Tropicos | Name - Pinnatella M. Fleisch.

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Pinnatella M. Fleisch.

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Project Name Data (Last Modified On 1/31/2014)

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Project data (Last Modified On 1/31/2014)

Discussion:

Pinnatella is a pantropical genus of 15 species. The center of diversity of the genus is in south-ern and southeastern Asia. The genus was revised by Enroth (1994a), who characterized it as having spreading to squarrose stipe leaves with recurved margins, small, single-celled teeth on the apical leaf margins, a strong costa ending near the apex, leaves with short marginal cells and an intramarginal limbidium of elongate cells, roughened setae, and a reduced, neckeroid-type peristome. Enroth (1994a) considered the genus critical in understanding the relationship between the Thamnobryaceae and Neckeraceae, because it had a thamnobryoid gametophyte, but a neckeroid sporophyte.

The single Central American species of Pinnatella is also the most broadly distributed and the only one present in the Neotropics and Africa. Since its sporophytes are not known in the Neotropics, only gametophytic features can be used to recognize it there. In Central America the genus could be confused with Homaliodendron, Porotrichum, or Thamnobryum. Homaliodendron differs from the Neotropical species of Pinnatella in lacking a stem central strand and in having closely appressed, plane-margined stipe leaves. Its leaves are more asymmetric that those of Pinnatella, they have shorter, weaker costae, and they lack an intramarginal limbidium of elongate cells. Most Neotropical species of Porotrichum are considerably larger than those of Pinnatella, and they have more asym-metric leaves, with typically weaker costae that taper and sometimes are toothed below or end in a spine. In addition, Porotrichum leaves usually have fusiform to elongate median leaf cells and large teeth on the apical margins; they lack an intramarginal limbidium of elongate cells. In technical terms, there is little distinction between the gametophytes of Thamnobryum and Pinnatella, while sporo-phytically Thamnobryum differs from Pinnatella primarily in having an unreduced hypnoid peri-stome. In practical terms, however, Central American Thamnobryum species are considerably larger than those of Pinnatella; they have more sharply serrate apical leaf margins and scale-like, appressed stipe leaves with plane leaf margins. According to Enroth (1994a), there are some species of Tham-nobryum that have an intramarginal limbidium of elongate cells similar to that seen in Pinnatella.

The name Pinnatella combines the Latin pinna (primary division of a compound leaf) with the diminutive -ella, and it probably refers to the irregularly pinnate branching of some of its species.

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Plants small, medium-sized, or robust (outside Central America), stipitate-frondose, somewhat flattened, forming dark green to sordid green or yellowish green, lax tufts. Stolons creeping; rhizoids smooth, reddish brown, not or sparsely branched, in circular clusters just below the leaf insertions, on stolons, and at the base of stipitate stems; leaves loosely imbricate, widely spaced, evenly foliate, triangular-lanceolate. Stems erect, stipitate, irregularly pinnate to bipinnate, complanate-foliate, at times flagellate-attenuate; stems in cross section with sclerodermis of small, thick-walled cells, grad-ing into somewhat larger, firm- to thick-walled cortical cells, central strand present or absent (outside Central America); paraphyllia absent; pseudoparaphyllia absent or sparsely present. Stipe leaves erect-spreading to spreading from a somewhat clasping, decurrent base, evenly foliate, triangular-lanceolate to ovate-triangular, acute to acuminate; margins entire to subserrulate, narrowly recurved to above midleaf; costae single, ending below apex. Stem leaves erect-spreading, strongly flattened, imbricate, somewhat plicate when dry, oblong-ligulate to oblong-ovate, more or less symmetric or asymmetric (outside Central America), broadly acute, rounded, or obtuse, sometimes apiculate or mucronate, shortly decurrent; margins usually shortly incurved below on one side, occasionally plane throughout, crenulate to serrulate above, crenulate to subentire below; costae single, strong, ending near the apex, or occasionally double or deeply bifurcate (outside Central America), often sinuose, forked above, and spurred below; cells smooth or prorate, upper cells isodiametric, irregularly rounded, rounded-hexagonal, or subrhomboidal; basal cells rectangular, oblong, or elongate; alar cells oblate, quadrate, or short-rectangular in several rows at the basal angles, at times poorly devel-oped; intramarginal limbidia of 1–several rows of somewhat elongate cells in lower 1/2 of leaf vari-ously developed. Branch leaves erect to erect-spreading, weakly flattened, at times incurved when dry, oblong-ovate, smaller than the stem leaves but otherwise similar. Asexual reproduction by axil-lary, microphyllous, flagelliform branches. Dioicous. Setae elongate, smooth below, roughened above, rarely smooth throughout. Capsules erect, symmetric, cylindrical; stomata on neck, rarely absent; opercula obliquely conic-rostrate; peristome diplolepideous; exostome teeth narrowly trian-gular, dorsal surface spiculose-papillose throughout, trabeculae weakly developed, not projecting; en-dostome as long as exostome teeth, basal membranes high, segments narrowly lance-subulate, spiculose-papillose throughout, narrowly perforate, cilia absent or rudimentary. Calyptrae without distinct slits (campanulate?), hairy (with paraphyses), smooth.