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Clistobothrium is a genus of phyllobothriidean tapeworms from the family Phyllobothriidae. Members of this genus parasitize the spiral intestine of mackerel sharks (order Lamniformes), which serve as their definitive hosts.

Adult Clistobothrium specimens have been collected from all five extant members of the family Lamnidae—the great white shark, the shortfin mako, the longfin mako, the porbeagle, and the salmon shark—as well as the only living representative of the family Pseudocarchariidae, the crocodile shark (Pseudocarcharias kamoharai). Clistobothrium larvae, or plerocerci, are transmitted to the intestines of their intended host through the consumption of infected prey: known secondary and/or paraptenic hosts of these tapeworms include marine mammals (esp. dolphins and pinnipeds), squaliform sharks, squid, oarfish, and sockeye salmon. This makes the presence of larval or adult Clistobothrium infection in an organism an invaluable long-term biomarker for those researching their host's predator-prey interactions with other organisms in the marine food web.

The systematics of this genus are an ongoing matter of debate among parasitologists, and are complicated by the difficulty of correctly identifying their larval forms, obtaining host cadavers for necropsies, and the inherent ethical concerns of doing so. , five species are currently recognized as valid by the World Register of Marine Species (WoRMS), but recent molecular phylogenetics support the existence of up to eleven.

Taxonomy
, five species of Clistobothrium have been formally described and recognized by the World Register of Marine Species:
 * Clistobothrium amyae Caira, Hayes & Jensen in Caira, Jensen, Hayes & Ruhnke, 2020
 * Clistobothrium carcharodoni Dailey & Vogelbein, 1990
 * Clistobothrium gabywalterorum Caira, Hayes & Jensen in Caira, Jensen, Hayes & Ruhnke, 2020
 * Clistobothrium montaukense Ruhnke, 1993
 * Clistobothrium tumidum (Linton, 1922) Ruhnke, 1993

Another two species were transferred to Clistobothrium following a phylogenetic review of the genus conducted in 2020, but are not yet recognized by the World Register of Marine Species:
 * Clistobothrium delphini (Bosc, 1802) van Beneden, 1868
 * Clistobothrium grimaldii (Moniez, 1889) Baylis, 1919

Four undescribed species are also known from this genus.
 * Clistobothrium n. sp. 1
 * Clistobothrium n. sp. 2
 * Clistobothrium n. sp. 3
 * Clistobothrium n. sp. 4

Etymology and nomenclatural history
The genus Clistobothrium was first erected in 1990 following the discovery and subsequent description of the type species, Clistobothrium carcharodoni. The genus derives its name from the Greek words clisto (κλειστός), meaning "closed," and bothrios (βόθρος), meaning "pit." Although this was the first Clistobothrium species described as such,

C. amyae, C. gabywalterorum
The definitive host of both Clistobothrium amyae and Clistobothrium gabywalterorum is the crocodile shark (Pseudocarcharias kamoharai).

C. carcharodoni, C. tumidum
The definitive host of both Clistobothrium carcharodoni and Clistobothrium tumidum is the great white shark (Carcharodon carcharias).

C. montaukense
The definitive host of Clistobothrium montaukense is the shortfin mako shark (Isurus oxyrinchus).

The plerocercoid stage has been recorded in giant oarfish (Regalecus glesne), indicating the possibility of a predator-prey relationship between the two species.

Clistobothrium n. sp. 1
The definitive host of Clistobothrium n. sp. 1 (formerly Clistobothrium cf. montaukensis) is the porbeagle shark (Lamna nasus).

The pleocercoid stage is known from three species: the western highfin spurdog (Squalus altipinnis), the longnose velvet dogfish (Centroselachus crepidater), and Russel's oarfish (Regalecus russelii).

Clistobothrium n. sp. 2
The definitive host of Clistobothrium n. sp. 2 is the longfin mako shark (Isurus paucus).

Clistobothrium n. sp. 3
The definitive host of Clistobothrium n. sp. 3 is the salmon shark (Lamna ditropis).

C. delphini, C. grimaldii, and Clistobothrium n. sp. 4
, the definitive hosts of Clistobothrium delphini, Clistobothrium grimaldii, and Clistobothrium n. sp. 4 remain unknown — all three species are known only from their pleocercoid stage.

The possibility of the megalodon having survived to the present-day and being the definitive host of these species has been jokingly posited as an explanation for their lack of adult records.