Ignicoccus islandicus, a species of archaea named by Karl Stetter

Ignicoccus islandicus is an archaea species living in marine hydrothermal vents such as those underwater fissures found in the Kolbeinsey Ridge north of Iceland, where this microbe was discovered (hence the epithet islandicus). Ignococci are hyperthermophiles. They are of great interest since they “play” host to even smaller archaea—some of the smallest organisms known: Nanoarchaeum equitans. These nano-sized microbes “sit”as parasites on the surface of ignicocci and also contain copies of parts of their host's genes within their own genome.

The World Register of Marine Species (WoRMS) provides data on the taxonomy of I. islandicus [1]:
Kingdom: Archaea
Phylum: Crenarchaeota
Class: Thermoprotei
Order: Desulfurococcales
Family: Desulfurococcaceae
Genus: Ignococcus
Species: I. islandicus (also in this genus: I. hospitalis, I. pacificus)

Tim Friend describes a presentation by German microbiologist Karl Otto Stetter at a conference in Yellowstone National Park (another hot spot of extremophile discoveries), during which Stetter talked about research on N. equitans, I. islandicus as well as the symbiotic (or parasitic) nanoarchaea-ignicoccus relationship:

Using the two-person research submersible Geo, samples were taken of sandy sediment and vent fluids at temperature around 90 degrees C [at the Kolbeinsey Ridge]. Black smoker samples obtained during a dive made on the submersible Alvin at a vent in in the Pacific also were analyzed. Initially, the samples from the mid-Atlantic ridge [Kolbeinsey Ridge] revealed a new genus and species of archaea, which Stetter named Ignicoccus islandicus. Electron microscopy photos taken at Stetter's lab of an additional Ignicoccus isolate revealed tiny strange spheres attached to its surface. This was shocking. No such thing had been seen on archaea. By culturing the organisms together Stetter was able to isolate Nanoarchaea then look for segments of its RNA. It does not possess the similar ribosomal RNA signature of other archaea. Tim Friend, 2007 [2].

Keywords: microbiology, nanobiology, hyperthermophile, crenarchaeon, nomenclature, taxonomy, history.

References and more to explore
[1] WoRMS taxon details: Ignicoccus islandicus Huber, Burggraf, Mayer, Wyschkony, Rachel & Stetter, 2000:
www.marinespecies.org/aphia.php?p=taxdetails&id=573489.
[2] Tim Friend: The Third Domain. The Untold Story of Archaea and the Future of Biotechnology. Joseph Henry Press, Washington, D.C., 2007; pages 121 to 124.