A comparative study of the gill area relationships in some talitrid amphipods

The total gill area and gill distribution of seven talitrid species taken from a variety of habitats have been studied. In the sandhoppers, Talitrus and Talorchestia, and in the landhopper, Arcitalitrus dorrieni, the greatest gill area is invested in the posterior gills (G6) whereas in the beachflea, Orchestia spp., G2 has the greatest area. Gills 3, 4 and 5 are characteristically small and G7 is consistently absent in all the species studied. Gill structure and deployment patterns are, in general, quite conservative within the Talitridae. The gills of A. dorrieni are, however, complex in shape and are more convoluted than in the other species studied.

Gill area/body dry weight relationships were established for each species and are compared with previously published data. The Talitridae show a reduction in total gill area compared with most aquatic amphipods. It was observed, however, that the slopes of the calculated regression lines were significantly different between the sandhopper and beachflea genera studied. The reduction in gill area within the Talitridae is discussed in relation to their colonization of land.     

Association of a juvenile phoretic uropodid mite with the beach hopper Traskorchestia traskiana (Stimpson, 1857) (Crustacea: Talitridae)

A phoretic association of an undescribed uropodid deutonymph (Acari: Uropodidae) with the beach hopper Traskorchestia traskiana (Crustacea: Talitridae) is examined. Only juvenile mites (deutonymphs) were found attached to the coxal gills of the 257 beach hoppers examined. Both prevalence (range = 27·1–75·0%) and mean intensity (range = 1·3–3·7) increased as host size increased, possibly due to increased exposure time to the mites and a greater area for attachment in larger hosts. Among the gills, the mites exhibited a preference for coxal gill 5, which may be due to pH and humidity gradients but did not seem to be influenced by grooming or agitation of the gills by adjacent appendages.     

Biodiversity of subterranean amphipod crustaceans: global patterns and zoogeographic implications

Gammaridean amphipod crustaceans are important components of subterranean groundwater communities in many parts of the world. Most subterranean species are stygobionts, which are defined by loss or reduction of eyes and pigment and restriction to hypogean waters. The global subterranean amphipod fauna is composed of about 740 species that are distributed among 36 families and 138 genera; however, 12 families contain about 94% of all hypogean amphipods recorded to date. With respect to number of stygobionts, the four most important families are the Niphargidae, Crangonyctidae, Hadziidae s. lat. (complex), and Bogidiellidae. Many regions of the world contain significant diversities of subterranean amphipods, but the central and southern European-Mediterranean and eastern and southern North American-West Indian regions are clearly superior in taxonomic diversity and species richness. Together these two regions contain about 77% of the world's subterranean amphipod fauna, and their high diversities are attributed in part to geographical heterogeneity and a unique combination of geological and ecological phenomena that include extensive karst terrains, absence of glaciation, and exposure to marine transgressions in the south. Other regions with significant diversities of subterranean amphipods include southern Africa, Australia-New Zealand, eastern Asia, central South America, central Asia, northeastern Africa, and islands of the Atlantic, Pacific, and Indian Oceans. The subterranean fauna of southeastern Asia remains very poorly known to date.     

Host-parasite studies of Trichophrya infesting cutthroat trout ( Salmo clarki ) and longnose suckers ( Catostomus catostomus ) from Yellowstone Lake, Wyoming

Trichophrya sp. (Protozoa) on the gills of cutthroat trout ( Salmo clarki ) and longnose suckers ( Catostomus catostomus ) was studied using light and electron microscopy and tracer techniques. All cutthroat trout, 14 cm in total length and above, from Yellowstone Lake, Yellowstone National Park, Wyoming, were infested with the suctorian. No trichophryans were found on fry or fingerling cutthroat trout. Sixty percent of the examined longnose suckers from the same location were infested. Light microscopy disclosed extensive pathology of gill epithelium in longnose suckers infested with Trichophrya that was not observed for infested cutthroat trout. Electron micrographs show damage to immediate host gill cells by both parasites, depicted by a reduction and lack of mitochondria. Both parasites form attachment helices (0.52 × 0.04 μ m), which may originate in the protozoan cell membrane and function for maintenance of parasite position on the host cell. There was no uptake of 14 C, injected into host fish, via the attachment helices by the parasite that further substantiated the mechanical function for the spiral structure. Protozoan feeding on host tissue may be accomplished by use of necrotic gill tissue and mucus.        

