Wim Vader

Notes on Norwegian marine amphipods 1–3

Abstract 1. The first Norwegian specimens of the lysianassid amphipod Acidostoma nodiferum Stephensen are recorded, and the distribution of the species is mapped. The animals were collected in association with the sea anemone Actinostola callosa (Verrill), which is in agreement with recent anatomical work suggesting ectoparasitical habits for species of Acidostoma. 2. The Norwegian records of the photid amphipod Leptocheirus hirsutimanus (Bate) are enumerated, and some notes given on a specimen recently collected near Bergen. Earlier reports of the occurrence of L. pilosus Zaddach in Norway are erroneous, but both this species and L. pectinatus (Norman) may eventually be found in Norwegian waters, judging from their distribution in NW Europe. 3. The lysianassid amphipod Onisimus normani G. O. Sars is shown, both from scattered notes in the literature and from recent observations near Bergen, to be a regular associate of a number of large sea anemone species. The distribution of O. normani is mapped and so...

What is, and what is not, Caprella acanthifera Leach, 1814 (Amphipoda, Caprellidea)? Part 1: the acanthifera-group

The taxon Caprella acanthifera auct., usually considered to be one ‘highly variable’ species, is shown here to consist of a number of closely related species. In this paper three species of the group lacking an axillary spine near the insertion of gnathopod 2 are described and illustrated; the taxa with an axillary spine will be dealt with in a separate paper. This paper redefines Caprella acanthifera Leach 1814, sensu stricto; the nominal taxa C. hystrix, C. calva, C. aspera, and C. leptonyx are considered to be junior synonyms. Also described are C. stella sp.n., from starfish at the Azores and C. cavediniae sp.n., living among algae in the Mediterranean. The sources of apparent morphological variability in caprellids are discussed.

Amphipods associated with the sea anemone, Bolocera tuediae, in Western Norway

Abstract A study has been made on the biology of the sea anemone, Bolocera tuediae (Johnston), its biotope, and the amphipod species associated with it. The study is based on regular sampling in Korsfjorden, western Norway, from August 1967 to November 1968, with occasional samples elsewhere. Onisimus normani Sars was present in 67 to 80% of the Bolocera collected in Korsfjorden. The incidence of infection showed a distinct seasonal variation, which can be explained by the annual cycle of the amphipod. Up to 20 specimens of Onisimus have been found in a single Bolocera. Small specimens of Bolocera are less frequently and heavily infected than big ones. Aristias neglectus Hansen was not found in Korsfjorden, but occurred regularly in Bolocera specimens from Raunefjorden. A. neglectus had earlier been reported in association with Porifera, Echinodermata, and Tunicata, but not with Coelenterata.

Redescription and biology of Stenothoe brevicornis Sars (Amphipoda: Crustacea), an obligate associate of the sea anemone Actinostola callosa (Verrill)

The amphipod Stenothoe brevicornis Sars, 1883 (Crustacea: Amphipoda: Stenothoidae) is redescribed using material from the Tromso area, northern Norway. It is characterized by a reduced armament of antennae and legs and very small secondary sexual differences. S. brevicornis is an obligate and host-specific associate of the actiniid sea anemone Actinostola callosa (Verrill). The amphipods spend their entire life-cycle among the tentacles of their host and feed mostly on host tissue. A short review of associations involving Stenothoe species is given. Most species live among hydroid polyps or algae, a few i or on sponges, ascidians, hydro-corals, and sea anemones.

Physiological adaptations in associated amphipods

Abstract Clear physiological differences exist in tolerance to the special conditions within the gastro-vascular cavity of sea anemones between species of lysianassid amphipods habitually found living in this habitat and closely related free-living species. The free-living amphipods, Orchomenopsis obtusa and Tryphosa horingii, are quickly killed by toxic substances produced by the sea anemone, both in in vivo experiments and in in vitro experiments using extracts from the mesenterial filaments, while the species associated with sea-anemones, Aristias neglectus and Onisimus normani, survive for long periods. The toxic substances are large organic molecules, probably of a protein nature. The different tolerances to the toxic substances seem to be genetically determined and not acquired during the life of the individual, in contrast to the situation in the anemone-fishes.

Occurrence of Stomatolepas elegans (Cirripedia: Balanomorpha) on a leatherback turtle from Finnmark, northern Norway

Stomatolepas elegans on a Dermochelys coriacea is reported at Seiland, Finnmark, northern Norway at the highest latitude recorded for this species or for any members of its subfamily (Platylepadidae), as well as for its turtle host. The distribution of the species of Stomatolepas is given and their taxonomy is briefly discussed. A recording of data on the different species of Stomatolepas gives the distribution on the host as well as the identity and the collecting locality of the latter.

Stegocephalid (Crustacea, Amphipoda) species collected in the biof ar and bioice programmes

Abstract The present paper presents a survey of the stegocephalid (Crustacea, Amphipoda) species collected during both the BIOFAR programme around the Faroe Islands and the BIOICE programme around Iceland. Altogether, the two programmes have secured 2419 stegocephalid specimens belonging to 16 species and 10 genera. 525 of these specimens were secured during the BIOFAR programme (47 different stations) while the remaining 1894 specimens were secured by the BIOICE programme from 66 different stations. Two new species are described, and 10 species new to the area reported.

Associations between gammarid and caprellid amphipods and medusae

Abstract Published records of association between non-hyperiid amphipods and medusae are reviewed. The amphipod partners belong to the families, Amphilochidae and Stenothoidae, the medusae are either Hydromedusae or Rhizostomeae. The amphipods seem to feed on secretions from their hosts.

Associations between amphipods and molluscs. A review of published records

Abstract Published records of association between amphipods and living molluscs are reviewed. Two types of associations can be distinguished: sheltering under intertidal gastropods or chitonids, and inquilinism in the branchial cavity of bivalves.

Prehensile pereopods in Gammaridean Amphipoda

A number of amphipod species in at least 14 different families have prehensile, usually subchelate, pereopods. Most of these species belong to one of two biological groups, i.e. pelagic predators or associates of large Crustacea. In the latter group prehensile pereopods appear to be an adaptation to prevent dislodgement during grooming behaviour of the host. Little clarity is to be gained by splitting off single crustacean-associated amphipod species wIth prehensile pereopods from their congeners which live in biologically similar associations with non-grooming hosts, as has been done recently for a number of monotypic genera, described ‘on prehensile pereopods’.