Key to the shallow water (<20 m) species of Solaster in the Aleutian Islands.

1a Rays six; R to 4 cm; adambulacral plates with a curved transverse series of 6–8 slender, bristling spines, and 2 long, slender furrow spines; color in life uniformly reddish to pale tan................................... Solaster hexactis sp. nov.

1b Rays, more than eight; R frequently greater than 10 cm ........................................................ 2

2a Rays 12–15; adambulacrals with a nearly strait transverse series of 4–6 rather thick spines, and a furrow series of 3–4 shorter spines; color in life often nearly uniform brown or orange tones, disc sometimes slightly paler, and/or with fine darker specks or mottling.............................................................................. Solaster dawsoni

2b Rays 10–11.......................................................................................... 3

3a Adambulacral furrow spines standing nearly as high as actinal series............................................. 4

3b Adambulacral furrows spines short, about half as high as actinal series........................................... 5

4a Adambulacral plates with actinal series of 5 (occasionally 6); spines of abactinal pseudopaxillae 1.5–2 times pedicel height, and bear 5–8 slender apical spicules to 0.2 mm in height; color in life typically salmon on disc, rays purplish or fuchsia............................................................................................. Solaster arctica

4b Adambulacrals with actinal series of 7–8 spines; spines of abactinal pseudopaxillae about 1–1.2 times pedicel height, and bear 5–10 stout apical thorns to 0.1 mm in height; color in life typically yellow /orange disc with purple rays, sometimes uniformly white, orange or purple........................................................... Solaster spectabilis sp. nov.

5a Disc broad, rays typically short, broad, soft, inflated; R:r usually 2.0–3.0; aboral pseudopaxillae small, round, with 5–9 spines; color in life often uniformly red, yellow, orange or purple, sometimes with broad purple radial stripe........ Solaster endeca

5b Disc small, rays long, slender; R:r typically 3–5.0; aboral pseudopaxillae round to oval, with 9–13 spines; color in life orange, yellow or red, with prominent blue-gray or purple radial stripe, rarely solid dark navy blue............. Solaster stimpsoni