Lattice organs in y-cyprids of the Facetotecta and their significance in the phylogeny of the Crustacea Thecostraca

Hoeg, J.T. and Kolbasov G.A. 2002. Lattice organs in y-cyprids of the Facetotecta and their significance in the phylogeny of the Crustacea Thecostraca. — Acta Zoologica (Stockholm) 83 : 67‐79 Scanning and transmission electron microscopy (SEM and TEM) were used to study lattice organs in facetotectan y-cyprids from the White Sea and from Norwegian and Bahamian waters. The larvae represent at least four and possibly five different species of Facetotecta. Y-cyprids have five pairs of lattice organs in the head shield (carapace) organized into two anterior pairs and three posterior pairs. Both groups of lattice organs are arranged around a large central pore. The facetotectan lattice organs are elongate areas with a longitudinal keel, just as in the Ascothoracida and some Cirripedia Acrothoracica. The terminal pore of the organs is situated posteriorly in all five pairs. TEM confirms that the organs have the same general morphology as in the Cirripedia and Ascothoracida, namely, a cuticular chamber into which project ciliary segments from the chemosensory cells. Unlike Cirripedia the cuticular roof of the chamber lacks any pores. We conclude that five pairs of lattice organs represent an autapomorphy for the Thecostraca, which supports the monophyly of this taxon. In the ground pattern the terminal pore is posterior in all five pairs. The anterior position of the pore in lattice organ pair 2 is apomorphic for the Cirripedia, while within this taxon an anterior position also in pair 1 is apomorphic for a monophylum comprising the Thoracica and the Rhizocephala. Minute pores in the roof of the organs is another apomorphy of the Cirripedia, but its elaboration into pores visible with SEM may have been subject to some homoplasy. Since lattice organs are omnipresent in the settling instar of the Thecostraca they probably serve a critical role for the function of these cypris or cypris-like larvae.

[1]  J. Høeg,et al.  Larval development of the rhizocephalan cirripede Briarosaccus tenellus (Maxillopoda: Thecostraca) reared in the laboratory: a scanning electron microscopy study , 1996, Hydrobiologia.

[2]  K. Crandall,et al.  PHYLOGENY OF THE THORACICAN BARNACLES BASED ON 18S rDNA SEQUENCES , 2000 .

[3]  R. Perl-Treves,et al.  ELUCIDATION OF THE PHYLOGENETIC RELATIONSHIP OF THREE THECOSTRACANS, VERRUCA, PARALEPAS, AND DENDROGASTER BASED ON 18S rDNA SEQUENCE , 2000 .

[4]  F. Schram,et al.  Crustaceans and the Biodiversity Crisis , 1999 .

[5]  J. Høeg,et al.  Scanning electron microscopy of acrothoracican cypris larvae (Crustacea, Thecostraca, Cirripedia, Acrothoracica, Lithoglyptidae) , 1999 .

[6]  J. Høeg,et al.  TEM studies on the lattice organs of cirripede cypris larvae (Crustacea, Thecostraca, Cirripedia) , 1998, Zoomorphology.

[7]  J. Gibert,et al.  Molecules and the body plan: the Hox genes of Cirripedes (Crustacea). , 1998, Molecular phylogenetics and evolution.

[8]  R. Perl-Treves,et al.  PHYLOGENETIC POSITION OF IBLA (CIRRIPEDIA: THORACICA) BASED ON 18S rDNA SEQUENCE ANALYSIS , 1998 .

[9]  J. Høeg,et al.  New evidence on the basic phylogeny of the Cirripedia Thoracica , 1998 .

[10]  G. Kolbasov.  The significance of symbiosis in the evolution of sessile barnacles (Cirripedia Balanoidea) , 1996 .

[11]  J. Høeg.  The biology and life cycle of the Rhizocephala (Cirripedia) , 1995, Journal of the Marine Biological Association of the United Kingdom.

[12]  J. Høeg,et al.  Cladistic analysis of the Cirripedia Thoracica , 1995 .

[13]  J. Høeg,et al.  New Frontiers in Barnacle Evolution , 1995 .

[14]  J. Høeg.  Sex and the single cirripede: a phylogenetic perspective , 1995 .

