Southern African skate biodiversity and distribution

The skates (Family Rajidae) have 12 genera and possibly 28 species off southern Africa (southern Angola, Namibia, South Africa and Mozambique). The geographic and bathymetric distribution and the taxonomic composition of the southern African skate fauna are analysed and the distribution mapped. The southern African skate fauna is best known off the temperate west coast of South Africa from the intertidal to approximately 1,200 meters, but poorly known below 1,200 m and sketchily known in warm-temperate and tropical parts of the area. Southern African skates of the temperate continental shelves above 100 m are not diverse and regularly include one species of the genus Dipturus, one species of Leucoraja, two species of Raja (including R. straeleni, the most abundant skate in southern African waters) and the giant skate Rostroraja alba. All of these skates are ‘shelf overlap’ species that range onto the outer shelves and uppermost slopes, and none are confined to inshore environments. Skate diversity increases on the outer shelves and upper slopes. At least half of the skate species are endemic to the southern African region; other species also occur off East or West Africa, a few extend to European waters, and records of one species, Amblyraja taaf, appear to be of strays from nearby sub-Antarctic seas. The genus Bathyraja and softnose skate group (Arhynchobatinae) are surprisingly limited (a single species) in deep-water off southern Africa (unlike other regions including the Antarctic), and almost all of southern African skates are members of the Rajinae. Amongst rajines, the tribes Amblyrajini (Amblyraja, two species, Leucoraja, two species, and Rajella, five species) Rajini (Dipturus, six species, Okamejei, one species, Raja, two species, and Rostroraja, one species), and Anacanthobatini (Anacanthobatis, two species, and Cruriraja, three species) predominate, while Gurgesiellini has a species of Neoraja and possibly two of Malacoraja.     

Phylogeny and biogeography of Chinese and Australasian Polystichum ferns as inferred from chloroplast trnL-F and rps4-trnS sequence data

Polystichum, one of the largest genera of ferns, occurs worldwide with the greatest diversity in southwest China and adjacent regions. Although there have been studies of Chinese Polystichum on its traditional classification, geographic distributions, and even a few on its molecular systematics, its relationships to other species outside China remain little known. Here, we investigated the phylogeny and biogeography of the Polystichum species from China and Australasia. The evolutionary relationships among 42 Polystichum species found in China (29 taxa) and Australasia (13 taxa) were inferred from phylogenetic analyses of two chloroplast DNA sequence data sets: rps4-trnS and trnL-F intergenic spacers. The divergence time between Chinese and Australasian Polystichum was estimated. The results indicated that the Australasian species comprise a monophyletic group that is nested within the Chinese diversity, and that the New Zealand species are likewise a monophyletic group nested within the Australasian species. The divergence time estimates suggested that Chinese Polystichum migrated into Australasia from around 40 Ma ago, and from there to New Zealand from about 14 Ma. The diversification of the New Zealand Polystichum species began about 10 Ma. These results indicated that Polystichum probably originated in eastern Asia and migrated into Australasia: first into Australia and then into New Zealand.     

Electric organs in skates: Variation and phylogenetic significance (Chondrichthyes: Rajoidei)

A total of 63 species of skates (Chondrichthyes: Rajoidei) were surveyed, along with three species of the outgroup (Chondrichtyes: Rhinobatoidei) for electric organs along the sides of the tail. All skate specimens examined possessed what appeared to be functional electric organs, and the three species of the outgroup lacked evidence of electric organs. The electric organs were tail-positive and arranged into horizontal columns divided by transverse septa. The electrocytes varied considerably within and among supraspecific taxa (subgenera and genera), but they could be broadly classified into cup-shape, modified cup-shape, intermediate-shape, and disc-shape cells, provided that the distinction was partially based on position of the electrocytes within their connective tissue chambers. The survey, in part, corroborates a phylogenetic hypothesis of skates and in some respects further resolves the hypothesis. The supraspecific taxa Atlantoraja and Rioraja have similar derived-type electrocytes, as do the five supraspecific taxa of Rajini, and Cruriraja and Anacanthobatis, and to a lesser extent the supraspecific taxa Arhynchobatis, Psammobatis, and Sympterygia, and the supraspecific taxa Notoraja, Pavoraja, and Pseudoraja, corroborating the hypothesis. The supraspecific taxa Amblyraja, Rajella, Leucoraja, Breviraja, and Dactylobatus were unresolved in the phylogenetic hypothesis, but the electrocyte survey suggested that Leucoraja, Breviraja, and Dactylobatus were derived with respect to Amblyraja and Rajella. © 1994 Wiley-Liss, Inc.     

