Timmiella (De Not.) Limpr., Laubm. Deutchl. 1: 590, 1888.
Type: Timmiella anomala (BSG) Limpr.
Trichstomum subg. Eutrichum Schimp., Corol. 28, 1856.
Barbula subg. Timmiella (De Not.) Kindb., Eur. N.
Amer. Bryin. 2: 245, 1897.
Barbula sect. Anomalae BSG, Bryol. Eur. 2: 75,
107 (fasc. 13–15 Mon. 13. 45), 1846.
Trichostomum sect. Timmiella De Not., Cronac. Briol.
Ital. 1: 14, 1866.
Plants loosely caespitose to cushion-forming, often
rosulate, green or often dark green above, brown below. Stems
branching irregularly or simple, to 1.5 cm in length, transverse section
rounded-pentagonal, often flattened, central strand very strong,
sclerodermis of 1–3 layers (occasionally substereid), hyalodermis present,
weak; axillary hairs of ca. 7 cells, all hyaline or basal cell
firm-walled; sparsely radiculose. Leaves incurved and tubulose when dry,
spreading when moist, long-elliptical to ligulate or broadly lanceolate,
often wasp-waisted, 3.5–5.0 mm in length, upper lamina broadly channeled
across leaf, margins plane to weakly incurved, distantly denticulate
or serrulate to near base, usually strongly serrate near apex, lamina
bistratose except along margins; apex acute; base often broadened,
elliptical, somewhat sheathing, occasionally with distinct shoulders; costa
percurrent, tapering to apex and much broadened below midleaf, superficial
cells ventrally quadrate and bulging, dorsally elongate and smooth, 6–19
rows of cells across costa ventrally at midleaf, costal transverse section
flattened, reniform or elliptical, two stereid bands present, ventral
epidermis present, this bistratose or occasionally tristratose,
dorsal epidermis present, unistratose, guide cells 6–16 in 1 layer, hydroid
strand present, often multiple, often on both ventral and dorsal sides of
guide cells; upper laminal cells quadrate to rounded-hexagonal, 9–12 µm
in width, 1:1, walls mostly evenly thickened, lumens occasionally rounded, superficially
bulging ventrally and nearly flat dorsally, cells bistratose medially but near
the costa not situated directly over each other; papillae absent; basal
cells differentiated straight across leaf, bulging-rectangular, 10–18 µm in
width, mostly 3–4:1, walls thin, hyaline to yellowish. Dioicous or monoicous
(autoicous, synoicous or apparently rhizautoicous). Perichaetia terminal,
inner leaves scarcely different from cauline leaves, base often shortly and
broadly clasping. Perigonia lateral on archegoniophore stem, as somewhat
flattened buds, or very small and terminal on perigoniate plant. Seta ca.
1.0–2.0 cm in length, 1 per perichaetium, yellowish to reddish brown, twisted
clockwise; theca 3.0–5.0 mm in length, brown, long-elliptical to
long-cylindrical, occasionally somewhat ventricose, exothecial cells 13–20 µm
in width, ca. 4–6:1, evenly thick-walled, stomates phaneropore, on neck of
theca, annulus of weakly differentiated cells or of up to several layers of
highly vesiculose cells, revoluble or deciduous in pieces; peristome teeth
of 16 paired teeth or 32 evenly spaced rami, linear-lanceolate to
filamentous, papillose to closely branching-spiculose, occasionally also
striate below, rudimentary or to 300–700 µm, with several articulations, straight
or twisted clockwise weakly once or less, basal membrane absent or very
low, essentially smooth. Operculum long-conic to rostrate, 0.6–1.7 mm in
length, cells in straight rows or twisted clockwise. Calyptra cucullate,
smooth, ca. 3.5 mm in length. Spores 10–13 µm in diameter, yellowish brown,
weakly papillose. Laminal color reaction to KOH yellow. Reported
chromosome number n = 13, 13+m, 14, 14+m, 14+m+1acc, 15.
Found
on rock and soil; in arid lands and mountainous areas of North and South
America, Europe, Asia and Africa.
Timmiella is characterized by the following combination of
distinguishing features: very strong stem central strand (Pl. 1, f. 7); laminal
margins plane to weakly incurved, denticulate to dentate; costa very wide, with
multiple hydroid strands; laminal cells medially bistratose but not vertically
aligned near the costa, epapillose, ventrally bulging and dorsally nearly flat
(Pl. 1, f. 2); peristome straight (Pl. 2, f. 6) or twisted clockwise (Pl. 1, f.
5).
Timmiella is one of only two genera in the Pottiaceae with
peristome teeth (in at least some species) twisted clockwise (Leptodontiella,
with one species, has teeth that are straight or twisted weakly clockwise).
Characters important in Timmiella are variations in sexual condition,
annulus development, and peristome size and degree of torsion. Timmiella
corniculata is dioicous, contrary to Brotherus' (1924–25) key. Propagula
are only doubtfully present in the genus; small, clavate, multicellular
propagula, ca. 50–70 µm in length, were found loosely associated with
gametophores in the type of T. brevidens, but may be due to admixture of
other species.
Additional
literature: Castaldo-Cobianchi et al. (1982), Chopra and Kapur (1989),
Gambardella et al. (1980), Kapur (1989, 1991), Ligrone (1986), Ligrone et al.
(1980a,b).
Number
of accepted species: 13.
Species
examined: T. anomala, T. barbuloides, T. brevidens (BM), T.
corniculata (NY), T. diminuta (NY), T. flexiseta (NY), T.
pelindaba (NY), T. subintegra (BM), T. umbrosa (NY).
New
heterotypic synonymy: Timmiella argentinica Broth. = Timmiella
acaulon (C. Müll.) Zand.
New
combinations: Timmiella acaulon (C. Müll.) Zand., comb. nov. (Trichostomum
acaulon C. Müll., Linnaea 42: 320, 1879; Tortella acaulon (C. Müll.)
Broth.).
