Genus Mercetaspis

Gómez-Menor Ortega, 1927

Appearance in life
Scale cover of adult female elongate, roughly shaped like a slightly short mussel shell, slightly convex, whitish with brown tinges, with yellow brown terminal exuviae; scale cover of immature male similar to that of female but smaller and slimmer.

Morphology
Adult female not pupillarial; body elongate oval, usually membranous except for pygidium, but one species with anterior end tending to become sclerotized with maturity; lateral lobes of free abdominal segments only slightly developed; marginal sclerotized spurs absent. Pygidium with median lobes well separated, not zygotic. Median lobes developed in the second instar; sometimes developed in the adult female; if present, each lobe usually wider than long, rounded or bluntly pointed (due to a single notch on either side of the lobe), or sometimes rather flattened, occasionally reduced to a sclerotized section of the posterior margin. Second lobes developed in the second instar, but vestigial or obsolete in the adult female. Ventral paraphyses absent. Gland spines absent or few, slender and often short, present singly on either side of pygidial segments and occasionally on the margins of prepygidial segments III and IV; a pair always present between the median lobes. Anus circular, situated in the anterior quarter of the pygidium; vulva situated near, or somewhat anterior to, centre of pygidium. Marginal macroducts numbering 3-5 on each side of the pygidium, single except for a pair sometimes present on segment VI, absent from between median lobes; each marginal macroduct enlarged, with a thick sclerotized rim and with the long axis of the orifice perpendicular to the margin. Dorsal macroducts quite small, arranged in segmental series on pygidium and abdominal segments; a submedian group usually present on segment VI. Ventral microducts, if present, also arranged segmentally on prepygidial segments. Submarginal dorsal bosses absent. Duct tubercles absent. Perivulvar pores absent or present in 3 sparse groups. Stigmatic disc pores present by anterior spiracles, and in some species, by posterior spiracles also. Antennae each with 2 or 3 setae.

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