Phylogenetic investigation and divergence dating of Poa (Poaceae,tribe Poeae) in the Australasian region

The Australasian region contains a significant proportion of worldwide Poa diversity, but the evolutionary relationships of taxa from this region are incompletely understood. Most Australasian species have been placed in a monophyletic Poa subgenus, Poa supersection Homalopoa section Brizoides clade, but with limited resolution of relationships. In this study, phylogenetic relationships were reconstructed for Australasian Poa, using three plastid (rbcL and matK genes and the rpl32‐trnL intergenic spacer) and two nuclear [internal/external transcribed spacer (ITS/ETS)] markers. Seventy‐five Poa spp. were represented (including 42 Australian, nine New Guinean, nine New Zealand and three Australian/New Zealand species). Maximum parsimony, maximum likelihood and Bayesian inference criteria were applied for phylogenetic reconstruction. Divergence dates were estimated using Bayesian inference, with a relaxed clock applied and rates sampled from an uncorrelated log‐normal distribution. Australasian Poa spp. are placed in three lineages (section Brizoides, section Parodiochloa and the ‘X clade’), each of which is closely related to non‐Australasian taxa or clades. Section Brizoides subsection Australopoa is polyphyletic as currently circumscribed. In Australasia, Poa has diversified within the last 4.3 Mya, with divergence dating results broadly congruent with fossil data that record the appearance of vegetation with a prominent grassland understorey or shrubland/grassland mosaic vegetation dating from the mid‐Pliocene. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 523–552.     

Australian biogeographical connections and the phylogeny of large genera in the plant family Myrtaceae

Aim To compare the phylogeny of the eucalypt and melaleuca groups with geological events and ages of fossils to discover the time frame of clade divergences. Location Australia, New Caledonia, New Guinea, Indonesian Archipelago. Methods We compare published molecular phylogenies of the eucalypt and melaleuca groups of the plant family Myrtaceae with geological history and known fossil records from the Cretaceous and Cenozoic. Results The Australasian eucalypt group includes seven genera, of which some are relictual rain forest taxa of restricted distribution and others are species‐rich and widespread in drier environments. Based on molecular and morphological data, phylogenetic analyses of the eucalypt group have identified two major clades. The monotypic Arillastrum endemic to New Caledonia is related in one clade to the more species‐rich Angophora, Corymbia and Eucalyptus that dominate the sclerophyll vegetation of Australia. Based on the time of rifting of New Caledonia from eastern Gondwana and the age of fossil eucalypt pollen, we argue that this clade extends back to the Late Cretaceous. The second clade includes three relictual rain forest taxa, with Allosyncarpia from Arnhem Land the sister taxon to Eucalyptopsis of New Guinea and the eastern Indonesian archipelago, and Stockwellia from the Atherton Tableland in north‐east Queensland. As monsoonal, drier conditions evolved in northern Australia, Arnhem Land was isolated from the wet tropics to the east and north during the Oligocene, segregating ancestral rain forest biota. It is argued also that the distribution of species in Eucalyptopsis and Eucalyptus subgenus Symphyomyrtus endemic in areas north of the stable edge of the Australian continent, as far as Sulawesi and the southern Philippines, is related to the geological history of south‐east Asia‐Australasia. Colonization (dispersal) may have been aided by rafting on micro‐continental fragments, by accretion of arc terranes onto New Guinea and by land brought into closer proximity during periods of low sea‐level, from the Late Miocene and Pliocene. The phylogenetic position of the few northern, non‐Australian species of Eucalyptus subgenus Symphyomyrtus suggests rapid radiation in the large Australian sister group(s) during this time frame. A similar pattern, connecting Australia and New Caledonia, is emerging from phylogenetic analysis of the Melaleuca group (Beaufortia suballiance) within Myrtaceae, with Melaleuca being polyphyletic. Main conclusion The eucalypt group is an old lineage extending back to the Late Cretaceous. Differentiation of clades is related to major geological and climatic events, including rifting of New Caledonia from eastern Gondwana, development of monsoonal and drier climates, collision of the northern edge of the Australian craton with island arcs and periods of low sea level. Vicariance events involve dispersal of biota.     

