Leptychaster anomalus is a small sea star with five arms up to 3.4 cm long, obvious marginals but no obvious spines. It is yellowish-white when dried. The ratio of arm to disc ranges from 1.3 to 2.0. Paxillae on the aboral surface are packed close together, smaller at the centre of disc and tip of the arm, each has 40 to 45 short, round-tipped spinelets. L. anomalus has 10 to 18 marginal plates. Its superomarginals, wider than their length, are covered with granuliform spinelets of even size; the inferomarginals have longer spinelets. The oral intermediates form V-shaped rows. The series adjacent to the adambulacrals extends three-quarters of arm length. The adambulacrals are square with a furrow series of 4 spinelets. The oral surface has three longitudinal series of smaller spinelets, 3 to 5 in each series. The tube feet are pointed. The mouth plates have 6 or 7 marginal spines and a similar number of suboral spines along the median suture and remainder of the plate. In overall appearance, the mouth plates bristle with spinelets.
Characteristics
Similar SpeciesDiffers from the other two species of Leptychaster mainly in the arm-to-disc ratio, L. anomalus having shorter arms.