Galactosomum timondavidi sp. n. (Trematoda: Heterophyidae) from Larus argentatus, with a Note on the Metacercaria

Galactosomum timondavidi, sp. n., from Larus argentatus Pont. taken near Marseille, France, differs distinctly from all other species in the genus in the following combination of characters: (i) spines on the wall of the ventrogenital sac, (ii) small, symmetric, unarmed ventral sucker, (iii) bilobed gonotyl, and (iv) undivided seminal vesicle. Of these, the most singular feature is the presence of spines on the wall of the ventrogenital sac. The single specimen identified as Microlistrum (= Galactosomum) cochleariforme by Joyeux and Baer (1928), and reidentified as Knipowitschetrema nicolai by Dubois and Mahon (1955), proved on examination to belong to G. timondavidi. Among material collected from gulls by one of us (G.P.) were nine specimens of Galactosomum. Study of these revealed that they represent a new species, and are identical with the single adult recorded by Joyeux and Baer (1928) as Microlistrum (= Galactosomum) cochleariforme from Macedonia, and with the metacercaria reported as Knipowitschetrema echinatum by Timon-David (1970). The species is named in honor of the late Prof. J. Timon-David of Marseille, who contributed greatly to the study of heterophyid and other trematodes in the Mediterranean. Galactosomum timondavidi sp. n. (Figs. 1-3)