In this paper we summarize current knowledge of the distribution, ecology, and
reproductive biology of 4 encrusting species in the soft coral family Alcyoniidae, with descriptions
of 2 new genera and 2 new species. The new genus Discophyton is erected for Alcyonium
rudyi, a species common in the lower intertidal of exposed rocky headlands from Vancouver
Island, British Columbia, Canada south to Point Lobos, California, USA. Discophyton rudyi n.
gen. & n. comb. propagates extensively by clonal fission, giving rise to characteristic aggregations
of small, regularly spaced, disc-shaped colonies. We describe 2 new species and place
them in a new genus, Thrornbophyton. Thrornbophyton coronatum n. gen. & n. sp. forms
irregularly shaped, membranous colonies on rock surfaces; it occurs subtidally along the southern
California coast from the Palos Verdes Peninsula to San Diego and on the California Islands.
Thrombophyton trachydermum n. gen. & n. sp. has a similar, membranous growth form; it
occurs both intertidally and subtidally on Vancouver Island, British Columbia, Canada, and in
the San Juan Archipelago, Washington, and intertidally in central California, USA. Alcyonium
pacificurn, reported for the first time from North American waters, occurs in subtidal kelp beds
around the Aleutian islands of Attu and Adak; its mushroom-shaped colonies are raised above
the substrate on a short stalk. D. rudyi, T. trachydermum, and A. pacijicum are all gonochores
that reproduce in late summer; in contrast, T. coronatum appears to reproduce in the spring.
D. rudyi and T. coronatum brood larvae internally to a late planula stage. A key to species is
presented for all shallow-water soft corals known to occur in the northeastern Pacific Ocean.