twisted; capsules ovoid to cylindric, mostly stegocarpous, occasionally spherical and then cleistocarpous and rhexolytic; neck usually small or nearly absent; annulus mostly of 1–2 rows of vesiculose cells, occasionally revoluble or deciduous in pieces; operculum short-conic to short-rostrate, cells in straight or oblique rows; usually elongate, peristome teeth occasionally absent, more usually erect or twisted usually clockwise, yellow, orange or red, rudimentary or consisting of 16 mostly twice cleft, spiculose, striate or papillose, lanceolate teeth, or 32 linear, usually densely spiculose filiform divisions, the basal membrane usually low or absent, occasionally very high and trabeculate. Calyptra cucullate, smooth, occasionally mitrate. Spores ca. 10–15 µm in diameter. Laminal color reaction yellow to orange-red or red in two percent KOH solution. Reported chromosome number generally x = 13.

     The conservation of the name Pottiaceae (Magill 1977b; Greuter 1988) apparently was unnecessary. The original discussion of Hyophilaceae Hampe, Linnaea 4: 68, 1847, is actually given as a footnote in which was said: “Ich habe diesen Namen den Früheren: Calympereae oder Syrrhopodonteae vorgezogen, weil sich diese Namen auf die Form der Haube, oder auf das Peristome beziehen; die Beschaffenheit des Peristoms kann dem Familiennamen nicht zum Grunde gelegt werden, wo das Peristom oft felt.” Argument may be made that there is no description here (“wo das Peristom oft felt” being merely rhetorical and applying to Hyophilaceae, Calympereae and Syrrhopodonteae equally), hence Hyophilaceae was not validly published prior to Pottiaceae; also, according to G. Zjilstra (pers. comm.), this is not a diagnosis since the phrase including “oft” does not cover the whole group. The name Tortulaceae, used for the Pottiaceae in some older literature, is a synonym of Ephemeraceae (Crosby & Magill 1981). Recently, Saito (1975a) agreed with Hilpert (1933) and Podpera (1954) in excluding Cinclidotus from the Pottiaceae and placing it into a separate family, the Cinclidotaceae Schimp. (= Ripariaceae Schimp. see Crosby & Magill 1981), a disposition followed here. For additional information on excluded genera and species, see the discussion of Excluded Taxa.

     The authorities for the names mentioned in the text are those of the names recognized as correct in the updated list of taxa (see Table of Contents). The specific and infraspecific nomenclature is mainly that of the Index Muscorum (van der Wijk et al. 1959–69), with additions and emendations based on research since the publication of that work as summarized in the updated list of taxa. Some of the names of subgenera and sections acknowledged as correct here may not, however, represent taxonomically valid or properly placed groups, but are merely starting points for revisionary study. Thorough revisionary work is required for most genera; for this reason, no emphasis is placed on citation of putative type specimens in that lectotypification, inappropriate here, is required for a majority of them; the specimens examined in the course of this study were annotated and their herbarium designations (Holmgren et al. 1990) are given here.

     All new combinations, new names and new synonymy are based on examination of material obtained on loan from the herbaria cited, or in relatively few cases, are based on my judgement that the novelty is clearly warranted. The vast majority of specimens seen during this study are “authentic” or syntype material as far as determinable with the literature immediately available, but their exact identity as types, although probable, remains to be more accurately ascertained through revisionary treatments and associated lectotypification not appropriate here. This study could not be done adequately, however, without a great deal of name shuffling.

     In the nomenclature list at the beginning of each generic treatment, names following the genus name are not indented if they are correct (e.g. accepted infrageneric names) while synonyms (of the genus or of infrageneric names) are indented. Synonyms that cannot be referred to a particular infrageneric taxon are placed immediately below the generic name. Infrageneric taxa are grouped by category, being arranged alphabetically (after the typical name), and include both those recognized by the present author and those unstudied supraspecific names given as correct names by van der Wijk et al. (1959–69). Synonyms are grouped by taxonomic category (subgenus, section, subsection), then arranged alphabetically.

            The citation of a species name under the heading “species examined” does not mean that the species has been extensively studied by me. It merely indicates that well-identified or syntype or type or otherwise authentic specimens of the species were examined. These fit well within the genus concept presented in the description, or at least cannot be easily referred to a different genus.

 

 

                                                     KEY TO SUPRAGENERIC TAXA

                                                                                 

The subfamilies and tribes recognized here are subclades defined by character state changes at ancestral nodes, but these groups are fairly coherent morphologically and may be described in the fashion of a standard key. The couplets of this key reflect the coordination of the subclades in Cladogram 16. See the section on morphology above or the glossary for explanation of specialized terms.

 

1. Upper lamina bistratose medially and the cells not vertically aligned (i.e. not directly over each other) near the costa but grading to vertically evenly stacked towards the leaf margin, leaves broadly to linearly lanceolate....................Subfamily Timmielloideae

1. Upper lamina unistratose or if bistratose then cells situated directly over one another throughout..............................................................................2

2. Upper laminal cells ventrally mamillose medially but several rows of cells bulging on both sides orginally, costal guide cells forming a thick-walled, multilayered cylinderSubfamily Gertrudielloideae

2. Upper laminal cells similarly bulging or not throughout leaf, guide cells either not multilayered or if so then thin-walled................................................3

3. Leaves lanceolate, margins plane to weakly incurved, apex acute, base sheathing, upper lamina KOH red, stereid bands two, guide cells 4–6, rows of cells across ventral surface of costa 10(–16).............................Subfamily Erythrophyllopsoideae

3. Not this combination of characters...............................................4

4. Leaves long-linear, margins plane, ventral stereid band larger than the dorsalSubfamily Chionolomoideae

4. Leaves lanceolate to spathulate, ventral stereid band absent or generally smaller than the dorsal.................................................................5

5. Sclerodermis commonly poorly differentiated, hyalodermis commonly present, leaves lanceolate, margins plane to weakly incurved, upper laminal cells KOH yellow, costa lacking a differentiated dorsal epidermis, clavate axillary propagula rare.......................................Subfamily Trichostomoideae

5. Not this combination of characters...........................................6

6. Stem sclerodermis commonly well differentiated from cells of central cylinder, which have abruptly larger lumens, leaves usually broadly lanceolate to narrowly elliptical, usually with two costal stereid bands, leaf base commonly differentiated in shape and ovate or rectangular, upper laminal cells equally convex on both free surfaces, clavate axillary propagula commonly present in some genera.........................................Subfamily Merceyoideae 7

7. Stem black, leaves long-triangular, capsule with a circumstomal ringTribe Tetracoscinodontieae

7. Not this combination of characters.......................................8

8. Upper lamina usually KOH red, dorsal stereid band usually reniformTribe  Bryoerythrophylleae

8. Not this combination of characters.....................................9

9. Stem central strand absent...........................Tribe Leptodontieae

9. Stem central strand usually present, or if absent then costa with one stereid band............................................Tribe Barbuleae

   6. Stem sclerodermis commonly not or poorly differentiated from cells of central cylinder, which generally grade in size into the cortical cells, leaves usually broadly ligulate to spathulate, usually with one stereid band in the costa, leaf base usually little differentiated in shape, sometimes upper laminal cell free surfaces ventrally bulging and dorsally weakly convex, clavate axillary propagula rare.....................Subfamily Pottioideae 10

   10. Upper laminal cells usually bulging ventrally and weakly convex dorsallyTribe Hyophileae

10. Upper laminal cells equally convex on both free surfaces.....Tribe Pottieae

 

                                                             KEY TO THE GENERA

                                                                                 

