Abstract
Lachnaea L. (Thymelaeaceae), a genus established in 1753, is endemic to the Cape Floristic
Region (CFR) of southern Africa. It demonstrates a high level of regional endemism, with
55% of the species endemic to one of the six centres in the CFR. The first detailed
taxonomic account of the genus was published by Meisner in 1840 based on the collections
of Drège. Three sections were recognised, namely Sphaeroclinium Meisn., Conoclinium
Meisn., and Microclinium Meisn., based mainly on the inflorescence structure. The
circumscription of Lachnaea has been extended to include all five species previously placed
in Cryptadenia Meisn. and at present 40 species and two subspecies are recognised. In this
study a detailed species-level phylogenetic tree for Lachnaea was produced using 3 283bp
of plastid DNA and 679bp of nuclear DNA for 38 accessions and various outgroups. The loci
sequenced were trnL intron and trnL-F spacer, rbcL, rps16 intron and the nuclear gene ITS.
Parsimony and Bayesian analyses yielded identical relationships and these are consistant
with morphological data, producing the best-supported phylogenetic assesment currently
available for the genus. Five informal groupings are also described in the study. The start of
the diversification of Lachnaea was estimated at 7.2Mya with a major proliferation around
6Mya. Sympatric speciation in this genus appears to be plausible with patterns suggesting
that altitudinal differences and pollinators have been involved in the speciation process.
Dr. M. van der Bank