Abstract: A new genus and species of camallanid nematode Spirocotyle otolithi is described here from the fish Otolithus rubber (Schneider) of Karachi coast. This is a medium sized nematode, pointed to its posterior extremity in male and blunt in female, with a buccal capsule oval in shape in both the sexes and having a sucker like structure in its anterior extremity. The wall of the buccal capsule is provided with fifteen spiral thicknings. Two unequal spicules are present in male. Ten pairs of caudal papillae are present, including five pairs preanal, four pairs postanal and one adanal. Valva in female is prominent, post equatorial.
INTRODUCTION
Nematodes are found in all the body parts of fish either as larvae or adults. The organs commonly infected are intestine, liver and body cavity. While other organs involved are heart, kidney, spleen, reproductive organs, eyes and gills. Nematode parasites specially the larvae may cause blockage of organs. This is caused when the worms are in a great quantity. If these are present in the capillaries of gills, they block or obstruct the capillaries, fish become unable to respire and die.
Glandular secretion and parasitic metabaolites may be toxic for the fish resulting in weight losses, illgrowth and inhibition of fertilization in hosts. Parasites produce proteolytic enzymes which are so strong that liquefy the effective muscles.
Among helminth parasites one of the greatly and deadly harmful are nematodes. these have direct or indirect effect on fish. A strong invasion of gut nematodes may destroy the intestine partially or wholly, as a consequence, the intestine stiffens, its peristaltic movements slow down and digestion is hampered. In some fishes blindness is also caused by certain nematode larvae. Nematodes are one of the common parasites of fishes of Karachi coast (Rasheed, 1963; 1965a, b; 1966, 1968, 1970; Bilqees et al., 1971; Akram, 1975; Ashraf et al., 1977; Bilqees, 1979; Bilqees and Fatima, 1980a, b; Bilqees and Akram, 1982; Bilqees et al., 2005; Akhtar and Bilqees, 2006).
There are also several reports on Camallanid nematodes (Khan and Yaseen, 1969; Rasheed, 1970; Bilqees et al., 1971; Khan and Begum, 1971; Rehana and Bilqees, 1973a,b; Akram, 1975; Zaidi and Khan, 1975; Ashraf et al., 1977).
Camallanid nematodes are also common in other parts of the world (Agarwal, 1930, Kulkarmi, 1935, Chakravarty, 1939, 1942; Annereaux, 1946; Karve, 1952; Kulasiri and Franando, 1956; Yeh, 1957; Agarwal, 1958; Chakravarty and Majumdar, 1959, 1960; Chakravarty et al., 1961; Yamaguti, 1961; Pande et al., 1963; Majumdar, 1965; Lal, 1965; Sinha and Sahay, 1965; Agarwal, 1966; Sahay and Narayan, 1966; Sahay, 1967; Verma and Verma, 1971; Majumdar and Datta, 1972; Bashirullah, 1973a,b; Gupta and Duggal, 1973; Bashirullah and Hafizuddin, 1974; Gupta and Srivastava, 1975; Bashirullah and Ahmed, 1976a,b ; Gupta and Garg, 1976, 1977; Kalyankar and Palladwar, 1977; Petter, 1978; Gupta and Gupta, 1979, 1980; Arya, 1980; Dhar and Fotedar, 1980; Soota, 1983; Morvec et al., 2003, 2004).
The genus Spirocamallanus of family Camallanidae Railliet and Henry (1915) and sub family Camallaninae Yeh (1957) has spiral thinkings in the buccal capsule. Similar nematodes were recovered during the present studies and these are distinctly different in having a small sucker like structure in the anterior region of buccal capsule in addition to other differences in the diagnostic features. Therefore, a new genus Spirocotyle is proposed referring the sucker-like structure in the buccal capsule. Species name S. otolithi refers to the fish host.
MATERIALS AND METHODS
The fish Otolithus rubber were collected from West wharf Karachi. A total of thirteen fishes were examined and one was found infected with nematodes. Nematodes were fixed and cleared in a mixture of equal amount of 70% alcohol and glycerine for a detail study, diagrams were made with the help of a camera lucida, measurements are given length by width in millimeters.
