Published online by Cambridge University Press: 06 October 2009
Atrispinum labracis (Van Beneden & Hesse) n.comb. syn. Microcotyle labracis Van Beneden & Hesse, 1863, parasitizes the bass Dicentrarchus labrax but almost only in the open sea; the very low prevalence of parasites on juvenile estuarine hosts was not due to intolerance of lower salinities in this habitat. The intensity of infection on open-sea bass was rarely more than 2 per fish but the strict localization of the habitat to the outer hemibranch of the ventral end of the first gill arch is thought to enhance the mating opportunities. The parasite attaches itself asymmetrically to the gill by a permanent morphological inclination of the body with respect to the haptor which is itself symmetrically aligned on a single primary lamella.
Substantial differences between the copulatory apparatus of A. labracis and that of Microcotyle donavini Van Beneden & Hesse, 1863, the type of Microcotyle, have made necessary the transfer of the parasite from Dicentrarchus labrax to Atrispinum Maillard & Noisy, 1979 and a consequent amendment to the diagnosis of the subfamily Atriasterinae Maillard & Noisy, 1979.