The natural environment in polar regions is being transformed, glaciers are melting and succession of microarthropods is being observed. We tested the hypothesis that habitat conditions, determined by the locality and character of the vegetation cover, play a significant role in such succession. The material for analysis was collected from four localities on King George Island in Antarctica: Arctowski Station, Demay Refuge, Republica del Ecuador Refuge and Comandante Ferraz Antarctic Station. From each locality, 30 samples (grasses, lichens, mosses) were collected and 310 508 microarthropod specimens were recorded, with 17 species (1 Mesostigmata, 9 Oribatida, 7 Collembola species) identified. Based on statistical analyses, it was shown that microarthropod communities differ both in individual localities and selected microhabitats. The greatest number of species was reported in the grass turf, while the greatest number of individuals was recorded in mosses. The dominant species at all the localities was Cryptopygus antarcticus antarcticus (299 203 individuals), which was found in greatest numbers in grasses and mosses. In turn, Tullbergia mixta (2485 individuals) was the dominant species of the lichens. Moreover, the following species, new to King George Island, were also identified: Flagrosuctobelba subcornigera, Liochthonius australis, Membranoppia ventrolaminata and Quadroppia monstruosa belonging to Oribatida as well as Archisotoma brucei belonging to Collembola.

This study examines global zoogeographic patterns of estuary-associated fishes using meta-assemblages compiled at the marine ecoregion scale. The classification of biogeographic regions based on estuary-associated fish species is assessed in relation to marine and freshwater zoogeographic patterns. Historical (palaeobiogeographic) and contemporary environmental factors that contribute to the establishment and maintenance of these regions are also discussed. Global patterns in estuary-associated fish species richness demonstrated that tropical ecoregions are more diverse and richer in species than temperate ecoregions; the tropical Indo-Pacific and the tropical western Atlantic were two major centres of high global species richness. Multivariate analyses identified several ecoregion groupings that broadly corresponded with both freshwater and marine biogeographic regions. These groupings could also be related to global marine palaeobiogeographic processes such as the closure of the Tethys Sea linkage during the Cenozoic as well as contemporary factors such ocean currents, upwelling areas and climatic factors, particularly rainfall and runoff.

A new endoparasitic monogenean of Paradiplectanotrema Gerasev, Gayevskaya & Kovaleva, 1987, Paradiplectanotrema klimpeli sp. nov., is described from the southern Balinese coast, Indonesia. The new species is much larger, wider and characterized by the longest dorsal anchors compared with the congeners. Ventral anchors and ventral bars are the smallest in the genus, with a distinct ratio of 1:1. This is the first species with a gladiator breast-plate-shaped dorsal bar, with a length:width ratio of 1:1. Oesophagi of the Common Grinner Saurida tumbil (Bloch, 1795) (Synodontidae) were infected (prevalence = 17%) at an intensity of 12 (1–21). This is the first record of the genus from the eastern Indian Ocean, and lizardfishes represent a new host family. We provide light microscopy (in situ in oesophagal folds), three-dimensional confocal illustrations and a morphometric comparison of all congeners, with remarks on the recently described first Indonesian endoparasitic Monogenea Pseudempleurosoma haywardi Theisen, Palm, Al-Jufaili & Kleinertz, 2017. First 28S DNA sequences for Paradiplectanotrema allocate the new species close to endoparasitc freshwater monogeneans. Its ecology differs from Pseudempleurosoma Yamaguti, 1965 by utilizing deep-water fishes instead of coastal, coral reef-associated hosts; however, both are infecting schooling, bottom-dwelling fishes.

The geographical distribution of the two species of the genus Parachaenichthys is allopatric and restricted to the inner shelves of South Georgia–South Sandwich Islands (P. georgianus) and South Orkney Islands–South Shetland Islands (P. charcoti). To evaluate the consistency between the geographical patterns of adult distribution and early life history traits of P. charcoti, sagittal otoliths were used to estimate growth rate and pelagic duration in larvae and juveniles of this species collected in the Bransfield Strait in winter and summer, respectively. Individual age was determined through microincrement counts, assuming they were daily increments. The Gompertz model was fitted to age–length estimates, providing a mean growth rate of 0.22 mm day-1 estimated for 28–204-day-old individuals. Larval hatching was spread over a relatively wide period, lasting from July throughout September. The pelagic larval duration of P. charcoti was about six months based on ageing data of larvae and juveniles, as reported for P. georgianus from South Georgia. The strong dependence of larvae on the inshore habitat may hamper their dispersal at large spatial scale limiting the connectivity among distant populations, providing clues to interpret the present geographical distribution of the two species.

