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BFNA Title: Haplodontium |
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XX. HAPLODONTIUM
Hampe, Ann. Sci. Nat.,
Bot. ser. 5(4): 336. 1865 * [Latin haplo, single,
and dontium,
tooth, the peristome is single] John SpencePlants small, in open to dense turfs or sometimes as scattered individuals,
light green to pink-green, often brown proximally. Stems 0.5--2(--3) cm, evenly foliate, unbranched
to freely branched by subfloral innovations, stolons absent; often densely tomentose
proximally, macronemata absent, rhizoids sparse to
abundant. Leaves somewhat twisted
or contorted to subsecund or sometimes imbricate
when dry, erect to erect spreading when wet; elliptic, ovate to oblong or
sometimes broadly lanceolate, not decurrent; margins
plane or narrowly revolute below, 1-stratose, limbidium absent, distal margins smooth or rarely weakly
serrulate, apex rounded-obtuse to broadly acute, apiculus
absent or occasionally present, costa subpercurrent
to percurrent or rarely excurrent,
transverse section typically lacking guide cells, adaxial
supracostal cells elongate, similar to adjacent laminal cells, laminal cells
rather uniform, elongate and thin walled, lax, rhomboidal to
elongate-rhomboidal, 40--120 x 10-20 \um, not pitted, distal cells not
oblique to costa, alar cells irregularly short- to
long-rectangular, but not distinctly differentiated. Specialized asexual reproduction absent. Sexual condition dioicous; perigonia
and perichaetia usually appearing lateral due to
rapid innovation growth, leaves the same size as or somewhat smaller than
vegetative leaves. Seta single,
yellow- to red-brown, 3--12 mm, curved to flexuose.
Capsule erect, suberect
to nutant, subglobose to
broadly pyriform, often somewhat obscured by
elongate innovations, 1--2.5 mm, sometimes curved or irregularly shaped, hypophysis not enlarged or inflated, exothecial
cells irregularly quadrate to short-rectangular; operculum flat to weakly
convex, apiculate or umbonate;
peristome single, typically exostomial but
sometimes of unknown origin, absent, or rarely double, teeth slender,
irregularly linear-lanceolate, hyaline, sometimes perforate, smooth or finely
papillose. Spores small,
10--20(--24) \um, pale, smooth or finely papillose, not shed in tetrads. Species ca. 40 (2 in the
flora): pantropical, subtropical to temperate,
centered in the mountains of Africa and South America, but extending to
Eurasia, Because of previous
over-reliance on the peristome, the taxonomy of Haplodontium
and Mielichhoferia remains confused. The gametophytes of the two genera are very
unlike, with Haplodontium species similar to
those of Plagiobryum and Plagiobryoides.
Recent genetics research has clearly shown that Mielichhoferia
is related to Pohlia, while the species
centered around H. macrocarpum are closer to
Bryum and relatives. As our two species are very similar gametophytically to the type of Haplodontium,
H. megalocarpum Arnott,
I have chosen to place them in Haplodontium.
Peristome reduction is common and complex in this genus, from double to
single to absent. SELECTED REFERENCES:
Brassard, G.R. and T. Hedderson. 1983. The
distribution of Mielichhoferia macrocarpa, a North American endemic moss. Bryologist
86: 273--275. Shaw, J. and H. A. Crum. 1984. Peristome homology in Mielichhoferia and a taxonomic account of North
American species. J. Hattori Bot. Lab. 57: 363--381. Showers, D. 1980. Mielichhoferia tehamensis,
sp. nov., from northern 1. Peristome
present, operculum plane or weakly convex, sometimes apiculate;
leaf margins narrowly revolute, at least proximally, distal lamina cells at
tip elongate; leaves somewhat twisted or secund
when dry ........... 1. Haplodontium macrocarpum 1. Peristome lacking;
operculum umbonate; leaf margins plane throughout,
distal lamina cells at tip short-rectangular to subquadrate;
leaves imbricate, stem julaceous …..…2. Haplodontium tehamense 1. Haplodontium macrocarpum (Hooker) Spence, Phytologia
87: 26. 2005 Weissia macrocarpa Hooker, Musci
Americani; or, Specimens of the Mosses Collected in
Plants pale light green to pink-green,
red-brown to brown proximally. Stems
0.5--3 cm, weakly to strongly branched, not julaceous.
Leaves flexuose to
weakly secund when dry, erect when wet, ovate to oblong or broadly
lanceolate, 0.6--2 mm; margins narrowly revolute proximally, apex broadly
acute to sometimes acuminate, apiculus absent or
rarely present, costa subpercurrent to percurrent, pale tan-brown or red, rarely excurrent in short to medium-length hairpoint,
laminal cells rather uniform, elongate and thin
walled, lax, rhomboidal to elongate-rhomboidal, 40--120 x 10--18 \um, cells
near leaf tip usually elongate, 3:1 or more, cells somewhat narrower along
margin but not forming a distinct limbidium. Seta single, yellow-brown, 4--12 mm,
curved to flexuose. Capsule erect to nutant, subglobse to short-pyriform,
1.3--2.5 mm, operculum flat to weakly convex, weakly apiculate,
peristome single, teeth slender, irregularly linear-lanceolate, hyaline,
sometimes perforate, smooth or finely papillose. Spores small, 12--20(--24) \um, pale, smooth or finely papillose. Capsules
mature summer (Jul--Aug). Rare on damp to seepy
rock faces or crevices, typically limestone; 0--3500 m, in southern latitudes
restricted to high elevations; widely disjunct, Arctic-alpine; Greenland;
Alta, Nfld., Nunavut; Alaska, Colo., Mont., Utah; Eurasia (ne Russia). A species of conservation concern. Although Haplodontium macrocarpum has
been thought to be associated with mineral-rich rock, collections come from a
wide variety of rock types. In the
Southern and Central 2. Haplodontium tehamense (Showers) Spence, Phytologia
87: 26. 2005 Mielichhoferia tehamensis Showers, Bryologist 83: 365, figs.
1--3. 1980 Plants shiny light green to yellow-green or
white-green, light brown below. Stems
0.5--1 cm, stongly branched, somewhat julaceous. Leaves
imbricate when dry, erect to erect-spreading when wet; elliptic to oblong, 0.5--1 mm; margins plane, apex
rounded-obtuse to broadly acute, apiculus absent,
costa subpercurrent, yellowish, laminal
cells rather uniform, elongate and thin walled, lax, rhomboidal to
elongate-rhomboidal, 40--80 (--100) x 10--20 \um, distal cells at tip
shorter, irregularly short-rectangular to subquadrate.
Seta red-brown, 3--7 mm, flexuose. Capsule
horizontal to nutant, short and broadly pyriform, 1.2--2.5 mm, operculum convex and umbonate, peristome absent. Spores small, 10--14 \um, pale, more or less smooth. Capsules
mature summer (Aug.). Rare in crevices of volcanic rock in montane areas; 2200--2600 m; Haplodontium
tehamense is
a distinctive species, with its eperistomate
capsule and somewhat julaceous stems. It is still
only known from a few locations in |
