Martin, Daniel; Romano, Chiara. (2021). Morphology and sexual dimorphism of living mature adults of Amphiduros fuscescens (Marenzeller, 1875) (Annelida, Hesionidae, Amphidurine), first reported for the Iberian Peninsula. Biodiversity Data Journal. 9: e66020: 1-13.
Morphology and sexual dimorphism of living mature adults of Amphiduros fuscescens (Marenzeller, 1875) (Annelida, Hesionidae, Amphidurine), first reported for the Iberian Peninsula
To date, the genus Amphiduros (Annelida: Hesionidae: Amphidurine) is considered as monotypic. Its single species, Amphiduros fuscescens (Marenzeller, 1875), is well characterised by lacking proboscideal papillae and emerging acicular chaetae, as well as by having three antennae, eight pairs of tentacular cirri and inflated dorsal cirri with characteristic alternating length and color (transparent, with median orange band and white tips) in live animals.Three specimens, one male and two female, were found below boulders at 5–7 m depth in Punta Santa Anna, Blanes, and Cala Maset, Sant Feliu de Guixols (Catalan Sea, NW Mediterranean, Iberian Peninsula). Our finding allowed us to describe different, unreported morphological traits, and lead us to support the existence of sexual dimorphism (in terms of colouring, cirri morphology and distribution of sexual products along the body). Despite the A. fuscescens has been previously reported from the Atlantic and the Mediterranean (particularly in SE French coasts), the specimens from Blanes represent the first record of the species from the Iberian Peninsula. In addition, our molecular results strongly support that Amphiduros pacificus Hartman, 1961 from California (currently synonymised with A. fuscescens) requires to be redescribed and reinstalled as a valid species. In turn, our morphological observations support suggesting all other non-Mediterranean reports of A. fuscescens, including the species still under synonymy (i.e., Amphidrornus izukai Hessle, 1925, Amphidromus setosus Hessle, 1925) as likely being a cryptic complex whose the taxonomic status require further assessment.
