Genus Plakina Schulze, 1880

Type species: Plakina monolopha Schulze, 1880 .

Definition: Encrusting Plakinidae with spicules diods, triods and calthrops (though all may be absent), and always with at least one type of homolophose calthrop, which may have one to four lophate actines and different ramification patterns. Irregular spicules are common and intraspecific variation in spicule shape may be high. One species is skeleton-less (Ruiz et al. 2017).