7. Leptostomopsis (Müller Hal. ex Brotherus) J. R. Spence & H. A. Ramsay, Phytologia. 87: 70. 2005. • [Genus Leptostomum and Greek -opsis, resemblance].
John R. Spence
Brachymenium sect. Leptostomopsis Müller Hal. ex Brotherus in H. G. A. Engler and K. Prantl, Nat. Pflanzenfam. 218[I,3]: 558. 1903
Plants small, in dense cushions, sometimes turfs, or rarely gregarious, pale green-silver, pinkish, or yellow-silver. Stems 0.4-2 cm, sometimes julaceous, strongly branching by subfloral innovations; rhizoids many, micronemata and macronemata present on stems. Leaves imbricate when dry, erect to erect-spreading when moist, broadly ovate to spathulate, somewhat concave, 0.2-2 mm; base not decurrent; margins recurved or sometimes plane proximally, plane distally, serrulate to distinctly serrate near apex, 1-stratose, limbidium present or absent; apex broadly rounded to acute; costa long-excurrent, sometimes percurrent in proximal leaves, awn hyaline, denticulate to spinose, guide cells present; alar cells usually distinct in quadrate groups or sometimes transversely elongate in small groups; laminal areolation heterogeneous; proximal laminal cells usually quadrate to short-rectangular, 1-2:1; medial and distal cells hexagonal, rhomboidal, or almost vermicular, 3-6:1, walls thin to thick, not pitted. Specialized asexual reproduction absent. Sexual condition dioicous; perigonia and perichaetia terminal, leaves same size as vegetative leaves or usually larger, not forming rosette, inner leaves little differentiated. [Seta usually single, straight to somewhat twisted. Capsule erect, oblong or cylindric, 2-4 mm; hypophysis inconspicuous to well differentiated; operculum weakly convex, short-conic, not rostrate; peristome diplolepidous-alternate; exostome pale yellow or tan, sometimes reddish, teeth slender lanceolate; endostome separate or rarely adherent to exostome, basal membrane low, segments absent, cilia absent. Spores shed singly, not as tetrads, 17-25 µm, finely papillose, pale yellow-tan or brown].
Species 10 (2 in the flora): s United States, Mexico, Central America, South America, se Asia, Africa; mostly subtropical to tropical environments.
Leptostomopsis is a distinctive genus superficially similar to Leptostomum. Recent molecular work suggests that the genus is basal to the remainder of Bryaceae. The genus was originally included in the polyphyletic Brachymenium. Although molecular work indicates that the genus should be placed in Bryaceae, morphologically it is close to Leptostomum and could be placed in Leptostomataceae. Plants of Leptostomopsis have reddish brown to yellow setae. The exostome teeth are not trabeculate.
