Appearance in life
Scale cover of adult female circular, usually pale, with central or subcentral exuviae. Scale cover of immature male similar to female but smaller and slightly more oval.
Adult female not pupillarial; body broadly pyriform to subcircular, membranous except for parts of pygidium. Pygidium often with distinctive pattern of dorsal sclerotization; with 3 pairs of unilobulate marginal lobes only. Lobes parallel to longitudinal axis of body, or only slightly convergent; median lobes each elongate or as long as wide, more or less exceeding lateral lobes; heavily sclerotized, with a basal sclerosis or sclerotized area extending into the pygidium from its base; may be sunk in a recess between second lobes. Second and third lobes graded in size, less sclerotized than median lobe, usually notched, at least at outer edges; paraphyses absent. Dorsal marginal setae never lanceolate; that at outer basal corner of each median lobe sometimes elongate, those present by second and third lobes sometimes thickened basally, tapering to apex. Well-developed, fringed plates present, as long as or slightly longer than lobes; 2 present between median lobes, 2 between median and second lobes, 3 between second and third lobes, and often present lateral to each third lobe as far forward as fifth abdominal segment, plates beyond third lobe each with an oblique outer margin that is often fringed but never with clavate processes. Anus elliptical, sometimes longer than median lobe, situated about one-fourth to one-third length of pygidium from apex; vulva situated further forward, usually in anterior half of pygidium. Dorsal macroducts variable in length, quite short and broad in type-species; usually 1 marginal duct between median lobes, 2 between median and second lobes, 2 between second and third lobes and 2-4 beyond third lobes on either side; submarginal ducts usually arranged in intersegmental rows or series, at least between segments VIII and VII and VII and VI on each side, but appearing rather scattered in some species. Preygidium with dorsal submarginal bosses present on segments I and III, usually membranous; without plates or duct tubercles, rarely with macroducts. Perivulvar pores present in 2-5 groups, usually 4. Stigmatic disc pores absent; antennae widely spaced, each bearing one seta and sometimes with a sclerotized spur.