Description and Complete Larval Development of a New Species of Baccalaureus (Crustacea: Ascothoracida) Parasitic in a Zoanthid from Tanabe Bay, Honshu, Japan

An unidentified species of Zoanthus from Tanabe Bay, Honshu, Japan, is the host of an endoparasitic ascothoracidan crustacean, Baccalaureus falsiramus, new species. This is the first record of this zoanthid genus serving as the host of an ascothoracidan and the second species of Baccalaureus from Japan. The morphology of the adult females, nauplii, and ascothoracid larva is described based upon a detailed study combining light microscopy and SEM. The female of this new species is characterized by a coiled carapace but very short, more or less distally upturned thoracic horns, and very long, ventrally directed papillae for seminal receptacle ducts lateral to thoracopods II-IV. Much variability is recognized in the antennule, thoracopods, penis, and abdominal ornamentation. Larval specimens were individually reared in the laboratory. Six lecithotrophic naupliar instars with rudimentary endites on the antennae and mandibles are present before the ascothoracid larva. The nauplii swam for about one month without feeding until the metamorphosis to the ascothoracid larva. Naupliar instars II-VI have a sculpture of concentric cuticular ridges on the marginal area of the dorsal shield. A nauplius eye is present through all naupliar instars as well as in the ascothoracid larva. Setae are gradually added to the antennules, but the antennae and mandibles remain essentially unchanged after instar III; rudimentary maxillules appear in instar II. The ascothoracid larva is a "Tessmann's larva" similar to one recently described from Hawaiian plankton, but lacking central pores within the carapace reticulations. Morphological and developmental features of the nauplii and ascothoracid larva are discussed

Induced metamorphosis in crustacean y-larvae: Towards a solution to a 100-year-old riddle

<p>Abstract</p> <p>Background</p> <p>The y-larva, a crustacean larval type first identified more than 100 years ago, has been found in marine plankton samples collected in the arctic, temperate and tropical regions of all oceans. The great species diversity found among y-larvae (we have identified more than 40 species at our study site alone) indicates that the adult organism may play a significant ecological role. However, despite intense efforts, the adult y-organism has never been identified, and nothing is therefore known about its biology.</p> <p>Results</p> <p>We have successfully and repeatedly induced metamorphosis of y-larvae into a novel, highly reduced juvenile stage by applying the crustacean molting hormone 20-HE. The new stage is slug-like, unsegmented and lacks both limbs and almost all other traits normally characterizing arthropods, but it is capable of vigorous peristaltic motions.</p> <p>Conclusion</p> <p>From our observations on live and preserved material we conclude that adult Facetotecta are endoparasitic in still to be identified marine hosts and with a juvenile stage that represents a remarkable convergence to that seen in parasitic barnacles (Crustacea Cirripedia Rhizocephala). From the distribution and abundance of facetotectan y-larvae in the world's oceans we furthermore suggest that these parasites are widespread and could play an important role in the marine environment.</p

Integrative taxonomy of crustacean y-larvae (Thecostraca: Facetotecta) using laboratory-rearing and molecular analyses of single specimens, with the description of a new vermiform species

Facetotecta, the taxon established for 'y-larvae', is the last major crustacean group for which the adult stage remains unknown. With only 14 described nominal species, all in the genus Hansenocaris, their incompletely known life cycle, small size and dearth of molecular data have hampered assessments of their true species diversity. Based on field studies during which > 11 000 y-larvae were sampled, a new integrative approach for studying the taxonomy of y-larvae is outlined. It focuses on last-stage nauplii and y-cyprids and includes methods for rearing lecithotrophic y-larvae for documenting the morphology of specimens with live photomicroscopy and scanning electron microscopy (SEM) and for obtaining molecular systematic data. This new and integrated approach, whereby each single specimen provides multiple kinds of information, was implemented to describe Hansenocaris demodex sp. nov., a unique y-larval form with semi-vermiform nauplii that occurs in the waters of Okinawa (southern Japan) and Taiwan. A preliminary Facetotecta phylogeny shows remarkable congruence between the morphology of all newly sequenced y-larvae and molecular data (18S rDNA). Four independent clades are formed by H. demodex and three other types/species of y-larvae, together being the sister-group to a smaller clade including H. itoi and unnamed species from GenBank