With the aim of evaluating the utility of marine parasites as indicators of zoogeographical regions in the South West Atlantic, we analyzed data on assemblages of long-lived larval parasites of 488 specimens of Percophis brasiliensis distributed in 11 samples from nine localities covering the entire distribution of the species in the Argentine biogeographical Province. Near half a million long-lived parasite individuals belonging to 17 species present in the whole sample displayed clear latitudinal patterns. Data for parasite assemblages at infracommunity and component community levels were analysed in relation to the geographical distance. Significant similarity decay of parasite assemblages over distance was observed, with those based on abundances and mean abundances showing departures from predicted values of regressions. These departures were represented by higher dissimilarities between samples coming from different zoogeographical regions than between those caught within the same region, independently of the distance separating them. Consequently, zoogeographical regions were identified in a distance-decay context. Multivariate analyses corroborated a close fit of similarity between assemblages to existing zoogeographical classifications. Regressions representing distance decay of similarity, and the identification of their outliers, can therefore shed light on the existence of discontinuities or uniformities in the geographic distribution of parasite assemblages and, in turn, in the zoogeography of their fish hosts.

New records of fish species are reported from Papua New Guinea: Gymnothorax angusticauda (Muraenidae) from Madang, Coloconger scholesi Chan 1967 (Colocongridae) from Madang and New Guinea, Acromycter longipectoralis Karmovskaya 2004 (Congridae), Doryrhamphus melanopleura (Bleeker, 1858) and Festucalex gibbsi Dawson 1977 (Syngnathidae) from Madang, Lioscorpius longiceps Günther 1880 (Setarchidae) from Madang, Morobe and New Guinea, Neomerinthe megalepis Fowler 1938 and Pontinus rhodochrous (Günther 1872) (Scorpaenidae) from Madang and New Guinea, Parabembras curtus (Temminck & Schlegel 1843) (Parabembridae) from Morobe and New Guinea, Chrionema chryseres Gilbert 1905 and Pteropsaron levitoni Iwamoto 2014 (Percophidae) from Madang and New Guinea, Blenniella caudolineata (Günther, 1877) and Petroscirtes xestus Jordan & Seale, 1906 (Blenniidae) from Madang, Synchiropus orstom Fricke 2000 (Callionymidae) from West Sepik, Sandaun and New Guinea, Rexea antefurcata Parin 1989 (Gempylidae), Lepidoblepharon ophthalmolepis Weber 1913 (Citharidae), Engyprosopon macrolepis (Regan, 1908) (Bothidae), Aseraggodes kimurai Randall & Desoutter-Meniger 2007 (Soleidae), Cynoglossus bilineatus (Lacepède, 1802) and Symphurus multimaculatus Lee, Munroe & Chen 2009 (Cynoglossidae) from Madang and Tylerius spinosissimus (Regan 1908) (Tetraodontidae) from Morobe and Papua New Guinea. This papers also includes new depths records for Coloconger scholesi, Lioscorpius longiceps, Neomerinthe megalepis, Pontinus rhodochrous, Parabembras curtus, Chrionema chryseres and Synchiropus orstom.

