Elysia cf. marginata sp. 4
“Elysia cf. marginata sp. 4": Parapodial edges smooth, with three successive colored bands: (1) black marginal band; (2) orange submarginal band; (3) very thick, white submarginal band, farthest from the edge. Sides of parapodia dotted by large black spots and larger white patches. Tail tapering to end of body but not pointed or elongated. Proximal two-thirds of rhinophores red, distal third black; white spot on head extending up each rhinophore. Rounded pericardium tapers to a point; white with black spots.
“Elysia cf. marginata sp. 4", nick-named "white lines", is one of 4 cryptic species in the Elysia marginata complex recently documented from the Indo-Pacific using a combination of molecular, morphological, and developmental characters. Found on the green algal genus Bryopsis, species in this complex are sometimes termed "E. ornata", which is a distinct Caribbean species, or "E. grandifolia", an Indo-Pacific taxon with no definitive characteristics.
known only from Japan
Members of the Elysia marginata complex and the related species E. rufescens are sources of anti-cancer compounds called kahalalides, depsipeptides derived from the algal diet of the slug; unrecognized cryptic species in this complex introduce confusion into drug discovery work by obscuring the source of new kahalalides. Clarifying taxonomic uncertainty is thus important for natural products chemistry and bioprospecting for novel chemotherapeutic agents.