Life Cycle: "Species of Glypthelmins have life cycles that utilize snails (e.g. Lymnaea) as first intermediate hosts, frogs as second intermediate hosts, and frogs as the definitive hosts (Rankin 1944; Martin 1969). The definitive host acquires the infection by eating the metacercariae which have encysted in the skin" (Gibson et al., 2008).
Description:
Body elongate or cylindrical. Tegument armed with small, serrate, scale-like spines extending from anterior end to varying levels of hindbody. Oral sucker subterminal, larger than ventral sucker. Ventral sucker in anterior or middle third of body. Prepharynx short. Pharynx well developed, sometimes wider than ventral sucker. Median glands around pharynx and oesophagus. Pharygeal glands present or absent. Intestinal bifurcation about halfway between pharynx and ventral sucker. Caeca extend to near posterior end of body, but do not reach it. Testes in hindbody, intercaecal or sometimes overlapping caeca, spherical to oval, entire, usually symmetrical or oblique, occasionally tandem. Cirrus-sac straight or curved, usually extending posteriorly beyond ventral sucker, contains bipartite seminal vesicle and coiled cirrus. Genital pore median, in forebody. Ovary submedian, spherical to oval, entire, sinistral and anterior to testes, sometimes close to or overlapping ventral sucker. Seminal receptacle small, usually situated posterior to ovary. Ootype, Laurer's canal and Mehlis' gland present. Uterus extends to posterior end of body, completely filling postcaecal space; transverse uterine loops usually intercaecal, occasionally overlapping caeca or expanding into extracaecal space; occasionally, uterine loops occupy pretesticular region. Metraterm muscular, approximately as long as cirrus-sac, dorsal to cirrus-sac.Eggs operculate. Vitellarium consists of numerous follicles forming extracaecal fields, sometimes expanding into intercaecal space; anteior margin of vitelline fields at different levels between ovary and pharynx; posteriorly vitelline follicles usually extend beyond posterior margin of testes, but do not reach posterior end of the body; fields confluent or not to intestinal bifurcation, cirrus-sac and testes. Excretory vesicle I-shaped, reaches posterior mergin of testes; pore terminal. Protonephridial formula 2[(3+3+3)+(3+3+3)]=36. In intestine of amphibians; Palaearctic, Oriental, Ethiopian, Nearctic and Neotropical regions.
Sources: Bray, R.A., Gibson D.I., and Jones, A. 2008. Keys to the Trematoda, Vol. 3, p. 357-358.
Rankin Jr., J.S. 1944. A Review of the Trematode Genus Glypthelmins Stafford, 1905, with an Account of the Life Cycle of G. quieta (Stafford, 1900) Stafford, 1905. Transactions of the American Microscopical Society, Vol. 63, No. 1, p. 30-43.
Marin, G.W. 1969. Description and Life Cycle of Glypthelmins hyloreus spp. n. (Digenea: Plagiorchiidae). The Journal of Parasitology, Vol. 55, No. 4, p. 747-752.