New genera of Bogidiellidae (Amphipoda: Gammaridea) from SW Pacific and Mediterranean marine caves

Two new genera and species of the stygobiont gammaridean amphipod family Bogidiellidae are described from anchialine or fully marine subterranean habitats in Mediterranean and SW Pacific Islands. Fidelidiella pectinata, from a littoral cave in Lifou (Loyalty Islands), differs from any other bogidiellid known thus far by the presence on the left mandible of a modified lacinia which is hypertrophied and expanded laterally, and by the possession of a transverse row of strong rounded processes on the anterior side of the distomedial corner of the fourth segment of the maxillipedal palp. This is the most easterly record of bogidiellid amphipods in the SW Pacific. Racovella uniramea, discovered in a Mallorcan anchialine cave, is remarkable among the Bogidiellidae in exhibiting a combination of only six distal spines on the basal endite of the maxillule, and presence of coxal gills on pereopods 3–6. We place particular emphasis on the determination of segmental homologies of all limbs and on the resolution of fine‐scale integumentary details, in order to provide a sound basis for future comparison with other family members.     

Four new species of Hargicotyle Mamaev, 1972 (Diclidophoridae) parasites on sciaenid fishes from Peru and Chile

Hargicotyle magna sp. nov., Hargicotyle paralonchuri sp. nov., Hargicotyle sciaenae sp. nov., from the gills of the Sciaenids Sciaena fasciata, Paralonchurus peruanus and Sciaena deliciosa, respectively, and Hargicotyle menticirrhi sp. nov. from the gill and mouth of Menticirrhus ophicephalus are described from the northern Chilean and central Peruvian coast. Distinct characteristics of the new species are the distribution of the vitelline follicles; the number and distribution of the testes, the size, shape and number of larval hooks; and the presence of one or two suckers in each clamp.     

Biogeography of amphipods (Crustacea: Amphipoda: Gammaridae) from the central Zagros Mountains,Iran, with descriptions of two new species

Seven species of gammarid amphipods were studied in the relatively small province of Charmahal-Va-Bakhteyari in the central Zagros Mountains, Iran. Of these, four are previously known (Gammarus proiectus, G. komareki, G. syriacus and G. balutchi), one is a new record for the region (G. pseudosyriacus) and two are new species (G. lordeganensis and G. bakhteyaricus). From the taxonomic point of view, head microsculpturing characters were found to be reliable as discriminating sets of characters useful in species identification. Habitat diversification and climatic fluctuations appear to be the main factors for species diversity of the area, and the Zagros Mountains act as a geographical barrier to species distribution.     

A taxonomic study on the Phtisicidae (Crustacea: Amphipoda) of New South Wales,Australia

The present study reviews the taxonomy of the Phtisicidae (Crustacea: Amphipoda) from the coast of New South Wales, Australia. The following seven species are described; Dodecas decacentrum Stebbing, 1910b, Dodecas hexacentrum Mayer, 1903, Hircella cornigera (Haswell, 1879b), Metaproto novaehollandiae (Haswell, 1879a), Notoprotomima smithi gen. nov., sp. nov., Paraproto sp. and Perotripus sp. Generic diagnoses of Notoprotomima gen. nov., Dodecas, Hircella and Metaproto are provided based on the present materials. Notoprotomima smithi is fully described as a new species of the new genus. Dodecas decacentrum differs from Dodecas hexacentrum by the presence of paired dorsodistal projections on pereonite 2, paired mid-dorsal projections on pereonites 3 and 4 and shorter gill length on pereonites 2 and 3. Hircella cornigera and Metaproto novaehollandiae are described in detail. The larger mature males of M. novaehollandiae possess the unusual massive type of the propodus of gnathopod 2. The extended distribution of Perotripus to the New South Wales coast is noted. A key for these phtisicid amphipods from New South Wales, Australia is provided.     

Biology and life cycle of Tmetonyx similis (G. O. Sars, 1891) (Amphipoda,Lysianassidae), a scavenging amphipod from the continental slope of the Mediterranean

The present study focused on the biology and life cycle of Tmetonyx similis, a scavenging amphipod inhabiting the continental slope of the north‐western Mediterranean. All the categories of individuals were observed in the samples. The emergence of offspring occurs in successive cohorts. The lifespan of the females is longer than that of the males, but the sex ratio is strongly in favour of the males. The fecundity was found to be lower than that of the other female crustaceans present in these samples. The growth pattern was modelled. A strong correlation was observed between the length and the weight of the animals collected. Several hypotheses are proposed to explain a sex ratio in favour of males. This result may be explained by a migratory process of the females of T. similis. A comparison of the reproduction strategy is given for the three main scavenger crustacean species (amphipods and isopod) collected in this area.     

