Dolabrifera dolabrifera ( Rang, 1828 )

Dolabrifera dolabrifera ( Rang, 1828) View in CoL has been

c o n s i d e r e d a p a n t r o p i c a l s p e c i e s o f s e a h a r e ( Aplysiidae ), typically found under rocks in the upper intertidal zone ( Kay, 1964; Bebbington, 1974) and on mudflat pools ( Bebbington, 1977). Numerous species names have been introduced for specimens from different geographical locations over the years, but nearly all of them have been synonymized with D. dolabrifera ( Engel & Hummelinck, 1936; Eales, 1944). Dolabrifera dolabrifera displays a considerable range of variation in colour, external morphology and anatomy ( Marcus, 1972), which suggests it could constitute a species complex. Recent molecular studies have shown that other tropical and subtropical widespread heterobranch sea slugs resulted to be species complexes with marked geographical structure ( Ornelas-Gatdula et al., 2012; Alexander & Valdés, 2013; Krug et al., 2013; Carmona et al., 2014a, b; Goodheart et al., 2015), and D. dolabrifera could be a similar case. Adding to the taxonomy complexity in Dolabrifera , the closely related temperate Australian species, Dolabrifera brazieri G. B. Sowerby II, 1870 , is considered distinct by some authors ( Klussman-Kolb, 2004; Burn, 2006), but the relationships between the two species is unclear.

Specimens of Dolabrifera contain secondary metabolites with potential medical applications. For example, the propionate-derived compound Dolabriferol with antibiotic properties ( Kigoshi & Kita, 2015) was originally characterized from specimens collected in the Caribbean region ( Ciavatta et al., 1996). Subsequent studies on other Caribbean animals revealed the presence of chemically related, but distinct compounds ( Jiménez-Romero, González & Rodríguez, 2012). Further research on specimens from the Eastern Pacific resulted in the isolation of 5α,8α- epidioxycholest-6-en- 3β- ol, a compound with antileishmanial properties ( Clark et al., 2013). This chemical diversity may be suggestive of a more complex taxonomy than previously recognized. The recent discovery of cryptic species complexes in other biomedically important groups of sea slugs ( Krug et al., 2013; Lindsay & Valdés, 2016) highlights the need for modern approaches to investigate the biodiversity of such groups.

In this article, we examine the systematics of Dolabrifera dolabrifera and D. brazieri using a combination of molecular and anatomical data to determine the taxonomic status of these two nominal species and unveil possible cryptic diversity in this group.