(Jensen 1992), thus it is important to determine the type locality of all available names for this species complex. No type locality was specified in the original description of Thallepus ornatus, but because Reverend Guilding [1797–1831] lived in St. Vincent and worked exclusively on Caribbean natural history (Howard & Howard 1985), it is almost certain that the specimen used in the drawing was found in the Caribbean Sea. Two other large species of Elysia
feeding on Bryopsis
spp. were described from the tropical Pacific. Both have a black band along the parapodial edge and a submarginal orange band similar to those of E. ornata
. The first species, E. grandifolia
(Kelaart, 1858), was described from Sri Lanka as having black and gold marginal lines along parapodia that fused with the tail (Kelaart 1858). The second species, E. marginata
(Pease, 1871) was originally described from the Hawaiian Islands and subsequently from Tahiti as having a white band between the orange and black marginal bands (Pease 1871). Authorities subsequently debated whether E.grandifolia
had denticulate teeth (Eliot 1904, 1908; O’Donoghue 1932). Both E. marginata
and E. grandifolia
were synonymized with E. ornata
based on morphological comparisons between Pacific and Caribbean material (Ev. Marcus 1980; Heller & Thompson 1983; Jensen 1992).
Recent integrative taxonomic work revealed that the E. marginata-grandifolia
complex contained four candidate species in Pacific, all distinct from each other and from E. ornata
by (1) molecular sequence analyses of two genetic loci; (2) external features including color of rhinophores and marginal bands, folding of parapodia into siphonal openings, tail shape, and pattern of dorsal vessels; and (3) color and pattern of ECY (Krug et al. 2013). Elysia ornata
is therefore restricted to the Caribbean, and some related Pacific species await formal description.
Other genetically distinct Indo-Pacific species have a similar external morphology and anatomy and have been placed in the synonymy of