This key was developed in part using the DELTA (DEscription Language for TAxonomy) system (Dallwitz 1974, 1980; Dallwitz & Paine 1986; Partridge et al. 1988). Data matrices were created using the descriptions in the taxonomic section. In order to make the key work, total variation was not scored for certain of the larger genera in that rare and unusual character states were sometimes not included. This was done to account for problems in key creation that are due to the presence in a genus of (1) species probably incorrectly assigned to a particular genus and requiring further study for correct disposition, (2) species possessing several of the reliable characteristics of that genus but with one or more additional characters considered reliable for a different genus, and (3) much reduced species with occasional secondary lack of features (e.g. ventral stereid band) whose absence was a key characteristic of other genera (e.g. genera of Pottieae). Gametophytic characters are emphasized in the key, reflecting taxonomic importance in the actual treatments, but closeness of taxa in the key does not imply a close phylogenetic relationship. Because artificial distinctions of sporophyte characteristics previously used to distinguish genera are not recognized, many genera necessarily key out in more than one place. To keep the number of couplets to a manageable minimum, reliable technical characters involving sectioning and color reactions to two percent potassium hydroxide solution are necessary at the beginning of the key. Emphasis on more immediately observable characters are practicable only in regional treatments. The key characters below are those of leaf morphology and anatomy unless otherwise noted.

   The number of times each genus appears in this key is dependent on the variation within the genus of the characters considered reliable for identification. This is a measure of the internal complexity of the genus, whether due to taxonomic heterogeneity or simple breadth of variation of a monophyletic taxon. An index of such complexity for each suprageneric group is the number of times of their genera occur in the key divided by the number of genera in the group, as follows: Timmielloideae, 1.0; Erythrophyllopsoideae, 1.0; Gertrudielloideae, 1.0; Chionolomoideae, 1.7; Trichostomoideae, 3.9 (Trichostomum occurs 11 times!); Merceyoideae, 2.8; tribe Tetracoscinodontieae, 1.0; tribe Bryoerythrophylleae, 2.2 (Pseudocrossidium occurs 4 times); tribe Leptodontieae, 1.5 (Triquetrella occurs 4 times); tribe Barbuleae, 4.2 (Didymodon and Gyroweisia each occur 9 times, Gymnostomum 7 times); Pottioideae, 2.3; tribe Hyophileae, 2.5 (Hyophila and Weissia each occur 9 times); tribe Pottieae, 2.2 (Aschisma and Trachycarpidium each occur 4 times). It is probable that, after revision, the Trichostomoideae and Barbuleae will prove less of a source of variation in taxonomic characters; taxa with low ratios are apparently presently well understood or at least easily characterized.

 

1(0).     Ventral costal stereid band absent (costa with a single stereid band).............2

Ventral costal stereid band present (costa with two stereid bands)...............51

 

2(1).     Ventral costal outgrowths absent..................................................3

Ventral costal outgrowths present as a pad of cells, lamellae or filaments.......41

 

3(2).     Stem central strand absent........................................................4

Stem central strand present......................................................16

 

               4–39 Costa with one stereid band, costal outgrowths absent, central strand absent

4(3).     KOH color reaction of upper laminal cell walls essentially yellow or orange.......5

KOH color reaction of upper laminal cell walls essentially red, usually a definite brick red......................................................................11

 

5(4).     Superficial walls of upper laminal cells similarly shaped on both sides of lamina; leaves when dry occasionally channeled but not distinctly tubulose..............6

Superficial walls of upper laminal cells ventrally bulging-mamillose, weakly convex dorsally; leaves tubulose when dry.............................................10

 

6(5).     Medial upper laminal cells small to medium sized, 7–14 µm in width................7

Medial upper laminal cells large, commonly more than 14 µm in width...............8

 

7(6).     Stem sclerodermis not or little differentiated; upper laminal papillae absent; basal  cell group differentiated and rising higher medially; length of stem usually 1.0 cm or more; basal cells usually with straight walls, little wider than upper medial cells; wide distribution.............................................Scopelophila

Stem sclerodermis clearly differentiated; upper laminal papillae present; basal cell group differentiated approximately straight across leaf; length of stem less than 1.0 cm, usually less than 0.6 cm; basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution.......................Gyroweisia

 

8(6).     Margins plane to incurved or involute; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; hydroid strand present; stem hyalodermis present (sometimes indistinct); southern South America, Australia..................................................Calyptopogon

Margins recurved to revolute; transverse section of dorsal costal stereid band round to semicircular; hydroid strand absent; stem hyalodermis absent.................9

 

9(8).     Transverse section of costa round or ovate or elliptical; basal cell group not or little differentiated from upper medial cells; leaves widest below midleaf; number of rows of cells across ventral surface of costa usually 2 but up to 4; stem sclerodermis clearly differentiated; tropics.........................Streptopogon

Transverse section of costa semicircular; basal cell group clearly differentiated, usually larger, less papillose, walls thinner; leaves widest at or above midleaf; number of rows of cells across ventral surface of costa commonly 4 or more; stem sclerodermis not or little differentiated; western North America...........Crumia

 

10(5).   Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; ventral costal epidermis absent; dorsal costal epidermis absent; leaf base clearly differentiated in shape; American tropics, eastern AsiaLuisierella

Basal cell group differentiated straight across leaf or rising higher medially; transverse section of dorsal costal stereid band round to semicircular; ventral costal epidermis present; dorsal costal epidermis present; leaf base little differentiated in shape; Brazil, India..................................Ganguleea

 

11(4).   Medial upper laminal cells small to medium sized, 7–14 µm in width ..............12

Medial upper laminal cells large, commonly more than 14 µm in width..............13

 

12(11). Dorsal costal epidermis absent; basal cell group clearly differentiated, usually larger, less papillose, walls thinner; theca ovoid to cylindrical; capsule stegocarpous; leaves usually widest at or above midleaf; wide distributionSyntrichia

Dorsal costal epidermis present; basal cell group not or little differentiated from upper medial cells; theca spherical; capsule cleistocarpous; leaves widest below midleaf; wide distribution................................................Acaulon

 

13(11). Margins plane to incurved or involute; length to width ratio of medial upper laminal cells 1–2:1....................................................................14

Margins recurved to revolute; length to width ratio of medial upper laminal cells 2–4:1 or more.................................................................15

 

14(13). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; costal ventral cells longitudinally elongate 3:1 or more; stem sclerodermis clearly differentiated; superficial walls of upper laminal cells strongly convex to bulging on both sides of lamina; southern South America, Australasia..........................................................Calyptopogon

Basal cell group differentiated straight across leaf or rising higher medially; transverse section of dorsal costal stereid band round to semicircular; costal ventral cells quadrate to very short-rectangular; stem sclerodermis not or little differentiated; superficial walls of upper laminal cells flat or very weakly convex on both sides of lamina; southern South America, Antarctica...........Sarconeurum

 

15(13). Hydroid strand absent; upper laminal papillae absent; theca longer, usually more than 1.5 mm in length; calyptra longer, 1.0 mm or more in length; plants caespitose, usually in a mat or turf; tropics....................................Streptopogon

Hydroid strand present; upper laminal papillae present; theca short, less than 1.5 mm in length; calyptra short, less than 1.0 mm; plants gregarious or scattered; wide distribution...........................................................Microbryum

 

             16–40 Costa with one stereid band, costal outgrowths absent, central strand present

16(3).   Medial upper laminal cells small to medium sized, 7–14 µm in width...............17

Medial upper laminal cells large, commonly more than 14 µm in width..............31

 

17(16). Dorsal costal epidermis absent...................................................18

Dorsal costal epidermis present..................................................23

 

18(17). KOH color reaction of upper laminal cell walls essentially yellow or orange......19

