Last Updated: June 10, 2026

Scanning electron micrograph (SEM) image of scolex of Echinobothrium sp.; SEM of bothria of Echinobothrium sp.; SEM of bothria of Echinobothrium rhynchobati; SEM of bothria of Echinobothrium sp.; examples of hosts of diphyllideans: Neotrygon kuhlii and Raja sp. (top), Mustelus schmitti (bottom). (Photos courtesy of V. Ivanov)

MORPHOLOGY: Scolex consisting of 2 bothria and a cephalic peduncle with or without spines. Apical rostellum present or absent. Proglottids hermaphroditic and acraspedote. Testes anterior to ovary. Genital pores mid-ventral. Ovary posterior, bilobed in cross section. Vitelline follicles arranged in lateral bands or circumcortically. Uterus sacciform, without a preformed uterine pore.

DIVERSITY: The order currently includes 3 genera and 49 valid species classified into 2 families.

PHYLOGENETIC RELATIONSHIPS: Molecular and morphological data suggest that the diphyllideans are monophyletic and are sister group to the Trypanorhyncha.

DEFINITIVE HOSTS: Parasites of elasmobranchs. Diphyllideans have been found in a number of batoid families (Rajidae, Myliobatidae, Rhinobatidae) and less frequently in a diversity of shark families (Triakidae, Hemiscylliidae and Scyliorhynidae.

SITE IN DEFINITIVE HOST: Spiral intestine.

GEOGRAPHIC DISTRIBUTION: Cosmopolitan (Atlantic, Pacific and Indian Oceans, Mediterranean and Red Seas).

LIFE-CYCLES: No record of a complete diphyllidean life-cycle has been published; however, there exist observations on a number of larval stages (plerocerci) of species of Echinobothrium and Ditrachybothridium, which occur in various organs of marine crustaceans and molluscs.

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Selected References:

Khalil, L. F. 1994. Order Diphyllidea van Beneden in Carus, 1963. pp. 45-49. In Khalil, L. F., Jones, A., Bray, R. A. (Eds.) Key to the cestode parasites of vertebrates. CAB International, Wallingford, U.K. PDF

Caira, J. N., K. Jensen, and C. J. Healy. 1999. On the phylogenetic relationships among the tetraphyllidean, lecanicephalidean, and diphyllidean tapeworm genera. Systematic Parasitology 42: 77-151. PDF

Ivanov, V. A. and E. Hoberg. Preliminary comments on a phylogenetic study of the order Diphyllidea van Benden in Carus, 1863. Systematic Parasitology 42: 21-27. PDF

Tyler, G. A. A monograph on the Diphyllidea (Platyhelminths: Cestodes). Bulletin of the University of Nebraska State Museum 20: 142 pp. PDF

Marques, F. P. L., K. Jensen, and J. N. Caira. 2012. Ahamulina n. gen. (Cestoda: Diphyllidea) from the polkadot catshark, Scyliorhinus besnardi (Carcharhiniformes: Scyliorhinidae), off Brazil. Zootaxa 3352: 51-59. PDF

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