Standardized diet compositions and trophic levels of skates (Chondrichthyes: Rajiformes: Rajoidei)

Skates by virtue of their abundance and widespread occurrence appear to play an influential role in the food webs of demersal marine communities. However, few quantitative dietary studies have been conducted on this elasmobranch group. Therefore, to better understand the ecological role of skates, standardized diet compositions and trophic level (TL) values were calculated from quantitative studies, and compared within and among skate and shark taxa. Prey items were grouped into 11 general categories to facilitate standardized diet composition and TL calculations. Trophic level values were calculated for 60 skate species with TL estimates ranging from 3.48 to 4.22 (mean TL = 3.80 ± 0.02 SE). Standardized diet composition results revealed that decapods and fishes were the main prey taxa of most skate species followed by amphipods and polychaetes. Correspondingly, cluster analysis of diet composition data revealed four major trophic guilds, each dominated by one of these prey groups. Fish and decapod guilds were dominant comprising 39 of 48 species analyzed. Analysis of skate families revealed that the Arhynchobatidae and Rajidae had similar TL values of 3.86 and 3.79 (t-test, P = 0.27), respectively. The Anacanthobatidae were represented by a single species, Cruriraja parcomaculata, with a TL of 3.53. Statistical comparison of TL values calculated for five genera (Bathyraja, Leucoraja, Raja, Rajella, Rhinoraja) revealed a significant difference between Bathyraja and Rajella (t-test, P = 0.03). A positive correlation was observed between TL and total length (L _T) with larger skates (e.g. >100 cm L _T) tending to have a higher calculated TL value (>3.9). Skates were found to occupy TLs similar to those of several co-occurring demersal shark families including the Scyliorhinidae, Squatinidae, and Triakidae. Results from this study support recent assertions that skates utilize similar resources to those of other upper trophic-level marine predators, e.g. seabirds, marine mammals, and sharks. These preliminary findings will hopefully encourage future research into the trophic relationships and ecological impact of these interesting and important demersal predators.     

AN EARLY CENOZOIC NEOSELACHIAN SHARK FAUNA FROM THE SOUTHWEST PACIFIC

Abstract: An early Cenozoic shark fauna, comprising at least 16 taxa, is described from Paleocene sedimentary rocks on the South Island of New Zealand. Although representing a remote Southern Hemisphere location, the fauna includes forms closely comparable to contemporary species from the Northern Hemisphere, in addition to the new species Chlamydoselachus keyesi and Centroselachus goordi. Comparison with closely related extant species suggests the fauna may be interpreted as a deep water one, typical of the outer continental shelf and upper slope. However, after palaeogeography, sedimentology and mineralogy of the enclosing rock, and the nature of similar faunas from elsewhere are taken into consideration, the fauna is interpreted to have occupied a mid‐shelf environment.     

The endemic plant families and the palms of New Caledonia: a biogeographical analysis

This paper provides a panbiogeographical analysis of the endemic plant families and the palms of New Caledonia. There are three endemic plant families in New Caledonia and several genera that were previously recognized as endemic families. Of these taxa, some are sister to widespread Northern Hemisphere or global groups (Canacomyrica, Austrotaxus, Amborella). The others belong to trans‐Indian Ocean groups (Strasburgeria), trans‐tropical Pacific groups (Oncotheca) or Tasman Sea/Coral Sea groups (Phelline, Paracryphia) that are sister to widespread Northern Hemisphere or global groups. In palms, the four clades show allopatric regional connections in, respectively: (1) western Indonesia, Malaysia and Thailand; (2) Vanuatu/Fiji and the southern Ryukyu Islands near Taiwan; (3) the western Tasman/Coral Sea (eastern Australia, New Guinea and the Solomon Islands); and (4) the eastern Tasman/Coral Sea (Lord Howe and Norfolk Islands, New Zealand, Vanuatu, Fiji and the Solomon Islands). The four clades thus belong to different centres of endemism that overlap in New Caledonia. The patterns are attributed not to chance dispersal and adaptive radiation but to the different histories of the eight terranes that fused to produce modern New Caledonia. Trans‐tropical Pacific connections can be related to the Cretaceous igneous plateaus that formed in the central Pacific and were carried, with plate movement, west to the Solomon Islands and New Zealand, and east to Colombia and the Caribbean.     