KOH color reaction of upper laminal cell walls essentially red, usually a definite brick red......................................................................20

 

19(18). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; stem sclerodermis not or little differentiated; costal ventral cells quadrate to very short-rectangular; guide cells commonly more than 6; Mexico, Andes, South Africa................................................Streptocalypta

Basal cell group differentiated straight across leaf or rising higher medially; transverse section of dorsal costal stereid band round to semicircular; stem sclerodermis clearly differentiated; costal ventral cells longitudinally elongate 3:1 or more; guide cells 2–6; wide distribution........................Gyroweisia

20(18). Capsule cleistocarpous; calyptra short, less than 1.0 mm; Australasia....Phascopsis

Capsule stegocarpous; calyptra longer, 1.0 mm or more in length..................21

 

21(20). Dorsal superficial laminal cell walls about same thickness as the ventral or weakly thicker near costa; basal cell group clearly differentiated, usually larger, less papillose, walls thinner; leaves widest at or above midleaf....................22

Dorsal superficial laminal cell walls throughout distinctly thicker than the ventral; basal cell group not or little differentiated from upper medial cells; leaves widest below midleaf; western North America, central Europe.............Hilpertia

 

22(21). Seta nearly absent to short, less than 1 cm; perichaetial leaves distinctly different in size or morphology, strongly sheathing the seta; austral oceanic islandsWillia

Seta elongate, 1 cm or longer; perichaetial leaves similar to cauline leaves or occasionally smaller or somewhat enlarged; wide distribution...........Syntrichia

 

23(17). Superficial walls of upper laminal cells similarly shaped on both sides of lamina24

Superficial walls of upper laminal cells ventrally bulging-mamillose, weakly convex dorsally.......................................................................29

 

24(23). Ventral costal epidermis absent..................................................25

Ventral costal epidermis present.................................................26

 

25(24). Leaf ventral surface above midleaf nearly plane to broadly channeled; leaves widest at or above midleaf; rather deep, narrow groove along costa absent; perichaetium terminal on main axis; seta nearly absent to short, less than 1 cm; pantropicalGymnostomiella

Leaf ventral surface above midleaf keeled; leaves widest below midleaf; rather deep, narrow groove along costa present; perichaetium lateral on main axis at ends of very short branches; seta elongate, 1 cm or longer; wide distributionAnoectangium

 

26(24). Hydroid strand absent............................................................27

Hydroid strand present; wide distribution..........................Pseudocrossidium

 

27(26). Perichaetium terminal on main axis, leaves usually broadly channeled across the ventral surface................................................................28

Perichaetium lateral on main axis at ends of very short branches, leaves usually strongly keeled; wide distribution...................................Anoectangium

 

28(27). Length of stem less than 1.0 cm, usually less than 0.6 cm; basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution.Gyroweisia

 

Length of stem usually 1.0 cm or more; basal cells usually with straight walls, little wider than upper medial cells; wide distribution.................Didymodon

 

29(23). KOH color reaction of upper laminal cell walls essentially yellow; margins plane to incurved or involute; transverse section of dorsal costal stereid band round to semicircular; guide cells 2–6; stem hyalodermis absent.........................30

KOH color reaction of upper laminal cell walls essentially orange; margins revolute to near apex; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; guide cells commonly more than 6; stem hyalodermis present (sometimes indistinct); Andes...............Gertrudiella

 

30(29). Margins plane or very weakly incurved; transverse section of costa round or ovate or elliptical; hydroid strand absent; leaf base clearly differentiated in shape; number of rows of cells across ventral surface of costa usually 2 but up to 4; tropics................................................................Weisiopsis

Margins clearly incurved to involute; transverse section of costa semicircular; hydroid strand present; leaf base little differentiated in shape; number of rows of cells across ventral surface of costa commonly 4 or more; American tropics, South Africa, Burma...........................................................Plaubelia

 

31(16). Margins plane to incurved or involute............................................32

Margins recurved to revolute.....................................................35

 

32(31). Transverse section of dorsal costal stereid band round to semicircular; upper laminal papillae present...............................................................33

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; upper laminal papillae absent; Mexico, Andes...............................................................Sagenotortula

 

33(32). Ventral costal epidermis absent; hydroid strand absent; superficial walls of upper laminal cells strongly convex to bulging on both sides of lamina; pantropicalGymnostomiella

Ventral costal epidermis present; hydroid strand present; superficial walls of upper laminal cells flat or very weakly convex on both sides.........................34

 

34(33). Number of rows of cells across ventral surface of costa usually 2 but up to 4; upper marginal cells in same number of layers as medial cells; upper marginal cells not longer than medial cells (sometimes larger); papillae per lumen 2–6, usually bifid or multifid; basal cell group differentiated and rising higher medially; southern South America, Antarctica.............................................Sarconeurum

Number of rows of cells across ventral surface of costa commonly 4 or more; upper marginal cells differentiated as a bistratose (or more) border; upper marginal cells rectangular and clearly longer than medial cells; papillae per lumen many, usually 6 or more, simple or bifid; basal cell group differentiated approximately straight across leaf; wide distribution...............................Hennediella

 

35(31). KOH color reaction of upper laminal cell walls essentially yellow or orange......36

KOH color reaction of upper laminal cell walls essentially red, usually a definite brick red......................................................................37

 

36(35). KOH color reaction of upper laminal cell walls essentially yellow; hydroid strand present; medial upper laminal cells small, 7–10 µm in width; papillae per lumen 2–6, usually bifid or multifid; wide distribution........................Tortula

KOH color reaction of upper laminal cell walls essentially orange; hydroid strand absent; medial upper laminal cells medium sized, 11–14 µm in width; papillae per lumen many, usually 6 or more, simple or bifid; western North America......Crumia

 

37(35). Dorsal costal epidermis absent; dorsal superficial laminal cell walls throughout distinctly thicker than the ventral; margins revolute; perichaetial leaves distinctly larger in size; western North America, central Europe........Hilpertia

Dorsal costal epidermis present; dorsal superficial laminal cell walls about same  thickness as the ventral or weakly thicker near costa; margins recurved; perichaetial leaves similar to cauline leaves or occasionally smaller or somewhat enlarged.......................................................................38

 

38(37). Basal cell group not or little differentiated from upper medial cells............39

Basal cell group clearly differentiated, usually larger, less papillose, walls thinner........................................................................40

 

39(38). Medial upper laminal cells 15–17 µm in width; leaf apex obtuse or acute to acuminate; upper laminal papillae present; sexual condition monoicous; upper marginal cells in same number of layers as medial cells; wide distribution...............Microbryum

Medial upper laminal cells commonly 18 µm in width or more; leaf apex broadly rounded; upper laminal papillae absent; sexual condition dioicous; upper marginal cells differentiated as a bistratose (or more) border; Mexico, Central America, Andes.................................................................Dolotortula

 

40(38). Upper laminal papillae absent (except sometimes along extreme margins of leaf); sexual condition dioicous; plants caespitose, usually in a mat or turf; length to width ratio of medial upper laminal cells 1–2:1; calyptra longer, 1.0 mm or more in length; wide distribution..................................................Chenia

Upper laminal papillae present; sexual condition monoicous; plants gregarious or scattered; length to width ratio of medial upper laminal cells 2–4:1 or more; calyptra short, less than 1.0 mm; wide distribution....................Microbryum

 

                               41–50 Costa with one stereid band, costal outgrowths present

41(2).   KOH color reaction of upper laminal cell walls essentially yellow or orange......42

KOH color reaction of upper laminal cell walls essentially red, usually a definite brick red......................................................................48

 

42(41). Ventral costal outgrowths differentiated as filaments or lamellae................43

Ventral costal outgrowths differentiated as a bulging pad of cells...............46

