Leiomitra Lindb.
Leiomitra Lindb., Acta Soc. Sci. Fennica 10: 515. 1875.
Trichocolea subg. Leiomitra (Lindb.) Spruce, J. Linn. Soc., Bot. 30: 353. 1895.
Basichiton Trevis., Mem. Reale Ist. Lombardo Sci. Lett. III, 4: 394. 1877.
Trichocolea sect. Cryptocaulia Hatcher ex R.M.Schust., Nova Hedwigia 15: 446. 1968.
Trichocolea sect. Cryptocaulia Hatcher, Lloydia 22: 213. 1959, sin. descr. lat.
Type: Leiomitra tomentosa (Sw.) Lindb. (≡Jungermannia tomentosa Sw.)
Plants soft-textured, felt-like, loosely prostrate, pale green to yellowish green to pure green, moderately large. Branching relatively sparing, usually irregular and monopodial and with branches soon similar in vigor to primary axis or (subg. Brachygyna) ± pinnate; branching (ours) all of the Frullania type; Acromastigum -type branches at times sparingly present in subg. Brachygyna. Stem paraphyllia present in some species, smooth in others, lacking differentiation of a cortex, the cortical cells thin-walled. Leaves Trichocolea -like in aspect, appearing as a mass of uniseriate, filamentous, interwoven cilia, the insertion succubous, 4-lobed, but becoming 5–8-lobed with secondary subdivision, the lobes asymmetric, the ventral 2–3 lobes larger than the dorsal, the lobes mostly 2–3-furcate, with each subdivision fringed with opposed, paired, uniseriate, elongated, tapered cilia that are mostly 3–7(8) cells long; disc low, formed of imperfectly rectangular, often ± tiered cells. Surface cilia and disc ± papillose above to striate-papillose proximally. Underleaves deeply bifid, the primary lobes often again bilobed (the underleaf then bisbifid); lobes armed as in leaves. No asexual reproduction.
Dioecious. Androecia terminal but eventually intercalary; bracts few, leaf-like; antheridia 1–2 per bract, the stalk biseriate. Gynoecia terminal on leading shoots (in subg. Brachygyna on short lateral branches), typically with 1–2 subfloral innovations, the innovations long and sterile or short and ♀. Coelocaule usually abbreviated, lacking surface paraphyllia, the bracts and bracteoles of first and second series inserted on the coelocaule, those of innermost series well developed, free (and then a true perianth completely lacking) or fused to form a low, vestigial perianth; calyptra present, free, smooth, globose to ovoid-globose, with unfertilized archegonia at or near the base (true calyptra) or scattered on at least the basal half (shoot-calyptra developed), the distal portion of sporophyte protected by the calyptra + bracts and/or a perianth.
Seta short. Capsule spherical to short-ellipsoidal (the length:width ratio less than 1.2:1), the wall (4)5–6-layered, the outer layer of cells hyaline, large, with small knot-like thickenings or the cells altogether devoid of thickenings; innermost layer of cells with small nodular thickenings, without spurs or semiannular bands.
Spores finely granular or granular asperulate. Elaters bispiral or less often 3-spiral or 2– 3-spiral.
Key to Species
A genus of ca. 12 species. The majority are tropical: Seven occur in the Neotropics (for species treatments see Hatcher, 1958 and Schuster, 2001d), two are Paleotropical, including Leiomitra breviseta (Steph.) R.M.Schust. which ranges from New Guinea to the Solomon Islands and the Philippines (see Piippo, 1984). Two species are present in southern South America, L. elegans (Lehm.) Hässel (also in Juan Fernandez) and L. smaragdina Hässel (see Hässel [2002] and also comments in Engel [1978]). A single species, L. lanata, occurs in New Zealand. Leiomitra julacea was placed in Castanoclobos by Engel and Glenny (2007).
Leiomitra differs from Trichocolea in having a very different branching pattern: irregular, sparing and monopodial, with the branches soon becoming similar in vigor to the main, leading shoot (Fig. 23: 1), but also in a) presence of a low but distinct calyptra (Fig. 23: 2); b) presence of at least a reduced but perceptible perianth (Fig. 23: 2); and c) the spherical capsule (Fig. 23: 4).
References: Hatcher (1958; rev.); Stewart (1978; oil-bodies of Leiomitra lanata); Taylor and Hollensen (1970; ♀ inflorescence of L. lanata); Schuster (2000a, 2001d).
