Signoret, 1869
Appearance in life
Scale cover of adult female elongate, shaped like a mussel shell, more or less convex, white to greyish white, with colourless to brown, terminal exuviae; thin, white ventral scale present, often left on substrate when the insect is removed for examination. Scale cover of immature male different from that of female; small and elongated, white, felted, sometimes tricarinate, with terminal exuviae.
Morphology
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Adult female not pupillarial; body elongate-fusiform, often widest at or near abdominal segment I, then tapering abruptly to apex of pygidium. Derm membranous except for pygidium; mesothorax, metathorax and abdominal segments I-III moderately produced laterally, without marginal sclerotized spurs. Pygidium triangular or slightly rounded, often with a distinct apical notch. Median lobes usually well developed, variably shaped according to species and often also related to substrate; sometimes strongly divergent and elongate, forming a notch in apex of pygidium (as in many leaf-forms); may be separated, sometimes by a gap wider than a median lobe. Median lobes usually zygotic, without distinct marginal setae between the bases; the lobes may be entirely divergent, or parallel at the base and divergent distally, or broad and close together basally (or even fused for more than half their length), then more or less divergent (as in many bark-forms); apically rounded or notched or serrated. Second lobes smaller than median lobes, bilobed, with apices rounded or notched or serrated. Third lobes usually bilobed, occasionally merged into pygidial margin. Small ventral paraphyses in some species arising from the angles of the inner lobules of second and sometimes third lobes, usually converging anteriorly. Gland spines well developed, absent from between the median lobes; usually present singly or in pairs between the lobes, more numerous on margins of free abdominal segments; becoming shorter (conical duct tubercles) and situated on ventral surface anterior to segment IV, usually at least as far forward as segment I. Anus circular to oval, usually situated between just posterior of the centre and anterior 1/3 of pygidium; vulva situated at, or just anterior to, centre of pygidium. Marginal macroducts same size as larger dorsal ducts, each orifice with the long axis perpendicular to the margin; usually associated with pore prominences or marginal serrations; usually numbering 7 on each side of the pygidium (1 between median and second lobe, 2 by third lobe, 2 on segment V and usually 2 on segment IV), absent from between median lobes. Some dorsal macroducts as large as marginal ducts, arranged in segmental rows of submarginal and submedian ducts along posterior margins of segments; usually present as far forward as abdominal segment I or thorax, and as far back as submargin of segment VI, but absent from segments VII or VIII; in some species, submedian macroducts sometimes accompanied, or replaced, by microducts. Submarginal dorsal bosses present, 3 on either side, usually on abdominal segments I, III and V. Conical duct tubercles present anterior to abdominal segment III. Perivulvar pores present in 5 groups. Stigmatic disc pores, usually 3-locular, present in a compact cluster by anterior spiracle; fewer by, or absent from, posterior spiracle. Antenna with 1 fleshy seta.