 

43(42). Transverse section of dorsal costal stereid band round to semicircular; transverse section of costa round to semicircular.........................................44

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; transverse section of costa distinctly flattened, usually reniform....................................................45

 

44(43). Ventral costal outgrowths differentiated as longitudinally elongated lamellae; spore diameter more than 15 µm; annulus of weakly differentiated cells; wide distribution........................................................Pterygoneurum

Ventral costal outgrowths differentiated as separate filaments three or more cells in length; spore diameter 8–15 µm; annulus of vesiculose cells, often in two or more rows; wide distribution................................................Crossidium

 

45(43). Margins plane to incurved or involute; axillary hairs with 1 or more basal cells with thicker or darker-colored walls; leaf apex cucullate; leaves tubulose when dry; spore diameter more than 15 µm; Mexico, Andes...........................Aloinella

Margins recurved to revolute; axillary hair basal cell walls hyaline and all cells of hair similar; leaf apex flattened, channeled or keeled; leaves when dry occasionally channeled but not distinctly tubulose; spore diameter 8–15 µm; wide distribution.....................................................Pseudocrossidium

46(42). Dorsal superficial laminal cell walls about same thickness as the ventral or weakly thicker near costa; length to width ratio of medial upper laminal cells 1–2:1..47

Dorsal superficial laminal cell walls throughout distinctly thicker than the ventral; length to width ratio of medial upper laminal cells 2–4:1 or more; North Temperate Zone.....................................................................Stegonia

 

47(46). Margins plane to incurved or involute; medial upper laminal cells 7–14 µm in width; leaf apex cucullate; upper laminal papillae absent; southwestern USA south through Andes................................................................Globulinella

 

Margins recurved to revolute; medial upper laminal cells commonly larger than 14 µm in width; leaf apex flattened, channeled or keeled; upper laminal papillae present; wide distribution.........................................................Tortula

 

48(41). Ventral costal outgrowths differentiated as filaments or lamellae; medial upper laminal cells commonly larger than 14 µm in width; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; leaf base clearly differentiated in shape; transverse section of costa distinctly flattened, usually reniform; wide distribution............Aloina

Ventral costal outgrowths differentiated as a bulging pad of cells; medial upper laminal cells small to medium sized, 7–14 µm in width; transverse section of dorsal costal stereid band round to semicircular; leaf base little differentiated in shape; transverse section of costa round to semicircular.......................49

 

49(48). Stem central strand absent; margins plane to incurved or involute; number of rows of cells across ventral surface of costa usually 2 but up to 4; medial upper laminal cells medium sized, 11–14 µm in width; leaf apex obtuse or acute to acuminate..50

Stem central strand present; margins recurved; number of rows of cells across ventral surface of costa commonly 4 or more; medial upper laminal cells small, 7–10 µm in width; leaf apex broadly rounded; Mexico, Andes.........................Saitoella

 

50(49). Basal cell group not or little differentiated from upper medial cells; leaf apex flattened, channeled or keeled; costal ventral cells longitudinally elongate 3:1 or more; leaves widest below midleaf; sporophyte commonly present, spherical, seta short; wide distribution..................................................Acaulon

Basal cell group clearly differentiated, usually larger, less papillose, walls thinner; leaf apex cucullate; costal ventral cells quadrate to very short-rectangular; leaves widest at or above midleaf; sporophyte unknown; Australia..................................................................Stonea

 

           51–67 Costa with two stereid bands, upper laminal cells KOH yellow or orange, central    strand absent

51(1).   KOH color reaction of upper laminal cell walls essentially yellow or orange......52

KOH color reaction of upper laminal cell walls essentially red, usually a definite brick red.....................................................................171

 

52(51). Stem central strand absent.......................................................53

Stem central strand present......................................................68

 

53(52). Margins entire or minutely and evenly crenulate..................................54

Margins denticulate or serrulate to toothed......................................60

 

54(53). Ventral costal epidermis absent..................................................55

Ventral costal epidermis present.................................................57

 

55(54). Basal cell group not or little differentiated from upper medial cells; peristome teeth present; seta elongate, 1 cm or longer; theca longer, usually more than 1.5 mm in length; annulus of vesiculose cells, often in two or more rows; austral areas and Mediterranean climates in the North Temperate Zone...............Triquetrella

Basal cell group clearly differentiated, usually larger, less papillose, walls thinner; peristome teeth absent; seta nearly absent to short, less than 1 cm; theca short, less than 1.5 mm in length; annulus of weakly differentiated cells......56

 

56(55). Transverse section of dorsal costal stereid band round to semicircular; medial upper laminal cells small, 7–10 µm in width; upper laminal papillae present; calyptra short, less than 1.0 mm; wide distribution..........................Hymenostylium

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; medial upper laminal cells medium sized, 11–14 µm in width; upper laminal papillae absent; calyptra longer, 1.0 mm or more in length; eastern Asia, India..........................................Reimersia

 

 57(54).  Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; wide distribution...Tortella

Basal cell group differentiated straight across leaf or rising higher medially...58

 

58(57). Leaf ventral surface above midleaf nearly plane to broadly channeled.............59

Leaf ventral surface above midleaf keeled; New Zealand..............Tetracoscinodon

 

59(58). Costal ventral cells quadrate to very short-rectangular; stem hyalodermis present (sometimes indistinct); length of stem usually 1.0 cm or more; basal cells usually with straight walls, little wider than upper medial cells; wide distributionTrichostomum

Costal ventral cells longitudinally elongate 3:1 or more; stem hyalodermis absent; length of stem less than 1.0 cm, usually less than 0.6 cm; basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution.Gyroweisia

 

60(53). Margins denticulate only near leaf base or at top of leaf sheath; North Temperate Zone, India, South Africa...............................................Eucladium

Margins denticulate or serrulate to toothed near apex or throughout..............61

 

61(60). Margins plane to incurved or involute; leaf ventral surface above midleaf nearly plane to broadly channeled; rather deep, narrow groove along costa absent......62

Margins recurved; leaf ventral surface above midleaf keeled; rather deep, narrow groove along costa present.....................................................63

 

62(61). Ventral costal epidermis absent; hydroid strand present; theca spherical; superficial exothecial cell walls with a central and lens-like superficial thickening; stem hyalodermis absent; Mexico, Angola................................Bryoceuthospora

Ventral costal epidermis present; hydroid strand absent; theca ovoid to cylindrical; superficial exothecial cell walls evenly thickened; stem hyalodermis present (sometimes indistinct); wide distribution............................Trichostomum

 

63(61). Basal cell group not or little differentiated from upper medial cells............64

Basal cell group clearly differentiated, usually larger, less papillose, walls thinner........................................................................65

 

64(63). Dorsal costal epidermis absent; stem hyalodermis present (sometimes indistinct); number of rows of cells across ventral surface of costa commonly 4 or more; transverse section of costa distinctly flattened, usually reniform; stomates absent; Andes......................................................Leptodontiella

Dorsal costal epidermis present; stem hyalodermis absent; number of rows of cells across ventral surface of costa usually 2 but up to 4; transverse section of costa round to semicircular; stomates present; austral areas and Mediterranean climates of the North Temperate Zone..........................................Triquetrella

 

65(63). Papillae per lumen 2–6, usually bifid or multifid................................66

Papillae per lumen many, usually 6 or more, simple or bifid......................67

 

66(65). Theca short, less than 1.5 mm in length; Andes.......................Leptodontiella

Theca longer, usually more than 1.5 mm in length; wide distribution....Leptodontium

 

