Gary C. B. Poore

Diversity and endemism of the benthic seamount fauna in the southwest Pacific.

Seamounts comprise a unique deep-sea environment, characterized by substantially enhanced currents and a fauna that is dominated by suspension feeders, such as corals. The potential importance of these steep-sided undersea mountains, which are generally of volcanic origin, to ocean biogeography and diversity was recognized over 40 years ago, but this environment has remained very poorly explored. A review of seamount biota and biogeography reported a total of 597 invertebrate species recorded from seamounts worldwide since the Challenger expedition of 1872. Most reports, based on a single taxonomic group, were extremely limited: 5 seamounts of the estimated more than 30,000 seamounts in the worlds oceans accounted for 72% of the species recorded. Only 15% of the species occurring on seamounts were considered potential seamount endemics. Here we report the discovery of more than 850 macro- and megafaunal species from seamounts in the Tasman Sea and southeast Coral Sea, of which 29–34% are new to science and potential seamount endemics. Low species overlap between seamounts in different portions of the region indicates that the seamounts in clusters or along ridge systems function as ‘island groups’ or ‘chains,’ leading to highly localized species distributions and apparent speciation between groups or ridge systems that is exceptional for the deep sea. These results have substantial implications for the conservation of this fauna, which is threatened by fishing activity.

Preliminary Phylogenetic Analysis of Generic Relationships Within the Callianassidae and Ctenochelidae (Decapoda: Thalassinidea: Callianassoidea)

A phylogenetic analysis of 106 representatives in the thalassinidean families Ctenochelidae and Callianassidae, based on 93 adult morphological characters, was performed to investigate the interrelationships between the 25 currently recognized genera. The callianideid, Callianidea typa H. Milne Edwards, was used as the out-group. The two in-group families, Ctenochelidae and Callianassidae, were both shown to be monophyletic. Monophyly of the four ctenochelid subfamilies (Anacalliacinae, Callianopsinae, Ctenochelinae, and the recently suggested Gourretinae) was not supported. Three callianassid subfamilies (Callianassinae, Cheraminae, and Eucalliacinae) were found to be monophyletic but with species compositions different from those presently understood. The fourth callianassid subfamily (Callichirinae) is paraphyletic and ancestral to the other subfamilies. Several species described as species of Callianassa s.l. were found to belong to other genera. Recent diagnosis of several small genera from the Americas and Japan has left larger traditional genera such as Callianassa s.l. and Cheramus paraphyletic. Glypturus is apparently paraphyletic as presently diagnosed. The taxonomic position of some species remains enigmatic largely because of missing data. A listing of all valid genera and species of Ctenochelidae and Callianassidae at the time of publication is provided.

Global Diversity of Marine Isopods (Except Asellota and Crustacean Symbionts)

The crustacean order Isopoda (excluding Asellota, crustacean symbionts and freshwater taxa) comprise 3154 described marine species in 379 genera in 37 families according to the WoRMS catalogue. The history of taxonomic discovery over the last two centuries is reviewed. Although a well defined order with the Peracarida, their relationship to other orders is not yet resolved but systematics of the major subordinal taxa is relatively well understood. Isopods range in size from less than 1 mm to Bathynomus giganteus at 365 mm long. They inhabit all marine habitats down to 7280 m depth but with few doubtful exceptions species have restricted biogeographic and bathymetric ranges. Four feeding categories are recognised as much on the basis of anecdotal evidence as hard data: detritus feeders and browsers, carnivores, parasites, and filter feeders. Notable among these are the Cymothooidea that range from predators and scavengers to external blood-sucking micropredators and parasites. Isopods brood 10–1600 eggs depending on individual species. Strong sexual dimorphism is characteristic of several families, notably in Gnathiidae where sessile males live with a harem of females while juvenile praniza stages are ectoparasites of fish. Protandry is known in Cymothoidae and protogyny in Anthuroidea. Some Paranthuridae are neotenous. About half of all coastal, shelf and upper bathyal species have been recorded in the MEOW temperate realms, 40% in tropical regions and the remainder in polar seas. The greatest concentration of temperate species is in Australasia; more have been recorded from temperate North Pacific than the North Atlantic. Of tropical regions, the Central Indo-Pacific is home to more species any other region. Isopods are decidedly asymmetrical latitudinally with 1.35 times as many species in temperate Southern Hemisphere than the temperate North Atlantic and northern Pacific, and almost four times as many Antarctic as Arctic species. More species are known from the bathyal and abyssal Antarctic than Arctic GOODS provinces, and more from the larger Pacific than Atlantic oceans. Two areas with many species known are the New Zealand-Kermadec and the Northern North Pacific provinces. Deep hard substrates such as found on seamounts and the slopes are underrepresented in samples. This, the documented numbers of undescribed species in recent collections and probable cryptic species suggest a large as yet undocumented fauna, potentially an order of magnitude greater than presently known.

