Commonness and rarity in the marine biosphere.

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.

Chirostylidae of Australia's western continental margin (Crustacea : Decapoda: Anomura), with the description of five new species.

Five new species from the squat lobster family Chirostylidae are described from the continental margin of western Australia: Uroptychus albus sp. nov., Uroptychus bardi sp. nov., Uroptychus jawi sp. nov., Uroptychus taylorae sp. nov., and Uroptychus worrorra sp. nov. New records of Indo-West Pacific species for Australia are: Gastroptychus brachyterus Baba, 2005, Gastroptychus investigatoris Alcock, 1899, Uroptychodes grandirostris (Yokoya, 1933), Uroptychodes inortenseni (Van Dam, 1939), Uroptychus scandens Benedict, 1902, Uroptychus ciliatus (Van Dam, 1933) and Uroptychus vandamae Baba, 1988. New distributional records are given for species previously recorded from Australia: Uroptychus flindersi Ahyong & Poore, 2004, Uroptychus hesperius Ahyong & Poore, 2004, Uroptychusjoloensis Van Dam, 1939, Uroptychus nigricapillis Alcock, 1901, and Uroptychus spinirostris (Ahyong & Poore, 2004). These new records expand the number of chirostylid species in Australia from 34 to 46. Keys to Australian species of the genera Gastroptychus, Uroptychodes and Uroptychus are provided.

Reappraisal of Hawaiian species of Corallianassa Manning, 1987 (Crustacea: Axiidea: Callichiridae).

Four species of the callichirid ghost shrimp genus Corallianassa Manning, 1987 are recognised in Hawaii based on evidence from morphology and the CO1 gene. Corallianassa borradailei (De Man, 1928) is a widespread Indo-West Pacific species now confirmed for Hawaii. Corallianassa lanceolata Edmondson, 1944 is an endemic species similar to C. assimilis (De Man, 1928) from Indonesia and Guam. Corallianassa martensi (Miers, 1884) is also a widespread Indo-West Pacific species. Callianassa (Callichirus) winslowi Edmondson, 1944 (Hawaii), Callianassa (Callichirus) nakasonei Sakai, 1967 (Japan) and Callianassa haswelli Poore & Griffin, 1979 (Australia) are treated as junior subjective synonyms of C. martensi. Callianassa (Callichirus) oahuensis Edmondson, 1944, long treated as a junior synonym of C. borradailei, is revived as a valid species of Corallianassa. The four species differ in the shape and dorsal setae of the telson, the extent of the carina along the upper margin of the major cheliped palm, the attitude of the rostrum, and the shape of the maxilliped 3.

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 Wallace's 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 Wallace's 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.

Redescription of the poorly known ghost shrimp species, Scallasis amboinae Bate, 1888, review of the genus, and description of a new species from the Ryukyu Islands, Japan (Decapoda: Axiidea: Callianassidae).

A poorly known callianassid ghost shrimp species, Scallasis amboinae Bate, 1888, is redescribed and illustrated on the basis of the holotype and new material from Papua New Guinea. A new species, S. inermis, is described from the Ryukyu Islands, Japan. Callianassa (Cheramus) pygmaea De Man 1928 is synonymised with S. amboinae. All seven species of Scallasis are diagnosed and compared.

Revision of Pleuroprion zur Strassen, 1903 (Holidoteidae) and re-evaluation of Spectrarcturus Schultz, 1981 (Arcturidae) (Crustacea, Isopoda, Valvifera).

Pleuroprion zur Strassen, 1903 is revised and restricted to its type species, Antares chuni zur Strassen, 1902, which is redescribed, using the type material from the German Deep-Sea Expedition in 1898-1899 and more recent material. Pleuroprion is transferred to Holidoteidae Wägele, 1989. Pleuroprion frigidum Hansen, 1916 is transferred to Astacilla Cordiner, 1793 (Arcturidae), while all other species previously placed in Pleuroprion, i.e. P. murdochi (Benedict, 1898), P. chlebovitschi Kussakin, 1972, P. fabulosum Gujanova, 1955, P. furcatum Kussakin, 1982, P. hystrix (Sars, 1877), P. intermedium (Richardson, 1899), P. iturupicum Kussakin Mezhov, 1979 and P. toporoki Kussakin, 1972, are transferred to Spectrarcturus Schultz, 1981 (Arcturidae). The type species of Spectrarcturus, S. multispinatus Schultz, 1981, is a subjective junior synonym of Arcturus murdochi Benedict, 1898, now S. murdochi comb. nov. Spectrarcturus murdochi (Benedict, 1898) is redescribed on the basis of its type material and new material from South Greenland.

