Genus Aonidomytilus

Leonardi, 1903

Appearance in life
Scale cover of adult female elongate, shaped like a mussel shell, flat to moderately convex, white to greenish or light brown, with terminal exuviae. Scale cover of immature male similar to that of female but much smaller.

Adult female not pupillarial; body elongate and fusiform, usually membranous except for the pygidium, but one species sclerotized also on prothorax; lateral lobes of free abdominal segments little developed, lacking marginal sclerotized spurs. Pygidium with two or three pairs of lobes; median lobes usually well separated, not zygotic; each lobe usually notched once or several times on either side. Second lobes smaller than median lobes; third lobes usually vestigial. Ventral paraphyses associated with the lobes usually absent. Gland spines short, present on pygidial segments only; a small pair usually present between the median lobes; replaced by submarginal, ventral duct tubercles when present on the prepygidium, never in conspicuous clusters. Anus shape variable, often circular, surrounded by a sclerotized area, situated near the centre of the pygidium or in the anterior half. Vulva position variable between somewhat posterior to centre of pygidium through to somewhat anterior to the centre. Marginal macroducts at least slightly larger than dorsal ducts, each with a thickened sclerotized rim and the long axis of the orifice perpendicular to the pygidial margin; never present between median lobes. Dorsal macroducts smaller than marginal ducts, arranged clusters or irregular rows. Sclerotic bosses absent from abdominal segments. Duct tubercles may be present on some segments anterior to pygidium. Perivulvar pores sometimes rather few, present in 5 (occasionally 4) groups. Stigmatic disc pores present by anterior spiracles only. Antennal setae usually numbering 2 or more.