A new species of Synagoga (Crustacea: Thecostraca: Ascothoracida) parasitic on an antipatharian from the Azores and Cape Verde Islands, with notes on its morphology, sexuality, host specificity, and biogeography

A new ascothoracidan species has been discovered in the Macaronesia region of the eastern Atlantic Ocean at SCUBA depths. Ten specimens including both sexes of the new species, described herein as Synagoga grygieri sp. nov., were collected from colonies of the antipatharian Antipathella wollastoni (Gray, 1857). Two previously described species of Synagoga, morphologically the most generalized ascothoracidan genus, were found as ectoparasites of an antipatharian and an alcyonacean, respectively, whereas all other records of this genus have been from marine plankton. Synagoga grygieri sp. nov. currently appears to be endemic to Macaronesia, but its true distribution may be wider as its host is known to range from the Mediterranean to the west coast of Africa, and a potentially synonymous congener of the host ranges somewhat northward. The new species is described as having separate males and females, although protandry cannot be fully excluded. This is the first study of a new form of Synagoga to be based on more than a few mature specimens of a single sex or on a single juvenile. Furthermore, it is the first in which SEM has been used to document features other than carapace ornamentation, in particular the distal antennular armature, frontal filament complex, and details of the mouth parts. On the carapace of adult stages, the first and third pairs of lattice organs are oriented with the terminal pore anterior, as in S. millipalus Grygier & Ohtsuka, 1995.