Observations on the locomotion and buoyancy of Phronima sedentaria (Forskål, 1775) (Crustacea: Amphipoda: Hyperiidea)

The buoyancy and locomotion of the hyperiid amphipod Phronima sedentaria (which lives in barrels constructed from the tissues of gelatinous animals) was studied. The amphipods were much denser than sea water. Barrels were slightly denser than sea water and had six times the mass of the amphipods living within them. Phronima sedentaria swims much more quickly (by a factor of about 3–4) when swimming without its gelatinous barrel. The barrel is asymmetrical with one aperture (entrance) having about three times the area of that of the other (exit). All sustained swimming was accomplished with the larger barrel aperture directed forwards and the significance of this is discussed. Water flow around the barrel and much of the flow through the barrel was laminar; turbulence was limited to the posterior third of the interior of the barrel and was associated with the beating of the pleopods that provide both propulsion and the respiratory current.     

On Simulium xanthinum,a curious yellow-bodied blackfly of the southwestern Palaearctic region (Diptera: Simuliidae)

An account is given of Simulium xanthinum, an unfamiliar simuliid of the southwestern Palaearctic area remarkable for its mainly bright orange-yellow adult and for the clear yellow-green colour of its larva when alive. The species is described in all life stages (except the unknown egg), and the name Simulium gaudi confirmed as a new synonym of S. xanthinum after examination of types and other material. The finding is reported of pupae and larvae in several limestone streams of Andalusia (southern Spain), notably in the headwaters of the Rio Guadalquivir. SEM examination of the heavily sculptured surface of the pupal gill seems to reveal the occurrence of rows of micropores, and this finding is briefly discussed for its bearing on current debate about the nature of the simuliid pupal gill plastron.     

Crymostygidae,a new family of subterranean freshwater gammaridean amphipods (Crustacea) recorded from subarctic Europe

Crymostygidae, a new family of gammaridean amphipods (Crustacea), is described from Iceland. The family is based on a new species and genus, Crymostygius thingvallensis, found in spring inlets feeding Lake Thingvallavatn, south-west Iceland. This is the first report of a stygobiont freshwater amphipod from Iceland and the northern-most report of a stygobiont species in Europe. The species apparently survived Pliocene and Pleistocene glaciations in the groundwater of a porous lava and may have persisted in Iceland for several million years.     

A new species of Exitomelita (Amphipoda: Melitidae) from a deep-water wood fall in the northern Norwegian Sea

The recently erected amphipod genus Exitomelita (Tandberg et al., 2012) has so far been found only associated with the deep-water hydrothermal vent field “Loki's Castle” in the Norwegian-Greenland Sea. There it was found on the black smoker chimney walls as well as within fields of the tubeworm Sclerolinum contortum in sulphide- and methane-rich sediments surrounding the vent field. A new species has now been found in a large wood fall of pine at 2800 m depth close to this vent field. This group of amphipods is apparently confined to reduced habitats, and our data support the theory that the vent fauna in this area is closely related to fauna found on cold seeps and wood falls in the northernmost Atlantic and Arctic Oceans. Here we present morphological and molecular data and a short discussion of the habitat of the new species, in addition to a comparison with the previously described species of Exitomelita.http://www.zoobank.org/urn:lsid:zoobank.org:pub:2B0B3CC2-AB6A-4006-83BB-182280CB22B8     

Biting mechanism of the amphipod Anonyx (Crustacea: Amphipoda: Lysianassoidea)

Anonyx amphipods feed extensively on dead or weakened animals, often of large size. They cut off strips of food using the wide incisor processes of their mandibles like a pair of shears. The mandibles and associated mouthparts are specialized for this shearing action. The strips of food are coiled and packed into their proventriculi.     

Revision of the isopod crustacean genus Mothocya Costa,in Hope, 1851 (Cymothoidae: Flabellifera), parasitic on marine fishes

The genus Mothocya is fully revised. Irona Schioedte and Meinert is placed in synonymy with Mothocya. All named species but one, including 18 new species, are described and figured in detail. A further eight undescribed species are listed. With one exception Mothocya species are all gill parasites found principally on atherinomorph fishes of the families Hemiramphidae, Belonidae, and Atherinidae. Brief accounts are given of the biogeography, biology and host-parasite interaction of the species of Mothocya. Keys to the species are provided for the different major biogeographic regions.     

