Pathologies elicited by the gymnophallid metacercariae of Bartolius pierrei in the clam Darina solenoides

Abstract

Darina solenoides (Mactridae), a common intertidal bivalve in the Argentine Patagonian coast, serves as both first and second intermediate host for the gymnophallid Bartolius pierrei (Trematoda: Digenea). Cercariae enter the clams actively by piercing the mantle border; young metacercariae ascend along the space between the outer mantle epithelium and shell and they settle in the dorsal general extrapallial space just ahead of the posterior adductor muscle. Host reaction comprises mantle tissue alterations (hyperplasia and metaplasia) leading to the encapsulation of the metacercariae by the formation of a one-cell-layer thick sac, which progressively detaches from the mantle epithelium. Sacs containing fully developed metacercariae, which are surrounded by a hyaline non-cellular envelope, become internal and are found in the postero-dorsal region of the visceral mass. Two sacs usually containing from two to 44 metacercariae, one at each side of the clam, were observed. In some cases, in which the infection seems not to proceed as usual, dead and dying metacercariae and their debris were found in the same position within the extrapallial space where the host reaction usually starts. In these cases, the mantle reaction is accompanied by an inner shell surface alteration consisting of calcium carbonate deposits partially surrounding the reaction complex or other abnormal calcifications in the form of loose mineral concretions.

Interactions between parasites of the cockleAustrovenus stutchburyi: hitch-hikers, resident-cleaners, and habitat-facilitators

“…A potential reason behind this phenomenon could be the different migration routes taken by the two trematodes through their cockle host before reaching their final settlement site. Unlike echinostome cercariae, which encyst in the foot by entering through the cockle's siphon to reach the mantle cavity (Wegeberg et al 1999) where P. spinosus resides, gymnophallid cercariae migrate through the extrapapillial space before settling between the outer mantle epithelium and inner shell surface (Cremonte and Ituarte, 2003). Thus, they do not encounter the copepod or its immediate environment.…”

Parasite‐mediated shell alterations in Recent and Holocene sub‐Antarctic bivalves: the parasite as modeler of host reaction

“…In D. solenoides , the reaction involved calcium deposition only in cases of high intensity of infection, and it takes place at later stages of infection. The calcium deposition consisted, at most, of a calcareous ridge partially surrounding a group of larvae immersed in a gelatinous substance (Cremonte & Ituarte 2003). The previous data support the idea that the type and characteristics of the reactions would be specific not at the genus level, but rather at the species level for the invading agent.…”

Devonian Pearls and Ammonoid-Endoparasite Co-Evolution

“…This would cause a distur− bance of the mantle at the aperture or anterior to the cephalic retractor insertion, thus leaving a trace in shell growth. Inter− estingly, some gymnophallid parasites are known to actively pierce the mantle border, ascend to the outer mantle epithe− lium to settle in the dorsal general extrapallial space just ahead the posterior adductor muscle in bivalves (Cremonte 2001;Cremonte and Ituarte 2003).…”