PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 114(1):237-261. 2001. Nauplii and copepodids of Scottomyzon gibberum (Copepoda: Siphonostomatoida: Scottomyzontidae, a new family), a symbiont of Asterias rubens (Asteroidea) V. N. Ivanenko, Frank D. Ferrari, and A. V. Smurov (VNI & AVS) Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow, 119 899, Russia; (PDF) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560-0534, U.S.A. Abstract. — Naupliar and copepodid stages of Scottomyzon gibberum (Scott & Scott, 1894) associated with the starfish Asterias rubens Linnaeus, 1767 in the North and White Seas were collected from the host or reared in the labo-ratory. There are six copepodid stages and four naupliar stages. Changes in size and proportions of the prosome of adult females result from an expansion of unsclerotized integument along the margins of the shield of the cephalotho-rax and tergites of the second and third thoracic somites. The monotypic genus Scottomyzon Giesbrecht, 1897 is transferred to a new family Scottomyzontidae on the basis of a 3-segmented abdomen for adults of both sexes, paired dor-solateral gonopores near the posterior margin of somite, paired ventral copu-latory pores near the middle of somite, and sexual dimorphism in oral siphon. Scottomyzon gibberum (Scott & Scott, 1894) currently is the only species in the monotypic genus Scottomyzon Giesbrecht, 1897 of the Asterocheridae. The copepod is associated with the starfish Asterias rubens Linnaeus, 1767 in the North Sea and the White Sea, and with many different species of starfishes in the Sea of Japan (Humes 1986, Kim 1992, Smurov 1993). In slightly more then 100 years since its description, this "highly interesting copepod" (Bresci-ani & Luetzen 1962:381) has been rede-scribed by Roettger (1969) and by Kim (1992). Roettger considered the unusual variability among mature females. Smurov & Ivanenko (1993) and Ivanenko & Smu-rov (1995, 1996) discussed growth of the adult female, morphology and settlement of the first copepodid stage, and bacterial in-festation of the exoskeleton of White Sea specimens. Descriptions of postembryonic develop-ment of siphonostomatoids associated with invertebrates are not as numerous as those of siphonostomatoids parasitizing fishes. Naupliar and copepodid stages of inverte-brate symbionts are described for the can-cerillid Cancerilla tubulata Dalyell, 1851 by Carton (1968) and the asterocherid As-terocheres simulans (Scott, 1898) by Mur-nane (1969), although some incorrect sche-matic illustrations and errors in identifica-tion of copepodid stages limit the use of these data. Development of parasitic nicoth-oids have been reported by Bowman & Kornicker (1967), Boxshall & Lincoln (1983), and Heron & Damkaer (1986). Knowledge about changes in morphology of adult parasitic copepods is not as well known as changes in adult free-living crus-taceans (Freeman 1993), and there are only a few studies of growth of the siphonosto-matoid females (Kabata 1979, Smith & Whitfield 1988, Piasecki 1989). We present here the first detailed description of the complete postembryonic development, in-cluding morphological changes in adult fe-
Nauplii And Copepodids Of Scottomyzon Gibberum (Copepoda : Siphonostomatoida : Scottomyzotidae, A New Family), A Symbiont Of Asterias Rubens (Asteroidea)
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