Diversification of New Zealand weta (Orthoptera: Ensifera: Anostostomatidae) and their relationships in Australasia

New Zealand taxa from the Orthopteran family Anostostomatidae have been shown to consist of three broad groups, Hemiandrus (ground weta), Anisoura/Motuweta (tusked weta) and Hemideina-Deinacrida (tree-giant weta). The family is also present in Australia and New Caledonia, the nearest large land masses to New Zealand. All genera are endemic to their respective countries except Hemiandrus that occurs in New Zealand and Australia. We used nuclear and mitochondrial DNA sequence data to study within genera and among species-level genetic diversity within New Zealand and to examine phylogenetic relationships of taxa in Australasia. We found the Anostostomatidae to be monophyletic within Ensifera, and justifiably distinguished from the Stenopelmatidae among which they were formerly placed. However, the New Zealand Anostostomatidae are not monophyletic with respect to Australian and New Caledonian species in our analyses. Two of the New Zealand groups have closer allies in Australia and one in New Caledonia. We carried out maximum-likelihood and Bayesian analyses to reveal several well supported subgroupings. Our analysis included the most extensive sampling to date of Hemiandrus species and indicate that Australian and New Zealand Hemiandrus are not monophyletic. We used molecular dating approaches to test the plausibility of alternative biogeographic hypotheses for the origin of the New Zealand anostostomatid fauna and found support for divergence of the main clades at, or shortly after, Gondwanan break-up, and dispersal across the Tasman much more recently.     

Good morning Gondwana

Summary

Vicariance and dispersion both must be considered as possibilities for the fauna and flora of New Zealand and New Caledonia. Oligocene submersion, promoted by the geologists and several biologists, does not seem to have been total. Refuge stations must have existed in mountains and even in plains in some surrounding areas. From there the relicts must have radiated after the partial submersion. Certain “primitive” Chrysomelidae Eumolpinae (Bohumiljania spp.) are closely related to Patagonian genera. Their case is not unique among the terrestrial organisms of New Caledonia. How to explain the occurrence of Amborella in New Caledonia and of the tuataras in New Zealand, already very probably extinct elsewhere during the Paleogene?     

Biodiversity and systematics of skates (Chondrichthyes: Rajiformes: Rajoidei)

Skates (Rajiformes: Rajoidei) are a highly diverse fish group, comprising more valid species than any other group of cartilaginous fishes. The high degree of endemism exhibited by the skates is somewhat enigmatic given their relatively conserved body morphology and apparent restrictive habitat, e.g. soft bottom substrates. Skates are primarily marine benthic dwellers found from the intertidal down to depths in excess of 3,000 m. They are most diverse at higher latitudes and in deepwater, but are replaced in shallower, warm temperate to tropical waters by stingrays (Myliobatodei). The number of valid skate species has increased exponentially, with more species having been described since 1950 (n = 126) than had been described in the previous 200 years (n = 119). Much of the renaissance in skate systematics has largely been through the efforts of a few individuals who through author–coauthor collaboration have accounted for 78 of the 131 species described since 1948 and for nine of 13 genera named since 1950. Furthermore, detailed regional surveys and accounts of skate biodiversity have also contributed to a better understanding of the diversity of the skates. A checklist of the living valid skate species is presented.     

Observations on the electric organ discharge of two skate species (Chondrichthyes: Rajidae) and its relationship to behaviour

Synopsis The electric organ discharge (EOD) of the little skate,Raja erinacea and winter skate,R. ocellata was recorded both from isolated individuals and from small groups using methods that allowed for the identification of individuals producing EODs. Pulse duration, train lengh, frequency, and pulse patterns are characterized and correlated with behaviour. The two species,R. erinacea andR. ocellata, were found to have characteristically different EOD pulse durations of 70 ms and 217 ms respectively. Isolated skates rarely discharged whereas groups of skates were found to discharge regularly. The EOD was evoked by tactile prodding, physical contact with other skates and electrical stimulation. Skates also discharged reflexively in response to an artificially induced head-positive DC stimulus, sine wave and monopolar square pulses. During approach and contact, skates responded to each other with interacting EOD displays. EOD interaction and pulse duration differences between other species suggest a possible intra-specific communication function of the EOD inRaja.     

