A new species of Cryptobia sp. n. (kineloplastida, bodinina, bodonidae) found in the blood of the farmed abalone, Haliotis diversicolor Reeve.

ABSTRACT A new species of Cryptobia, was found in the blood of diversicolor abalone, Haliotis diversicolor Reeve, derived from farming ponds, on the coast of the south China sea in December 2000. Stained with Giemsa smear, most organisms are spindle-shaped, 12.5 [+ or -] 1.88 [micro]m in length, 2.50 [+ or -] 0.85 [micro]m in width (n = 20), and the nucleus is 1.81 [+ or -] 0.61 [micro]m in length, and 1.22 [+ or -] 0.33 in width. Two unequal flagella are derived from a flagella pocket. The kinetoplast is mostly single, located anterior to the nucleus. Transmission may be direct, from one host to another through lesions on the skin or gill, or it may be also by a vector.

KEY WORDS: parasite, Cryptobia spp, new species, Haliotis diversicolor Reeve

INTRODUCTION

Since the early 1990s, epizootic mortalities have been observed in many sea-board farmed discus abalones Haliotis discus hannai, and diversicolor abalone, H. diversicolor Reeve in China. There are severa; varied pathogenetic organisms found in cultured abalones, including virus (Li et al. 1998, Nakatsugawa et al. 1998, Wang et al.2000, Fang et al.2002), bacteria (Li et al. 1996, Liu et al.2000, 2001, Lee et al. 2001), parasites (Bower et al. 1989, Cogging & Lester 1995, Ruck & Cook 1998, Ruck & Cook 1999, Chen et al. 2001) and rickettsiae-like organisms (Moore & Robbins 2000, Chen et al. 2001), and the like. A dinoflagellate has been found in blood of pathogenic abalones, H. diversicolor Reeve. This study describes the structure of the parasite in farmed abalones on the coast of south China.

MATERIALS AND METHODS

Cultured diversicolor abalones with a mean length of 680 mm (580-720 mm), and mean weight of 20 g, were obtained occasionally from 4 farming ponds in Shanwei, Guangdong Province. After dissection, inhalant lymph blood of abalone was obtained from the heart and then smeared on to slides. Smears were fixed in methanol for about 5 min, stained with Giemsa's fluid diluted 1:10 with water at pH 7.0-7.2 PBS for about 30 min, then rinsed well in distilled water. Results were observed microscopically.

RESULTS

Most of detected abalones (n = 20) were infected by parasites. The parasite density was 2-8 Cryptobia sp. in every view (x400) (Fig. 1 and Fig. 2). The organisms are spindle shaped, 12.5 [+ or -] 1.88 [micro]m in length, and 2.5 [+ or -] 0.85 [micro]m in width. The nucleus is ellipsoidal with an endosome, situated at 20% to 25% of body length from anterior extremity, The nucleus is 1.81 [+ or -] 0.61 [micro]m in length, and 1.22 [+ or -] 0.33 [micro]m in width. The kinetoplast is mostly single spherical, located anterior to the nucleus. Two unequal flagella are derived from a flagella pocket. The anterior flagellum, 8.85 [+ or -] 1.23 [micro]m in length, is shorter than the posterior one (15.38 [+ or -] 2.46 [micro]m). The undulating membrane is not well developed and forms a narrow undulating membrane when stained with Giemsa smear (Fig. 3).

[FIGURES 1-3 OMITTED]

DISCUSSION AND CONCLUSION

The flagellates mostly are pathogenic protozoa that cause disease and mortality in freshwater and seawater hosts. They have been often found in the gills (Lom & Dykova 1992, Diamant 1990), epidermis (Kreier 1977, Kinne 1980), intestinal tract (Kozloff 1948), as well as bloodstream (Chen & Hsieh 1964, Zhao & Ma 1992). A species appearing identical to Cryptobia helices has also been reported living in the reproductive organs and intestines of pulmonate land snails in Europe (Leidy 1846). In this investigation a new hemoflagellate (Cryptobia sp.) occurred firstly in the blood of abalone. It differs from other described species in its shape and body size, as well as the shape of the nucleus and flagellum (Table 1).

In recent years, Cryptobiosis, caused by the hemoflagellate, has been found in many fishes (Lom. & I. Dykova 1992, Kreier 1977, Kinne 1980). The use of monoclonal antibody probes and immuno-chomotherapeutic strategies have been reported to detect the pathogenic hemoflagellate (Lukes et al.1998, Ardelli & Woo 2001). There are few effective chemotherapies against the parasite in intensive abalone culture facilities. It is, therefore, necessary to develop a sensitive detection technique and an effective control method against this parasitic organism.

TABLE 1.

The comparison of two haemoflagellates.

                                                    Body Length
                                                      x Width
    Parasites                Hosts                   ([micro]m)

Cyptobia             Misgurnus                      52.82 x 7.9
  chongqingensis       anguillicandat-us
This Cryptobia sp    Haliotis               (12.5 [+ or -] 1.88) x
                       diversicolor          (2.5 [+ or -] 0.25)

                            Anterior                 Posterior
                           Flagellum                 Flagellum
    Parasites              ([micro]m)                ([micro]m)

Cyptobia                  42.8 x 2.37                    --
  chongqingensis
This Cryptobia sp      8.85 [+ or -] 1.23       15.38 [+ or -] 2.46

                        Situated nucleus
                         Length x Width
    Parasites              ([micro]m)               Kineloplast

Cyptobia                  6.93 x 2.37                Bar-shaped
  chongqingensis
This Cryptobia sp    (1.81 [+ or -] 0.61) x       Ellipsoidal with
                     (1.22 [+ or -] 0.33)            a endosome

    Parasites                Source

Cyptobia                  Zhao and Ma
  chongqingensis              1992
This Cryptobia sp          This paper

Cryptobi sp. nov.

Synonym, Cryptobia abalonesis Chen 2001; Host and site, (Gastropod)
Haliotis diversicolor Reeve. bloodstream of lymph sinus; Locality and
date, Seaboard farms of Shanwei, Guangdong Province, December 2000;
Depositions, Type specimens and slides will be deposited in the South
China Sea Fisheries Institute, CAFS, China, and in the collection of
the authors.

ACKNOWLEDGMENTS

This work was supported by Department of Science and Technology of Guangdong Province, PRC., under grant No. 2KB05301N.

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BISHENG CHEN, (1) * LIWEN XU, (1) ZHIXUN GUO, (1) AND HONGZHI YANG (2)

(1) South China Sea Fisheries Research Institute, CAFS, People's Republic of China; (2) Longgang District Fisheries Research Institute, Shenzhen, People's Republic of China

* Corresponding author. E-mail: [e-mail]