A review of naupliar development within the Harpacticidae, with naupliar description of Zaus wonchoelleei Kangtia, Dahms, Song, Myoung, Park & Khim, 2014 (Copepoda, Harpacticoida)

All six naupliar stages of the harpacticoid copepod Zaus wonchoelleei Kangtia, Dahms, Song, Myoung, Park & Khim, 2014 are described. A key for the identification of the naupliar stages is provided. Stages can be distinguished by number of segments of the exopod of antenna 2, setation of the limbs including the bud of the caudal ramus, and presence and setation of the bud of maxilla 1. In phylogenetic reconstructions there are several characters which link two taxa of different harpacticoid groups, the Harpacticidae of Exanechentera and the Thalestridae of Podogennonta. The Harpacticidae and the free-living genera of the Thalestridae develop from a 3-segmented naupliar antennular precursor in Harpacticidae and a 1-segmented antennule in Thalestridae to a 6-segmented antennule at copepodid I. Both families also share a single, stout spine terminally on the inner process of the mandibular naupliar endopodite which is unique for harpacticoid nauplii. A peculiar medial bifid seta on the antennal basis at nauplius I and II is also unique. This seta is replaced by a medial seta of the coxa at nauplius III, which has the same structure as the aforementioned set which gets reduced.