Scolex with 4 bothridia borne on stalks; bothridia of most with marginal and/or facial loculi, arrangement of loculi variable; myzorhynchus present or absent. Vas deferens joining cirrus at anterior margin, rather than proximal end, of cirrus sac; post-poral testes usually lacking. Vagina opening anterior to cirrus sac; ovary bi- or tetra-lobed; vitellarium follicular; follicles arranged in 2 lateral fields, occasionally encroaching on median line of proglottid. Worms generally small, most species range in length from 3 mm to 3 cm.
Currently, 13 valid genera are assigned to the order.
The order was recently established to house a subset of genera formerly assigned to the Order Tetraphyllidea, following a molecular phylogenetic analysis which showed the tetraphyllideans bearing stalked bothridia to comprise a distinct clade from those mostly lacking stalks. Interrelationships among genera remain to be formally determined.
The rhinebothrideans parasitize elasmobranchs (sharks and rays) as adults; most species are known from batoids (i.e., stingrays, eaglerays, skates, guitarfish, etc.).
Spiral intestine.
Cosmopolitan, with greatest diversity in tropical and subtropical regions, but some genera (e.g., Echeneibothrium and Pseudanthobothrium) more common in cooler waters. Mostly marine; some species infecting freshwater stingrays of South America and Borneo.
Likely a three host life-cycle but no complete life-cycle is known. Eggs develop in utero or in water, and hatch liberating a hexacanth that is eaten by a crustacean, likely a copepod; the hexacanth penetrates into haemocoel where it develops into a procercoid. Consumption of the procercoid in the copepod by the second intermediate host, likely a bivalve mollusk or teleost, leads to development of the plerocercoid which usually bears an apical sucker and 4 retractable acetabula that may be facially loculated, or exceptionally (Rhodobothrium) consists of a bladder containing a distal pedunculated swelling and a scolex.
Selected References:
Euzet, L. 1994. Order Tetraphyllidea. Pp. 149–194. In Khalil, L. F., Jones, A., bray, R. A. (Eds.) Keys to the cestode parasites of vertebrates. CAB International, Wallingford, U.K. PDF
Healy, C. J. 2006. A revision of selected Tetraphyllidea (Cestoda): Caulobothrium, Rhabdotobothrium, Rhinebothrium, Scalithrium, and Spongiobothrium. Ph.D. Dissertation. University of Connecticut.
Healy, C. J., J. N. Caira, K. Jensen, B. L. Webster, and D. T. J. Littlewood. 2009. Proposal for a new tapeworm order, Rhinebothriidea. International Journal for Parasitology 39: 497–511. PDF
Ruhnke, T. R. 2010. A monograph on the Phyllobothriidae (Platyhelminthes: Cestoda). Bulletin of the Nebraska State Museum. 25: 205 pp. PDF
Taxon Coordinator:
Dr. Florian Reyda
State University of New York
College at Oneonta
Department of Biology
108 Science I
Oneonta, NY 13820-4015
PHONE: 1-607-436-3719
E-MAIL: florian.reyda@oneonta.edu
Dr. Claire Healy
Royal Ontario Museum
Department of Natural History
100 Queen's Park
Toronto, ON M5S 2C6
CANADA
PHONE: 1-416-586-8063
E-MAIL: claireh@rom.on.ca
