THE DETECTION OF Ochetosoma heterocoelium (TRAVASSOS, 1921) (TREMATODA: DIGENEA: OCHETOSOMATIDAE) IN Chironius exoletus (LINNAEUS, 1758) (OPHIDIA: COLUBRIDAE)

Ochetosoma heterocoelium (TRAVASSOS, 1921) (TREMATODA: DIGENEA: OCHETOSOMATIDAE) IN

Chironius exoletus (LINNAEUS, 1758) (OPHIDIA: COLUBRIDAE)

R. J. DA SILVA

, R. R. RODRIGUES, M. F. B. STEIN, G. P. M. SIPOLI, R. PINHÃO , C. A. M. LOPES

1 Center for the Study of Venoms and Venomous Animals – CEVAP – UNESP, Botucatu, State of São Paulo, Brazil.

ABSTRACT. Two hundred and fifty-two specimens of Ochetosoma heterocoelium (Travassos, 1921) (Trematoda: Digenea: Ochetosomatidae) were detected in the mouth and esophagus of the snake Chironius exoletus (Linnaeus, 1758) (Ophidia: Colubridae) at the serpentarium of the Center for the Study of Venoms and Venomous Animals (CEVAP) of São Paulo State University (UNESP) in Botucatu, State of São Paulo, Brazil.

KEY WORDS: Ochetosoma heterocoelium, Chironius exoletus, snakes, trematode.

Among the parasitic fluke of Brazilian snakes, the species of the genus Ochetosoma (Braun, 1901) are those which most frequently occur (1). Ochetosoma heterocoelium (4,5) (Travassos, 1921) has been detected in different species of snakes (1,2). Corrêa (1) reports on the presence of Ochetosoma heterocoelium in 18 species of snakes, among them Chironius bicarinatus (Wied, 1820) and Chironius fuscus (Linnaeus, 1758). Later, Corrêa et al. (2) described another case of occurrence of this parasite in Bothrops insularis (Amaral, 1921). However, the occurrence of Ochetosoma heterocoelium in Chironius exoletus (Linnaeus, 1758) has never been mentioned in the literature. This paper reports on the detection of flukes of the species Ochetosoma heterocoelium in the mouth and esophagus of Chironius exoletus.

The main characteristics of the host snake are: adult, female, 1440 mm total length, 570 mm tail length, ventral scales 151, subcaudal scales 152-152, anal plate divided, paraventral keeled scales only, scales with an apical pit at neck region, supralabials 9-9 (5th and 6th supralabials contacting the eye), infralabials 10-11 (1st to 6th infralabials contacting genials), two pairs of genials, preocular 1-2 (not in contact with frontal), postocular 2-2 (upper postocular in contact with parietal), temporal 1+2, loreal 1, dorsal 12-12-8 and tail reduction 6 to 4 from the 7th pair of subcaudal scales.

The comparison of the morphological characteristics described above with those of the work of Wiest (6) allowed us to identify the species Chironius exoletus. In Brazil, this species inhabits evergreen tropical rainforest, gallery forests, and possibly some deciduous mesophytic subtropical forests along the country’s coast (6).

This specimen of Chironius exoletus was captured in an area outside of the facilities of the School of Veterinary Medicine and Animal Husbandry (FMVZ) of São Paulo State University (UNESP) in Botucatu, and then sent to the Center for the Study of Venoms and Venomous Animals (CEVAP) on August 1, 1997. The above-mentioned School is located beside the University’s Botanical Garden where this specimen probably used to live until it was captured. The referred specimen died in captivity on November 11, 1997. After death, the snake was preserved and placed in CEVAP’s scientific collection of snakes under the number 077.

At that time, a great quantity of flukes was observed in the mouth and esophagus of this snake. Two hundred and fifty-two flukes were collected and then preserved for later identification.

