Studies on Jungermanniidae. IV. On Scapaniaceae, Blepharidophyllaceae and Delavayellaceae

Until recent decennia, Delavayella Steph. and Blepharidophyllum Angstr, wer e assigned to the Scapaniaceae. Although the former had been treated as for ming a separate family, Delavayellaceae: more recently it has been again re garded as a member of the Scapaniaceae. Blepharidophyllum, regarded as repr esenting a subfamily of Scapaniaceae, is now regarded as belonging to an au tonomous family, Blepharidophyllaceae. The three groups chiefly agree in su perficial criteria: all have vertically oriented leaves, canaliculate or co nduplicate; all tend to develop dentition/ciliation of leaf margins; all ha ve frontally compressed perianths. Analysis of a suite of more fundamental criteria shows that the Delavayellaceae are quite isolated and lack obvious phylogenetic 'moorings'. Blepharidophyllaceae may show some remote affinit ies to Scapaniaceae but the latter are more allied to Jungermanniaceae subf . Lophozioideae (Lophoziaceae) than to Blepharidophyllaceae. Phylogenetic i mplications are discussed. Criteria of phylogenetic relevance in ordering these three families include : (1) Rhizoid dispersion. Thus Scapaniaceae, with scattered rhizoids, appea r to derive from lophozioid ancestors (Jungermanniaceae) versus the bundled rhinoids of Blepharidophyllaceae - a type of rhizoid dispersion not seen i n 'true' Jungermanniaceae. (2) Type of asexual reproduction. Thus Delavayel laceae, with solitary, parenchymatous, pluricellular gemmae, are wholly iso lated from Scapaniaceae and Blepharidophyllaceae, in which catenate, 1-2-ce lled gemmae, found in branched chains, occur. (3) Leaf symmetry. Thus Delav ayellaceae have bilobed leaves with dorsal lobes larger than ventral versus bilobed leaves with somewhat to clearly smaller dorsal lobes in Scapaniace ae + Blepharidophyllaceae. (4) Leaf lobing. In Blepharidophyllaceae leaves are? aside from some derivative taxa, bisbifid; in Scapaniaceae + Belavayel laceae they are simply bifid. (5) Shoot apex orientation. (6) Mycorrhizal r elationships. The three families seem joined in one basic criterion: all taxa are strongl y bilateral, lacking any trace of appendages (underleaves, bracteoles) from vegetative as well as gametangial regions. In this regard Scapaniaceae are dearly distinct from Lophozioideae, in which gynoecia, aside from in some derivative tar;a, preserve large to small bracteoles, even when vegetative regions lack underleaves.