Assessing the Zoantharian Diversity of the Tropical Eastern Pacific through an Integrative Approach.

Zoantharians represent a group of marine invertebrates widely distributed from shallow waters to the deep sea. Despite a high diversity and abundance in the rocky reefs of the Pacific Ocean, very few studies have been reported on the diversity of this group in the Tropical Eastern Pacific coasts. While molecular techniques recently clarified some taxonomic relationships within the order, the taxonomy of zoantharians is still highly challenging due to a lack of clear morphological characters and confusing use of different data in previous studies. Our first insight into the zoantharian diversity at El Pelado Marine Protected Area - Ecuador led to the identification of six species: Terrazoanthus patagonichus; Terrazoanthus sp.; Antipathozoanthus hickmani; Parazoanthus darwini; Zoanthus cf. pulchellus; and Zoanthus cf. sociatus. A metabolomic approach using UHPLC-HRMS was proven to be very efficient as a complementary tool in the systematics of these species and specialized metabolites of the ecdysteroid and alkaloid families were identified as key biomarkers for interspecific discrimination. These results show good promise for an application of this integrative approach to other zoantharians.

Terrazoanthines, 2-Aminoimidazole Alkaloids from the Tropical Eastern Pacific Zoantharian Terrazoanthus onoi.

The first chemical study of the common species Terrazoanthus onoi, present off the coast of Ecuador, led to the identification of a new family of 2-aminoimidazole alkaloids named terrazoanthines A-C (1-3). Homologues 1 and 2 feature an unprecedented 6-(imidazol-5-yl)benzo[d]imidazole. Acyl substitution pattern and complete configurational assignments were deduced from comparison between experimental and theoretical 13C NMR and ECD data, respectively. These compounds may represent key derivatives in the biosynthesis of zoanthoxanthins.