Matoniaceae: Ferns with a Heritage

Ferns are one of those groups of organisms, like sharks and cockroaches, that are not really as ancient as most people imagine. For all that ferns are indelibly associated in the public conscience with antediluvian imagery of steamy coal swamps and great lumbering reptiles, the dominant fern groups that can be seen today did not arise until the Cretaceous and diversified as part of a flora that would have been largely modern in appearance (Schneider et al. 2004). Nevertheless, there are some fern lineages around today that might be said to have a genuine claim to a more venerable pedigree. One such group is the Matoniaceae.

Matonia pectinata, copyright Ahmad Fuad Morad.

In the modern flora, the Matoniaceae are a small family, including only three or four species in two genera, Matonia and Phanerosorus, found in south-east Asia (Lindsay et al. 2003). The two genera are distinct in appearance and habits. Matonia is found on more or less exposed montane summits and ridges and has pedate fronds with pectinate pinnae radiating from an erect central stipe that may grow well over a metre in height. Phanerosorus is found on vertical limestone walls and has pendulous, branching fronds whose pinnae are simple or more weakly pectinate (Kato & Setoguchi 1999). Both genera have the fronds arising from a long, hairy, creeping rhizome. Lateral veins in the pinnules show one or more bifurcations and in Matonia these branching forks may anastomose with each other to form a reticulate vein pattern. The genera also share features of the reproductive anatomy such as massive, deciduous sporangia.

Phanerosorus major, copyright Wally Suarez.

The fossil record of Matoniaceae indicates that they were far more widespread in the past; indeed, Matonia was illustrated from preserved compression fossils before it was described as a living genus (Klavins et al. 2004). Leaf fossils of Matoniaceae go back to the Late Triassic, and the Middle Triassic stem taxon Soloropteris rupex has been more tentatively assigned to the family (van Konijnenburg-van Cittert 1993). Fossil forms are more similar to Matonia in overall appearance and this is presumed to be the plesiomorphic morphology for the family. A certain resemblance exists between Phanerosorus and younger fronds of Matonia and it seems likely that the former genus evolved from Matonia-like forms by a process of paedomorphosis (Kato & Setoguchi 1998). The family was most widespread during the Jurassic and Early Cretaceous but became extinct in temperate regions of the Northern Hemisphere during the Late Cretaceous. It persisted longer in the Southern Hemisphere, with the stem taxon Heweria kempii known from the Early Tertiary of Australia, but at some point following that it became restricted to its modern localised range.

REFERENCES

Kato, M., & H. Setoguchi. 1999. An rbcL-based phylogeny and heteroblastic leaf morphology of Matoniaceae. Systematic Botany 23 (4): 391–400.

Klavins, S. D., T. N. Taylor & E. L. Taylor. 2004. Matoniaceous ferns (Gleicheniales) from the Middle Triassic of Antactica. Journal of Paleontology 78 (1): 211-217.

Konijnenburg-van Cittert, J. H. A. van. 1993. A review of the Matoniaceae based on in situ spores. Review of Palaeobotany and Palynology 78: 235–267.

Lindsay, S., S. Suddee, D. J. Middleton & R. Pooma. 2003. Matoniaceae (Pteridophyta)—a new family record for Thailand. Thai Forestry Bulletin 31: 47–52.

Schneider, H., E. Schuettpelz, K. M. Pryer, R. Cranfill, S. Magallón & R. Lupia. 2004. Ferns diversified in the shadow of angiosperms. Nature 428: 553–557.