67(65). Upper marginal cells in same number of layers as medial cells, not longer than medial cells (sometimes larger); seta nearly absent to short, less than 1 cm; theca usually 1.5–3.5 mm in length; marginal cell walls not thicker than those of medial cells; Andes.......................................................Streptotrichum

Upper marginal cells differentiated as a bistratose border, rectangular and clearly longer than medial cells; seta elongate, 1 cm or longer; theca more than 3.5 mm in length; marginal cell walls thicker than those of medial cells; AndesTrachyodontium

 

          68–170 Costa with two stereid bands, upper laminal cells KOH yellow or orange, central  strand present

68(52). Margins entire or minutely and evenly crenulate..................................69

Margins denticulate or serrulate to toothed.....................................148

 

69(68). Hydroid strand absent............................................................70

 

Hydroid strand present..........................................................130

 

70(69). Inflated, banana-shaped alar cells absent or alar cells merely swollen and rounded71

Inflated, banana-shaped alar cells present and decurrent as a pad on the stem; Mexico, West Indies...............................................Weissiodicranum

 

71(70). Superficial walls of upper laminal cells similarly shaped on both sides of lamina72

Superficial walls of upper laminal cells ventrally bulging-mamillose, weakly convex dorsally......................................................................119

 

72(71). Ventral costal stereid band smaller than the dorsal or of nearly equal size......73

Ventral costal stereid band distinctly larger than the dorsal...................116

 

73(72). Margins plane to incurved or involute............................................74

Margins recurved to revolute....................................................107

 

74(73). Margins plane or very weakly incurved............................................75

Margins clearly incurved to involute............................................105

 

75(74). Dorsal costal epidermis absent...................................................76

Dorsal costal epidermis present..................................................89

 

76(75). Capsule cleistocarpous, i.e., rupturing (usually) irregularly....................77

Capsule stegocarpous, i.e., dehiscing by an operculum............................80

 

77(76). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border............................78

Basal cell group differentiated straight across leaf or rising higher medially (occasionally rising weakly along extreme basal margin as a line of elongate cells); wide distribution............................................Trichostomum

 

78(77). Ventral costal epidermis absent; theca spherical; stomates absent; calyptra papillose, distinctly roughened or strongly mamillose; central North America, Europe...................................................................Aschisma

Ventral costal epidermis present; theca ovoid to cylindrical; stomates present; calyptra smooth or nearly so...................................................79

 

79(78). Leaf base little differentiated in shape; axillary hairs with 1 or more basal cells with thicker or darker colored walls; capsule surface evenly mamillose or with distinct protuberances of strongly bulging cells basally or throughout; stem hyalodermis absent; theca short, less than 1.5 mm in length; South America, Africa, Oceania...........................................................Trachycarpidium

Leaf base clearly differentiated in shape; axillary hair cell walls hyaline and all cells of hair similar; capsule surface nearly smooth; stem hyalodermis present (sometimes indistinct); theca longer, usually more than 1.5 mm in length; wide distribution.............................................................Tortella

 

80(76). Transverse section of dorsal costal stereid band round to semicircular...........81

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped..........................................84

 

81(80). Costal ventral cells quadrate to very short-rectangular..........................82

Costal ventral cells longitudinally elongate 3:1 or more.........................83

 

82(81). Costa ending before the leaf apex; wide distribution....................Gymnostomum

Costa percurrent to excurrent; wide distribution.......................Trichostomum

 

83(81). Stem sclerodermis not or little differentiated; length of stem usually 1.0 cm or more; basal cells usually with straight walls, little wider than upper medial cells; wide distribution..............................................Gymnostomum

Stem sclerodermis clearly differentiated; length of stem less than 1.0 cm, usually  less than 0.6 cm; basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution........................................Gyroweisia

 

84(80). Guide cells 2–6; length of stem usually 1.0 cm or more...........................85

Guide cells commonly more than 6; length of stem less than 1.0 cm, usually less than 0.6 cm; Mexico, Andes, South Africa................................Streptocalypta

 

85(84). Stem hyalodermis absent..........................................................86

Stem hyalodermis present (sometimes indistinct)..................................87

 

86(85). Medial upper laminal cells small, 7–10 µm in width; leaf apex obtuse to broadly acute; costa ending before the leaf apex; wide distribution...........Gymnostomum

Medial upper laminal cells medium sized, 11–14 µm in width; leaf apex narrowly acute to acuminate; costa percurrent to excurrent; American tropics, eastern AsiaTuerckheimia

 

87(85). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; perichaetial leaves distinctly different in size or morphology, sometimes strongly sheathing; wide distributionTortella

Basal cell group differentiated straight across leaf or rising higher medially; perichaetial leaves similar to cauline leaves or occasionally smaller or somewhat enlarged.......................................................................88

 

88(87). Costa ending before the leaf apex; wide distribution....................Gymnostomum

Costa percurrent to excurrent; wide distribution.......................Trichostomum

 

89(75). Transverse section of costa round to semicircular................................90

Transverse section of costa distinctly flattened, usually reniform..............103

 

90(89). Guide cells 2–6..................................................................91

Guide cells commonly more than 6; Philippines........................Pachyneuropsis

 

91(90). Capsule cleistocarpous, i.e., rupturing (usually) irregularly....................92

Capsule stegocarpous, i.e., dehiscing by an operculum............................94

 

92(91). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border............................93

Basal cell group differentiated straight across leaf or rising higher medially; wide distribution.........................................................Trichostomum

 

93(92). Axillary hairs with 1 or more basal cells with thicker or darker colored walls; stem hyalodermis absent; capsule surface evenly mamillose or with distinct protuberances of strongly bulging cells basally or throughout; theca short, less than 1.5 mm in length; South America, Africa, Oceania............................Trachycarpidium

Axillary hair basal cell walls hyaline and all cells of hair similar; stem hyalodermis present (sometimes indistinct); capsule surface nearly smooth; theca longer, usually more than 1.5 mm in length; wide distribution............Tortella

 

94(91). Stem sclerodermis not or little differentiated...................................95

Stem sclerodermis clearly differentiated.........................................99

 

95(94). Stem hyalodermis absent..........................................................96

Stem hyalodermis present (sometimes indistinct)..................................97

 

96(95). Medial upper laminal cells small, 7–10 µm in width; leaf apex obtuse to broadly acute; costa ending before the leaf apex; wide distribution...........Gymnostomum

Medial upper laminal cells medium sized, 11–14 µm in width; leaf apex narrowly acute to acuminate; costa percurrent to excurrent; American tropics, eastern AsiaTuerckheimia

 

97(95). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; perichaetial leaves distinctly different in size or morphology, sometimes strongly sheathing; wide distributionTortella

Basal cell group differentiated straight across leaf or rising higher medially; perichaetial leaves similar to cauline leaves or occasionally smaller or somewhat enlarged.......................................................................98

 

98(97). Costa ending before the leaf apex; wide distribution....................Gymnostomum

Costa percurrent to excurrent; wide distribution.......................Trichostomum

 

99(94). Perichaetium terminal on main axis..............................................100

Perichaetium lateral on main axis at ends of very short branches; wide distributionMolendoa

 

100(99). Costal ventral cells quadrate to very short-rectangular.........................101

Costal ventral cells longitudinally elongate 3:1 or more........................102

 

101(100).          Leaf base little differentiated in shape; leaves widest at or above midleaf; wide distribution.............................................................Hyophila

Leaf base clearly differentiated in shape; leaves widest below midleaf; wide distribution.........................................................Trichostomum

 

102(100).          Basal cells usually with straight walls, little wider than upper medial cells; wide  distribution..............................................................Barbula

Basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution...........................................................Gyroweisia

 

103(89). Perichaetium terminal on main axis..............................................104

Perichaetium lateral on main axis at ends of very short branches; wide distributionMolendoa

