This genus was created by R. I. Pocock with the New Zealand Sphaerotherium angulatum, Butler, 1878, as type species.
From his above mentioned work the following particulars may be gathered:—
1. "Male copulatory organs:—The movable digit of both pairs of copulatory forceps are composed of a single segment.
2. "Female vulva as in Zephronia" (i.e.: 'composed of two pieces, a proximal hairy piece bearing the aperture, and a distal usually polished piece'), but the proximal plate divided into two distinct pieces, whereof the external partially overlaps the internal.
3. "Tarsi as in Zephronia" (i.e.: 'distally narrowed, claw terminal, the upper spine close to but behind the claw.')
The characters numbered one and two rank, of course, amongst the very best. As to the structure of the tarsi, it is not possible so far to allow it the same importance as the position of the dorsal spine seems to vary and the distance between it and the claw is a question of more or less.