Revision of Pherecardia Horst, 1886 (Annelida, Amphinomidae)

Amphinomid annelids are classified after the shape of caruncle, the presence and type of branchiae along body segments, and the type of chaetae present. Pherecardia Horst, 1886 was proposed to include species having a large caruncle with a heart-shaped median ridge and lateral lobes. However, generic delineation was not well understood at the time, and some species currently referred to the genus were described in Hermodice Kinberg, 1857 and Amphinome Bruguière, 1789. Pherecardia currently includes four shallow water species: P. maculata Imajima, 2003 from Japan; P. parva Monro, 1924 from the Macclesfield Bank; P. polylamellata de Silva, 1961 from Sri-Lanka; and P. striata (­Kinberg, 1857) from the French Polynesia. Two other species have also been proposed as congeneric: A. ­bruguieresi de Quatrefages, 1866; and A. formosa de Quatrefages, 1866. The genus is best known for its type species, Pherecardia striata (Kinberg, 1857), a common and widespread, large and readily recognized species characterized by numerous longitudinal dorsal pigmented stripes and recorded across the Indo-Pacific from East Africa to the East Pacific. This species has been regarded as relevant for coral reef ecology since it attacks injured predatory crown-of-thorns starfish (Acanthaster planci (Linnaeus, 1758)). Here we review the genus based on examination of type and additional material from 10 museum collections and mitochondrial DNA comparisons of representative specimens from various localities. We recognize three species: P. striata, P. distincta (Hoagland, 1920) (new combination, including P. polylamellata as synonym), and P. maculata (retained pending the study of topotypical specimens). Pherecardia parva is transferred to Pherecardites Horst, 1912 and renamed as Pherecardites monroi because of homonymy with Pherecardites parva Horst, 1912. Amphinome bruguieresi is regarded as a junior synonym of ­Eurythoe indica (Schmarda, 1861); the status of A.formosa cannot be determined. Keys are included for species of Pherecardia and Pherecardites.