A morphological analysis of Syzygium, with a focus on fibre bundles and description of a new subgenus

Syzygium is a large genus (1200–1500 species) of Old World tropical trees, currently divided into five subgenera containing widely different numbers of species. Syzygium subgenus Perikion was defined by the presence of fibre bundles in the hypanthium wall, although until now this feature has not been investigated or images published. Furthermore, discovery of fibre bundles in certain species outside Syzygium subgenus Perikion calls for reassessment of the subgenus. In this paper, a morphological analysis is presented for all species previously associated with Syzygium subgenus Perikion or known to have fibre bundles. Results indicate the need for description of a new subgenus, Syzygium subgenus Oborapi, characterized by a distinctly goblet-shaped calyx, presence of fibre bundles in the hypanthium/mesocarp, prominent black lenticels on the abaxial leaf surface, ascending ovule orientation and species diversity centred on the Sunda Shelf. Fibre bundles are photographed and documented for the first time from a range of species and at different magnifications. A preliminary list of species is presented for Syzygium subgenus Perikion and Syzygium subgenus Oborapi, with recommendations for further investigation.

[1]  K. M. Ngo,et al.  Genomic insights into rapid speciation within the world’s largest tree genus Syzygium , 2022, Nature Communications.

[2]  Bhawna Sobti,et al.  Dietary fiber components, microstructure, and texture of date fruits (Phoenix dactylifera, L.) , 2020, Scientific Reports.

[3]  L. A. Craven.  Studies in Papuasian Syzygium (Myrtaceae): 1. Subgenus Perikion revised , 2019, Blumea - Biodiversity, Evolution and Biogeography of Plants.

[4]  T. Vasconcelos,et al.  A Systematic Overview of the Floral Diversity in Myrteae (Myrtaceae) , 2019, Systematic Botany.

[5]  T. Vasconcelos,et al.  A New Subtribal Classification of Tribe Myrteae (Myrtaceae) , 2019, Systematic Botany.

[6]  P. Sinu,et al.  Ant pollination of Syzygium occidentale, an endemic tree species of tropical rain forests of the Western Ghats, India , 2018, Arthropod-Plant Interactions.

[7]  D. Soltis,et al.  Phylogeny and Evolution of the Angiosperms: Revised and Updated Edition , 2018 .

[8]  S. Oldfield,et al.  GlobalTreeSearch: The first complete global database of tree species and country distributions , 2017 .

[9]  T. Vasconcelos,et al.  Myrteae phylogeny, calibration, biogeography and diversification patterns: Increased understanding in the most species rich tribe of Myrtaceae. , 2017, Molecular phylogenetics and evolution.

[10]  J. Parnell,et al.  A revision of Syzygium Gaertn. (Myrtaceae) in Indochina (Cambodia, Laos and Vietnam) , 2015 .

[11]  J. Diniz‐Filho,et al.  Clade-specific responses regulate phenological patterns in Neotropical Myrtaceae , 2015 .

[12]  Evgeny M. Zdobnov,et al.  BUSCO: assessing genome assembly and annotation completeness with single-copy orthologs , 2015, Bioinform..

[13]  Tandy J. Warnow,et al.  ASTRAL-II: coalescent-based species tree estimation with many hundreds of taxa and thousands of genes , 2015, Bioinform..

[14]  Alexandros Stamatakis,et al.  RAxML version 8: a tool for phylogenetic analysis and post-analysis of large phylogenies , 2014, Bioinform..

[15]  R. Hall.  Biotic Evolution and Environmental Change in Southeast Asia: Sundaland and Wallacea , 2012 .

[16]  P. S. Ashton.  Myrtaceae , 2022, Tree Flora of Sabah and Sarawak.

[17]  J. Parnell,et al.  Comparative leaf anatomy and phylogeny of Syzygium Gaertn. , 2011, Plant Systematics and Evolution.

[18]  E. Biffin,et al.  An infrageneric classification of Syzygium (Myrtaceae) , 2010 .

[19]  C. Labandeira,et al.  Pollination drops, pollen, and insect pollination of Mesozoic gymnosperms , 2007 .

[20]  P. Gadek,et al.  Molecular systematics of Syzygium and allied genera (Myrtaceae): evidence from the chloroplast genome , 2006 .

[21]  Christopher J. Quinn,et al.  Relationships within Myrtaceae sensu lato based on a matK phylogeny , 2005, Plant Systematics and Evolution.

[22]  D. Frodin.  History and Concepts of Big Plant Genera , 2004 .

[23]  M. Harrington,et al.  Molecular systematics of the Acmena alliance (Myrtaceae): phylogenetic analyses and evolutionary implications with reference to Australian taxa , 2004 .

[24]  B. Hyland.  A Revision of Syzygium and Allied Genera (Myrtaceae) in Australia , 1983, Australian Journal of Botany.

[25]  R. Schmid.  A RESOLUTION OF THE EUGENIA-SYZYGIUM CONTROVERSY (MYRTACEAE) , 1972 .

[26]  M. Henderson.  The genus Eugenia (Myrtaceae) in Malaya. , 1949 .

[27]  F.A.W. Miquel.  Flora van Nederlandsch Indië /door F. A. W. Miquel. , 1855 .