Caribbean species of Eiconaxius (Decapoda: Axiidea: Axiidae).

The type status of specimens of three species of the axiid genus Eiconaxius Bate, 1888 from the Caribbean Sea is clarified. Eiconaxius agassizi Bouvier, 1905, E. borradailei Bouvier, 1905 and E. caribbaeus (Faxon, 1896) are diagnosed and illustrated. Axius (Eiconaxius) communis Bouvier, 1905, Axius (Eiconaxius) rotundifrons Bouvier, 1905, and Axius (Eiconaxius) caribbaeus carinatus Bouvier, 1925, hitherto treated as valid species, are synonymised with E. caribbaeus. Lectotypes are selected for Eiconaxius agassizi Bouvier, 1905 and Eiconaxius borradailei Bouvier, 1905.

More cautionary tales: family, generic and species synonymies of recently published taxa of ghost and mud shrimps (Decapoda: Axiidea and Gebiidea).

Re-examination of the holotype of Neoaxius nicoyaensis Sakai, 2017 showed that it is conspecific with the axiid Guyanacaris caespitosa Squires, 1979 and thus Neoaxius Sakai, 2017 and Neoaxiidae Sakai, 2017 are respectively subjective junior synonyms of Guyanacaris Sakai, 2011 and Axiidae Huxley, 1879. The types and numerous specimens of the callianassid Trypaea vilavelebita Sakai Türkay, 2012 are juveniles of the common northeastern Atlantic-Mediterranean species, Callianassa subterranea (Montagu, 1808); the name is therefore a subjective junior synonym. The monotypic callianopsid genera Pleurocalliax Sakai, 2011, Neocallianopsis Sakai, 2011 and Phaetoncalliax Sakai, Türkay, Beuck Freiwald, 2015 are found not to differ from Callianopsis de Saint Laurent, 1973, the only alleged differences found to be untrue or trivial. Phaetoncalliax mauritana Sakai, Türkay, Beuck Freiwald, 2015 and Neocallianopsis africana Sakai, Türkay, Beuck Freiwald, 2015 are thereby transferred to Callianopsis, the latter a subjective junior synonym of the former. Contrary to the assertion of its author, the gourretiid Pseudogourretia portsudanensis Sakai, 2005, the only species in its genus, has no pleurobranchs. The genus Pseudogourretia Sakai, 2005 is therefore synonymised with Gourretia de Saint Laurent, 1973. The respective holotypes of Paracalliax stenophthalmus Sakai, Türkay, Beuck Freiwald, 2015 and Paracalliax bollorei de Saint Laurent, 1979 were re-examined. Both are from the Banc d'Arguin, off Mauritania, and are identical at the species level. The upogebiid Kuwaitupogebia nithyanandan Sakai, Türkay Al Aidaroos, 2015 from Kuwait is identical to Upogebia balmaorum Ngoc-Ho, 1990 from the Seychelles, Madagascar and tropical Western Australia. Kuwaitupogebia Sakai, Türkay Al Aidaroos, 2015 is therefore synonymised with Upogebia Leach, 1814 and Kuwaitupogebiidae Sakai, Türkay Al Aidaroos, 2015 with Upogebiidae Borradaile, 1903.

Synonymy and problematic species of Eiconaxius Spence Bate, 1888, with descriptions of new species (Crustacea: Decapoda: Axiidea: Axiidae).

