BELL, NEIL E.* AND ANGELA E. NEWTON. Department of Botany, Natural History Museum, London SW7 5ED, UK. - Preliminary studies of characters associated with pleurocarpy in the Rhizogoniaceae (Bryales).
The Rhizogoniaceae is a predominantly southern hemisphere family of
eubryalean mosses with a centre of diversity in Australasia and a
distribution pattern suggestive of a late mesozoic Gondwanic origin.
Many of the taxa are unusual with respect to characters associated
with the distinction between acrocarpy and pleurocarpy, having been
variously considered acrocarps or pleurocarps due to the occurrence of
lateral perichaetial modules basally or distally on upright, tufted,
determinate shoots. Such observations are consistent with recent
cladistic analyses suggesting that at least some members of the family
may be critical to the understanding of the evolution of pleurocarpy.
As a prelude to a planned combined morphological and molecular
phylogenetic study of the group, a preliminary examination of
morphological characters was undertaken within the context of recent
clarifications and redefinitions of pleurocarpy and acrocarpy. Initial
observations confirm that the family contains both unambiguously
acrocarpous and unambiguously pleurocarpous taxa according to
currently accepted definitions and further suggest that the forms of
pleurocarpy found within the Rhizogoniaceae are associated with sets
of character states that are different from those associated with the
Key words: acrocarpy, morphology, phylogeny, pleurocarpy, Rhizogoniaceae