Auranticordis is a genus of rare tetraflagellate eukaryotic organisms within the phylum Cercozoa. Currently there is only one characterized species within this genus: Auranticordis quadriverberis. Auranticordis cells are heart shaped and can range from 35 - 75 µm long and 25 - 70 µm wide. These cells move in a forward gliding motion, and are predators in interstitial marine sand habitats. Auranticordis cells contain several features that are unique and dissimilar from other cercozoans, such as black bodies, reduced acristate mitochondria (both features that may indicate a preference to a semi-anoxic habitat), putative primary endosymbionts, many orange pigmented extrusomes and the absence of permanently condensed chromosomes.
Etymology
The heart-like cell shape and orange colouration of Auranticordis quadriverberis are the basis for the genus name. The latin words “aurantium” and “cordis” mean “orange” and “heart”, respectively.
Type species
Auranticordis quadriverberis
History
Currently, there is only one defined species with the genus Auranticordis: Auranticordis quadriverberis. It was first discovered and characterized in 2008 by Chantangsi, Esson & Leander [1] while completing a project focused on characterizing cercozoan diversity in British Columbia, Canada, and has since never been further investigated. This is likely due to the fact that Auranticordis quadriverberis is low in abundance and difficult to find, with only 65 cells isolated thus far. Additional species within this genus have not yet been discovered.
Habitat
Auranticordis has only been isolated and characterized from marine sand samples collected at Spanish Banks, British Columbia, a sandy tidal flat located on the southern shore of English Bay, BC. Metabarcoding and environmental sequencing data from a variety of studies (data provided by the Global Biodiversity Information Facility) indicates that Auranticordis may be a cosmopolitan species however no further Auranticordis individuals have been isolated. The current known habitat of Auranticordis, based on the type species, are benthic environments, specifically interstitial marine sand. Evidence of this is both provided by its discovery in marine sand samples, and the presence of muciferous bodies (a type of extrusome) on the external surface of the cell which may aid in allowing Auranticordis cells to adhere to sand by producing a sticky substance. Seasonality of Auranticordis is currently unknown due to limited research available. Auranticordis (Auranticordis quadriverberis) has only been observed and isolated in the months of March and May of 2007.
It is currently unknown whether or not Auranticordis is a purely heterotrophic species, consuming other microorganisms as food, or whether or not it may photosynthesize as well . Auranticordis is likely predatory and feeds on bacteria based on observed ingested bacteria within the cell, however the exact method of feeding is unknown. Predators of Auranticordis are currently unknown and it is likely that Auranticordis plays a minimal role in the food web and nutrient cycling within marine sand environments given the low abundance of this genus.
Description
External morphology
Auranticordis cells are orange in colour and large, with Auranticordis quadriverberis cells observed to be 35 - 75 µm long and 25 - 70 µm wide. Auranticordis cells do not contain a wall, are heart shaped and consist of four lobes. From the anterior to posterior end, these cells are covered in longitudinal ridges supported by microtubules. Auranticordis cells have four hair-covered flagella arranged in pairs that originate from the anterior end of the cell, lay along the ventral groove and emerge at the posterior end of the cell, allowing the cell to glide forwards. This trait is dissimilar from most cercozoans, which are typically biflagellated, with the exception of Cholamonas cyrtodiopsidis, which is another tetraflagellated cercozoan. Cells are consistently observed to be flagellated, with pseudopodia and amoeboid stages not observed. As well, Auranticordis cells are not able to significantly alter their shape.