|Subclass:||Rhynchostomatia Jankowski, 1980|
Otto Friedrich Müller, 1773
Dileptus is a genus of unicellular ciliate protists, belonging to the class Litostomatea. Members of the genus are found in fresh and salt water. Like most of the free-living Litostomes, Dileptus is an aggressive predator, carrying an arsenal of toxin-bearing trichocysts (toxicysts) in a prehensile proboscis, with which it stuns its microscopic victims before consuming them. 13 species and subspecies of Dileptus are currently recognized.
Appearance and characteristics
Dileptus cell bodies are elongate, with a well-developed prehensile proboscis at the front end. The cytostome is at the base of this trunk-like organ and is well fortified with stiff microtubular rods (nematodesmata). The surface of the cell is uniformly covered with cilia arranged in longitudinal rows. The body may narrow at the back end, forming something like a tail. Multiple contractile vacuoles lie in a row along the dorsal surface.
History and Classification
Dileptus was first seen and described by O. F. Müller in 1773, who reports having found the creature "in water where duckweed dwells." He describes the organism in detail, recording its sharp posterior and noting the presence of a "long neck" which has a tendency to assume a spiral shape. The species Müller named Vibrio anser is generally understood to be a synonym of the traditional species Dileptus anser (now known as Pseudomonilicaryon anser). In a later work, Animalcula Infusoria, published posthumously in 1786, he repeats the earlier description of the creature and adds several illustrations of it 
Müller named the creature he observed in 1773 Vibrio anser (anser being Latin for "goose"), placing it in a genus of proboscis-bearing protists that included, among other species, the "swan-necked" ciliate Lacrymaria olor.
In 1841, M. Félix Dujardin created the genus Dileptus and moved Müller's Vibrio anser to it. By the time a full revision of the genus was published in 1963, the genus included about 50 species. In their revision of 2012, Peter Vďačný and Wilhelm Foissner restricted the genus Dileptus to dileptids "having more than 50 dispersed macronuclear nodules that divide individually," which left only ten nominal species within the group. Many traditionally recognized members of Dileptus, including the well-known species Dileptus anser, have been moved to other genera, such as Pseudomonilicaryon and Rimaleptus.
Species of Dileptus
- Dileptus anatinus Golińska, 1971
- Dileptus beersi Jones, 1956
- Dileptus costaricanusFoissner, 1995
- Dileptus dubius Vuxanovici, 1959
- Dileptus estuarinus Dragesco, 1960
- Dileptus jonesi Dragesco, 1963
- Dileptus margaritifer (Ehrenberg, 1833)
- Dileptus multinucleatus Vuxanovici, 1959
- Dileptus sphagnicola Vdacny & Foissner, 2011
- Dileptus viridis (Ehrenberg, 1833) Foissner, 1987
- Kudo, Richard (1954). Protozoology. Springfield, Illinois: C.C. Thomas.
- Lynn, Denis. The Ciliated Protozoa: Characterization, Classification and Guide to the Literature. 3rd Edition. Springer, 2008. p. 187 ISBN 978-1-4020-8238-2 e-ISBN 978-1-4020-8239-9
- Miller, Stephen (May 1968). "The Predatory Behavior of Dileptus Anser". Journal of Protozoology 15 (2): 313–19. doi:10.1111/j.1550-7408.1968.tb02128.x.
- Vďačný, Peter; Foissner, Wilhelm (2012). Monograph of the Dileptids (Protista, Ciliophora, Rhynchostomatia). Linz : Land Oberösterreich, Biologiezentrum/Oberösterreichische Landesmuseen. p. 266.
- Vd'ačný, Peter; et al. (June 2011). "Morphological and molecular phylogeny of dileptid and tracheliid ciliates: Resolution at the base of the class Litostomatea (Ciliophora, Rhynchostomatia).". European Journal of Protistology. (Epub ahead of print). doi:10.1016/j.ejop.2011.04.006. PMC 3234341. PMID 21641780.
- Carey, Phillip G., Marine Interstitial Ciliates: An Illustrated Key. Chapman and Hall, 1992, ISBN 978-0-412-40610-2
- Müller. O.F. Vermium Terrestrium et Fluviatilium, seu Animalium Infusoriorum, Helminthecorum, et Testaceorum non Marinorum, succincta Historia. 2 vols. 1773. Copenhagen and Leipzig. p. 46
- Pritchard, Andrew (1861). A History of Infusoria, including the Desmidiaceae and the Diatomoaceae,British and Foreign. 4th Ed.. London: Whittaker. p. 63.
- "Dileptus anser". Systematics of Protozoa. National Institute for Environmental Studies. Tsukuba-City, Japan.
- Müller, O.F. (1786). Animalcula Infusoria, Fluvia Tilia et Marina. Hauniae, Typis N. Mölleri.