BFNA Title: Thelia-Theliaceae
Author: B. Allen
Date: March 8, 2010
Edit Level: R
Version: 1

Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden

BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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THELIACEAE (Brotherus) M. Fleischer

 

Bruce H. Allen

 

Plants glaucous, bluish, yellowish-grey, or dark-green, in dense mats. Stems creeping or ascending, often densely tomentose, in cross section with small, firm- to thick-walled epidermal cells, enlarged cortical cells, central strand present; paraphyllia subfoliose or absent; pseudoparaphyllia filamentous or foliose-ciliate. Axillary hairs 3--6 cells long, basal cell subrectangular, reddish brown, distal cells oblong, hyaline. Rhizoids from clusters of initials abaxial to the leaf insertions. Leaves erect-appressed or imbricate when dry, erect-swollen when wet, densely foliate, concave; stem and branch leaves sometimes dimorphic. Sexual condition phyllodioicous; dwarf males on tomentum or leaves of female plants. Seta elongate. Capsule erect, stomata present; peristome diplolepideous. Calyptra cucullate, smooth, naked.

 

Genera 1, species 3: North America, Mexico, West Indies (Dominican Republic).

 

The Theliaceae are small plants that occur in dense, often extensive mats. Their single costate leaves have short, stoutly unipapillose leaf cells, and well differentiated alar cells. Some members of the group have subfoliose paraphyllia and some also have foliose-ciliate pseudoparaphyllia. They have long setae; erect, more or less symmetric capsules; narrow exostome teeth that are smooth at base, but otherwise papillose; rudimentary endostomes; and cucullate calyptrae.

There has been considerable controversy over the systematic position of Thelia with the genus variously placed in the Anomodontaceae, Hylocomiaceae, Leskeaceae, Theliaceae, or Thuidiaceae. The disagreements are due to the classical moss dilemma: gametophytic features that indicate one relationship, but sporophytic features pointing to a different one. Thelia was revised by H. A. Crum (1966); he noted the genus was gametophytically similar to the Thuidiaceae, but had the sporophyte, especially the peristome structure, of Anomodon. He placed Thelia in the Thuidiaceae by the differentiated stem leaves; polymorphous, ciliate paraphyllia; and stout, curved papillae. W. R. Buck and D. H. Vitt (1986) placed Thelia in the Anomodontaceae on the basis of short leaf cells with well-developed papillae, and narrow, white, papillose exostome teeth. There is good molecular support (T.-Y. Chiang and B. A.  Schaal 2000a, 2000b) for placing Thelia in the Hylocomiaceae. B. Goffinet and W. R. Buck (2004) and B. Goffinet et al. (2009) placed Thelia in the monotypic Theliaceae due to questions concerning the sample size of the molecular study.

 

1. THELIA  Sullivant in A. Gray, Manual (ed. 2), 660. 1856. [Greek Thele, nipple, refers to the prominent leaf papillae of the genus]

 

Plants small to medium-sized. Stems with elongate surface cells, 1-pinnately or irregularly branched; branches erect-ascending, simple or irregularly branched. Rhizoids smooth, reddish brown, densely branched. Leaves deltoid-ovate, broadly acute to obtuse, apiculate or piliferous, decurrent; margins long-ciliate to ciliate below, ciliate-papillose above; costae single, 1/2-- 3/4\x leaf length, sometimes spurred or forked, at times double; cells rhombic to fusiform, stoutly 1-papillose abaxially, papillae columnar, simple or 3--6 branched, alar cells quadrate or subrectangular. Seta smooth, flexuose when dry, yellowish when young, red when mature. Capsule cylindric to ovoid-cylindric, symmetric to somewhat curved, smooth to weakly wrinkled when dry; exothecial cells at mouth red, oblate to quadrate, proximally enlarged, quadrate to short-rectangular; thin- to firm-walled; stomata on neck; operculum conic-subulate; annulus rudimentary, of 2--3 layers of thin-walled cells, persistent; exostome teeth white, linear, outer surface smooth at base, finely papillose distally, trabeculae and median line thickened, inner surface lightly papillose, trabeculae weak, teeth united at base on a short, smooth membrane; endostome rudimentary, white, lightly papillose, basal membrane low or high, segments reduced to stubs or reaching 1/2\x exostome length, cilia 1--2, nub-like or absent. Spores smooth to lightly papillose.

 

Thelia is remarkable in its glaucous to bluish green color, thick, densely tomentose mats, and tumid to julaceous stems and branches. The stem leaves are distinctive by deltoid-ovate with rhombic cells, simple or 3-6 branched, columnar papillae, and frequently long-ciliate margins. The sporophyte has a long setae and typically erect, symmetric, cylindrical to ovoid-cylindrical capsules. Its diplolepideous peristome is yellowish-white with narrow exostome teeth that are smooth at base, but otherwise papillose. The endostome is rudimentary with segments and cilia often reduced to nub-like projections on a low or high basal membrane.