New records of fish species are reported from New Caledonia, including Polyipnus aquavitus Baird, 1971 (Sternoptychidae), Porogadus melampeplus (Alcock, 1896) (Ophidiidae), Hoplichthys citrinus Gilbert 1905 (Hoplichthyidae), Plectrogenium nanum Gilbert 1905 (Plectrogeniidae), Lioscorpius trifasciatus Last, Yearsley & Motomura 2005 (Setarchidae), Neomerinthe megalepis Fowler 1938 and Phenacoscorpius megalops Fowler 1938 (Scorpaenidae), Ocosia apia Poss & Eschmeyer, 1975 (Tetrarogidae), Hoplostethus atlanticus Collett 1889 (Trachichthyidae), Zenion longipinnis Kotthaus, 1970 (Zeniontidae), Plectranthias foresti Fourmanoir 1977, Plectranthias pelicieri Randall & Shimizu, 1994, Plectranthias rubrifasciatus Fourmanoir & Randall, 1979 and Rabaulichthys squirei Randall & Walsh, 2010 (Serranidae), Synagrops philippinensis (Günther 1880) (Acropomatidae), Stegastes insularis Allen & Emery 1995 (Pomacentridae), Cirrhilabrus rubrimarginatus Randall 1992 (Labridae), Pteropsaron neocaledonicus Fourmanoir & Rivaton, 1979 (Percophidae), Centrodraco ornatus (Fourmanoir & Rivaton, 1979) and Draconetta xenica Jordan & Fowler 1903 (Draconettidae), and Acanthurus maculiceps (Ahl 1923) (Acanthuridae). A record of Plectropomus maculatus (Bloch 1790) (Serranidae) from Grande Terre, New Caledonia is confirmed. This paper also includes new depth records of Zenion longipinnis, Plectranthias rubrifasciatus, Synagrops philippinensis, Centrodraco ornatus and Draconetta xenica.

A checklist of the fishes of Ascension Island is presented. The species Rhincodon typus, Alopias superciliosus, Isurus oxyrinchus, Carcharhinus obscurus, Galeocerdo cuvier, Sphyrna lewini, Hexanchus griseus, Manta birostris, Gymnothorax vicinus, Hippocampus sp., Epinephelus itajara, Cookeolus japonicus, Apogon pseudomaculatus, Phaeoptyx pigmentaria, Remora albescens, Caranx bartholomaei, Carangoides ruber, Decapterus tabl, Seriola dumerili, Thalassoma sanctaehelenae, Cryptotomus sp., Ruvettus pretiosus, Acanthocybium solandri, Auxis rochei, Auxis thazard, Euthynnus alletteratus, Katsuwonus pelamis, Thunnus alalunga, Thunnus obesus, Xiphias gladius, Istiophorus platypterus, Kajikia albida, Makaira nigricans, Tetrapturus pfluegeri, Hyperoglyphe perciformis, Schedophilus sp., Cantherhines macrocerus, Sphoeroides pachygaster and Diodon eydouxii are recorded for the first time from Ascension Island. We have recognized two previous records as identification errors and indicate 11 other records as doubtful. Including the 40 new records, we now list 173 fish species from Ascension Island, of which 133 might be considered ‘coastal fish species’. Eleven of these (8.3%) appear to be endemic to the island and a further 16 species (12%) appear to be shared endemics with St Helena Island.

During a recent expedition to Ascension Island in the southern Atlantic Ocean, a polyplacophoran of the genus Acanthochitona was collected, corresponding to the first recorded species of this molluscan class from this remote island. A scanning electron microscope study reveals a close affinity to Acanthochitona subrubicunda, which was so far only known from the Cape Verde Archipelago. Due to the lack of comparable type material the new finding warrants a confirmed identification and is only tentatively attributed to Acanthochitona subrubicunda. It is hypothesized that the class Polyplacophora was either overlooked during earlier surveys or colonized the island in more recent time. If the latter scenario took place, a transport by ships is thinkable.

This is the first report on the Zoantharia fauna (Cnidaria: Hexacorallia) of the isolated oceanic island of Ascension, southern Atlantic, where zoantharians are a dominant component of the shallow-water benthos. Specimens from two expeditions (1983, 2012) were examined regarding external morphology and molecular phylogeny using three DNA markers, which confirmed the presence of four zoantharian species: Palythoa caribaeorum; Palythoa aff. clavata; Parazoanthus swiftii; and Zoanthus sp. Two of these, Palythoa aff. clavata and Parazoanthus swiftii, were previously only known from the western Atlantic and Caribbean. Molecular examination of the zooxanthellae (=Symbiodinium spp.) of Palythoa specimens showed that they were in association with only one type, subclade C1.