The collected flukes were fixed with Railliet & Henry’s solution as described by Pessôa (3). After fixation, part of the flukes was stained by chloride carmine technique, adapted from Pessôa’s (3). Then, the flukes to be stained were placed in 70º GL ethyl alcohol for 15 minutes, immersed in chloride carmine for 5 min, briefly washed in 70º GL ethyl alcohol, placed in 80º GL ethyl alcohol for 10 min, in 90º GL ethyl alcohol for 10 min and then in absolute ethyl alcohol for 15 min. Then, clearing in creosote (30 min) and permanent mount in permount were carried out.

Two hundred and fifty-two flukes were collected from the mouth and esophagus of a Chironius exoletus snake and a sample with 10 specimens was utilized for the morphometrical evaluation, using an OPTIMAS 4.10 System for Analysis of the Computerized Images. The results of the morphometrical analysis are shown in Table 1. The main characteristics of these flukes are: elongated body with oral and ventral suckers; the oral sucker is located at the anterior end of the body, while the ventral sucker lies at the median portion; the pre-pharynx is absent; the esophagus is short; the intestinal caeca are broad, short, unequal and finish on the ventral sucker surface; the lateral genital pore is located at the pharynx level; the cirrus sac is large, oblique and extends from the genital pore to the ventral sucker; a large protrusible cirrus and a big seminal vesicle are observed; the ovary is small, round and located below or on the ventral sucker surface; the vitelline glands are composed of thick lateral follicles located from the region of the intestinal caeca to the posterior region of the testes; the uterus lies between the testes and posteriorly to the ventral sucker.

TABLE 1.
Mean and standard deviation values for the morphometrical variables obtained with an OPTIMAS 4.10 Computerized System for the Analysis of Images using 10 specimens of Ochetosoma heterocoelium (Travassos, 1921).

The morphological characteristics described above are highly compatible with those described by Travassos et al. (5). This allowed us to identify this species as Ochetosoma heterocoelium (Figure 1).

FIGURE 1.
Specimen of Ochetosoma heterocoelium (Travassos, 1921) isolated from snake Chironius exoletus (Linnaeus, 1758).(x 40).

This is the first case described in the literature on the occurrence of this fluke in Chironius exoletus.

ACKNOWLEDGEMENTS

The authors are indebted to Profa. Dra. Maeli Dal Pai Silva, of the Department of Morphology of the Institute of Biosciences of Botucatu, for her assistance with the staining technique and morphometrical analysis of the flukes, to Tânia Machado de Alcântara e Márcia Guimarães da Silva, graduate students of the Department of Pathology of the School of Medicine of Botucatu, for their assistance with the photomycrographies, and to Heloisa Maria Pardini Toledo for her assistance with the English review.

REFERENCES

01 CORRÊA AAS.

Fauna de trematóides parasitos de ofídios da área geográfica brasileira. São Paulo: Universidade de São Paulo, ICB,

1990. (Tese- Doutoramento)

02 CORRÊA FMA., PAULINO RC., BUONONATO MA., FEDERSONI JR. PA. Ochetosoma heterocoelium (Travassos, 1921) (Trematoda: Digenea: Ochetosomatidae) em novo hospedeiro. Mem. Inst. Butantan, 1990, 52: 11-6.

03 PESSÔA SB. Parasitologia médica. 11.ed. Rio de Janeiro: Guanabara Koogan, 1982. 872p.

04 TRAVASSOS L. Contribuições para o conhecimento da fauna helmintológica brasileira. XII. Sobre espécies brasileiras da sub-família Brachycoelinae. Arq. Esc. Sup. Agric. Med. Vet. Niterói, 1921, 5, 59-67.

05 TRAVASSOS L., FREITAS JFT., KOHN A. Trematódeos do Brasil. Mem. Inst. Oswaldo Cruz, 1969, 67, 1-886.

06 WIEST JR JA. Revision of the neotropical snake genus Chironius fitzinger (Serpentes, Colubridae). College Station: Texas A & M University, 1978. 370p. (Thesis).

Publication Dates

• Publication in this collection
  16 Apr 1999
• Date of issue
  1999