Symbiotic copepods from the ascidians, a hidden diversity of the Mediterranean Sea: Haplostomides magnus n. sp. (Cyclopoida: Botryllophilidae)

This paper reports the first occurrence of five species of symbiotic copepods associated with ascidian species collected in two Sicilian harbours (southern Italy) in the central Mediterranean Sea. These findings integrate the poor information on the symbiotic copepods in ascidian species, with the description of Haplostomides magnus n. sp. (Cyclopoida: Botryllophilidae) found as commensal in the colonial ascidian Polyclinum aurantium. The morphological diagnostic features of the new species include a caudal ramus bearing two spines and two setae, a unique armature condition within this genus. Brief descriptive notes are also provided for several species of copepods associated with ascidian species: Lichomolgus canui Sars G.O., 1917 (Cyclopoida: Lichomolgidae), found in Styela plicata, Doropygus pulex Thorell, 1859 (Cyclopoida: Notodelphyidae), found in Ascidiella aspersa, and Pachypygus gibber (Thorell, 1859) (Cyclopoida: Notodelphyidae) collected among the fouling community. A species belonging to the genus Asterocheres (Siphonostomatoida: Asterocheridae) was also found associated with Styela plicata.