Larval and Juvenile Ascothoracida (Crustacea) from the Plankton

Two kinds of previously recorded ascothoracid larvae from plankton over coral reefs in Hawaii and the Virgin Islands are redescribed as possible representatives of the Lauridae and Petrarcidae, respectively. A bathyal, tropical Atlantic ascothoracid larva from an epibenthic sled sample cannot confidently be identified to family. A planktonic, juvenile ascothoracidan from the eastern Indian Ocean belongs to the genus Synagoga

Laboratory Rearing of Ascothoracidan Nauplii (Crustacea : Maxillopoda) from Plankton at Okinawa, Japan

Seven ascothoracidan nauplii of instars II-IV and one ascothoracid-Iarva were captured in inshore plankton at Sesoko Island, Okinawa, Japan, and the nauplii reared in the laboratory until, in two cases, they metamorphosed into ascothoracid-larvae. Naupliar instars II-VI and the ascothoracid-larvae are described and compared to larvae of Baccalaureus falsiramus Ito & Grygier from Tanabe Bay, Honshu, which they closely resemble. Pigmented structures in the ascothoracid-larvae possibly represent vestigial compound eyes. Competing hypotheses about the claw guard and proximal sensory process of ascothoracidan antennules are discussed in light of new ontogenetic data

Cryptoniscidae s.s. (Isopoda : Epicaridea) : Nomenclatural History and Recommendations

The nomenclatural history of the parasitic isopod family Cryptoniscidac Kossmann, 1880 sensu stricto is reviewed, and irregularities are exposed and corrected. Eumetor Kossmann, 1872 and its type species E. liriopides Kossmann, 1872 are available but unrecognizable except by host. Cryptoniscus curuatus fraisse, 1877 is designated here as the type species of Danalia Giard, 1887. Danalia lobiancoi Giard & Bonnier, 1890 is a nomen nudum since it was merely mentioned in a list with its host. At least five of the 12-13 available nominal species currently assigned to Danalia are nearly unrecognizable except by host. Neither Zeuxokoma Zimmer, 1927 nor Zeuxokoma Neave, 1940 qualifies as an available replacement name for the preoccupied Zeuxo Kossmann, 1872 because of lack of reference to the earlier name and lack of a type species designation, respectively. Zeuxokoma nom. nov. is proposed here as a replacement name for Zeuxo Kossmann, and Zeuxo alplzei Kossmann, 1872 is designated here as the type species. The nominal subfamily Fabinae Danforth, 1970 (1963?) is unavailable because neither work involved was published in the sense of the International Code of Zoological Nomenclature. The nominal family Danaliidae Altes, 1982 includes Cryptoniscus Miiller, 1864, and is thus a junior synonym of CryptoniscidaeKossmann, 1880

New Species of Synagoga (Crustacea : Ascothoracida) from Plankton off Okinawa, Japan, with a SEM Study of the Carapace

A free-swimming adult male of the ascothoracidan crustacean Synagoga millipalus sp. nov. is described from plankton in the East China Sea off Okinawa, Japan. This is the first Pacific record of the genus. The new species is distinguished at length from its most similar congener, S. paucisetosa Grygier from the bathyal equatorial Atlantic. The ornamentation of the carapace is described by scanning electron microscopy. The inner surface has a continuous but regionally differentiated, submarginal palisade of partly fused spines as well as lanceolate guard setae with distally pointing barbs, a deep anterior pit, concentric zones of pores, and a cluster of minute pores at the posterior angle. The external surface has rimmed pores and hair sensilla, but most of the diverse outer integumental organs reported from another morphologically generalized ascothoracidan, Waginella metacrinicola (Okada), are absent. Two of the five pairs oflattice organs ( = cardic organs) along the hinge line have anterior rather than posterior pores. This orientation differs from that of other ascothoracidans and tends to weaken a recent analysis, using Ascothoracida as the outgroup, of lattice organ variation among the cyprid larvae of Cirripedia

Comment On The Proposed Conservation Of The Generic Names Porites Link, 1807, Galaxea Oken, 1815, Mussa Oken, 1815 And Dendrophyllia Blainville, 1830 (Anthozoa, Scleractinia)

Volume: 60Start Page: 49End Page: 5

Dendrogaster (Crustacea: Ascothoracida) from California: Sea-star parasites collected by the Albatross

Volume: 42Start Page: 443End Page: 45