Commonness and rarity in the marine biosphere

Significance Tests of biodiversity theory have been controversial partly because alternative formulations of the same theory seemingly yield different conclusions. This has been a particular challenge for neutral theory, which has dominated tests of biodiversity theory over the last decade. Neutral theory attributes differences in species abundances to chance variation in individuals’ fates, rather than differences in species traits. By identifying common features of different neutral models, we conduct a uniquely robust test of neutral theory across a global dataset of marine assemblages. Consistently, abundances vary more among species than neutral theory predicts, challenging the hypothesis that community dynamics are approximately neutral, and implicating species differences as a key driver of community structure in nature. Explaining patterns of commonness and rarity is fundamental for understanding and managing biodiversity. Consequently, a key test of biodiversity theory has been how well ecological models reproduce empirical distributions of species abundances. However, ecological models with very different assumptions can predict similar species abundance distributions, whereas models with similar assumptions may generate very different predictions. This complicates inferring processes driving community structure from model fits to data. Here, we use an approximation that captures common features of “neutral” biodiversity models—which assume ecological equivalence of species—to test whether neutrality is consistent with patterns of commonness and rarity in the marine biosphere. We do this by analyzing 1,185 species abundance distributions from 14 marine ecosystems ranging from intertidal habitats to abyssal depths, and from the tropics to polar regions. Neutrality performs substantially worse than a classical nonneutral alternative: empirical data consistently show greater heterogeneity of species abundances than expected under neutrality. Poor performance of neutral theory is driven by its consistent inability to capture the dominance of the communities’ most-abundant species. Previous tests showing poor performance of a neutral model for a particular system often have been followed by controversy about whether an alternative formulation of neutral theory could explain the data after all. However, our approach focuses on common features of neutral models, revealing discrepancies with a broad range of empirical abundance distributions. These findings highlight the need for biodiversity theory in which ecological differences among species, such as niche differences and demographic trade-offs, play a central role.

Composition and diversity of Crustacea Isopoda of the southeastern Australian continental slope

Abstract The continental slope of southeastern Australia is a complex hydrological region where sediments is biogenic and largely derived from the nearby shelf. The isopod fauna of the slope between 200 and 3150 m depth has been investigated on four transects (32°S–42°S). Forty-six non-quantitative epibenthic sled, beam-trawl, corer and trawl samples captured 6870 isopod individuals. A total of 359 species belonging to 36 families is recognised, 10% of which can be identified to known species, a much smaller fraction than in previous comparable surveys; 69% are asellotes. Species estimates made using the rarefaction method suggest that the number of species on the southeastern Australian slope is greater than that found on several better-studied slopes in the Atlantic, Arctic or Antarctic. This seems to agree with the observation that species diversity in midlatitudes in the Southern Hemisphere is higher than at similar latitudes in the Northern Hemisphere. The implication of this observation is that estimates of the number of species in the deep sea by Grassle and Maciolek may be too low. The number of species decreased less rapidly with depth at the more southern transects (off Bass Strait and Tasmania) than at the northern transect (off Sydney). Most species were very rare: only 32 occurred in five or more of the 46 samples; half occurred in only one sample. Classification and ordination of sites discriminated between shallow samples (200–520 m) and deeper samples (>400) with good characterisation of sample groups by species groups. Discrimination of transects was weak and gave little support for biogeographic regionalisation of the slope fauna.

First Record of Spelaeogriphacea From Australasia: a New Genus and Species From an Aquifer in the Arid Pilbara of Western Australia

Spelaeogriphacea are reported for the first time from Australia. A new genus and species, Mangkurtu mityula, are described and the only other two genera diagnosed. The species, the third extant in the order, seems more similar to the Brazilian Potiicoara brasiliensis than to the South African Spelaeogriphus lepidops but all have unique apomorphies. The species is found in the aquifer in the Tertiary Millstream Dolomite of the Pilbara region of Western Australia. It is part of a fauna with clear Gondwanan affinities. This fauna is distinct from those found in aquifers in the lower and upper parts of the same drainage basin.

Species differentiation in Synidotea (Isopoda : Idoteidae) and recognition of introduced marine species : a reply to Chapman and Carlton

ABSTRACT Nominal species of the idoteid isopod genus Synidotea from Japan (S. laevidorsalis), western U.S.A. (S. laticauda), South Africa (S. hirtipes), and Australia (S. keablei and S. grisea) are shown to be morphologically distinct. Others probably are also. Contrary to the views of Chapman and Carlton (1991, 1994), the Japanese species has not been widely distributed by shipping. The Australian species fail several of Chapman and Carltons attributes of introduced species: their recent discovery and restricted distribution are anticipated in a poorly explored fauna, there is no evidence of postintroduction range extension, no known human mechanisms of introduction exist, they are not associated with known introductions, nor with altered environments, and exotic evolutionary origin cannot be assessed while the phylogeny of the genus is not known. The species in the western U.S.A. is ecologically as well as morphologically distinct, being estuarine rather than marine. A record of S. laevidorsalis from the Gironde estuary, France, is, in fact, of S. laticauda and therefore an introduction from the U.S.A. rather than from Japan. This study demonstrates the importance of careful taxonomic analysis before it is concluded that marine species are introduced.

