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BFNA Title: Donrichardsia |
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BRACHYTHECIACEAE -- Donrichardsia Michael S. Ignatov
Plants medium-sized to robust, rigid, terete
to homomallous, in dense to loose mats, green or yellowish, dark, or brownish
green, not or slightly glossy. Stems prostrate,
occasionally curved at end, with central strand, densely to moderately
densely, irregularly loosely branched, branches prostrate to ascending;
axillary hairs 2--4-celled, colored throughout. Stem leaves erect-appressed to erect-spreading, broadly ovate to
ovate-oblong, broadly acute, sometimes abruptly cuspidate or shortly
apiculate; concave, shallowly longitudinally plicate; margin serrulate to
serrate throughout, with small acute or blunt teeth; costa strong, wide,
1/12--1/2\x leaf width, short-excurrent, percurrent, or ending at 0.8--0.95\x
leaf length; basal cells ovate-rectangular, short, thick-walled, basal cells
adjacent to decurrencies somewhat enlarged and
forming an indistinct group, or almost undifferentiated from adjacent cells;
mid leaf cells 1-stratose or partly 2--4-stratose, elongate to linear, moderately
thick-walled. Branch leaves slightly
differentiated, usually narrower and having longer mid leaf cells; juvenile
branch leaves obtuse to acute. Sexual condition dioicous; perichaetial
leaves with slightly reflexed acumina. [Seta red-brown, rough. Capsule red-brown, inclined to
horizontal, curved; annulus separating as fragments; operculum rostrate;
peristome xerocastique, perfect. Spores small. Calyptra unknown.] Species: 4 (2
in the flora): e North America, e Asia, There are
contrasting opinions on the systematic position of Donrichardsia. According to M.
Ignatov and S. Huttunen (2002) and S. Huttunen et al. (2007), however, it includes aquatic
species closely related to and possibly derived from Oxyrrhynchium. Sporophytes have not been found in Selected references: Crum, H. and L. E. Anderson 1979. Donrichardsia, a new genus of Amblystegiaceae (Musci).
Fieldiana: Botany, New Series. 1: 1--8. Crum, H. and L.
E. Anderson 1981. Mosses of 1. Costa
1/5--1/2\x lamina width; lamina partly 2- to multistratose
. . 1. Donrichardsia macroneuron 1. Costa
1/7--1/15\x lamina width; lamina 1-stratose . . 2. Donrichardsia pringlei 1. Donrichardsia macroneuron (Grout)
H.A. Crum & L.E.
Anderson, Fieldiana, Bot., n.s. 1: 7.
1979 Hygroamblystegium macroneuron Grout, Bryologist 36:
1. 1933; Eurhynchium macroneuron (Grout) H. A. Crum Stems 5--14 cm, branches to 1 cm. Stem
leaves 0.9--1.5(--1.8) x 0.4--0.8 mm; ovate-oblong, plicate; costa
1/5-1/2\x laminal width, excurrent, percurrent or ending 3--6 cells before
apex, sometimes laterally spurred; basal cells 7--10 \um wide; basal cells
adjacent \um,to decurrency almost undifferentiated; mid-leaf cells 30--65
x 6--9 somewhat flexuose. Branch leaves 1--1.5 x 0.15--0.8 mm.
Sporophytes unknown. Rocks,
shallowly submerged in water of calcareous springs at base of limestone slope
in narrow canyons; 570 m; Donrichardsia
macroneuron is known only from Seven Hundred Springs, Edwards County,
Texas. The station was described in detail by R. Wyatt and A. Stoneburner (1980), who tried to find more
localities in similar habitats nearby, but without success. Plants of Donrichardsia macroneuron have
a very broad costa reminiscent of that of Hygroamblystegium noterophilum.
The latter species has short, oblong-rhomboidal cells that are never linear
and flexuose. In dubious cases, the juvenile leaves around the branch
primordia can be examined (see description of the family Brachytheciaceae). 2. Donrichardsia pringlei
(Cardot) Huttunen & Ignatov,
Syst. Assoc. Special Vol.
71: 138, fig. 142. 2007 Rhynchostegium pringlei Cardot, Rev.
Bryol. 37: 70. 1910; Eurhynchium pringlei (Cardot) H. A. Crum & L. E. Anderson Stems to 3--10 cm, branches to 0.4--1.2 cm. Stem
leaves 0.7--1.4 x 0.5--0.8 mm; costa stout, but less than 1/10\x leaf
width, reaching 0.85--0.95\x leaf length, smooth or ending in an indistinct
spine; basal cells near costa ca. 10 \um wide; basal cells adjacent to \um.decurrency 12--20 x 10--15 \um; mid-leaf cells
(25--)40--60(--80) x 5--7 Branch
leaves 0.7--1.1 x 0.4--0.7 mm. Sporophytes unknown. Rocks
in streams and creeks; 300--650(--1950) m elev.; From
the previous assignments, Donrichardsia pringlei is superficially similar to Oxyrrhynchium hians and Rhynchostegium, particularly to
R. aquaticum.
The last species is autoicous, and if sporophytes are present, it is
immediately distinguished by a smooth seta. When sterile, R. aquaticum is
also not difficult to distinguish from D.
pringlei as the costa usually reaches
0.7--0.85\x leaf length and lacks a spine (or it is indistinct); whereas, the
costa of D. pringlei
is 0.85--0.95\x leaf length and,
if not subpercurrent, it ends in an indistinct spine. Oxyrrhynchium hians is
mainly a terrestrial plant, also having a shorter costa but its costa ends in
a prominent spine, at least in the branch leaves. |
