LA FARGE, CATHERINE. Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9. - The Circumscription of the Dicranaceae (Bryopsida), with special emphasis on the subfamily Dicranoideae Based on cp DNA: trnL and rps4.
Chloroplast DNA regions ( trnL(UAA) – trnF (GAA)) are used to explore
the systematic relationships of families and subfamilies within the
Dicranales. Special emphasis is given to subfamily Dicranoideae of the
Dicranaceae, with 17 of the 23 genera represented. 77 taxa are
sequenced for trnL - trnF and 69 for rps4, 1247 characters were
aligned in the final matrix, of which 1000 characters were used for
the analyses. The combined data set was analyzed using maximum
parsimony (MP) and maximum likelihood (ML) to examine the generic and
familial relationships within the order. Bootstrap values and decay
indices show that the data support the following relationships within
the Dicranales: 1) the Dicranaceae are polyphyletic, 2) the
subfamilies Paraleucobryoideae and Dicranoideae are polyphyletic, 3)
the Rhabdoweisiaceae (cf Vitt 1984) are expanded to include members of
the Dicranaceae, 4) the subfamily Campylopodioideae has a firm sister
relationship to the Leucobryaceae, 5) the Dicranelloideae (represented
by a single species) is excluded from the Dicranaceae sensu stricto,
6) the Dicnemonaceae form a monophyletic clade, including Mesotus
(subfamily Mesotoideae, cf Allen 1987) that are nested within the
Dicranaceae, 6) the Fissidentaceae are nested within the Dicranaceae
rather than forming independent lineages, 7) the Ditrichaceae are
polyphyletic. The data strongly suggest the need for a reevaluation
and circumscription of the Dicranaceae. Within the Dicranaceae sensu
stricto there are 4 major clades: 1) Leucoloma - Sclerodontium as the
basal clade, 2) Dicranoloma – Braunfelsia – Cryptodicranum -
Holodontium, 3) Chorisodontium – Orthodicranum – Paraleucobryum –
Dicranum - Eucamptodontopsis –Schliephackea - Holomitrium, and 4)
Dicnemon,- Eucamptodon- Mesotus clade. Excluded from the Dicranaceae
sensu stricto are Arctoa, Brothera, Campylopus, Cynodontium,
Dicranella, Dicranodontium, Dicranoweisia, Hydrodicranum, Kiaeria,
Kingiobryum, Oncophorus, Oreas, Symblepharis, and Trichodontium.
Key words: cpDNA, Dicranaceae, Dicranoideae, molecular data, phylogenetics