Myriocoleopsis
Epiphytic or lithophytic (not in Victoria), autoicous. Asexual reproduction by discoid gemmae produced on leaf surface. Stems irregularly branched, with creeping leafless primary stems and ascending to erect secondary stems with leaves (not in Victoria), or stems not differentiated and all creeping; branches emerging from main stem near and ventral to an unmodified lateral leaf, and with a lobed and foliose collar at base. Leaves distant to contiguous, widely spreading, sometimes rising away from substrate, narrowly attached to stem; lobe ovate or obovate (not in Victoria), entire to crenulate by projecting cells, with a rounded apex; lobule smaller than lobe, sometimes not developing (not in Victoria), reduced to a linear flat or slightly recurved fold along the basal margin of leaf, or well-developed, ovate in outline, inflated, fused along basal margin to lobe forming an arching keel continuous with curve of adjoining lobe margin, free along apical margin with 2 marginal teeth; tooth furthest from stem 2 cells long, with hyaline papilla at base on inner surface of lobule; tooth closest to stem unicellular; cells hexagonal, mammillose, thin-walled, with small trigones (not in Victoria) or without trigones, without intermediate thickenings, with 2–numerous spherical to ellipsoid, smooth or coarsely granular oil bodies. Underleaves absent. Perianth pyriform, 5-keeled, with a short beak at apex, without tubercles or teeth.
Four species, two from tropical South America, one from Vietnam and the fourth, M. minutissimum (Sm.) R.L.Zhu, Y.Yu & Pócs, widespread throughout tropical to temperate regions, including Victoria (Yu et al. 2013, 2014).
The Victorian species, M. minutissimum, was previously included in Cololejeunea but was transferred to Myriocoleopsis because in phylogenies of chloroplast and nuclear DNA it was placed in a lineage formed by the three species traditionally placed in this genus (Yu et al. 2013, 2014). Myriocoleopsis minutissimum is unique among Myriocoleopsis in not having leafless primary creeping stems that give rise to leafy secondary stems that are erect from the substrate. This morphology is a response to a frequently submerged habitat on rocks in fast flowing streams, a habitat that M. minutissimum does not occur in (Reiner-Drehwald & Gradstein 1995). However, Myriocoleopsis minutissimum does share similar stem anatomy, lobe and lobule form, and an inflated 5-keeled perianth, which lead Reiner-Drehwald & Gradstein (1995) to suspect its close relatedness before DNA sequences became available.
Reiner-Drehwald, M.E. & Gradstein, S.R. (1995). Myricoleopsis riparia (Lejeuneaceae), a new species from south-eastern Brazil and north-eastern Argentina. Journal of Bryology 18: 479–484.
Yu, Y., Pócs, T., Schäfer-Verwimp, A., Heinrichs, J., Zhu, R.-L. & Schneider, H. (2013). Evidence for rampant homoplasy in the phylogeny of the epiphyllous liverwort genus Cololejeunea. Systematic Botany 38: 553–563.
Yu, Y., Pócs, T. & Zhu, R.-L. (2014). Notes on Early Land Plants Today. 62. A synopsis of Myriocoleopsis (Lejeuneaceae, Marchantiophyta) with special reference to transfer of Cololejeunea minutissima to Myriocoleopsis. Phytotaxa 183: 293–297.