Four specimens of the peristediid genus Satyrichthys were sampled with bottom long-lines from a depth of 180 m during the VA ‘Farumas’ Reef Fish Survey off North Malé Atoll, Maldives, in 1999. The largest and smallest of these specimens were deposited at Bernice Pauahi Bishop Museum (BPBM 34965, standard length (SL) 278.25 mm; BPBM 41160, SL 413.65 mm). Based on measurements and meristic counts, BPBM 34965 is characterized as Satyrichthys laticeps and BPBM 41160 is characterized as Satyrichthys cf. kikingeri. Satyrichthys laticeps is not only recorded for the first time for the Republic of the Maldives, but also complements distribution data on the species in the north-eastern Indian Ocean. Satyrichthys kikingeri, hitherto known only from a single specimen collected in 2012 from Rasdhoo Atoll in the Maldives, is now documented by a second specimen.

The Macaronesian Islands in the mid-Atlantic pose a number of questions relating to their colonization by littoral tanaidaceans, as these taxa have no obligate dispersive phase. Recent surveys of the four main archipelagos discovered twelve species of tanaidacean, four of which are new to science, in seven genera (one new to science). In addition, some taxa described by Vanhöffen at the beginning of the last century were rediscovered. All the taxa are described, and their zoogeography, likely origin, and possible means of colonization are discussed.

Three new freshwater ameirid species were discovered in the Western Australian subterranean habitats and described in this paper. They all proved to belong to the genus Nitocrellopsis Galassi, De Laurentiis & Dole-Olivier, 1999, representing the first record of this genus in Australia. Nitocrellopsis operculata sp. nov. was collected in 2003 in the Pilbara region, during the Pilbara Regional Survey, led by the Western Australian Department of Environment and Conservation (DEC). It can be distinguished from all other congeners by the reduced armature of the antennal exopod, which is an autapomorphic feature. Also, no other species of Nitocrellopsis has cuticular windows on prosomal or urosomal somites, or six elements on the third exopodal segment of the second leg. Nitocrellopsis halsei sp. nov. and N. pinderi sp. nov. are sister-species, collected in 2007 in the neighbouring Yilgarn region, by the private environmental consulting company Bennelongia Pty Ltd. Numerous morphological similarities include somite ornamentation, armature patterns of the swimming legs and the fifth leg, as well as the shape and armature of the antennula, antenna and almost all mouth appendages, while the main differences between the two are observed in the body size and habitus appearance, caudal rami shape and size, presence/absence of large lateral pores on the fourth pedigerous somite, number of spinules on the anal operculum, number of setae on the madibular endopod, and shape of the exopod of the fifth leg. Although they differ from any other congener by a combination of characters, no significant autapomorphic features were observed. In order to find a more natural allocation of these three species, a cladistic analysis is performed on all current members of Nitocrellopsis and three outgroup taxa, based on 45 morphological characters. The resulting cladogram shows that the ingroup is well defined by at least four synapomorphies, but the Australian species from the two regions are only remotely related to each other, showing the importance of looking at small-scale patterns when inferring Gondwanan biogeography. Three sister-species pairs are recognized in the genus and a key to all 12 members is provided.

New biological species and high levels of inter- and intraspecific genetic divergence were discovered in an allozyme study of some North European members of the acanthocephalan genus Echinorhynchus (sensu lato), parasites of fish and malacostracan crustaceans. (i) A strong differentiation between the marine E. gadi and the fresh- and brackish-water E. salmonis (genetic identity I ≃ 0) supports a generic distinction between these taxa; however, the subdivision would not entirely concur with the concepts of Echinorhynchus (sensu stricto) and Metechinorhynchus suggested earlier. (ii) Samples of E. gadi from the Baltic, Norwegian and North Seas included three distinct, partially sympatric biological species (spp. I–III; I ≃ 0·5). (iii) E. bothniensis, previously only known from the northern Baltic Sea, represents a complex of freshwater taxa with an intermediate host relationship to the ‘glacial relict’ Mysis spp. and with a distributional and host analogy to the North American E. leidyi. A population in a northern lake in the Barents Sea basin is closely related to E. bothniensis of the Baltic area, but is probably specifically distinct; the divergence between these populations (I ≃ 0·6) is similar to that between their Mysis host species. (iv) Considerable intraspecific differentiation (Fst = 0·25), probably reflecting post-glacial population bottlenecks, was found between Baltic and nearby lacustrine E. bothniensis, and between Atlantic and Baltic E. gadi sp. I.