Dietary comparisons of six skate species (Rajidae) in south-eastern Australian waters

The diet of six skate species caught as bycatch in south-eastern Australian waters was examined over a 2-year period. The skates were segregated into two regions (continental shelf and continental slope) based on prey species and depth of capture. The shelf group consisted of four species, Dipturus sp. A, D. cerva, D. lemprieri and D. whitleyi, while the slope group comprised two species, Dipturus sp. B and D. gudgeri. The two groups varied in feeding strategies with the shelf species generally occupying a broader feeding niche and preying on a larger diversity of prey including a variety of crustaceans (brachyurans, anomurans, achelates, carideans and dendobranchiates), cephalopods, elasmobranchs and teleosts. Within the slope group, Dipturus sp. B and D. gudgeri were more specialised. Dipturus sp. B preyed primarily on anomurans (galatheids) and bachyurans (homolids), whereas D. gudgeri preyed primarily on teleosts. A size related change in diet was evident for all species with the exception of D. gudgeri in which all sizes preyed predominantly on teleosts. Smaller representatives of the four shelf species all preyed on numerous amounts of caridean shrimps, in particular Leptochela sydniensis. In contrast, the continental slope species, Dipturus sp. B consumed anomurans when small, shifting to brachyurans with increasing size. Of the six skate species examined in this study, three were secondary consumers (trophic level <3) and the remaining three tertiary consumers (trophic level >4). Although ANOSIM found significant differences in dietary composition between species within groups, there was some overlap in prey species amongst co-existing skates, which suggests that there is some degree of resource partitioning amongst them.     

Survey of the variation in alar and malar thorns in skates: Phylogenetic implications (Chondrichthyes: Rajoidei)

A total of 62 species, representing 24 of the 28 supraspecific taxa of skates, was surveyed for the presence, distribution, and structure of alar and malar thorns. The survey revealed that alar thorns are almost universally present in mature male skates, and that malar thorns are of two types that may have separate origins. The location and orientation of alar thorns differed in two major clades of skates (groups I and II). They were either exposed on the disc with the crown oriented obliquely to the long axis of the base or imbedded in slits in the integument and oriented parallel to the long axis of the base. Group I possessed the former type of thorns and, with several exceptions, group II possessed the latter type. Group I either lacked malar thorns or possessed malar thorns that were most likely derived from generalized placoid scales. Group II possessed, with several exceptions, malar thorns derived from enlarged placoid scales. Within group I the supraspecific taxa Atlantoraja and Rioraja possessed unique alar thorns that were reclined laterally and associated with lateral grooves in the integument. Within group II the supraspecific taxa Anacanthobatis, Cruriraja, Dipturus, Okamejei, Raja, the North Pacific Assemblage, and the Amphi-American Assemblage had a large barb on the distal section of the crown of the alar thorn that suggests that these taxa form a clade. The crown of the alar thorns of the latter five supraspecific taxa was undulatory, thus supporting their monophyletic status. Another assemblage within group II had ridges that ran most of the length of the crown of the alar thorns corroborating their monophyletic status. The survey also suggested that variation of integumentary grooves associated with the alar thorns in Bathyraja, and presence or absence of malar thorns in Psammobatis, may be phylogenetically informative. © 1996 Wiley-Liss, Inc.     

Molecular phylogeny and timing of radiation in Lessonia (Phaeophyceae,Laminariales)

The genus Lessonia Bory de Saint‐Vincent is distributed solely in the Southern Hemisphere, with four species found in South America and five in Australasia. Our goal was to determine the evolutionary relationships between the Lessonia species of the two disjunct areas and hypothesize dispersal patterns and timing of radiation. We combined mitochondria, plastid and nuclear markers in a comprehensive dataset from multiple individuals per known species. Furthermore, for some species we added samples from multiple populations to take account of their widespread distribution over known bioregions. In all analyses the Australasian Lessonia formed a monophyletic group and in most analyses the South American species form a paraphyletic grade. Delimitations of the accepted species are highly supported except for L. variegata J. Agardh and L. nigrescens Bory de Saint‐Vincent. We showed for the first time four lineages for the New Zealand endemic Lessonia variegata with an unexpected high level of genetic differentiation. Our analysis cannot resolve whether the dispersal of the common ancestor of this genus was from the Americas to Australasia or vice versa. Molecular clock analysis suggested that a sudden radiation took place in Australasia c. 3.5 Mya when almost all Australasian species diverged within a time frame of only 35 000 years.     

