ON THE TAXONOMIC SIGNIFICANCE OF LOBULE CHARACTERS IN THE LEJEUNEACEAE (HEPATICAE)

The taxonomic importance of some lobule characters in the Lejeuneaceae is reviewed and clarified in this paper: (1) The free margin of lobul e is defined as the margin between the stem and the distal end of the keel. The number of the cells along the free margin is variable. This is especially true in the genera with distal hyaline papilla, in which the length of the lobule tooth and the number of the cells in the fre e margin exhibit considerable intraspecific variation. There is no con sistent difference in the number of the cells in the free margin betwe en the genera with a proximal hyaline papilla and those with a distal hyaline papilla. (2) This paper emphasizes the use of ''the first toot h'', ''the second tooth'' etc. from distal to proximal for describing lobule teeth, in order to avoid confusion. In the Ptychanthoideae the free margin bears 1-11 distinct lobule teeth, and the number, form and position of the lobule teeth sometimes provide taxonomic criteria in the separation of both genera and species; in the Lejeuneoideae the fr ee margin has no more than two lobule teeth. Often the first tooth or the second tooth is reduced, or sometimes both lobule teeth are obscur e. (3) Two positions of the hyaline papilla occur in the Lejeuneaceae: hyaline papilla on the free margin, proximal to the first tooth; or h yaline papilla on the inner side of the lobule, near the proximal base of the first tooth. The species of the Lejeuneaceae in which the hyal ine papilla occurs on the inner side of the lobule, usually have more than two lobule teeth; the taxa with 1-2 lobule teeth usually have a m arginal hyaline papilla. Therefore, different positions of the hyaline papilla strongly depend on the appearance of the lobule teeth. The po sition of the hyaline papilla shows less taxonomic importance than the lobule teeth.