Metahygrobiella R.M.Schust.
Metahygrobiella R.M.Schust., Bryologist 64: 205. 1961.
Type: Metahygrobiella acuminata (Herzog) R.M.Schust. (≡Hygrobiella acuminata Herzog)
Plants usually soft and flaccid, for the most part pellucid, whitish to locally brownish or purplish in some taxa, the shoots sometimes becoming flagelliform, but geotropic, rhizoidous, flagelliform axes lacking. Stems soft, the cortical cells thin to weakly thick-walled, usually larger than medullary. Rhizoids often sparse, scattered. Branching sparing to common, the branches of the Frullania type in some taxa; ventral-intercalary and/or lateral-intercalary branches present in some taxa. Leaves remote to contiguous, rarely imbricate, transversely to subtransversely oriented, the insertion transverse at least in dorsal sector but at times (Metahygrobiella drucei) distinctly succubous below, the insertion lines extending to stem midline dorsally; leaves concave to concave-conduplicate, the concavity oriented toward shoot apex, bifid to 0.35–0.55; lobes acute to subacuminate, the apices at times filiform. Cells lax, subhyaline, weakly chlorophyllose, thin-walled, trigones absent, the cells large, those above to 40 µm × 70 µm. Oil-bodies lacking or with numerous, hyaline, minute (ca. 1 µm in diam.) oil-droplets. Underleaves absent (at times locally present in M. drucei). Asexual reproduction lacking or (M. mollusca) by 1-celled greenish gemmae at tips of erect shoots.
Dioecious. Androecia terminal but eventually becoming intercalary on elongated, leafy axes, laxly spicate; bracts leaf-like but bases more concave, the lobes erect; antheridia 1(2) per bract, the stalk 2-seriate; bracteoles lacking. Gynoecia on long, leafy axes; bracts and bracteoles bifid, the margins usually entire. Perianth long-tubular, trigonous distally, the mouth crenulate varying to laciniate; perianth (1)2(3)-stratose toward base.
Seta of the 8+4(5) type, the inner cells not much smaller. Capsule short- to long-ellipsoidal, the wall bistratose; outer layer of cells usually tiered, oblong, without obvious two-phase ontogeny: all or nearly all longitudinal walls with sinuous-nodular, confluent thickenings; inner layer of cells with well-developed semiannular bands.
Spores with close papillae and short-vermiculate markings or tuberculate-vermiculate; spore:elater diam. ratio 1.4–1.8:1. Elaters rather rigid, at most only moderately tortuous, bispiral to the tips.
A genus of ca. 10 species, most occurring in tropical sectors of the old world. The genus occurs in New Guinea (three species), Borneo (three species), the Philippines, Amboina, Malaya, southern Japan (Kyushu), the Himalayas (Metahygrobiella albula (Steph.) Grolle) and Hawaii (M. lucens (A.Evans) H.A.Mill.). Two species occur in the south temperate zone: M. tubulata (Hook.f. & Taylor) R.M.Schust. ex J.J.Engel of southern South America and the Falkland Islands (Engel, 1978, 1990a) and M. drucei from our area. Metahygrobiella monoica E.A.Hodgs. of New Zealand was transferred to Lophozia, as Lophozia monoica (E.A.Hodgs.) J.J.Engel.
References: Schuster (1964a, 2002a).