The nomenclature of the Recent Pentastomida (Crustacea), with a list of species and available names

The taxonomy of the Recent members of the crustacean subclass Pentastomida is based on nine accepted family names derived from 12 available names, 24 generic names derived from 37 available names (plus two incorrect subsequent spellings and one nomen nudum) and 124 accepted species names derived from 183 available names of which six remain incertae sedis as to their generic assignment. Compilation of this list has revealed that existing catalogues have included misspellings, wrong attributions and dates of the authors of taxa, and incorrectly nominated type-species. These are corrected here with reference to the original descriptions and diagnoses. Notably, all families except one were erected much earlier and by authors other than Fain (1961), who was credited by Martin & Davis (2001) and other authors before and afterwards with seven of the nine families they recognised. Other significant taxonomic anomalies are revealed. Raillietiellidae Sambon, 1922 is a senior synonym of Cephalobaenidae Heymons, 1922, the name in popular usage for the family including Cephalobaena Heymons, 1922 and Raillietiella Sambon, in Vaney & Sambon, 1910; here the two genera are placed in separate families following Almeida & Christoffersen (1999). Heymonsia Hett, 1934, considered a junior synonym of Raillietiella, is a nomen nudum. Raillietiella geckonis (Diesing, 1850) is a potential senior synonym of several SE Asian species of this genus. Raillietiella frenata Ali, Riley & Self, 1981 is a widely used species name but is a subjective junior synonym of R. hebitihamata Self & Kuntz, 1960 according to its own authors. Morphological and molecular evidence suggest that R. indica Gedoelst, 1921 is a subjective senior synonym of both species. The priority of Linguatulidae Haldeman, 1851 over Linguatulida Vogt, 1851, erected as a family in the same year, is established by applying the First Reviser rule. Linguatula serrata Frölich, 1789 is herein selected as the type-species of Prionoderma, making it an objective synonym of Linguatula Frölich, 1789. The priority of L.serrata over Taenia rhinaris Meyer, 1789 and T.capraea Abildgaard, 1789, all published in the same year, is established by applying the First Reviser rule. The purported synonymy of Netrorhynchus Zenker, 1827, also misspelled Nettorhynchus, with Armillifer Sambon, 1922 would seem to be ill-founded and without popular support. Armillifer australis Heymons, 1935, published as a subspecies of A.moniliformis (Diesing, 1836), is both a senior synonym and a homonym of A. australis Riley & Self, 1981. Humboldt (1812) is confirmed as the author of Porocephalus Humboldt, 1812 and P. crotali Humboldt, 1812. Pentastomidae Shipley, 1909 is an older family name than its subjective synonym Porocephalinae Sambon, 1922, but prevailing usage allows the latter to be retained as a family name. Cayerina mirabilis Kishida, 1927 is a genus and species from a Japanese frog that has not appeared in the more recent pentastome literature. Sebekia minor (Wedl, 1861) is an objective senior synonym of the more widely used S. wedli Gigioli, in Sambon, 1922. The importance of the many junior synonyms will become evident should refined morphological and molecular evidence reveal cryptic species or greater host-specificity than presently recognised.

Morphological, molecular and biogeographic evidence support two new species in the Uroptychus naso complex (Crustacea: Decapoda: Chirostylidae).

The tropical to subtropical squat lobster Uroptychus nasoVan Dam, 1933 (Chirostylidae) is a widely distributed species originally described from Indonesia, subsequently reported from the Philippines, Taiwan, Japan and it has recently been discovered on the continental slope of north-western Australia. Populations of U. naso occur along the Indo-Pacific Ocean continental margin crossing the recently proposed marine analog of Wallaces line, responsible for past population fragmentation and ancient speciation. Sequence data from mitochondrial (COI, 16S) and nuclear (H3) DNA regions were used to assess genealogical relationships among geographically disjoint populations of the species throughout its known distribution range. Several mitochondrial lineages, corresponding to geographically isolated populations and three cryptic species were encountered, namely, U. naso sensu stricto and two new species, Uroptychus cyrano and Uroptychus pinocchio spp. nov. U. pinocchio is encountered only in Japan, Taiwan and the Philippines; U. cyrano is confined to north-western Australia; and U. naso consists of three genetically distinct populations distributed on both sides of the marine Wallaces line. Fossil-calibrated divergence time approximations indicated a most recent common ancestor (MRCA) for U. naso and U. cyrano from early Eocene whilst northern and southern populations of the former have been separated probably since the Miocene. These patterns may represent a standard distribution trend for several other deep-sea invertebrate species with similar geographical ranges.

ON STABILISING THE NAMES OF THE INFRAORDERS OF THALASSINIDEAN SHRIMPS, AXIIDEA DE SAINT LAURENT, 1979 AND GEBIIDEA DE SAINT LAURENT, 1979 (DECAPODA)

The names Gebiidea and Axiidea, erected by de Saint Laurent (1979), have priority over others for the two infraorders of shrimps previously included in Thalassinidea. Importantly, Thalassinidea are not monophyletic and the name should be replaced. Gebiidea and Axiidea, besides having priority and describing two monophyletic taxa, are now in common use (130 citations) and are more stable than alternative schemes proposed by Sakai (2005 and later). The history of the names of higher taxa applied to these groups is reviewed, and all family-group taxa listed.