Kim Larsen

PROPOSED NEW STANDARDIZED ANATOMICAL TERMINOLOGY FOR THE TANAIDACEA (PERACARIDA)

Abstract A summary of terminologies and nomenclature currently or previously employed to describe tanaidacean appendages and somites are presented together with a proposed new standardized terminology for the order Tanaidacea. Standardized expressions and nomenclatures are suggested for all tanaidacean somites, appendages, and their articles, as well as for the orientation of tanaidacean appendages.

The fauna of hydrothermal vents on the Mohn Ridge (North Atlantic)

Abstract The macrofauna of the newly discovered hydrothermal vent field on the Mohn Ridge at 71°N was investigated. Samples were collected during the cruise BIODEEP 2006 using the ROV ‘Bathysaurus’. A total of 180 species-level taxa were identified. The region contains very few vent-endemic species, but some species of Porifera, Crustacea and Mollusca may be vent-associated. Dense aggregations of motile non-vent species such as Heliometra glacialis and Gorgonocephalus eucnemis surrounded the vent area, but the area in general only held small numbers of sedentary animals. Calcareous sponges comprised an unusually high portion of the sponge species found and they constitute one of the first pioneers among the sessile invertebrates settling on these vents. Possible explanations for the structure of the fauna in the region are discussed.

TANAIDOMORPHAN SYSTEMATICS-IS IT OBSOLETE?

A new species of the genus Bathytanais is described and its impact on the unstable taxonomy of the family Paratanaidae is discussed. A full description of the adult female and the manca of Bathytanais juergeni, new species, is presented. Males remain unknown for the genus. Scanning electron micrographs of B. juergeni reveal that the carapace consists of articulated plates, not a uniform carapace, and that the coxae of pereiopods 4-6 are expanded to form sternal plates. The genus Bathytanais is retained in the family Paratanaidae, but the family is redefined. The related families/subfamilies Anarthruridae, Typhlotanaidae, and Leptognathiinae are critically reviewed. The taxonomic concepts that were suggested by Sieg for the above-mentioned families fail when setal homologies are critically evaluated. The number of articles in the uropodal rami, often used in generic and family diagnoses, is found to be ambiguous, owing to partial fusion of articles.

The embryonic development of the olfactory system in Amphiprion melanopus (Perciformes: Pomacentridae) related to the host imprinting hypothesis

Development of the olfactory system in anemonefish embryos of the species Amphiprion melanopus was examined from day six post-fertilization, until hatching (day nine). An olfactory placode with receptor cells lining the epithelium and nerve axons from the placode into the olfactory bulb, was observed on newly hatched embryos. In addition, two different secondary bilateral receptor systems were found. These findings may firstly support the anemonefish host imprinting hypothesis, and secondly indicate that the ontogenetic timing of this imprinting mechanism occurs towards the end of the embryonic development.

DEEP-SEA TANAIDACEANS (CRUSTACEA: PERACARIDA) FROM THE ALBATROSS CRUISES 1885-86 WITH KEYS TO THE SUBORDER NEOTANAIDOMORPHA

Previously unidentified tanaidacean material from the US Albatross cruises 1885–86 revealed a number of new species. Most species belonged to the suborder of Neotanaidomorpha, of which two new species were found. Neotanais gardineri n. sp. is described. The species N.insolitus is transferred to the genus Venusticrus. Additional information of previously described species of Neotanais is given. The existence of a cheliped ischium within the Neotanaidae is noted. A species list for the new material from the Albatross Expedition is given as well as complete keys to the females of the suborder Neotanaidomorpha. Species of the suborder Tanaidomorpha were also found. The new species Collettea wilsoni is described (Family indet). Also found were two undesribed species of Anarthruridae (Anarthrurinae), as well as a large number of Agathotanais ingolfi.

THE TANAIDACEAN FAUNA (PERACARIDA) FROM A DEEP-SEA COLD-SEEP IN THE GULF OF MEXICO

Abstract The tanaidaceans collected by submersible from a deep-sea cold-seep site in the Gulf of Mexico were examined. Three new genera and four new species are described. Species belonging to the genera Coalecerotanais new genus, Bathyleptochelia new genus, Crurispina new genus, Araphura, and Paranarthrura were identified. The tanaidacean fauna of this cold seep was composed of several evolutionary lines of both shallow-water and deep-water origin. Mouthpart dissimilarity suggests that several different feeding strategies are employed.

A New Polymorphic Species of Leptochelia (Crustacea: Tanaidacea) from Guinea Bissau, West Africa, with Comments on Genetic Variation within Leptochelia

ABSTRACT Anew species of Leptochelia, namely L. africana, is described from Guinea Bissau, West Africa, following the collection of specimens during the Laboratory of Marine Community Ecology and Evolutions sampling expedition to Macaronesia and Portugals former colonies. Genetic and morphological analysis separates this species from the other east-Atlantic species of Leptochelia, a genus known for its combination of many cryptic species, considerable intra-specific variation, and multiple morphological forms. The diagnostic characters of the female are: antennule proximal article more than 3 times as long as wide, article 2 not longer than article 3; dorsodistal spiniform seta on antennal article 2 weaker than ventrodistal; setae not arising from a process; maxilliped basis with three distal setae longer than endites, palp article 2 with outer spiniform seta arising from a process; uropod exopod biarticulated, longer than proximal endopod article; and endopod terminal article longer than other articles. The males are structurally more complicated and cannot be assigned diagnostic characters based on morphology alone. The primary males have an uniarticulated uropod exopod, whereas that of the secondary males is biarticulated.

Amphipoda (Crustacea: Peracarida) from chemically reduced habitats; the hydrothermal vent system of the north-east Pacific. Part II. Melitidae and Eusiridae

The amphipod fauna from habitats in hydrothermal vents on the Juan de Fuca Ridge, Escabana Trough, and Gorda Ridge and from experimental wood deployments is examined. The material revealed one new species of Melitidae, Bathyceradocus wuzzae , and one of Eusiridae, Leptamphopus fragilis .

A NEW GENUS AND SPECIES OF FRESHWATER TANAIDACEAN, PSEUDOHALMYRAPSEUDES AQUADULCIS (APSEUDOMORPHA: PARAPSEUDIDAE), FROM NORTHERN TERRITORY, AUSTRALIA

Abstract A new genus, Pseudohalmyrapseudes, and species, P. aquadulcis, of apseudomorphan tanaidacean from a freshwater spring in the Northern Territory, Australia, is described and illustrated. The new genus is placed in the family Parapseudidae and is closely related to Halmyrapseudes but differs by possessing: 1) a four- or five-articulated inner antennular flagellum; 2) a male cheliped lacking carpal lobes and with a defined tooth on the dactylus; 3) setae on the dorsal margins of the basis of the pereopods 2–4; 4) the ventral margin of merus and carpus of pereopod 6 bearing simple setae. Pseudohalmyrapseudes is suggested to occupy a phylogenetic position between Halmyrapseudes and Longiflagrum. Apseudes mussauensis conforms to the diagnosis of Pseudohalmyrapseudes and is transferred to this genus.

Revision of the tanaidomorphan deep-sea genus Tanaella (Crustacea: Tanaidacea)

The genus Tanaella is revised and the generic diagnosis redefined. Both genders of the type species, Tanaella unguicillata and T. ochracea are redescribed. Two new species, T. prolixcauda and T. mclellandi, are described from deep-sea localities in the Gulf of Mexico. Male Tanaella possess fully functional mouthparts resembling, but not identical to, those of the females. Distribution and ecological information are given for all species in the genus and a key to Tanaella is also given.