[15]  T. Spears,et al.  Phylogenetic Study of Cirripedes and Selected Relatives (Thecostraca) Based on 18s Rdna Sequence Analysis , 1994 .

[16]  J. Høeg,et al.  Scanning electron microscopy of lattice organs in cyprids of the Rhizocephala Akentrogonida (Crustacea: Cirripedia) , 1994 .

[17]  J. Høeg,et al.  Comparative SEM Studies of Lattice Organs: Putative Sensory Structures on the Carapace of Larvae from Ascothoracida and Cirripedia (Crustacea Maxillopoda Thecostraca) , 1994 .

[18]  D. Walossek.  The Upper Cambrian Rehbachiella and the phylogeny of Branchiopoda and Crustacea , 1993, Fossils and Strata.

[19]  J. Høeg.  The Phylogenetic Position of the Rhizocephala: Are They Truly Barnacles? , 1992 .

[20]  M. Grygier.  TOWARDS A DIAGNOSIS OF THE FACETOTECTA (CRUSTACEA : MAXILLOPODA : THECOSTRACA).(Taxonomy and Systematics)(Proceedings of the Sixty-Second Annual Meeting of the Zoological Society of Japan) , 1991 .

[21]  T. Itô.  Naupliar Development of Hansenocaris furcifera Ito (Crustacea : Maxillopoda : Facetotecta) from Tanabe Bay, Japan , 1990 .

[22]  T. Itô,et al.  Description and complete larval development of a new species of Baccalaureus (Crustacea: Ascothoracida) parasitic in a zoanthid from Tanabe Bay, Honshu, Japan. , 1990 .

[23]  T. Itô.  A New Species of Hansenocaris (Crustacea : Facetotecta) from Tanabe Bay, Japan , 1989 .

[24]  Makoto Takenaka,et al.  Identification of Bifurcate Paraocular Process and Postocular Filamentary Tuft of Facetotectan Cyprids (Crustacea : Maxillopoda) , 1988 .

[25]  M. Grygier.  New records, external and internal anatomy, and systematic position of Hansen's y-larvae (Crustacea: Maxillopoda: Facetotecta) , 1987 .

[26]  T. Itô.  Proposal of New Terminology for the Morphology of Nauplius Y (Crustacea: Maxillopoda: Facetotecta), with Provisional Designation of Four Naupliar Types from Japan , 1987 .

[27]  T. Itô.  Three Forms of Nauplius Y Type VIII Larvae (Crustacea : Facetotecta) from the North Pacific , 1987 .

[28]  T. Ito.  PROBLEMS IN THE TAXONOMY OF NAUPLIUS Y AND CYPRIS Y (CRUSTACEA) : Taxonomy and Systematics , 1986 .

[29]  T. Itô.  A New Species of "Cypris Y" (Crustacea : Maxillopoda) from the North Pacific , 1986 .

[30]  T. Itô.  Three Types of "Nauplius Y" (Maxillopoda : Facetotecta) from the North Pacific , 1986 .

[31]  M. Grygier.  Comparative morphology and ontogeny of the ascothoracida, a step toward a phylogeny of the maxillopoda , 1985 .

[32]  T. Itô.  ANOTHER CYPRIS Y FROM THE NORTH PACIFIC, WITH REFERENCE TO THE BENDING BEHAVIOR EXHIBITED BY A CYPRIS Y SPECIMEN OF THE FORMERLY DESCRIBED TYPE (CRUSTACEA : MAXILLOPODA) , 1984 .

[33]  S. Ohtsuka,et al.  CYPRIS Y FROM THE NORTH PACIFIC (CRUSTACEA : MAXILLOPODA) , 1984 .

[34]  Wayne P. Maddison,et al.  Outgroup Analysis and Parsimony , 1984 .

[35]  P. S. Lake.  Trialdehyde Fixation of Crustacean Tissue for Electron Microscopy , 1973 .

[36]  A. Fosshagen.  Marine biological investigations in the Bahamas , 1972 .

[37]  T. Schram.  14. Cypris y, a later developmental stage of nauplius y Hansen , 1970 .