Gymnomitriaceae H.Klinggr.
Gymnomitriaceae H.Klinggr., Höh. Crypt. Preuss. 16. 1858. (“Gymnomitria”)
Marsupellaceae Buch, Suom. Maksasammalet 20, Helsinki. 1936, nom. inval. Müll.Frib. in Rabenhorst, Krypt.-Fl. Deutschland 36: 555. 1954 + 6: 757. 1956, nom. inval.
Type: Gymnomitrion Corda, nom. cons.
Plants firm, opaque, generally stiffly ascending to erect, sometimes from a creeping caudex, the shoot apices lacking autonomous curvature (except Prasanthus), silvery grey or greenish grey, usually developing, at least locally, brown, red, reddish brown or vinaceous pigments, the plants ± determinate in height (except Herzogobryum and Acrolophozia, which are ± procumbent), small to medium in size, to 3.5 mm wide. Branching of leafy shoots usually from older sectors, the distal sector usually unbranched, the branches lateral-intercalary (from lateral or, more often, ventral half of leaf axils); ventral-intercalary and/or Frullania -type branches rare (Herzogobryum); Radula -type basiscopic branches very rare. Stems firm, the cortex usually in 1(2) layers of slightly to conspicuously thick-walled cells surrounding 2–4 layers of often densely chlorophyllose, often pigmented, thick-walled intracortical cells slightly to conspicuously smaller in size, the intracortical cells typically becoming gradually larger and thin-walled toward the axis middle; stem not dorsiventrally differentiated, without mycorrhizal infection of medulla. Rhizoids scattered, often lacking in upper sectors of leafy shoots, issuing only from stem. Leaves alternate, vertical, varying from stiffly and pectinately spreading to closely and tightly erect-appressed, remote to densely imbricate, ± transversely oriented, the insertion virtually transverse (under 15° succubous), the dorsal end of insertion transverse, extended across and beyond stem midline (lateral merophytes dorsally interlocking), usually bilobed to 0.1–0.4(0.6), rarely emarginate or undivided, almost never trifid; apex and often margins often becoming decolorate and bleached lending a greyish color to the plant, the margins entire or crenulate. Cells firm, the walls thin or somewhat thickened, but usually not evenly thick-walled, the trigones small to large and bulging, the median cells small (usually 12–24 µm wide); surface smooth or delicately papillose or (Acrolophozia) coarsely papillose. Oil-bodies usually 2–4, rarely 5–6(7) per cell, obscurely to clearly granular, lacking in thick-walled or decolorate marginal cells. Underleaves usually reduced to slime papillae, rarely minute, 2–3 cells wide and acute to subulate, the ventral merophytes usually not more than 2 cells broad. Asexual reproduction absent.
Dioecious or paroecious, less frequently autoecious. Androecia on leading shoots, terminal but usually becoming intercalary, not strongly differentiated from vegetative sectors; bracts usually leaf-like, somewhat more concave, lacking a dorsal-basal tooth, in paroecious species notably larger and with the dorsal margin ampliate and frequently incurved; antheridia 1–4 per bract, the body with irregular, non-tiered cells, the stalk usually conspicuously elongated, usually 2-seriate. Gynoecia on leading shoots, bilateral, with 1–3 subfloral innovations (especially when not fertilized), the bracts leaf-like; bracteole absent (except Herzogobryum and Acrolophozia). Perianth usually ± included (except Herzogobryum and Acrolophozia), abbreviated to vestigial (lacking in Gymnomitrion), the perianth usually subtended by a ring- or tube-like Isotachis -type perigynium that sometimes is bulbous ventrally and then forming a marsupium-precursor.
Seta usually rather short, the capsule often barely exserted, of many cell rows (except Marsupella spp. and Cephalomitrion). Capsule spherical, the wall 2-, rarely and locally 3-stratose; outer layer of cells never strongly elongated, with one-phase ontogeny, with all but shortest walls with usually strong, radial (nodular) thickenings that occasionally are coalescent; inner layer of cells with radial thickenings that locally to commonly tangentially extend to form incomplete to complete semiannular bands.
Spores finely granulate, 2–2.5× elaters in diam. Elaters weakly tapered on ends, with 2, rarely 3 or 4 spirals.
A family with some eight genera, as follows:
1) Acrolophozia R.M.Schust., with three species, all Austral;
2) Apomarsupella R.M.Schust. has three species, one (A. africana (Steph.) R.M.Schust.) that occurs in Chile and in the mountains of Central Africa (cf. Váňa, 2003);
3) Gymnomitrion Corda, with 13–15 species (Schuster, 1974a), two occurring in our area, one in Australia, G. incompletum (Gottsche) R.M.Schust., one in Chile, G. concinnatum (Lightf.) Corda, and one present in South Africa, G. laceratum (Steph.) Horik.
4) Herzogobryum Grolle, with five Austral species;
5) Marsupella Dumort., with 40–45 species, including two that occur in our area;
6) Nanomarsupella R.M.Schust., of the northern Andes;
7) Nothogymnomitrion R.M.Schust., monotypic, of New Zealand, Tasmania and southern South America, Falkland Islands, South Georgia, Tristan da Cunha;
8) Prasanthus Lindb. & Arnel l, with only P. suecicus (Gottsche) Lindenb. & Arnell of the high-Arctic regions of the Northern Hemisphere.
Schuster (2002a) removed Stephaniella Jack and Stephaniellidium S.Winkler ex Grolle from the Gymnomitriaceae and placed them in the family Stephaniellaceae (R.M.Schust.) R.M.Schust. Lophonardia R.M.Schust., with only L. caespitosa R.M.Schust., which was included in the Gymnomitriaceae (e.g., Schuster, 2002a), is now considered a synonym of Lophozia laxifolia (Mont.) Grolle (Gradstein et al., 2001, p. 115; Engel and Gradstein, 2003, p. 764). Poeltia Grolle of Nepal was placed as a subgenus of Marsupella by Schuster (1996d, 2002a). Paramomitrion R.M.Schust. of the northern Andes was placed in the Gymnomitriaceae by Schuster (1996d) and Gradstein et al. (2001), but was placed in the Jungermanniaceae subfam. Eremonotoideae by Schuster (2002a) and that placement is followed here.
