Cyclopoid copepods (Ascidicolidae, Notodelphyidae) associated with Phallusia nigra Savigny, 1816 (Ascidiacea) in the Red Sea: a new ascidicolid and first descriptions of the males from two notodelphyids

Abstract

A new species of copepod, Styelicola omphalus n. sp., of the family Ascidicolidae is described as an associate or symbiont of the ascidian Phallusia nigra Savigny, 1816 from the Red Sea. As major differential features of the new species, the body is large, more than 4 mm long, the antennule is 5-segmented, the mandibular palp is armed with one or two apical setae, and the maxillary syncoxa, maxilliped, and endopods of legs 1-4 are unarmed. This is the first confirmed ascidicolid reported from the Red Sea. Supplementary descriptions for two additional copepods from the same host, but in the family Notodelphyidae, are provided. Males of Bonnierilla projecta Stock, 1967 and Janstockia phallusiella Boxshall and Marchenkov, 2005 are detailed for the first time. The occurrence and location of the three species of copepods differed within the host. Styelicola omphalus was found in approximately 3% of hosts examined, consistently attached to the visceral mass. Bonnierilla projecta , in contrast, occurred in 63% of hosts and was located in the pharyngeal sac, and J. phallusiella was found attached to the internal surface of the tunic (atrium) in 11% of the hosts examined. Although the ascidian P. nigra has a circumtropical distribution, the copepods discussed above have only been reported from the Red Sea. Approximately 25 species of copepods are known as associates of Phallusia worldwide, but these appear restricted to only three (possibly five) of the 20 species currently recognized in this ascidian genus.