Blepharoplast Morphology in Treubia tasmanica (Hepaticae: Treubiales)

Abstract

Detailed ultrastructural analysis and diagrammatic representation of the blepharoplast in Treubia tasmanica reveal a morphology strongly resembling that reported for Haplomitrium. The major distinguishing features common to both include: 1) A very wide spline (with up to 104 microtubules, Treubia's spline is the widest reported for any bryophyte); 2) a spline aperture of the open type; 3) the aperture located on the left side of the spline midline; 4) the anterior basal body located on the left of the spline midline; 5) the left-divergent orientation of the anterior basal body; and 6) nearly total overlap between the anterior and posterior basal bodies. These same six characters exhibit sharply contrasting expressions in the three metzgerialian representatives similarly analyzed. The evidence presentedfor Treubiafurther supports the isolated position of the group and its elevation to ordinal rank. It also reveals an important affinity with the calobryalian line. The Treubiaceae is a small family of liverworts consisting of only two extant genera: Treubia with seven species (Schuster & Scott 1969) and Apotreu- bia with two (Schuster 1984). The initial description of the generic type, Treubia insignis Goebel (1891), and subsequent morphological studies, e.g., those by Campbell (1916), Griin (1914), Schuster and Scott (1969), and Wijk (1928), have shown the members of the Treubiaceae to be anacrogynous while having an intermediate position between the thallose and foliose conditions. Further, this unusual family has long been viewed as having an isolated position in the Metzgeriales; however, the interpretations of its affinities within that order have been largely con- jectural (for examples see the taxonomic mono-