Fig. 3

Growth disturbances caused by marginal mantle setae, on both ventral and dorsal post-metamorphic shells of Eohadrotreta zhenbaensis. a, five bunches of pronounced ridges and associated narrow median troughs on ventral mature shell (double-headed arrows). b-c ventral valve; (b) general view of a juvenile specimen showing two pairs of fine folds on protegulum by arrows and ten bunches of ridges with narrow median troughs by double-headed arrows; (c) detailed view, show ridges extending anteriorly from the margin of the halo. d fourteen bunches of ridges with associated nick points on dorsal mature shell by double-headed arrows. e lateral view showing the pronounced drapes interrupted by nick points, and ridges on ventral post-metamorphic shell, the upper box indicates the area shown in (a) and lower box indicates area shown in (g). f demonstrate ridges by double-headed arrows and the related nick points by tailed arrows. g the continuous distribution of the nick points extending to the margin of post-metamorphic shell by double-headed arrows, noting the divergence of ridges by arrow. Abbreviations: ha, halo; ms, metamorphic shell; pr, protegulum; ps, post-metamorphic shell. Scale bars: a, c-d, f, 20 μm; b, g, 50 μm; e, 100 μm