Scapaniaceae Mig.
Scapaniaceae Mig., Krypt.-Fl. Deutschland 1: 479. 1904.
Type: Scapania (Dumort.) Dumort.
Plants procumbent (rarely closely creeping) to erect, especially with crowding, in direct light developing brownish or reddish or purplish pigments, small to vigorous, the shoots to 8 mm wide, the shoot tips autonomously arched away from substrate. Branching sparing, irregular, remote, the branches nearly always lateral-intercalary, lateral in position in leaf axils but at times at ventral end of axil (then simulating ventral-intercalary branches); ventral-intercalary branches present in Diplophyllum subg. Macrodiplophyllum and D. recurvifolium; Frullania -type branches sometimes present in Scapania subg. Jensenia; basiscopic, Radula -type branches present in a few taxa. Stems often mycorrhizal with age, the cortex ± well differentiated, in (1)2–4(5) layers of thick-walled, often smaller, usually pigmented cells. Rhizoids usually frequent, scattered. Leaves basically vertically oriented, complicate-bilobed, usually strongly folded and with the lobes connected by a keel, the keel sharp or, less often, blunt, frequently ridged or winged, the ventral lobe slightly to more often distinctly larger (the lobes exceptionally subequal), the insertion extended to stem midline but not beyond, basically with the dorsal half at least in part (and often largely) transverse, but with ventral half oblique and succubous (mechanically thus ensuring that the dorsal lobe lies over the ventral); lobe apices rounded-apiculate, the lobe margins usually variously, often copiously dentate to ciliate, sometimes entire, the free margin of the dorsal lobe often decurrent, the decurrent strips running down stem midline. Cells ± collenchymatous, medium-sized (rarely over 25–35 µm wide in lobe middle); surface usually clearly papillose. Oil-bodies (Schuster, 2002a) in all cells, usually (1)2–10 per cell, granular or granular-botryoidal. Underleaves lacking, even in gynoecium or associated with gemmae production; ventral merophytes maximally reduced, the ventral ends of leaf insertions impinging on stem midline. Asexual reproduction by gemmae, the gemmae almost universally present, 1–2(5)-celled, with strongly protuberant angles, formed in branched chains from margins of uppermost leaf lobes (the leaves usually little or unmodified).
Dioecious, less often autoecious or paroecious. Androecia on leading leafy shoots, terminal but with age becoming intercalary, the bracts leaf-like but bases ventricose, at times moderately smaller than leaves; antheridia (1)2–4(7) per bract, the stalk uniseriate (2-seriate in subg. Austrodiplophyllum spp.); paraphyses often present. Gynoecia on leading leafy shoots, the bracts leaf-like, marginally to moderately larger than leaves; bracteole lacking. Perianth conspicuous, elongated, without stem-derived components, dorsiventrally compressed (sporadically weakly so), the mouth wide or only weakly contracted, distally smooth and with two flat faces, but these sometimes plicate.
Seta strongly elongating, massive, of many rows of undifferentiated cells. Capsule ovoid-ellipsoidal (rarely almost spherical), the wall (3)4–6(7)-stratose; outer layer of cells with radial (I-shaped) thickenings on all longer and all but shortest transverse walls, the thickenings usually clearly separated; inner layer of cells with semiannular bands.
Spores mostly 11–20 µm in diam., papillose or with confluent papillae and then vermiculate, 1.3–3× elater diam. Elaters feebly tortuous, bispiral (1-spiral in Douinia), with weakly tapered ends.
A family chiefly of cool to cold to Arctic regions of the Northern Hemisphere. Grolle (1983) divided the family into four subfamilies and included seven genera. One of the genera, Delavayella Steph., a monotypic genus ranging from the Himalayas to Thailand, was placed in subfamilyDelavayelloideae by Grolle (1966f, 1983), but is assigned to a separate family, the Delavayellaceae R.M.Schust. by Schuster (1961c, 1974a, 1999c, 2002a) and by Potemkin (1999). Grolle (1983) recognized subfamilyBlepharidophylloideae, as did Schuster (1974a), but the group was placed at the family rank by Schuster (1974a, 1999c, 2002a), by Engel (1990a), where the family name was validated, and by Potemkin (1999). Krunodiplophyllum Grolle (Grolle, 1965d) was placed in the synonymy of Diplophyllum subg. Austrodiplophyllum by Engel and Merrill (1998). Potemkin (1999) removed Diplophyllum and Douinia into the separate family Diplophyllaceae, and merged Macrodiplophyllum with Scapania. The Scapaniaceae eventually may become monogeneric if these taxonomic placements are accepted, especially with the inclusion of molecular studies.
We include three genera in the family. The two larger genera, Scapania and Diplophyllum, occur in our area; Douinia Buch is monotypic and found in Europe, western North America and Japan. Schuster (2002a, p. 460) remarks that the “few antipodal taxa…appear, probably, to be derived from Laurasian antecedents and the family is here regarded as of Laurasian origin.”
Description of family after Schuster (2002a) but freely modified.
