A New Species of Herpyllobius Steenstrup and Lütken, 1861 (copepoda: Cyclopoida) Parasitic on Lamispina Horsti (haswell, 1892) (annelida, Flabelligeridae) from Western Australia

Herpyllobiid copepods are highly transformed mesoparasites that infect marine benthic polychaete annelids. The genus Herpyllobius Steenstrup and L & uuml;tken, 1861, the most diverse in the family, was known to infect exclusively polychaetes of the family Polynoidae, but it was recently reported also on another family. Species of Herpyllobius have been reported mainly from cold latitudes including Arctic and Antarctic areas, except for two subtropical species. During the taxonomic examination of flabelligerid polychaetes collected from a Western Australian coral reef system, a mesoparasitic copepod was found infecting a specimen of Lamispina horsti (Haswell, 1892). The copepod represents an undescribed species of Herpyllobius . The new species, Herpyllobius paulayi n. sp. belongs to a group of congeneric species (Group III) lacking intergenital processes or sclerotized dots. It diverges from the other species in this group by its possession of a unique combination of characters: 1) a globose ectosoma with pilose surface; 2) elongate, thick cylindrical egg sacs with +10 egg rows; 3) endosoma discoid, short, with two lateral, asymmetrical flattened processes and a medial lobe; 4) it attaches to the host prostomium; and 5) it infects a non-polynoid subtropical polychaete species.