Achatinella species shells are diverse in patterns, colors, and shapes, but all average about in length. Most have smooth glossy, and oblong or ovate
shells which show a variety of colors, including yellow, orange, red, brown, green, gray, black, and rainbow. There are three recognized subgenera within the genus
Achatinella. Subgenera are distinguished according to shells characteristics only. Genus
Achatinella Swainson, 1828: The dextral or sinistral shell is imperforate or minutely perforate, oblong, ovate or globose-conic; smooth or longitudinally corrugated, with only weak traces of spiral
sculpture. Shell color is in spiral bands or streaks in the direction of the growth lines. The lip is simple or thickened within and sometimes slightly expanding. The
columella bears a strong callous fold. Type species of the genus
Achatinella is
Achatinella apexfulva (Dixon). Subgenus
Bulimella Pfeiffer, 1854: Shell shape is oblong-conic or ovate. The
spire is obtuse, rounded or convexly-conic near the
apex. The outer lip is thickened by a strong callous rib within the
aperture (except in
Achatinella abbreviata and
Achatinella lila). Type species of the subgenus
Bulimella is
Achatinella byronii Newcomb. Subgenus
Achatinellastrum Pfeiffer, 1854: The shell is imperforate, ovate-conic or oblong-conic and smooth. The
embryonic whorls are not flattened. The outer lip is thin or only slightly thickened within the apex but not expanded. These are the most generally distributed of the
Achatinella species and show a prolific area of intergrading color patterns. Type species of the subgenus
Achatinellastrum is
Achatinella stewartii (Green, 1827). == Ecology ==