A new blue Astrangia coral (Scleractinia) from the Southwestern Atlantic

Abstract

Astrangia Milne Edwards & Haime, 1848 is a small, poorly known genus of Scleractinia, composed of 15 extant species with circumtropical to temperate distributions. Only two species of this genus have been distinguished in shallow-water environments along the Brazilian coast: A. solitaria (Le Sueur, 1817) and A. rathbuni Vaughan, 1906. Here, we describe a new, blue Astrangia species from the northeastern Brazilian coast. Scanning electron microscopy images of the corallites supported the taxonomic analysis and the description of the new species. Early confused with Astrangia woodsi Wells, 1955, an incrusting coral with blue-gray polyps, the new species is a zooxanthellate, solitary brooding coral and can easily be recognized in biofouling communities because of its solitary shape instead of the colonial development of A. woodsi. The new species was observed on artificial substrates, co-occurring with non-native invertebrates, such as the bryozoan Triphyllozoon arcuatum (MacGillivray, 1889), and “sun corals” of the genus Tubastraea Lesson 1830). This is the second Astrangia species reported from Brazil, updating the inventory for the entire South Atlantic to five recorded species. Its reproduction mode as a brooder was determined through histological examination, showing embryos in the mesenteries. A key to all extant Astrangia species is provided together with an infographic about its distribution and environmental preferences across the globe.