BFNA Title: Pseudoditrichaceae
Pseudoditrichaceae Steere & Iwatsuki
Plants acrocarpous, scattered or gregarious. Stems short, 1--3 mm, unbranched. Leaves erect-spreading, secund, linear-lanceolate from an oblong ± sheathing base, serrulate to irregularly serrate at the shoulders, costa narrow, delicate proximally, nearly filling the acumen; cells ± thick-walled, in leaf base long-rectangular, longer on costa (distal portion of leaf), irregularly rhombic at the shoulders. Specialized asexual reproduction common, of ± spherical, reddish brown rhizoidal tubers, axillary, filiform to bulbiform gemmae. Sexual condition dioicous; male plants smaller, with less secund leaves than females; perichaetial and perigonial leaves scarcely differentiated. Seta single, reddish brown, delicate, ca. 6 mm. Capsule suberect, ovoid, reddish brown; exothecial elongate-rectangular, thick-walled, with straight or slightly sinuose, thickened walls, slightly collenchymatous; annulus present, revoluble; operculum short-conic; peristome diplolepideous-alternate, exostome pale yellow to hyaline, narrowly lanceolate, somewhat irregular, trabeculate, pitted basally, papillose distally, endostome hyaline to pale yellow, segments divided to base and diverging, halves of adjacent segments converging opposite exostome teeth, basal membrane low, scarcely exceeding the capsule rim, cilia absent. Calyptra fugacious, cucullate, smooth or slightly papillose distally. Spores shed singly, 15--21 \um, papillose.
Genus 1 (species 1): Arctic North America.
Steere, W. C. and Z. Iwatsuki. 1974. Pseudoditrichum
mirabile gen. et. sp. nov. (Musci: Pseudoditrichaceae fam. nov.), a
unique moss from
The family Pseudoditrichaceae consists of one genus and
one species, known only from the type specimen collected near
Steere & Iwatsuki,
Plants very small. Leaves narrowly lanceolate from an ovate to oblong base, erect-spreading, ± secund. Capsule exostome teeth lanceolate, ± irregular; endostome segments split to the base, divergent and appearing opposite, basal membrane nearly absent.
Species 1, Arctic
1. Pseudoditrichum mirabile Steere & Iwatsuki, Can. J. Bot. 52. 701. 1974
Plants tiny. Capsule suberect, ovoid.
Capsules mature summer (July). Moist calcareous silt, under Populus; N.W.T.
mirable was collected in 1948 but not described until 1974. The gametophytes look like a very small Ditrichum, but the peristome is definitely
diplolepideous (and therefore this taxon is not related to Ditrichum). It has not been recollected since its