Cardiopteridaceae - Circumscription

Circumscription

Prior to the seminal study by Kårehed in 2001, Cardiopteridaceae had consisted of only Cardiopteris. For example, Hermann Sleumer considered it to be monogeneric in his treatment of the family for Die Natürlichen Pflanzenfamilien in 1942. John Hutchinson did likewise in 1973.

In 2001, Icacinaceae was shown to be polyphyletic. It has since been divided into five segregate families: Cardiopteridaceae, Stemonuraceae, Pennantiaceae, Metteniusaceae, and Icacinaceae sensu stricto. Icacinaceae sensu stricto will eventually be divided further.

In the 2001 study of Icacinaceae, Kårehed transferred Citronella, Gonocaryum, and Leptaulus from Icacinaceae to Cardiopteridaceae. He also provisionally placed Metteniusa, Dendrobangia, and Pseudobotrys there as well, until further studies could give some firm indication of their true relationships.

In 2007, a molecular phylogenetic study showed that Metteniusa belongs to a group of asterids known as the lamiids. The order Aquifoliales, which includes Cardiopteridaceae, belongs to another asterid group called campanulids.

The inclusion of Pseudobotrys in Cardiopteridaceae remains doubtful. DNA sequences submitted to GenBank in 2009 indicate that Dendrobangia does not belong in Cardiopteridaceae and is more closely related to genera like Apodytes.

Cardiopteridaceae, sensu Kårehed, is rather diverse in spite of having only six genera. Because of the distinctive structure of Cardiopteris, some authors today, continue to put Cardiopteris in a family by itself. The other five genera are then placed in Leptaulaceae, a family created by Philippe van Tieghem in 1897. The monophyly of Leptaulaceae has never been tested by phylogenetic analysis of DNA sequences.

Read more about this topic:  Cardiopteridaceae

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