 

104(103).          Peristome twisted; leaf base (of sterile leaves) little differentiated in shape; superficial walls of upper laminal cells flat or very weakly convex on both sides of lamina; stem hyalodermis absent; basal cell group differentiated and rising higher medially; length of stem less than 1.0 cm, usually less than 0.6 cm; Mediterranean region.................................................Leptobarbula

Peristome straight or absent; leaf base commonly clearly differentiated in shape; superficial walls of upper laminal cells strongly convex to bulging on both sides of lamina; stem hyalodermis present (sometimes indistinct); basal cell group differentiated approximately straight across leaf; length of stem usually 1.0 cm or more; wide distribution..............................................Trichostomum

 

105(74). Transverse section of dorsal costal stereid band round to semicircular..Quaesticula

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped.........................................106

 

106(105).          Upper laminal margins not sharply and narrowly infolded; leaf base little differentiated in shape; leaves widest at or above midleaf; stem sclerodermis clearly differentiated; axillary hair basal cell walls hyaline and all cells of hair similar; wide distribution..........................................Hyophila

Upper laminal margins sharply and narrowly infolded; leaf base clearly differentiated in shape; leaves widest below midleaf; stem sclerodermis not or little differentiated; axillary hairs with 1 or more basal cells with thicker or darker colored walls; wide distribution..........................................Weissia

 

107(73). Stem sclerodermis not or little differentiated; wide distribution.......Gymnostomum

Stem sclerodermis clearly differentiated........................................108

 

108(107).          Ventral costal epidermis absent; austral regions and Mediterranean climates of the North Temperate Zone.................................................Triquetrella

Ventral costal epidermis present................................................109

 

109(108).          Perichaetium terminal on main axis..............................................110

Perichaetium lateral on main axis at ends of very short branches; wide distributionMolendoa

 

110(109).          Transverse section of dorsal costal stereid band round to semicircular..........111

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped.........................................114

 

111(110).          Leaf plane to broadly channeled ventrally, costa lacking a ventral groove.......112

Leaf channeled or keeled, costa with a rather deep, narrow groove ventrally.....113

 

112(111).          Length of stem less than 1.0 cm, usually less than 0.6 cm; basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution.Gyroweisia

Length of stem usually 1.0 cm or more; basal cells usually with straight walls, little wider than upper medial cells; wide distribution.................Didymodon

 

113(111).          Basal cells usually with straight walls, little wider than upper medial cells; wide distribution..............................................................Barbula

Basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution...........................................................Gyroweisia

 

114(110).          Leaf plane to broadly channeled ventrally, costa lacking a ventral groove.......115

Leaf channeled or keeled, costa with a rather deep, narrow groove ventrally.Barbula

 

115(114).          Leaves widest at or above midleaf; axillary hair basal cell walls hyaline and all cells of hair similar; peristome teeth absent; leaves tubulose when dry; wide distribution.............................................................Hyophila

Leaves widest below midleaf; axillary hairs with 1 or more basal cells with thicker or darker colored walls; peristome teeth present; leaves occasionally channeled but not distinctly tubulose when dry; wide distribution.....................Didymodon

 

116(72). Stem hyalodermis absent.........................................................117

Stem hyalodermis present (sometimes indistinct); tropics.........Pseudosymblepharis

 

117(116).          Stem sclerodermis not or little differentiated; Philippines..........Pachyneuropsis

Stem sclerodermis clearly differentiated........................................118

 

118(117).          Length of stem less than 1.0 cm, usually less than 0.6 cm; basal cells inflated and bulging, considerably wider than upper medial cells; wide distribution.Gyroweisia

Length of stem usually 1.0 cm or more; basal cells usually with straight walls, little wider than upper medial cells; wide distribution.................Didymodon

 

119(71). Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border...........................120

Basal cell group differentiated straight across leaf or rising higher medially..125

 

120(119).          Ventral costal stereid band smaller than the dorsal or of nearly equal size.....121

Ventral costal stereid band distinctly larger than the dorsal...................124

 

121(120).          Ventral costal epidermis absent; stomates absent; capsule cleistocarpous and rupturing mainly along weak transverse walls at butt ends of long-rectangular exothecial cells; central North America, Europe..........................Aschisma

Ventral costal epidermis present; stomates present; capsule rupturing irregularly if cleistocarpous, or stegocarpous...............................................122

 

122(121).          Upper laminal margins not sharply and narrowly infolded; guide cells commonly more than 6........................................................................123

Upper laminal margins sharply and narrowly infolded; guide cells 2–6; wide distribution..............................................................Weissia

 

123(122).          Medial upper laminal cells small, 7–10 µm in width; papillae per lumen one or occasionally two; calyptra papillose, distinctly roughened or strongly mamillose; number of rows of cells across ventral surface of costa usually 6 or more; South Africa................................................................Hypodontium

Medial upper laminal cells medium sized, 11–14 µm in width; papillae per lumen usually two or more; calyptra smooth or nearly so; number of rows of cells across ventral surface of costa 4–6; Mexico, Andes, South Africa..........Streptocalypta

 

124(120).          Calyptra smooth or nearly so; papillae per lumen usually two or more; spore diameter 8–15 µm; upper marginal cells not longer than medial cells (sometimes larger); tropics........................................................Pseudosymblepharis

Calyptra papillose, distinctly roughened or strongly mamillose; papillae per lumen one or occasionally two; spore diameter more than 15 µm; upper marginal cells rectangular and clearly longer than medial cells; South Africa........Hypodontium

 

125(119).          Transverse section of dorsal costal stereid band round to semicircular; Mexico, West Indies................................................................Quaesticula

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped.........................................126

 

126(125).          Transverse section of costa round or ovate or elliptical........................127

Transverse section of costa semicircular........................................128

 

127(126).          Upper laminal margins not sharply and narrowly infolded, with an intramarginal border of elongate cells; leaf base little differentiated in shape; stem sclerodermis clearly differentiated; leaves widest at or above midleaf; stem hyalodermis absent; West Indies..........................................................Teniolophora

Upper laminal margins sharply and narrowly infolded, leaf not bordered intramarginally by differentiated cells; leaf base clearly differentiated in shape; stem sclerodermis not or little differentiated; leaves widest below midleaf; stem hyalodermis present (sometimes indistinct); wide distribution.............Weissia

 

128(126).          Perichaetium terminal on main axis; upper laminal cell walls thin to evenly thickened, lumens quadrate to rounded.........................................129

 

Perichaetium lateral on main axis at ends of very short branches; upper laminal cell walls clearly trigonous or porose, lumens irregularly angular or stellate; Brazil, India, Philippines................................................Hymenostyliella

 

129(128).          Upper laminal margins not sharply and narrowly infolded; leaf base little differentiated in shape; stem sclerodermis clearly differentiated; axillary hair basal cell walls hyaline and all cells of hair similar; leaves widest at or above midleaf; wide distribution...............................................Hyophila

Upper laminal margins sharply and narrowly infolded; leaf base clearly differentiated in shape; stem sclerodermis not or little differentiated; axillary hairs with 1 or more basal cells with thicker or darker colored walls; leaves widest below midleaf; wide distribution.........................................................Weissia

 

130(69). Ventral costal outgrowths absent................................................131

Ventral costal outgrowths present as a pad of cells, lamellae or filaments......147

 

131(130).          Dorsal costal epidermis absent..................................................132

Dorsal costal epidermis present.................................................138

 

132(131).          Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border...........................133

Basal cell group differentiated straight across leaf or rising higher medially..135

 

