Mushroom corals as newly recorded hosts of the hydrozoan symbiont Zanclea sp

Mushroom corals (Anthozoa: Scleractinia: Fungiidae) have been well documented as hosts of a rich associated fauna, but no records involving the symbiotic hydrozoan genus Zanclea (Hydrozoa: Capitata: Zancleidae) are known. These small (~1 mm long), coral-associated hydroids have only been reported from associations involving 23 non-fungiid scleractinian host species in the Indo-Pacific. Since both groups, Fungiidae and coral-dwelling Zanclea hydroids, are known to occur on Indo-Pacific coral reefs, it was unclear why no mushroom coral hosts were known. Therefore, a survey in the Maldives was performed aiming at the discovery of Zanclea–Fungiidae associations. Subsequently, 10 new host species were discovered and the number of recorded coral host genera increased from 17 to 24, taking recent taxonomic revisions into account. These findings indicate that the coral-associated biodiversity is still insufficiently explored.