Takagi, S. 2003 Some burrowing diaspidids from eastern Asia (Homoptera: Coccoidea).. Insecta Matsumurana (New Series) 60: 67-173.

Notes: Twenty-five species of scale insects belonging to 18 genera, four tribes, and two subfamilies of the family Diaspididae from Malaysia, the Philippines, Singapore, and Japan are dealt with. Twenty-four species and 14 genera are described as new. The females of all the 25 species are cryptic on the plant body, burrowing into the epidermis of the bark or leaves, under the dense cover of trichomes on the lower surface of the leaves, or among the dense erect hairs on the twigs. Morphological modifications in the adult females are not uniform. Generally, the trullae are dentate or serrate and the dorsal ducts are few and slender. These tendencies are apparently associated with burrowing, but are not without exception. The marginal glanduliferous processes of the pygidium are much reduced in some species, but are well represented in others. Two species are highly advanced burrowing forms in view of the fact that the adult females form extraordinarily large burrows, in which the male crawlers with much shortened legs stay to complete their metamorphosis. One species is an unusual form of uncertain relationship, but the other shows little morphological modification except for the body shape as compared with non-burrowing related forms. Burrowing starts in the second-instar female, which is similar to the adult female especially in the pygidial appendages. In some species, the second-instar males also burrow, and they are homomorphic, being similar to the adult and second-instar females of the same species in the pygidial appendages. However, not all homomorphic second-instar males burrow. Heteromorphic forms of the second-instar male have been observed in seven species among the examined Diaspidini, and they are variable especially in the structure of the pygidial margin. Heteromorphism in the second-instar male could be due to atavism but, in their morphology, most of the heteromorphic forms observed in this study apparently reflect the change effected in the female in adaptation to burrowing.