Botrylloides crystallinus n. sp., a new Botryllinae Adams & Adams, 1858 (Ascidiacea) from Mediterranean Sea

Botrylloides crystallinus n. sp., collected on sublittoral hard substrata in North Mediterranean Sea is here described. The species presents a seasonal life cycle with a spring-summer regression of the zooids and their buds as known in the congeneric species B. leachii (Savigny, 1816), from which however differs in many unusual morphological traits.