SEM of scolex of XX; hooks of Taenia hydatigena; hooks of T. polyacantha; mature proglottids of T. hydatigena; gravid proglottid of T. hydatigena. (Photos courtesy of A. Jones)

MORPHOLOGY: Strobila either long with numerous segments, or small with few segments. Scolex with 4 suckers. Rostellum usually present (rarely absent), usually armed with 2 rows (rarely, 1 row) of hooks of characteristic taenioid shape. Hooks in anterior row longer than hooks in posterior row. Testes numerous, in intervascular fields, confluent in mid-line or not. Vas deferens present. Cirrus-sac elongate to pyriform, crosses excretory vessels or not. Genital pores marginal, alternating irregularly. Ovary usually bilobed, median, near posterior margin of segment. Vagina opening posteriorly to cirrus-sac; vaginal sphincter or pad present or absent. Vitellarium compact, posterior to ovary. Uterus typically a longitudinal stem with numerous lateral branches, or branches poorly-developed or absent. Eggs with thick-walled, striated embryophore. Second larval stage a cysticercus, modified cysticercus, or unilocular hydatid cyst or multilocular hydatid cyst producing protoscoleces in brood capsules by asexual proliferation.

DIVERSITY: Two subfamilies (Taeniinae and Echinococcinae), each with a single valid genus. Approximately 50 valid species, however, exact number of valid genera and species is controversial.

PHYLOGENETIC RELATIONSHIPS: The family is monophyletic. Its closest relatives, according to cladistic analysis, are the Metadilepididae and Paruterinidae. Molecular analyses tend to support these relationships.

DEFINITIVE HOSTS: Carnivorous and omnivorous mammals.

SITE IN DEFINITIVE HOST: Intestine.

GEOGRAPHIC DISTRIBUTION: Cosmopolitan.

LIFE-CYCLES: Two-host life-cycle. Larval stages in herbivorous mammals.

Selected References:

Abuladze, K. I. 1964. [Principles of Cestodology. Vol. IV. Taeniata of animals and man and diseases caused by them.] [Ed. K. I. Skrjabin.] Moscow: Izdatelstvo Nauka, 530 pp. [In Russian.] [English translation, 1970, Israel Program for Scientific Translations, iv +549 pp.]

Verster, A. 1969. A taxonomic revision of the genus Taenia Linnaeus, 1758 s. str. Onderstepoort Journal of Veterinary Research 36: 3-58.

Rausch, R. L. 1994. Family Taeniidae Ludwig, 1886. pp. 665-672. In Khalil, L. F., Jones, A., Bray, R. A. (Eds.) Keys to the cestode parasites of vertebrates. CAB International, Wallingford, U.K.

Hoberg, E. P., A. Jones, and R. A. Bray. 1999. Phylogenetic analysis among the families of the Cyclophyllidea (Eucestoda) based on comparative morphology, with new hypotheses for co-evolution in vertebrates. Systematic Parasitology 42: 51-73. PDF

Loos-Frank, B. 2000. An up-date of Verster's (1969) 'Taxonomic revision of the genus Taenia Linnaeus' (Cestoda) in table format. Syst. Parasitol. 45(3): 155-83.