Tropicos | Name - Anomodon Hook. & Taylor

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Anomodon Hook. & Taylor

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Project data (Last Modified On 12/18/2013)

Discussion: Anomodon is a north temperate genus of 18 species (Crosby et al. 2000) also found in Mexico,
Central America, and the Caribbean. It has creeping primary stems and long, erect, variously
branched secondary stems. Anomodon leaves are mostly ovate at base with apices that vary from slender
acuminate to broadly obtuse. Its juxtacostal leaf cells near the insertions are elongate and smooth
to weakly porose, otherwise the cells are short and densely pluripapillose. The species of Anomodon
are so similar in overall aspect that it is seems clear they represent a natural group, but they also exhibit
remarkable character state variation: a stem central strand, pseudoparaphyllia, stomata, and
compound annulus can be present or absent. The peristome also is variable, e.g., the exostome can be
white, yellowish, or faintly red, papillose throughout or horizontally striate at base, and the endostome
varies from 3/4 the exostome length to rudimentary.
The leaf cell papillae in Anomodon are massive and often forked in a manner normally associated
with Pottiaceae species. The genus, however, is closely linked to the smooth-celled Herpetineuron.
The characteristic sinuose costa of Herpetineuron occurs in a weaker, flexuose to wavy state in all
species of Anomodon, and the juxtacostal basal leaf cell differentiation of Anomodon is found in
H. acutifolium (Mitt.) Granzow. Although most Anomodon species have papillose-crenulate leaf margins,
there are some species with irregularly dentate (A. attenuatus) or coarsely serrate (A. dentatus
Gao) leaf margins that approach those seen in H. toccoae.
Anomodon has been associated with the Leskeaceae or Thuidiaceae, since its sporophytes resemble
those of the Leskeaceae and its gametophytes resemble those of the Thuidiaceae (see
Granzow-de la Cerda 1997). Buck and Vitt (1986) recognized the Anomodontaceae, and moved it to
the Leucodontales near the Cryphaeaceae. The positioning of the Anomodontaceae in the Leucodontales
is based on the differentiation of its stems into creeping, sympodially branched primary stems
with reduced leaves and erect, secondary stems with full-sized leaves. Anomodon shows some similarity
to the thamnioid genera of the Neckeraceae in costal and leaf form, especially in those members
of the genus that have more or less asymmetric, complanately arranged leaves (e.g., A. minor).
Anomodon was revised by Granzow-de la Cerda (1997). A revision of the east Asiatic species of
Anomodon (Iwatsuki 1963) remains an extremely useful treatment of the genus.
The name Anomodon combines the Greek a (not), nomo (law or rule), and odon (tooth), and refers
to the mistaken observation that its endostome segments came from the same cell layers as the exostome
teeth.

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Plants small, medium-sized, or robust, in dull, dark green to yellow green, lax or dense mats. Primary
stems creeping; leaves reduced, at times scale-like; rhizoids red brown, in clusters at abaxial
side of leaf insertions, not or weakly and irregularly branched. Secondary stems erect to loosely
spreading, simple or variously branched; secondary stems and branches at times transformed at tips
into stolons or attenuate-flagellate branches; cross section with sclerodermis well developed, cortical
cells enlarged, central strand present or absent; paraphyllia absent; pseudoparaphyllia present or absent.
Secondary stem and branch leaves similar or differentiated, ovate-lanceolate, oblong-lanceolate,
ligulate, or lance-ligulate from an ovate base, decurrent or non-decurrent; apices acute, broadly rounded
to obtuse, at times apiculate; margins plane, erect, or recurved, entire or sparsely serrulate; costae single,
ending below the apex, yellow, often wavy above, in cross section cells homogeneous, thickwalled;
cells quadrate, oblate, or irregularly hexagonal, densely pluripapillose, juxtacostal cells near
the insertion elongate, straight-walled or porose, weakly papillose to smooth. Dioicous. Setae elongate.
Capsules erect, more or less symmetric; stomata present or absent; opercula obliquely or straight
conic-rostrate; annuli rudimentary or compound; peristome double; exostome teeth white to yellow,
at times reddish orange at base, narrowly triangular to linear, dorsal (outer) surface papillose-striate
at base or papillose throughout, trabeculae variously projecting; endostome papillose, to 1/2 the exostome
length or rudimentary, segments narrow and perforate or reduced to stubs, basal membranes
low, cilia rudimentary or absent. Spores spherical, subspherical, or oblong, lightly papillose. Calyptrae
cucullate, smooth.