Aurigamonas solis n. gen., n. sp., a soil-dwelling predator with unusual helioflagellate organisation and belonging to a novel clade within the Cercozoa

A flagellate predator, Aurigamonas solis n. gen., n. sp., with numerous radiating axopodia-like appendages, has been isolated in culture from soils. Despite its heliozoan-like appearance, Aurigamonas is not a sit-and-wait predator but a mobile hunter and its stiff appendages are not microtubule-supported axopodia but elongate haptopodia, each supported by a cylindrical core of microfilaments and bearing at its capitate tip a single extrusome-like body (haptosome). Prey flagellates are trapped on the sticky tips of the haptopodia and a large funnel-shaped pseudopodium then emerges to engulf the prey or suck out part of it for internal digestion. Pseudopodial contact is accompanied by killing, possibly as a result of the injection of spicules by the predator. Cytoplasmic haptosomes appear to induce formation of a haptopodium on making contact with the plasma membrane. Propulsion of the organism along the substratum is effected by beating of a long trailing flagellum, the short and inconspicuous second flagellum lacks motility. Small subunit rDNA sequencing shows that Aurigamonas arose within the Cercozoa. Its closest relatives are Cercobodo agilis and several flagellates currently known only as environmental sequences. This conclusion is supported further by the presence of only a single amino acid insertion in the polyubiquitin sequence of Aurigamonas solis. (c) 2005 Elsevier GmbH. All rights reserved.