133(132).          Ventral costal epidermis absent; stomates absent; calyptra papillose, distinctly roughened or strongly mamillose; leaf apex obtuse to broadly acute; capsule cleistocarpous and rupturing mainly along weak transverse walls at butt ends of long-rectangular exothecial cells; central North America, Europe.........Aschisma

Ventral costal epidermis present; stomates present; calyptra smooth or nearly so; leaf apex narrowly acute to acuminate; capsule rupturing irregularly if cleistocarpous, or stegocarpous...............................................134

134(133).          Margins plane or very weakly incurved; upper laminal margins not sharply and narrowly infolded; leaf base little differentiated in shape; costal ventral cells longitudinally elongate 3:1 or more; stem hyalodermis absent; South America, Africa, Oceania...................................................Trachycarpidium

Margins clearly incurved to involute; upper laminal margins sharply and narrowly infolded; leaf base clearly differentiated in shape; costal ventral cells quadrate to very short-rectangular; stem hyalodermis present (sometimes indistinct); wide distribution..............................................................Weissia

 

135(132).          Transverse section of dorsal costal stereid band round to semicircular; Central and South America, Australia................................................Uleobryum

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped.........................................136

 

136(135).          Leaf ventral surface above midleaf nearly plane to broadly channeled; margins plane to incurved or involute; narrow groove along ventral surface of costa absent; costal ventral cells quadrate to very short-rectangular; transverse section of costa round to semicircular...................................................137

Leaf ventral surface above midleaf keeled; margins recurved; rather deep, narrow groove along ventral surface of costa present; costal ventral cells longitudinally elongate 3:1 or more; transverse section of costa distinctly flattened, usually reniform; Europe, North Africa, southern and eastern Asia............Dialytrichia

 

137(136).          Margins plane or very weakly incurved; upper laminal margins not sharply and narrowly infolded; leaves widest at or above midleaf; axillary hair basal cell walls hyaline and all cells of hair similar; stem sclerodermis clearly differentiated; AustraliaCalymperastrum

Margins clearly incurved to involute; upper laminal margins sharply and narrowly infolded; leaves widest below midleaf; axillary hairs with 1 or more basal cells with thicker or darker colored walls; stem sclerodermis not or little differentiated; wide distribution.........................................Weissia

 

138(131).          Capsule cleistocarpous..........................................................139

Capsule stegocarpous............................................................142

 

139(138).          Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border...........................140

Basal cell group differentiated straight across leaf or rising higher medially..141

 

140(139).          Margins plane or very weakly incurved; upper laminal margins not sharply and narrowly infolded; leaf base little differentiated in shape; costal ventral cells longitudinally elongate 3:1 or more; stem hyalodermis absent; South America, Africa, Oceania...................................................Trachycarpidium

Margins clearly incurved to involute; upper laminal margins sharply and narrowly infolded; leaf base clearly differentiated in shape; costal ventral cells quadrate to very short-rectangular; stem hyalodermis present (sometimes indistinct); wide distribution..............................................................Weissia

 

141(139).          Margins plane or very weakly incurved, not sharply and narrowly infolded above; stem hyalodermis absent; capsule cleistocarpous and rupturing mainly along weak transverse walls at butt ends of long-rectangular exothecial cells; austral areasTetrapterum

Margins clearly incurved to involute, sharply and narrowly infolded above; stem hyalodermis present (sometimes indistinct); capsule rupturing irregularly if cleistocarpous, or stegocarpous; wide distribution........................Weissia

 

142(138).          Costal ventral cells quadrate to very short-rectangular.........................143

Costal ventral cells longitudinally elongate 3:1 or more........................146

 

143(142).          Transverse section of dorsal costal stereid band round to semicircular; American tropics, South Africa, Burma............................................Plaubelia

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped.........................................144

 

144(143).          Upper laminal margins not sharply and narrowly infolded; axillary hair basal cell walls hyaline and all cells of hair similar...................................145

Upper laminal margins sharply and narrowly infolded; axillary hairs with 1 or more basal cells thicker or darker colored; wide distribution..................Weissia

 

145(144).          Transverse section of costa round to semicircular; peristome teeth absent; leaves widest at or above midleaf; leaves tubulose when dry; calyptra 1.0–3.0 mm; wide distribution.............................................................Hyophila

Transverse section of costa distinctly flattened, usually reniform; peristome teeth present; leaves widest below midleaf; leaves when dry occasionally channeled but not distinctly tubulose; calyptra more than 3.0 mm; wide distributionPseudocrossidium

146(142).          Transverse section of costa round to semicircular; theca short, less than 1.5 mm in length; upper marginal cells in same number of layers as medial cells; wide distribution..............................................................Barbula

Transverse section of costa distinctly flattened, usually reniform; theca longer, usually more than 1.5 mm in length; upper marginal cells differentiated as a bistratose (or more) border; Europe, North Africa southern and eastern AsiaDialytrichia

 

147(130).          Ventral costal outgrowths differentiated as filaments or lamellae; margins recurved to revolute; transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; leaf apex flattened, channeled or keeled; transverse section of costa distinctly flattened, usually reniform; wide distribution.....................................................Pseudocrossidium

Ventral costal outgrowths differentiated as a bulging pad of cells; margins plane to incurved or involute; transverse section of dorsal costal stereid band round to semicircular; leaf apex cucullate; transverse section of costa round to  semicircular; southwestern USA south through Andes...................Globulinella

 

148(68). Margins denticulate only near leaf base or at top of leaf sheath................149

Margins denticulate or serrulate to toothed near apex or throughout.............150

 

149(148).          Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; dorsal costal epidermis absent; superficial walls of upper laminal cells ventrally bulging-mamillose, weakly convex dorsally; stem sclerodermis not or little differentiated; peristome teeth present; South Africa...........................................Hypodontium

Basal cell group differentiated straight across leaf or rising higher medially; dorsal costal epidermis present; superficial walls of upper laminal cells similarly shaped on both sides of lamina; stem sclerodermis clearly differentiated; peristome teeth absent; wide distribution..........................................Molendoa

 

150(148).          Dorsal costal epidermis absent..................................................151

Dorsal costal epidermis present.................................................157

 

151(150).          Ventral costal stereid band smaller than the dorsal or of nearly equal size; upper laminal margins not sharply and narrowly infolded.............................152

Ventral costal stereid band distinctly larger than the dorsal; upper laminal margins sharply and narrowly infolded near apex; Southeast Asia, Borneo........Chionoloma

 

152(151).          Ventral costal epidermis absent; theca spherical................................153

Ventral costal epidermis present; theca ovoid to cylindrical....................154

 

153(152).          Superficial exothecial cell walls with a central and lens-like thickening; costal ventral cells longitudinally elongate 3:1 or more; number of rows of cells across ventral surface of costa commonly 4 or more; axillary hair basal cell walls hyaline and all cells of hair similar; papillae per lumen one or occasionally twoBryoceuthospora

Superficial exothecial cell walls thickened; costal ventral cells quadrate to very short-rectangular; number of rows of cells across ventral surface of costa usually 2 but up to 4; axillary hairs with 1 or more basal cells with thicker or darker colored walls; papillae per lumen usually two or more; central North America, Europe...................................................................Aschisma

 

154(152).          Perichaetium terminal on main axis; perichaetial leaves similar to cauline leaves or occasionally smaller or somewhat enlarged.....................................155

Perichaetium lateral on main axis at ends of very short branches; perichaetial leaves distinctly different in size or morphology, strongly sheathing the seta; wide distribution.........................................................Pleurochaete

 

155(154).          Guide cells 2–6; length of stem usually 1.0 cm or more..........................156

Guide cells commonly more than 6; length of stem less than 1.0 cm, usually less than 0.6 cm; Mexico, Andes, South Africa................................Streptocalypta