In the field, Thelia could be confused with Myurella because both genera have terete stems and branches that occur in mats or cushions, radiculose stems, and a similar color. Myurella, however, rarely occurs in dense mats, its leaves have short, double costae, serrate or sinuous-dentate margins, and lower, unbranched papillae.

 

1. Leaf cell papillae simple............................................................................. 2. Thelia hirtella

1. Leaf cell papillae with 3--6 branches at apex.

2. Stems creeping, densely, regularly branched, often densely tomentose; branches evenly thickened, raggedly imbricate, simple; branch leaves usually with spreading, piliferous apices.............................................................................................. 1. Thelia asprella

2. Stems often ascending, sparsely, irregularly branched, lightly tomentose; branches clavate, smoothly imbricate, irregularly branched; branch leaves with erect, apiculate apices.... 3. Thelia lescurii

 

1. Thelia asprella Sullivant in A. Gray, Manual (ed. 2), 660. 1856  E

Leskea asprella Schimper in P. Bruch, W. P. Schimper & W. Gümbel, Bryol. Eur. 5: 136. 1850 (fasc. 44--45); Hypnum hirtellum (Hedwig.) Müller Hal. var. furcatum Müller Hal.

 

Stems creeping, 1-pinnatedly branched, branches erect-ascending, slender and terete, simple; paraphyllia not seen; pseudoparaphyllia filamentous. Stem and branch leaves more or less similar, erect-appressed when dry, erect-swollen when wet, densely foliate, 0.8--1 mm, broadly acute to obtuse, abruptly contracted to long, clear, often spreading piliferous acumina, (occasionally long-apiculate), decurrent; margins plane throughout, or plane distally and erect to somewhat incurved basally, ciliate basally, ciliate-papillose distally; cells rhombic nearly throughout, 12--20 x 8--12 \um, stoutly 1-1-papillose abaxially, papillae usually 3--6 branched, oblong across the base, alar cells quadrate or subrectangular. Seta 8--12 mm. Capsule symmetric to somewhat curved, smooth to weakly wrinkled when dry, 2--2.5 mm; operculum 1--1.3 mm. Calyptra 2--3 mm. Spores 6--10 \um, smooth to lightly papillose.

 

tree trunks, rotting stumps, humus, and on soil at base of trees, over rocks, or on ground; low to moderate elevations (20--790 m); Ont., Que.; Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.C., Nebr., N.H., N.J., N.Y., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.

 

Thelia asprella is a fairly small species that usually grows in large, dense mats at the base of trees. --Thelia hirtella and T. asprella are nearly identical in aspect; both species have terete, regularly branched, densely radiculose stems, and piliferous leaves. Thelia hirtella differs from T. asprella most clearly in having unbranched leaf cell papillae. In addition, the leaves in T. hirtella are dimorphic with stem leaves much larger and more densely ciliate than the branch leaves. Thelia lescurii and T. asprella are similar in having leaf cells with 3--6 branched papillae, but otherwise are quite different as noted by the key characters. In addition, Thelia lescurii is a larger plant than T. asprella that nearly always grows on soil or over rocks. In the field T. lescurii can often be distinguished from T. asprella because its short-apiculate leaves give the plants a smoothly imbricate appearance. In T. asprella the piliferous apices are often spreading and this gives the plants ragged appearance.

 

2. Thelia hirtella (Hedwig) Sullivant in A. Gray, Manual (ed. 2). 660. 1856

 

Pterigynandrum hirtellum Hedwig, Sp. Musc. Frond. 83. 1801.

 

Stems creeping, 1-pinnatedly branched, branches erect-ascending, slender and terete, simple; subfoliose paraphyllia present; pseudoparaphyllia foliose-ciliate. Stem and branch leaves dimorphic, erect-appressed when dry, erect-swollen when wet, densely foliate. Stem leaves 1--1.3 mm, broadly acute, sharply contracted to long, sometimes spreading, piliferous acumina, decurrent; margins plane throughout, or plane distally and erect to somewhat incurved basally, densely long-ciliate; cells rhombic to fusiform, 14--30 x 3--10 \um, stoutly 1-papillose abaxially, papillae simple, columnar and curved, at base near the costa, smooth, elongate, and porose, oblong, smooth, more or less porose across the base, alar cells quadrate or subrectangular. Branch leaves 0.6--0.9 mm; margins dentate-toothed at base, sharply serrate distally; apical and median cells rhombic, 14--20 x 3--8 \um, at base near the costa, smooth, fusiform, sometimes porose. Seta 4--12 mm. Capsule erect, cylindric to ovoid-cylindric, symmetric to somewhat curved, smooth to weakly wrinkled when dry, 1--2 mm; operculum 0.8--1 mm. Calyptra 2--2.5 mm.Spores 12--16 \um, smooth to lightly papillose.