Despite the hydroid fauna of the Mediterranean Sea being considered one of the best known in the world, the eastern basin of the Mediterranean Sea remains nearly unexplored. This paper reports on 38 species collected along the Levant Sea coast (mainly Lebanon), of which three are new records for the Mediterranean and nine for the Levant Sea. Six alien species, i.e. Eudendrium carneum, Sertularia marginata, Sertularia techocarpa, Macrorhynchia philippina, Diphasia digitalis and Dynamena quadridentata, are described in detail and illustrated on the basis of Levant Sea material. The last four species are considered as immigrants from the Red Sea. The synonymy of Sertularia stechowi, described from Japan, with S. techocarpa is established. Taken as a whole, the collection comprised a majority of circum-(sub)tropical species, and a reduced proportion of Atlantic–Mediterranean elements and Mediterranean endemics. The ecology (seasonality, depth distribution and habitat preference) of the indigenous species resulted similar to what is known for the more studied western Mediterranean, with some exceptions. Adding the present species inventory to the scanty published information, the total of hydroid species known from the Levant Sea rises to 70, indicating the need for future investigation in this sector of the Mediterranean Sea.

Two specimens of the spottail moray Gymnothorax equatorialis were identified for the first time off the west coast of the State of Baja California Sur. This discovery also constitutes the northernmost record of this species on the Pacific Coast. The possible causes of its occurrence in the north-eastern Pacific are discussed and information about the conditions of collections and characteristic morphometry are presented.

On the island of Madagascar and five neighbouring islands: Aldabra, the Comoros, Mauritius, Réunion and the Seychelles, the number of hitherto found Ptyctima species is 57, including 37 Phthiracaroidea (of which ten are new to science), 18 Euphthiracaroidea (one new to science) and two Mesoplophoroidea. Of those 57 species, 30 are endemic (53%), ten Ethiopian species (17%), 12 pantropical species (21%) three oriental (5%) and two semicosmopolitan (3%). Endemism of Phthiracaroidea (62%) is similar to Euphthiracaroidea (59%). Similarity between the ptyctimous fauna of Madagascar and the neighbouring islands is very small—only one or two species are common. Moreover, the fauna of Mauritius is completely different from that of Madagascar. The ptyctimous fauna of Madagascar and the near islands must have been shaped before separation of Madagascar from Africa, which is suggested by the presence of the phylogenetically oldest and the youngest genera of Phthiracaroidea and Euphthiracaroidea. On the other hand, a large number of species of late derived genera Notophthiracarus and Hoplophorella may indicate a relatively late colonization of the islands by Phthiracaroidea. Dispersion of Ptyctima onto Madagascar and the neighbouring islands took place from the east—the Oriental region or from the south—the Australian region.

The first list of Trichoptera from lakes Vico and Bolsena is reported. It is the result of research carried out in 1955 and 19711979 in lake Vico, and in 1957 and 1959-1990 in lake Bolsena. The distribution of caddisflies around the littoral zone depends on the environmental characteristics of the microhabitats. Overall, 16 species from 7 families were collected, 8 of which were found in both lakes, whereas 5 were only collected in Lake Vico, and 3 only occurred in Lake Bolsena. Hydroptila aegyptia and Ecnomus tenellus were the most abundant species in Vico, Tinodes waeneri and T. maclachlani in Bolsena. The trophic categories of the larvae and their gregarines were identified.

Published and unpublished data are used to investigate possible mechanisms of species diversification in two key groups of Antarctic organisms: the Notothenioidei and the Euphausiidae. Species distributions are mapped onto molecular phylogenies, and this evidence is interpreted in light of the various ecological and historical factors which characterize the Southern Ocean. The joint effect of diverse agents (vicariance, “jump” dispersal) appears to be determinant in several cases for species divergence. A review of results from population genetics studies, together with new molecular evidence, confirm the importance of physical barriers (oceanographic fronts) in reducing migration, thereby promoting speciation, at least in notothenioids.