Seamount egg‐laying grounds of the deep‐water skate Bathyraja richardsoni

Highly localized concentrations of elasmobranch egg capsules of the deep‐water skate Bathyraja richardsoni were discovered during the first remotely operated vehicle (ROV) survey of the Hebrides Terrace Seamount in the Rockall Trough, north‐east Atlantic Ocean. Conductivity–temperature–depth profiling indicated that the eggs were bathed in a specific environmental niche of well‐oxygenated waters between 4·20 and 4·55° C, and salinity 34·95–35·06, on a coarse to fine‐grained sandy seabed on the seamount's eastern flank, whereas a second type of egg capsule (possibly belonging to the skate Dipturus sp.) was recorded exclusively amongst the reef‐building stony coral Solenosmilia variabilis. The depths of both egg‐laying habitats (1489–1580 m) provide a de facto refuge from fisheries mortality for younger life stages of these skates.     

Orthoglymma wangapeka gen.n., sp.n. (Coleoptera: Carabidae: Broscini): a newly discovered relict from the Buller Terrane,north‐western South Island,New Zealand,corroborates a general pattern of Gondwanan endemism

Orthoglymma Liebherr, Marris, Emberson, Syrett & Roig‐Juñent gen.n. (Coleoptera: Carabidae: Broscini) is described to accommodate the single type species Orthoglymma wangapeka Liebherr, Marris, Emberson, Syrett & Roig‐Juñent sp.n., known from the Wangapeka Track, Kahurangi National Park, north‐western South Island, New Zealand. Orthoglymma wangapeka sp.n. is analysed cladistically along with a comprehensive array of 42 other broscine generic terminals and four out‐group taxa, using information obtained from 73 morphological characters, and placed as adelphotaxon to the remainder of subtribe Nothobroscina, a clade distributed in New Zealand, southern South America and Australia. Based on fossil evidence for Carabidae, the occurrence of Orthoglymma wangapeka sp.n. on the Buller Terrane, a geological feature once situated on the eastern margin of Gondwana, and early cladistic divergence of Orthoglymma from the remaining Nothobroscina, Orthoglymma wangapeka sp.n. is interpreted as a Gondwanan relict. The New Zealand arthropod fauna is reviewed to identify other taxa in existence at the time of Cretaceous vicariance of New Zealand and Australia. These candidate Gondwanan taxa, all of which are specified using fossil data or molecular divergence‐based estimates, are analysed biogeographically. Where phylogenetic hypotheses are available, primordial distributions are optimized using event‐based, dispersal‐vicariance (DIVA) analysis. The hypothesized Gondwanan‐aged taxa demonstrate inordinate fidelity to the Gondwanan‐aged geological terranes that constitute the western portions of New Zealand, especially in the South Island. Persistence of these relicts through a hypothesized ‘Oligocene drowning’ event is the most parsimonious explanation for the concentration of Gondwanan relicts in the Nelson, Buller and Fiordland districts of the South Island. Geographic patterns of Gondwanan‐aged taxa are compared with distributions of taxa hypothesized to have colonized New Zealand across the Tasman Sea from Australia and New Caledonia, subsequent to Cretaceous vicariance. These post‐Gondwanan taxa exhibit very different patterns of distribution and diversification in New Zealand, including: (i) abundant endemism in Northland, and the islands and peninsulas of the North Island; (ii) species geographically restricted to areas underlain by the youngest Rakaia and Pahau geological terranes; and (iii) species exhibiting exceedingly widespread geographic distributions spanning geological terranes of disparate ages.