 

Tree trunks, rotting stumps, humus, and soil usually at base of trees, occasionally on rocks; low to medium elevation (0--1220 m); N.B., N.S., Ont., Ont., Que.; Ala., Ark., Conn., Del., Fla., Ga., Ill. Ind., Kans., Ky., La., Maine, Md., Mass., Mich., Miss., Mo., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Va., W. Va., Wis.; Mexico (Tamaulipas); West Indies (Dominican Republic).

 

Thelia hirtella has the broadest distribution of any Thelia species, ranging from southern Nova Scotia south to Florida and west to northeastern Mexico, eastern Texas, and eastern Oklahoma. The deltoid-shaped leaves of T. hirtella are decurrent, and abruptly contracted above into long, piliferous (at times spreading) apices. The stem leaf margins are long-ciliate, but those of the branch leaves are dentate toothed at base and sharply serrate above. Thelia hirtella has rhombic upper leaf cells with stout, unbranched, columnar papillae on the dorsal side, but are smooth to somewhat bulging cell walls on the ventral side. The costae in T. hirtella are faint and often spurred or forked.

In general aspect T. hirtella and T. asprella are very similar; both have terete, regularly branched, densely tomentose stems, and piliferous leaves. Often T. lescurii can be distinguished from T. hirtella in the field by branches clavate-shaped and smoothly imbricate. In contrast the branches of T. hirtella have a somewhat ragged appearance due to its often spreading, piliferous leaf apices.

 

3. Thelia lescurii Sullivant in Gray, Manual (ed. 2), 660. 1856  E

 

Thelia asprella Sullivant in Gray var. lescurii (Sullivant. in Gray) Habeeb

 

Stems weakly creeping or crowded and ascending, irregularly branched, branches also irregularly branched, primary and secondary branches identical in form, erect-ascending, clavate; paraphyllia not seen; pseudoparaphyllia foliose-ciliate. Stem and branch leaves more or less similar, imbricate when wet or dry, densely foliate, 0.8--1 mm, broadly acute to obtuse, abruptly short-apiculate, decurrent; margins plane or erect to incurved, stem leaf margins short-ciliate basally, branch leaf margins ciliate-papillose; cells rhombic nearly throughout, 42--22 x 7--9 \um, stoutly 1-papillose abaxially, papillae usually 3--6-branched, across the base oblong, smooth, often porose, alar cells quadrate or subrectangular. Seta 8--17 mm. Capsule symmetric or somewhat inclined, smooth to weakly wrinkled when dry, 1.5--3 mm; operculum 0.5--1 mm. Calyptra ca. 2 mm. Spores 10--16 \um, smooth to lightly papillose.

 

Sandy soil, road banks, or soil over rock (granite, limestone or sandstone), rarely at the base trees or on rotting logs; low to moderate elevations (50--513 m); Ala., Ark., Del., Fla., Ga., Ill., Ind., Kans., Ky., La., Miss., Mo, Nebr., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C.,  Tenn., Tex., Va., Wis.

 

Thelia lescurii is generally larger than the other species of Thelia and unlike those species it almost always grows on soil or thin soil over rock. Plants of T. lescurii have mostly ascending, sparsely and irregularly branched stems that are weakly tomentose because only those parts of the stems in contact with the substrate have tomentum. The branches in T. lescurii are thickened, often clavate-shaped, and irregularly branched. This combination of features, along with its ascending stems, gives the plants a compact aspect quite different from that of T. asprella or T. hirtella. Thelia lescurii could be confused in the field with Myurella because both occur on calcareous soil, have a similar color, and smoothly terete stems and branches. The leaves of Myurella, however, have short, double costae and considerably lower leaf cell papillae.

 

Literature cited.

Buck, W. R. and D. H. Vitt. 1986. Suggestions for a new familial classification of pleurocarpous mosses. Taxon 35: 21--60.

Chiang, T.-Y. and B. A. Schaal. 2000a. Molecular evolution of the atpB-rbcL noncoding spacer of chloroplast DNA in the moss family Hylocomiaceae. Bot. Bull. Acad. Sin. 41: 85--92.

Chiang, T.-Y. and B. A. Schaal. 2000b. The internal transcribed spacer 2 region of the nuclear ribosomal DNA and the phylogeny of the moss family Hylocomiaceae. Pl. Syst. Evol. 224: 127--137.

Crum, H. 1966. A taxonomic account of the genus Thelia. Bull. Natl. Mus. Canada 216: 123--127.

Fleischer, M. 1923. Die Musci der Flora von Buitenzorg. Volume 4. Leiden.

Goffinet B. & W. R. Buck. 2004. Systematics of Bryophyta (mosses): from molecules to a revised classification. Monogr. Syst. Bot. Missouri Bot. Gard. 98: 205--239.

Goffinet B., W. R. Buck and A. J. Shaw. 2009. Morphology, anatomy, and classification of the Bryophytes, pp. 55--138. In: B. Goffinet & A. J. Shaw, Bryophyte Biology. Cambridge University Press, Cambridge.