NEIHPID

Velasquezotrema tripurensis (Roy et Tandon Roy et Tandon) Back

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Taxonomy

Platyhelminthes »
       TREMATODA »
              Digenea »
                     Gastrothylacidae Stiles et Goldberger, 1910 »
                            Velasquezotrematinae Roy et Tandon, 1990 »
                                   Velasquezotrema Eduardo et Javellana, 1987 »
                                           Velasquezotrema tripurensis, Roy et Tandon 1990

Host

Bos (indicus)

Habitat

Rumen

Locality

Dharmanagar (Tripura)

Description

Body elongated with rounded extremities, slightly bent in ventral direction, 6.78-11.75 mm in length, 2.57-3.61 mm in greatest width at level little behind genital pore; ratio of body width to body length 1:2.14-1:3.96. Acetabulum sub-terminal or ventral, external diameter 0.58-0.858 mm; ratio to body length 1:9.37-1:16.64; of gastrothylax type as described by Näsmark (1937); units of dorsal and ventral circular muscles on lateral sides as follows : d. e. c. m. 37-46, d.i.c.m. 17-22, v.e.c.m. 32-42, v.i.c.m.16-24. Oral aperture with long tegumental papillae. Pharynx 0.31-0.49 mm in length, 0.36-0.45 mm in maximum width; ratio to body length 1:16.66-1:28.88, to diameter of acetabulum 1:1.29-1:2.88; of calicophoron type (sensu Dinnik, 1964) in median sagittal section. Oesophagus 0.18-0.27 mm in length; ratio to body length 1:38-1:62.61; musculature of its wall thickened at its posterior end to form osophageal sphincter, small gland cells extending along sides of pharynx and oesophagus, sometimes accumulating at posterior level of oesophagus. Caeca irregularly bent in dorso-ventral direction, their blind ends directed posteriorly or ventrally terminating at posterior level of ovary. Testes four-lobed , tandem or obliquely tandem, inter-caecal or extended beyond caecal level in lateral direction, located in posterior half of body between posterior limit of ventral pouch and ovary and Mehlis' gland; anterior testis 0.99-1.26 mm in length, 1.17-1.67 mm in width; posterior testis 0.81-1.22 mm in length, 1.17-1.67 mm in width. Vesicula seminalis thin walled; pars prostatica long, pars musculosa moderately developed. Ovary 0.22-0.36 mm by 0.18-0.45 mm post-testicular. Mehlis' gland close to ovary. Laurer' s canal not crossing excretory vesicle or duct, opening dorsally about 0.90-0.99 mm anterior (in sagittal section) to excretory pore. Uterus following median course with straight or sometimes with few loose coils in posterior part. Vitellaria consisting of few loose or small clusters of vitelline glands in lateral fields or encroaching into inter-caecal regions, extending from little behind oesophageal bifurcation to lower level of posterior testis or slightly beyond. Eggs 0.108-0.158 mm by 0.054-0.090 mm. Excretory vesicle between acetabulum and Laurer's canal, opening dorsally. Genital pore ventral, inside ventral pouch at level little behind oesophageal bifurcation; terminal genitalium in middle of thick, muscular, protrusible, circular structure which in extended condition comes out through ventral pouch opening and appears as a distinct circular disc on body surface (in whole mount); in withdrawn condition this muscular disc provides a deep extending ventral atrium, the inner walls of which are provided with ,wide-spaced and dome-shaped papillae (in sagittal section); sphincter papillae weakly developed. This type of terminal genitalium is designated as the tripurensis type (new type).

Ventral pouch narrow, more or less triangular, opening at level just before oesophageal bifurcation and extending posteriorly up to middle of body length, just posterior to anterior testis.

Remarks

Eduardo and Javellana (1987) created the genus Velasquezotrema to accomodate Fischoederius brevisaccus Eduardo, 1981. They assigned it to the subfamily Gastrothylacinae of the family Gastrothylacidae along with other three genera, Gastrothylax Poirer, 1883; Carmyerius Stiles and Goldberger, 1910; and Fischoederius Stiles and Goldberger, 1910; and distinguished it from all of them on account of the limited extent of itsventral pouch which reaches only up to the middle of the body length.Yet, another gastrothylacid paramphistome, Duttiella cephaloporus Srivastava, Prasad and Maurya, 1980, is characterised by a genital sucker which is present in no other genus of the family.

The present species also belongs to the genus Velasquezotrema owing to the presence of a small ventral pouch. However, it differs from the type species in several features: the greatest diameter of its body occurs in the region a little behind the genital opening and not in the middle or posterior half of the body; its oesophagus is provided with an oesophageal sphincter; it possesses a terminal genitalium which is characterised by presemce of papillae in the wall of the protrusible ventral atrium, the presence of a genital sphincter and weak sphincter papillae.Besides, the presence of circular and protrusible disc,which lodges the terminal genitalium, is a feature exclusive to the presnet form. This genital disc is very prominent and appears as mushroom shaped in the live infixed worms. In V. brevisaccus the terminal genitalium is lodge on hemispheical bulge. In the present form acetabular region lacks dome-shaped papillae and fine topography of the latter is also found to be different; the tuberculate apical structures of the papillae in the present form are not described for V. brevisaccus.

In view of these differences from V. brevisaccus, the present form, considered a new species and named after the type locality V. tripurensis.

Specific diagnosis

Oesophageal sphincter present, terminal genitalium tripurensis type, i.e., presence of dome-shaped papillae in the wall of protrusible ventral atrium, sphincter papillae weakly developed.

Helminthological collections record

NEHU/Z - TM/1

Specimen Type

Holotype: IV/300; Paratype: IV/301; Series of T.S: 302; Series of S.S: 303; in Zoological Survey of

References

Eduardo ,S .L. and Javellana (1987).  A new genus, Velasquezotrema, for Fischoederius brevisaccus Eduardo,1981. Philipinne Journal of Veterinary Medicine, 24: 29-34. Endrejat, E. (1964). Helminths and helminthic diseases in Assam. Indian Veterinary Journal. 41:pp 538-542.

Stiles, C. W. and Goldberger, J. (1910). A study of Watsonius (n.g.) watsoni of man and of allied species of mammalian trematode worms of the superfamily Paramphistomidea. Bulletin of the Hygienic Laboratory , Public Health and Marine- Hospital Service of the United States. No.60, pp 259.

Srivastava,C. B., Praad, A and Maurya, A.C. (1980). A new pouch amphistome. Duttiella cephaloporus gen. et sp., Nov (Family: Gastrothylacidae) from buffaloes. Proceedings of National Academy of Science, India, 50(b): 4.