Memórias do Instituto Oswaldo Cruz Fundação Oswaldo Cruz, Fiocruz ISSN: 1678-8060 EISSN: 1678-8060 Vol. 90, Num. 5, 1995, pp. 621-622

RESEARCH NOTE

Phyllocaulis variegatus (Mollusca: Veronicellidae), a New Intermediate Host for Brachylaima sp. (Digenea: Brachylaimatidae)

Silvana C Thiengo, Suzana B Amato *

Departamento de Malacologia, Instituto Oswaldo Cruz, Av. Brasil 4365, 21945-900 Rio de Janeiro, RJ, Brasil *Departamento de Biologia Animal, Universidade Federal Rural do Rio de Janeiro, Caixa Postal 74512, 23851-970 Seropedica, RJ, Brasil

Code Number: OC95125
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During a search for the natural intermediate hosts of Angiostrongylus costaricensis Morera & Cespedes, 1971 in Brazil, terrestrial molluscs were collected nocturnally and diurnally from three localities near the dwellings of people reportedly suffering from abdominal angiostrongylosis: (1) Caicara (RS) (27.16S 53.26W), (2) Crissiumal (RS) (27.30S 54.07W) and (3) Uberlandia (MG) (18.56S 48.18W). The field work was performed in localities 1 and 2 during autumn and spring of 1991, and in locality 3 during spring and autumn of 1993 and l994.

The cephalopodal mass of shelled molluscs, and the eviscerated body of the slugs were individually minced and digested with pepsin (4 mg%) in a 0.7% HCL solution, for 2 hr at 37 C. The digested samples were placed in a Baermann apparatus and allowed to sediment for 6 hr, prior to examination. The viscera of the molluscs were placed separately in small Petri dishes with Ringer solution, and as well as the sediment collected from the bottom of the Baermann funnels, were examined under the stereomicroscope for helminth larvae. The latter were fixed and processed according to JFR Amato (1985 Manual de Tecnicas para Preparacao de Colecoes Zoologicas, Sao Paulo, SP, 11pp.).

Specimens of the veronicellid Phyllocaulis variegatus (Semper, 1885) were found harbouring metacercariae of a digenetic trematode identified as belonging to the genus Brachylaima Dujardin, 1843 in the pericardial sac (Fig. 1). Metacercariae of another brachylaimatid, Postharmostomum Winterberg, 1923 (Fig. 2) were also observed in specimens of Bradybaena similaris (Ferussac, 1821), Subulina octona (BruguiIre, 1792) and of Bulimulus tenuissimus (Orbigny, 1835). The metacercariae were mainly found in the pericardial sac, although many dead specimens were also collected in the sediment of Baermann funnels. Table shows the prevalence of Brachylaima sp. in P. variegatus and Postharmostomum sp. in other mollusc hosts for each locality surveyed.

Veronicellid slugs occur in large number in South and Central America, where they are considered agricultural pests and the most important intermediate hosts of A. costaricensis (P Morera et al. 1988 Rev Biol Trop (Costa Rica) 36: 575-576). P. variegatus occurs in Argentina, Paraguay, Uruguay and in South and Southeast Brazil (JW Thome 1993 BiociEncias 1: 61-75).

The genus Brachylaima is included in the subfamily Brachylaimatinae, family Brachylaimatidae. Although S Yamaguti (1971 Synopsis of Digenetic Trematodes of Vertebrates, Keigaky Publishing Co., Tokyo 1074 pp.) uses the name Brachylaimidae (Joyeux et Foley, 1930) Miller, 1936, he calls attention to the grammatical correction made by MJ Ulmer (1951 Trans Am Microsc Soc 70: 189-238), who named this family Brachylaimatidae because Brachylaima is a neutral gender, and not feminine as believed by Miller.

Fig. 1: metacercaria of Brachylaima sp.X64

Fig. 2: metacercaria of Postharmostomum sp.X112

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Mollusc host     Caicara, RS  Crissiumal, RS   Uberlandia, MG
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Bradybaena similaris               3/92=3.26% 136/284=47.9%
Phyllocaulis 
variegatus       9/37=24.32%       10/212=4.72%
Bulimulus tenuissimus   -          -          1/139=2.9%
Subulina octona         -          -          3/35=8.57%
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Metacercariae of Postharmostomum and Brachylaima are commonly found in the pericardial sac of terrestrial gastropods. They differ in body shape, the metacercariae of Brachylaima being more elongated than those of Postharmostomum. In Brachylaima the caeca are straight and somewhat sinuous and the acetabum is at the level of the first third of the body length whereas in Postharmostomun the caeca are winding and serpentine and the acetabulum is closer to midbody.

Species of Brachylaima have been reported to use several species of molluscs as intermediate host (Yamaguti loc. cit.), but none of them have been so far collected in P. variegatus.

Whole mount specimens were deposited in the Helminthological Collection of the Instituto Oswaldo Cruz, No. 33.219 a-b.

Acknowledgements: to Angela C Alves and Levi Marcon for assistance in the field work; to Dr Aventino Agostini, Universidade de Passo Fundo, RS, for the facilities supplied during the field work and to Dr W Lobato Paraense, Departamento de Malacologia, Instituto Oswaldo Cruz, Rio de Janeiro, for critical reading of the manuscript.

Copyright 1995 Fundacao Oswaldo Cruz

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