|Family||Gastrothylacidae Stiles et Goldberger, 1910|
|Subfamily||Gastrothylacinae Stiles et Goldberger, 1910|
|Genus||Gastrothylax Poirier, 1883|
|Species||Gastrothylax crumenifer (Creplin, 1947) Poirier, 1883|
|Hosts||Bos indicus, Bubalus bubalis, Ovis aries, Capra hircus|
|Localities||Guwahati, Silchar, Karimganj (Assam); Shillong, Nongstoin, Tura, Jowai (Meghalaya); Aizawl (Mizoram); Agartala (Tripura)|
Body elongated, 10.84-18.39 mm in length, 5.01-7.32 mm in width, ratio of body width to body length 1:1.64-1:3.41. Ventral pouch present, reaching to posterior level of posterior testis. Acetabulum terminal, 1.62-4.52 mm in external diameter; ratio to body length 1:3.64-1:6.69; of gastrothylax type (sensu Näsmark, 1937) in median sagittal section; units of dorsal and ventral circular muscles on lateral sides as follows : d.e.c.m. 56-72, d.i.c.m. 54-60, v.e.c.m. 55-72, v.i.c.m. 58-66. Pharynx 0.54-0.76 mm in length, 0.49-0.76 mm in width; ratio to body length 1:16.71-1:20.77, to diameter of acetabulum 1:3.16-1:6.25, of calicophoron type (sensu Dinnik, 1964) in median sagittal section. Oesophagus 0.45-0.72 mm long. Intestinal caeca long, wavy, reaching up to anterior level of testes. Testes deeply lobed, side by side, between caecal ends and acetabulum; left testis 0.45-2.26 mm in length, 0.40-2.16 mm in width; right testis 0.45-2.16 mm in length, 0.40-1.80 mm in width. Ovary inter-testicular, 0.22-0.45 mm by 0.31-0.45 mm, close to Mehlis' gland. Vitellaria small, follicular, extending from intestinal fork to acetabulum. Terminal genitalium of gracile type (sensu Näsmark, 1937) in median sagittal section, opening into ventral pouch.
Sey (1983) regarded only G. crumenifer Creplin, 1847) Poirier, 1883 and G. compressus Brandes, 1898 as the valid species of the genus Gastrothylax. In view of the variable nature of the characters used for their diagnosis, G. glandiformis Yamaguti, 1939 and G. indicus Dutt, 1978, were regarded as synonyms of G. crumenifer by him. Further G. orientalis, described as a new species by Bambroo (1970) from sheep in Srinagar (Jammu and Kashmir) and also the form reported as G. glandiformis, from the same host and locality by the same author, are identical with G. crumenifer (see Srivastava, 1982). This gastrothylacid species, G. crumenifer has been recorded from ruminant hosts in various localities in India such as Uttar Pradesh (Srivastava, 1946), Madras and Bombay (Gupta and Dutta, 1967b), Jammu and Kashmir (Bali, 1976), Meghalaya (Soota and Ghosh, 1977) and Himachal Pradesh (Tandon and Sharma,1981). However, in Sey's (1983) opinion, the form described by Gupta and Dutta, (1967b) is not G. crumenifer but G. compressus on account of having a smaller number of circular muscle units in the acetabulum and shorter intestinal caeca.