Morphological and molecular studies on life cycle stages of Diphtherostomum brusinae (Digenea: Zoogonidae) from northern Portugal

Abstract

Diphtherostomum brusinae was first recorded by the present study in the north of Portugal. Sporocysts, containing cercariae and encysted metacercariae, were observed in the gonads and digestive gland of the gastropod Nassarius reticulatus. Metacercariae were also found infecting the foot, mantle border and gills of the cockle Cerastoderma edule. The adult form was lodged in the rectum of the definitive host Diplodus sargus. The morphology of the three parasitic stages was studied by light (LM) and scanning electron microscopy (SEM). Despite the close similarity between cercaria and metacercaria, SEM data provided information that allowed their differentiation, namely the presence of a dense crown of microvilli around the oral cavity of the cercariae, which was absent in the metacercariae. In addition, the metacercariae presented a specific pre-acetabular rectangular band with conspicuous triangular spines. The adult showed characteristics of D. brusinae species, in particular the presence of acetabular lips, compact vitellaria and large elliptical eggs. Sequenced ITS1 data clearly demonstrated that the cercariae and metacercarial cysts from N. reticulatus, the cysts from C. edule and the adult isolated from D. sargus were life cycle stages that belonged to the same species, i.e. D. brusinae. Two transmission strategies in the life cycle of this species were observed: (1) cercariae encyst within the sporocysts of N. reticulatus and await ingestion by the definitive host; and (2) N. reticulatus naturally emits cercariae; they encyst in C. edule or the environment and are ingested by the definitive host.

Morphological and molecular analysis of metacercariae of Diphtherostomum brusinae (Stossich, 1888) Stossich, 1903 from a new bivalve host Mytilus galloprovincialis

“…In the ventral ( fig. 3C) and pre-acetabular region, the spines were strong and triangular but not arranged in a rectangular band as noted by Pina et al (2009). A ring with 16 papillae was observed around the oral sucker ( fig.…”

A survey of larval digeneans in the commonest intertidal snails from Northern Patagonian coast, Argentina

“…Larvae were identified as belonging to the genus Diphterostomum Stossich, 1903 by the presence of 2 short and divergent caeca (Bray 2008). It is similar to Diphterostomum brusinae, having four lips on the ventral sucker, which are also present in the adult form described by Pina et al (2009) …”

Parasites as biological tags for stock identification of blackspot seabream, <i>Pagellus bogaraveo</i>, in Portuguese northeast Atlantic waters

“…Therefore this species should also be useful as an indicator. The life cycle of D. vividum is not fully known, but other Diphterostomum species use gastropods such as Nassarius reticulatus as first intermediate hosts, and bivalves such as Cerastoderma edule and Mytilus galloprovincialis as second intermediate hosts (Bray and Gibson 1986, Pina et al 2009, Francisco et al 2011. These species have low vagility, which may contribute to the restricted geographical distribution of this parasite.…”