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New Caledonia: The major centre of biodiversity for volutomitrid molluscs (Mollusca: Neogastropoda: Volutomitridae)

Recent deep‐sea explorations in the South Pacific have documented around New Caledonia the most diverse fauna of gastropods of the family Volutomitridae anywhere in the world. Fourteen species (nine new, two remaining unnamed) are recorded, all essentially confined to the 250–750 m depth range. The high number of species in the New Caledonia region does not appear to be an effect of sampling intensity, but appears to result from four factors: regional spatial heterogeneity, frequency of hard substrates, syntopy, and a historical heritage shared with Australia and New Zealand, which until now ranked as the major centre of volutomitrid diversity. In the New Caledonia region, volutomitrids show a marked preference for hard bottoms and up to three species may co‐occur in the same dredge haul. Many species appear to have extremely narrow geographical distributions within the region (e.g. a single seamount or a single submerged plateau); conversely, Microvoluta joloensis, the only non‐endemic volutomitrid present in New Caledonia, ranges from the Mozambique Channel to Tonga.     

Panbiogeography of New Caledonia,south‐west Pacific: basal angiosperms on basement terranes,ultramafic endemics inherited from volcanic island arcs and old taxa endemic to young islands

Aim To investigate areas of endemism in New Caledonia and their relationship with tectonic history. Location New Caledonia, south‐west Pacific. Methods Panbiogeographical analysis. Results Biogeographical patterns within New Caledonia are described and illustrated with reference to eight terranes and ten centres of endemism. The basement terranes make up a centre of endemism for taxa including Amborella, the basal angiosperm. Three of the terranes that accreted to the basement in the Eocene (high‐pressure metamorphic terrane, ultramafic nappe and Loyalty Ridge) have their own endemics. Main conclusions New Caledonia is not simply a fragment of Gondwana but, like New Zealand and New Guinea, is a complex mosaic of allochthonous terranes. The four New Caledonian basement terranes were all formed from island arc‐derived and arc‐associated material (including ophiolites) which accumulated in the pre‐Pacific Ocean, not in Gondwana. They amalgamated and were accreted to Gondwana (eastern Australia) in the Late Jurassic/Early Cretaceous, but in the Late Cretaceous they separated from Australia with the opening of the Tasman Sea and break‐up of Gondwana. An Eocene collision of the basement terranes with an island arc to the north‐east – possibly the Loyalty Ridge – is of special biogeographical interest in connection with New Caledonia–central Pacific affinities. The Loyalty–Three Kings Ridge has had a separate history from that of the Norfolk Ridge/New Caledonia, although both now run in parallel between Vanuatu and New Zealand. The South Loyalty Basin opened between Grande Terre and the Loyalty Ridge in the Cretaceous and attained a width of 750 km. However, it was almost completely destroyed by subduction in the Eocene which brought the Loyalty Ridge and Grande Terre together again, after 30 Myr of separation. The tectonic history is reflected in the strong biogeographical differences between Grande Terre and the Loyalty Islands. Many Loyalty Islands taxa are widespread in the Pacific but do not occur on Grande Terre, and many Grande Terre/Australian groups are not on the Loyalty Islands. The Loyalty Islands are young (2 Myr old) but they are merely the currently emergent parts of the Loyalty Ridge whose ancestor arcs have a history of volcanism dating back to the Cretaceous. Old taxa endemic to the young Loyalty Ridge islands persist over geological time as a dynamic metapopulation surviving in situ on the individually ephemeral islands and atolls found around subduction zones. The current Loyalty Islands, like the Grande Terre terranes, have inherited their biota from previous islands. On Grande Terre, the ultramafic terrane was emplaced on Grande Terre in the Eocene (about the same time as the collision with the island arc). The very diverse endemic flora on the ultramafics may have been inherited by the obducting nappe from prior base‐rich habitat in the region, including the mafic Poya terrane and the limestones typical of arc and intraplate volcanic islands.     

New records of rotifers from the South Island lakes,New Zealand

Thirty-five lakes in the South Island of New Zealand were surveyed for rotifers during 1988–1991. Of 85 taxa identified, 31 are first records for New Zealand, bringing the rotifers recorded from the country to 331. Four species (Keratella australis, K. slacki, Lecane herzigi and L. tasmaniensis), previously recorded as endemic forms only in Australia, are now added to the New Zealand checklist. Several of the new records are photographed, and scanning electron micrographs of the trophi are shown. Comments are made on the Australasian endemics and rotifer biogeography in New Zealand.