 

156(155).          Stem hyalodermis absent; American tropics, eastern Asia................Tuerckheimia

Stem hyalodermis present (sometimes indistinct); wide distribution.....Trichostomum

 

157(150).          Superficial walls of upper laminal cells similarly shaped on both sides of lamina158

Superficial walls of upper laminal cells ventrally bulging-mamillose, weakly convex dorsally......................................................................165

 

158(157).          Rather deep, narrow groove along costa absent...................................159

Rather deep, narrow groove along costa present..................................164

 

159(158).          Margins plane to incurved or involute...........................................160

Margins recurved to revolute....................................................163

160(159).          Perichaetium terminal on main axis; upper marginal cells not longer than medial cells (sometimes larger); perichaetial leaves similar to cauline leaves or occasionally  smaller or somewhat enlarged..................................................161

Perichaetium lateral on main axis at ends of very short branches; upper marginal cells rectangular and clearly longer than medial cells; perichaetial leaves distinctly different in size or morphology, strongly sheathing the seta; wide distribution.........................................................Pleurochaete

 

161(160).          Leaves widest at or above midleaf; wide distribution.......................Hyophila

Leaves widest below midleaf.....................................................162

 

162(161).          Stem hyalodermis absent; American tropics, eastern Asia................Tuerckheimia

Stem hyalodermis present (sometimes indistinct); wide distribution.....Trichostomum

 

163(159).          Leaves widest at or above midleaf; axillary hair basal cell walls hyaline and all cells of hair similar; peristome teeth absent; leaves tubulose when dry; wide distribution.............................................................Hyophila

Leaves widest below midleaf; axillary hairs with 1 or more basal cells with thicker or darker colored walls; peristome teeth present; leaves when dry occasionally channeled but not distinctly tubulose; wide distribution................Didymodon

 

164(158).          Ventral costal epidermis absent; basal cell group not or little differentiated from upper medial cells; theca longer, usually more than 1.5 mm in length; calyptra short, less than 1.0 mm; stem transverse section triangular; austral areas and Mediterranean climates of the North Temperate Zone...................Triquetrella

Ventral costal epidermis present; basal cell group clearly differentiated, usually larger, less papillose, walls thinner; theca short, less than 1.5 mm in length; calyptra longer, 1.0 mm or more in length; stem transverse section rounded-pentagonal; wide distribution.....................................Barbula

 

165(157).          Hydroid strand absent...........................................................166

Hydroid strand present..........................................................169

 

166(165).          Basal cell group differentiated as a vee, with at least laterally differentiated cells rising higher marginally as a tapering border; leaf base clearly differentiated in shape; wide distribution...........................Pleurochaete

Basal cell group differentiated straight across leaf or rising higher medially; leaf base little differentiated in shape...........................................167

 

167(166).          Transverse section of costa round or ovate or elliptical; upper marginal cells differentiated intramarginally as a bistratose border; upper marginal cells rectangular and clearly longer than medial cells; marginal cell walls thicker than those of medial cells; West Indies...................................Teniolophora

Transverse section of costa semicircular; upper marginal cells in same number of layers as medial cells; upper marginal cells not longer than medial cells (sometimes larger); marginal cell walls not thicker than those of medial cells168

 

168(167).          Leaves widest at or above midleaf; upper laminal cell walls thin to evenly thickened, lumens quadrate to rounded; axillary hair basal cell walls hyaline and all cells of hair similar; perichaetium terminal on main axis; annulus of vesiculose cells, often in two or more rows; wide distribution.............................Hyophila

Leaves widest below midleaf; upper laminal cell walls clearly trigonous or porose, lumens irregularly angular or stellate; axillary hairs with 1 or more basal cells with thicker or darker colored walls; perichaetium lateral on main axis at ends of very short branches; annulus of weakly differentiated cells; Brazil, India, Philippines.......................................................Hymenostyliella

 

169(165).          Leaf base little differentiated in shape; guide cells 2–6; seta nearly absent to short, less than 1 cm; upper laminal cells medially unistratose...............170

Leaf base clearly differentiated in shape; guide cells commonly more than 6; seta elongate, 1 cm or longer; upper laminal cells medially bistratose, the cells staggered, not one directly above the other in section; wide distributionTimmiella

 

 170(169).         Transverse section of dorsal costal stereid band round to semicircular; axillary hairs with 1 or more basal cells with thicker or darker colored walls; peristome teeth present; American tropics, South Africa, Burma....................Plaubelia

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped; axillary hair basal cell walls hyaline and all cells of hair similar; peristome teeth absent; wide distribution.....Hyophila

 

                          171–181 Costa with two stereid bands, upper laminal cells KOH red

171(51). Margins entire or minutely and evenly crenulate.................................172

Margins denticulate or serrulate to toothed.....................................179

 

172(171).          Transverse section of dorsal costal stereid band round to semicircular..........173

Transverse section of dorsal costal stereid band clearly flattened or ventrally indented, reniform or crescent-shaped.........................................176

 

173(172).          Margins plane to incurved or involute; costal hydroid strand present............174

Margins recurved to revolute; costal hydroid strand absent......................175

 

174(173).          Dorsal costal epidermis absent; medial upper laminal cells commonly larger than 14 µm; transverse section of costa round or ovate or elliptical; number of rows of cells across ventral surface of costa usually 2 but up to 4; superficial walls of upper laminal cells flat or very weakly convex on both sides of lamina; southern South America, Antarctica.............................................Sarconeurum

Dorsal costal epidermis present; medial upper laminal cells 7–14 µm in width; transverse section of costa semicircular; number of rows of cells across ventral surface of costa commonly 4 or more; superficial walls of upper laminal cells strongly convex to bulging on both sides of lamina; Andes......Erythrophyllastrum

 

175(173).          Rather deep, narrow groove along costa absent; peristome teeth present; spore diameter 8–15 µm; wide distribution.....................................Didymodon

Rather deep, narrow groove along costa present; peristome teeth absent; spore diameter more than 15 µm; USA, Mexico, India, eastern Asia...........Bellibarbula

 

176(172).          Stem sclerodermis not or little differentiated; Andes.............Erythrophyllopsis

Stem sclerodermis clearly differentiated........................................177

 

177(176).          Stem hyalodermis absent ........................................................178

Stem hyalodermis present (sometimes indistinct); wide distributionBryoerythrophyllum

 

178(177).          Hydroid strand absent; rather deep, narrow groove along costa absent; number of rows of cells across ventral surface of costa usually 2 but up to 4; superficial walls of upper laminal cells strongly convex to bulging on both sides of lamina; wide distribution............................................................Didymodon

Hydroid strand present; rather deep, narrow groove along costa present; number of rows of cells across ventral surface of costa commonly 4 or more; superficial walls of upper laminal cells flat or very weakly convex on both sides of lamina; Mexico south through Andes.......................................................Mironia

 

179(171).          Ventral costal epidermis absent; southwestern USA, Mexico, Andes.......Rhexophyllum

Ventral costal epidermis present................................................180

 

180(179).          Stem hyalodermis absent.........................................................181

Stem hyalodermis present (sometimes indistinct); wide distributionBryoerythrophyllum

 

181(180).          Hydroid strand absent; rather deep, narrow groove along costa absent; number of rows of cells across ventral surface of costa usually 2 but up to 4; superficial walls of upper laminal cells strongly convex to bulging on both sides of lamina; wide distribution............................................................Didymodon

Hydroid strand present; rather deep, narrow groove along costa present; number of rows of cells across ventral surface of costa commonly 4 or more; superficial walls of upper laminal cells flat or very weakly convex on both sides of lamina; Mexico  south through Andes.......................................................Mironia