The Chromosomes of Two Species of Treubia Goebel, with a Note on the Morphology of Leaf-like Organs

Abstract

Treubia tasmanica Schust. & Scott and Treubia lacunosa (Col.) Prosk. have gametic complements of 9 chromosomes, each complement including two trabanted nucleolar chromosomes of similar size and morphology. Their complements differ from those of other families of liverworts but are most similar to those of certain thallose Metzgeriales. Observations on etiolated plants and early stages of the development of leaf-like appendages of T. tasmanica accord with the view that dorsal scales and lateral leaves are two distinct and separate types of organ. In their study of the Treubiaceae, Schuster and Scott (1969) described and discussed the morphology of Treubia Goebel and critically reviewed previous inter- pretations of its characteristic features and possible affinities. They confirmed Schuster's (1968) creation of the Treubiineae as a suborder of the Metzgeriales and emphasized the isolation of the family. Seven species were described, one of them (T. insignis Goebel) with four subspecies. With regard to the chromosome complements of Treubia spp., Schuster and Scott mentioned Griin's (1914) record of n 8 for T. insignis, which they regarded as probably invalid, and cited a personal communication from Jane Taylor giving n = 9 for T. lacunosa (Col.) Prosk. In addition to the records cited by Schuster and Scott, Lorbeer (1934) found n = 9 in female plants of T. insignis from Borneo and stated that none of the chromosomes was heterochromatic and that there was no micro- chromosome. All of these records are to some extent incomplete and none of them is illustrated.