Genus Unaspis

MacGillivray, 1921

Appearance in life
Scale cover of adult female elongate, shaped like a mussel shell but often with a median longitudinal ridge, fairly flat to more or less convex, brownish or black, with dark terminal exuviae. Scale cover of immature male different from that of female; small, white, felted, tricarinate, with yellow terminal exuviae.

Adult female not pupillarial; body elongate, sometimes fusiform, often widest at metathorax or abdominal segment I, then tapering to apex of pygidium. Derm usually membranous except for pygidium, but a few species with body forwards from abdominal segment I becoming sclerotized with maturity; free abdominal segments I-III with slightly to moderately produced lateral lobes, without marginal sclerotized spurs. Pygidium slightly rounded, sometimes with a small apical notch formed by divergent median lobes. Median lobes usually well developed, not zygotic, with a pair of small marginal setae between the bases; either quite widely spaced, symmetrical and parallel-sided, or set quite close together basally and divergent, with inner margins longer than outer margins, the latter forming a slight notch at apex of pygidium; the lobes rounded or serrate. Second and third lobes similar in size, well developed, deeply bilobed, the lobules rounded. Slender ventral paraphyses 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 posterior free abdominal segments; becoming shorter (conical duct tubercles) and situated on ventral surface further anteriorly. Anus circular, situated between centre and anterior 1/3 of pygidium; with a median furrow extending from anus to median lobes. Vulva situated at, or just anterior to, centre of pygidium. Marginal macroducts same size as larger dorsal ducts, each orifice sclerotized, 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. Dorsal macroducts same size as or smaller than marginal ducts, numerous, scattered or loosely arranged in segmental series submarginally and submedially, present as far posteriorly as abdominal segments VII and VIII. Ventral conical duct tubercles sometimes present. Perivulvar pores absent or present in 5 groups. Stigmatic disc pores present in a compact cluster by anterior spiracle; fewer by, or absent from posterior spiracle. Antennae situated near anterior margin, each with 1 or 2 setae, occasionally more.