Free-living stages of three species of parasitic copepods (Siphonostomatoida, Eudactylinidae) reared from eggs, with discussion on the ontogenetic features in the Siphonostomatoida

Abstract

Five naupliar stages and the infective copopodid stage of Eudactylina dasiati Izawa, 2011, Dangoka japonica Izawa, 2011, and an unidentified eudactylinid species are described based on free-living larvae reared from eggs detached from ovigerous females, which were recovered from the branchial lamellae of Japanese elasmobranchs, Dasyatis akajei (Muller & Henle, 1841) (Dasyatidae), Rhinobatos schlegelii Muller & Henle, 1841 (Rhinobatidae), and Alopias vulpine (Bonnaterre, 1788) (Alopiidae), respectively. These species of Eudactylinidae, along with Gangliopus pyriformis Gerstaecker, 1854 (Pandaridae) are the only Siphonostomatoida known to have five naupliar stages prior to the infective copepodid I. Naupliar morphology and the antennular segmentation in the Siphonostomatoida are discussed. Siphonostomatoid nauplii may possess six caudal elements and limb buds of the maxillae, maxillipeds, and two legs, but not maxillules. In the Siphonostomatoida, the naked first antennular segment of the nauplius may be retained to the adult stage.