Spirocotyle otolithi n.g.n.sp. (fig. 1-4)
Type Host: Otolithus rubber (Sciaenidae)
Type Locality: Fish harbour, Karachi coast.
Location: Intestine
Fish examined: 13 host examined, one infected with, one one female and male
Cat. No. Holotype male JUW. N.20; Allotype female JUW.N. 21
DESCRIPTION
| Order: | Spiruidea (Diesing, 1861) |
| Family: | Camallanidae (Railliet and Henry, 1915) |
| Sub family: | Camallaninae (Yeh, 1957) |
| Genus: | Spirocotyle n. gen. |
These are moderate sized worms, male is smaller than female. The body of the worms tapers gradually at its anterior and posterior extremity which is curved ventrally. The cuticle of the body is striated through out its length. The buccal capsule is oval in shape in both the sexes, with simple well-developed basal ring. Inner surface of the whole capsule provided with 15 spiral thickenings. A prominent sucker is present at the anterior region of buccal capsule. Muscular oesophagus is shorter and narrower than glandular oesophagus. Excretory vesicle is prominent. The tail is pointed in male and blunt in female.
Male: Length of body 10.4, maximum width 0.34. The wall of the buccal capsule is provided with 15 spiral thickenings, 0.11 in length and 0.09 in its maximum width at its glandular oesophagus region. A prominent sucker is present at the anterior region of buccal capsule. The nerve ring is 0.048 from anterior extremity. Oesophagus is divided into anterior muscular portion and posterior club shaped curved glandular portion. The anterior muscular portion measures 0.65 in length and 0.15 in width, while the glandular portion is much wider and measures 0.98 in its length and 0.28 at its maximum width. the nerve ring, 0.3 in length and 0.11 in its width. The spicules similar in shape, unequal in length, large spicules is 0.71 long and small spicule is 0.34 long. Twelve pairs of caudal papillae are present, including seven pairs preanal, five pairs postanal. The tail is conical, 0.05 long with pointed end.
| Fig. 1: | Anterior end of male, holotype |
| Fig. 2: | Posterior end of male, holotype |
Female: Length of body 14.8, maximum width 0.6. The mouth leads into a buccal capsule which is similar in structure to that of male specimen and having a prominent sucker. It measures 0.11 in length and 0.1 in its width. The oesophagus is similar to that of male specimen except in size. The anterior muscular part is 0.45 in length and 0.26 at its maximum breadth. The longer posterior glandular part measures 1.18 in length and 0.43 in its maximum breadth.
| Fig. 3: | Anterior end of female Allotype |
| Fig. 4: | Posterior end of female Allotype |
The nerve ring is 0.27 from its anterior extremity. The tail is straight and oval with three prominent cuticular projections measuring about 0.1, 0.5, 0.8 from one groove to other. A pear shaped excretory vesicle is present, 0.02 in length. The valva, subterminal, 0.17 from posterior extremity.
DISCUSSION
The genus under study resembles in the buccal with Spirocamallanus but there are morphological differences like, a prominent sucker in buccal capsule in both male and female, size of the body, size of the oesophagus, in number of spiral thickenings and size of spicules in male specimen and pear shaped excretory vesicle in female specimen, three cuticular projections at posterior end of female specimen. therefore it is desirable to propose a new genus Spirocotyle. The genus name Spirocotyle refers to the sucker-like structure in the buccal capsule and its relation to a Spirocamallanus, the species name to the fish host. The sucker-like structure is not found in any of the previously described spirocamalanid nematodes or other related genera.
Generic diagnosis: Camallanidae, sub family Camallaninae, moderate sized worms: Buccal capsule is provided with 15 spiral thickenings; a prominent sucker in buccal capsule; tridents absent; oesophagus divided into an anterior muscular and a longer and wider posterior glandular part.
Male: Posterior extremity in male, curved ventrally; tail conical, caudal alae present, with 7 pairs preanal, 5 pairs post anal, spicules unequal.
Female: Posterior extremity flat with three short, blunt processes; excretory pore terminal; vulva is sub terminal; parasites of marine fish.
| Type species: | Spirocotyle otolithi |
| Type locality: | Karachi coast, Pakistan |