New and unusual abyssal gammaridean Amphipoda from the north-east Pacific

Seventeen species of gammaridean amphipods were identified from sediment trap collections in the north-east Pacific, off the central California coast from depths of 3450–4050 m. Four new monotypic genera, Anisocallisoma (Family Scopelocheiridae), Triquetramana (Family Eusiridae), Octomana and Macroarthrus (Family Pardaliscidae) and eight new species, Cyphocaris latirama, Schisturella spinirama, Paracallisoma spinipoda, Anisocallisoma armigera, Triquetramana brevipalpa, Octomana hadromischa, Macroarthrus victoriae, Oedicerina denticulata are described. A number of new and unusual morphological characteristics were discovered, most notably in the family Pardaliscidae, where two of the new genera belong. In addition, new distributional and/or depth records are established for the following species: Procyphocaris indurata (K. H. Barnard, 1925), Scopelocheiropsis abyssalis Schellenberg, 1926a, Rhachotropis distincta (Holmes, 1908), Cleonardo biscayensis Chevreux, 1908b, Cleonardo macrocephala Birstein and Vinogradov, 1955, Pardaliscopsis tenuipalpa Chevreux, 1911, Halice aculeata Chevreux, 1912 and the genus Oedicerina Stephensen, 1931. In order to assist future identification, the new species are fully diagnosed and illustrated. Three tables for comparing characters and a key to the species of Oedicerina are also provided. Additional morphological information and figures are given for existing species that hitherto were poorly described and illustrated. Sediment traps normally employed in studying organic matter fluxes are herewith used for the first time as a source of deep-sea amphipods, and this potentially exciting method is discussed. The high proportion of new taxa illustrates the deficiencies in our knowledge of the abyssal fauna in this area, emphasizes the importance of continued collecting in the deep-sea, and demonstrates the need for increased taxonomic effort to document this diversity.     

Biogeography of coastal and anchialine amphipods of Ascension Island,South Atlantic Ocean

Over 8000 amphipods were examined from coastal (primarily intertidal) and anchialine pool habitats of Ascension Is. Twenty-seven species, of which 14 are undescribed, were identified. Comparison of species from Ascension with amphipods found in possible source areas suggests that most colonization of the island by these animals has been via the Benguela Current. Possible western Atlantic faunal contributions are significantly lower than for other marine taxa that have been studied at Ascension, all of which are generally characterized by having dispersive larval stages. The high proportion of apparently endemic species, which exceeds that described for amphipods of other oceanic islands, is probably due to both the island's isolation and incomplete faunal surveys in possible source areas. Amphipod species diversity is low, a probable consequence of the size, isolation, youth and low habitat variability of Ascension Is. Consistent with other Atlantic islands that have been studied, nestlers predominate (56% of the species), with tubicolous species (33%) of secondary importance and inquilines (11%) making only a minor contribution. Three species occur in the anchialine pool habitat. Rather unexpectedly, caprellid amphipods are absent.     

A revision of Monocotyle Taschenberg, 1878 (Monogenea: Monocotylidae) with descriptions of three new species from Australia

Monocotyle is revised and three new species are proposed. Monocotyle corali sp. nov. is described from the gills of the cowtail ray, Pastinachus sephen (Forsskål) (Dasyatididae), and is distinguished from other members of Monocotyle by the large hamuli with a distinct tail on the guard and by the male copulatory organ with three loops and a wing-like accessory piece at the distal end. Monocotyle jordani sp. nov. from the gills of the southern eagle ray, Myliobatis australis Macleay (Myliobatididae), is differentiated by the male copulatory organ with a large, unique accessory piece. Monocotyle youngi sp. nov., from the gills of Himantura fai Jordan and Seale (Dasyatididae), has marginal haptoral papillae armed with 12 to 15 sclerites, a male copulatory organ with 20 loops and a unique accessory piece at the distal end. Monocotyle trygoni (Venkatanarsaiah and Kulkarni, 1980) Timofeeva, 1985 is synonymized with M. spirophallus Tripathi, 1959 and M. spirophallus is redescribed fully. There are now 16 valid species of Monocotyle and a key to species is presented. Additional data and illustrations of important taxonomic characters are provided. The developmental sequence of the male copulatory organ of M. spiremae Measures, Beverley-Burton and Williams, 1990 from juvenile to adult is described. The anterior glands and the type of secretion they contain are also documented for several species of Monocotyle.     

A new South American genus and species in the amaryllidid group of lysianassoid Amphipoda

Erikus dahli, a new genus and species in the amaryllidid group of lysianassoid amphipods, is described and illustrated from South American material.