SYSTEMATIC BIOLOGY

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PHYLUM CARPEDIEMONADA

INTRODUCTION TO THE CARPEDIEMONADA

Carpediemonada (kar-pe-de-a-mo-NA-da) comes from three Latin roots that mean seize (carpe); the day (die); and unit (monus).  The phylum was named for the single common genus, Carpediemonas.  This may not describe the taxa (except the reference to the unit, meaning cell); however, Ekebom et al. (1996) must have felt that they had to "seize the day" when they discovered the strange organism.

This strange group was first reported from substrate samples taken in the Great Barrier Reef in 1996 (Ekebom et al. 1996), when its excavate status was recognized.  Unlike other members of this kingdom, the carpediemonads are free-living.  Also, the cell does have a typical excavate feeding groove in which the 3-vaned recurrent flagellum resides. Typical of the other excavates, Carpediemonas does not mitochondria and lives in anoxic organic-rich mud where it feed on bacteria.

A. Differential Interference micrograph of Carpediemonas  showing the flagella and the ventral groove or excavate.

carpediemonas_ifz-mbl.gif (6476 bytes)

B. An illustration of Carpediemonas.

Images taken from:
http://microscope.mbl.edu/baypaul/microscope/images/  

SYNOPTIC DESCRIPTION OF THE CARPIEDIEMONADA

The following description comes from Patterson (1999), Simpson and Patterson (2001) and Cavalier-Smith (2003).

I. SYNONYMS: carpediemonads.

II. NUMBER: 1 or 2 species known.

III. PHYLUM CHARACTERISTICS:

A. Structure and Physiology

Cell Form: Unicellular.

Flagella: Two apical flagella, one anteriorly-directed and the other posteriorly-directed.  The recurrent flagellum has 3 vanes and lies in the excavate feeding groove.

Basal Bodies: Three basal bodies, one of which is barren.  All three elaborate roots, two support the sides of the feeding groove.

Cell Covering: Naked; with excavate feeding groove.

Chloroplasts: Not present.

Food Reserves: Not reported.

Mitochondria: Not present.

Golgi: Present.

Nucleus: Uninucleate.

Centrioles: Not reported.

Inclusions and Ejectile Organelles: Food vacuoles.

B. Mitosis, Meiosis and Life History

Mitosis: Unknown.

Meiosis: Unknown.

Sexual Reproduction and Life History:

Unknown.

C. Ecology: Free-living in anoxic, organically-rich mud; marine.

SYSTEMATICS OF THE CARPEDIEMONADA

This phylum holds uncertain status until its relationships to other excavates can be determined.  It is based on a single (maybe a few) species in the genus, Carpediemonas (Figures A&B).   Ekebom et al. (1996) recognized that although it was an excavate taxon, it was unusual in that it was free-living, had two flagella and three basal bodies.   A resolution to the position of this taxon may do much to resolve the unknown relationships within the Kingdom Euexcavatae.  

HIERARCHICAL CLASSIFICATION OF THE CARPEDIEMONADA

This system is a modification of Cavalier-Smith (2003).

CLASS CARPEDIEMONADEA  

The class has a single order (CARPEDIEMONADIDA) with the characters of the phylum.

Carpediemonas.

This page is maintained by Jack R. Holt.  Last revised 02/14/2008.