Phylogenetic assessment of a new species of <i>Amigdoscalpellum</i> Zevina, 1978 (Cirripedia: Scalpellidae) associated with caryophyllid cup corals from New Zealand, with a key to the genus

Abstract A new species of deep-sea scalpellid barnacle from northern New Zealand, Amigdoscalpellum calicicolum sp. nov., is described with the aid of micro-computed tomography and analysed phylogenetically. This species is associated with solitary cup corals of the scleractinian coral genus Caryophyllia Dana, 1846, in which they are partially embedded in or overgrown by the coenosteum. Individual specimens were oriented towards the centre of the host polyp and, once removed from the host, left clear scars where the host had grown around them. The newly described species presents a unique combination of morphological features, including a transversely arched carina, a vestigial inframedian latus, an expanded carinolatus that projects dorsally well beyond the carina, no rostral peduncular scales, and very short, uniarticulate caudal appendages. Phylogenetic reconstructions based on mitochondrial and nuclear loci placed A. calicicolum sp. nov. within a clade along with other species of Amigdoscalpellum. Nonetheless, the current sparsity of molecular resources as well as the confused state of the taxonomy of the family Scalpellidae prevents a conclusive determination of its evolutionary relationships.