Altumia gen. n.

Diagnosis.

Clavulariinae with a thin and soft encrusting base, sometimes resembling a short stolon. Polyps erect when expanded, separate from each other; the stolon may feature a few polyps, occasionally only one. Polyps fully retractile into base of the colony, forming low truncated dome-shaped mounds. No sclerites in any part of the colony. Colonies lack symbiotic algae (zooxanthellae). Type species: Altumia delicata sp. n. by original designation and monotypy.

Etymology.

The generic name is derived from the Latin ‘altum’, deep, referring to the habitat of the new genus at MCE depths and beyond. Gender female.

Molecular results.

Maximum likelihood and Bayesian analyses yielded identical tree topologies that both support the phylogenetic placement of Altumia n. gen. as the sister taxon to Acanthoaxis wirtzi ( Acanthoaxiidae), within a larger well-supported clade that also includes the Clavulariidae genera Carijoa F. Müller, 1867 and Cryptophyton Williams, 2000 (Figure 1). Pairwise genetic distances (Kimura 2-parameter) between Altumia n. gen. and Acanthoaxis (mtMutS: 9.4%, COI: 2.9%) are comparable to values among different genera and some family-level clades of octocorals (McFadden et al. 2011).