Evolutionary relationships in Syzygium and allies (Myrtaceae), with particular emphasis on Fijian and New Caledonian species groups

A project undertaken at The Centre for Plant Biodiversity Research, CSIRO Plant Industry, Canberra, and supervised by L Craven

Syzygium together with its allies is the largest group of rainforest Myrtaceae in the southwest Pacific and is there represented by about 400 species.

Within this group, there are significant issues to be resolved as to generic circumscription and acceptance.  Doubts exist as to the validity of at least some of Syzygium’s presently recognised close relatives such as Acmena, Acmenosperma, Cleistocalyx, Piliocalyx and Waterhousea.  The issues were reviewed by Craven (2001) who argued for recognition of a single genus, i.e. Syzygium.

The present project was aimed at collecting material of species of Syzygium, Cleistocalyx and Piliocalyx in Fiji and New Caledonia for molecular sequence and morphological studies.  Significant diversity exists in the complex in Fiji and New Caledonia as evidenced by the large number of genera (such as Acicalyptus, Caryophyllus, Cleistocalyx, Cupheanthus, Jambosa, Pareugenia, Piliocalyx, Syzygium) recognised in these islands by previous botanists.  It is important that this diversity be re-assessed and a broader project is currently underway in Canberra to develop an inferred phylogeny and revised classification of the Syzygium group of genera.  The PBF-funded project was field oriented, the subsequent laboratory and phylogenetic analyses not being an integral part of the work.

Two weeks fieldwork in Viti Levu, Fiji, were undertaken by Ed Biffin and Lyn Craven in April-May 2003.  Sixty-six collections of Syzygium, Cleistocalyx and Piliocalyx were made, of which 60 were accompanied by tissues collected for DNA analysis.  Of the 41 species of the generic complex recorded for Fiji, about 30 were sampled.  The New Caledonian fieldwork was conducted over three weeks in June-July 2003.  Approximately 90 species of the generic complex occur in New Caledonia and about 30 of these were collected during the fieldwork.  Sixty-one collections of Syzygium, Cleistocalyx and Piliocalyx were made, nearly all of which were also sampled for DNA analysis.  Based upon the diverse morphology of the species collected, it appears that a substantial representation of the group’s diversity on the island was obtained thus ensuring that the phylogenetic studies will be based upon a broad sampling.

Local scientists were involved in the project as far as possible.  It is planned that staff of the Fijian plant biodiversity unit in Suva, the South Pacific Regional Herbarium, will be collaborating in some of the taxonomic outputs from the project.

Reference

Craven, L.A. (2001) - Unravelling knots or plaiting rope:  What are the major taxonomic strands in Syzygium sens. lat. (Myrtaceae) and what should be done with them? pp. 75-85. In ‘Taxonomy: the cornerstone of biodiversity. Proc. Fourth Fl. Mal. Symp. (Eds Saw, L.G., Chua, L.S.L. and Khoo, K.C.) (Inst. Pen. Perhutanan Malaysia: Kuala Lumpur)

Piliocalyx francii, New Caledonia

Syzygium amplifolium and Isaac Rounds, Fiji

Syzygium elegans, New Caledonia

Syzygium kuebiniense, New Caledonia

Syzygium macranthum, New Caledonia

Syzygium multipetalum, New Caledonia