The genus Eiconaxius Spence Bate, 1888, is rediagnosed. Eiconaxiopsididae Sakai, 2011 and its type genus,                         Eiconaxiopsis Sakai, 2011 are shown to be based largely on an error-the dactylus of pereopod 3 of the type species, Eiconaxiopsis heinrichi Sakai, 2011 is not as was originally illustrated but similar to all other species of Eiconaxius. The synonymies of Eiconaxiopsis with Eiconaxius and Eiconaxiopsididae with Axiidae are confirmed. Eiconaxius faxoni Sakai, 2011 is made an objective junior synonym of Eiconaxius albatrossae Kensley, 1996 (both share the same types). Eiconaxius malaku sp. nov. is erected to replace Eiconaxius indonesicus Sakai, 2011 (nomen nudum). Eiconaxius parvus Spence Bate, 1888 is redescribed based on numerous specimens from Fiji, and Wallis and Futuna. Eiconaxius vaubani sp. nov., which differs from all other species of the genus in the shape of the rostrum and proportions of pereopod 4, is described.

Digging deeper: new gene order rearrangements and distinct patterns of codons usage in mitochondrial genomes among shrimps from the Axiidea, Gebiidea and Caridea (Crustacea: Decapoda).

BACKGROUND: Whole mitochondrial DNA is being increasingly utilized for comparative genomic and phylogenetic studies at deep and shallow evolutionary levels for a range of taxonomic groups. Although mitogenome sequences are deposited at an increasing rate into public databases, their taxonomic representation is unequal across major taxonomic groups. In the case of decapod crustaceans, several infraorders, including Axiidea (ghost shrimps, sponge shrimps, and mud lobsters) and Caridea (true shrimps) are still under-represented, limiting comprehensive phylogenetic studies that utilize mitogenomic information. METHODS: Sequence reads from partial genome scans were generated using the Illumina MiSeq platform and mitogenome sequences were assembled from these low coverage reads. In addition to examining phylogenetic relationships within the three infraorders, Axiidea, Gebiidea, and Caridea, we also investigated the diversity and frequency of codon usage bias and mitogenome gene order rearrangements. RESULTS: We present new mitogenome sequences for five shrimp species from Australia that includes two ghost shrimps, Callianassa ceramica and Trypaea australiensis, along with three caridean shrimps, Macrobrachium bullatum, Alpheus lobidens, and Caridina cf. nilotica. Strong differences in codon usage were discovered among the three infraorders and significant gene order rearrangements were observed. While the gene order rearrangements are congruent with the inferred phylogenetic relationships and consistent with taxonomic classification, they are unevenly distributed within and among the three infraorders. DISCUSSION: Our findings suggest potential for mitogenome rearrangements to be useful phylogenetic markers for decapod crustaceans and at the same time raise important questions concerning the drivers of mitogenome evolution in different decapod crustacean lineages.

Resurrection of Rhynchoplax Stimpson, 1858, with the description of two new species from Japan and Australia (Crustacea: Decapoda: Brachyura: Hymenosomatidae).

Rhynchoplax Stimpson, 1858, is resurrected from synonymy with Halicarcinus White, 1846. Rhynchoplax hondai Takeda & Miyake, 1971, a species based on an immature female, is rediagnosed and two new species, R. magnetica n. sp. from northeastern Australia and R. minutula n. sp. from the Ryukyu Islands, Japan, are described. They differ from R. hondai in the shape of the rostrum, form of the subhepatic region and the armature of the pereopodal meri. All differ from the type species R. messor Stimpson, 1858, in having a longer and simple rostrum without supraocular pseudorostral spines and the absence of a postocular spine.

Reappraisal of species attributed to Halicarcinus White, 1846 (Crustacea: Decapoda: Brachyura: Hymenosomatidae) with diagnosis of four new genera and one new species from New Ireland, Papua New Guinea.

Species of Hymenosomatidae previously treated as species or junior synonyms of species of Halicarcinus White, 1846 are assigned to this and other genera. Halicarcinus is restricted to seven valid species; Rhynchoplax Stimpson, 1858, since 1980 synonymised with Halicarcinus, is now recognised with four species; four species are added to Micas Ng & Richer de Forges, 1996 (making five in total); and four new genera are erected: Culexisoma n. gen. (two species, one newly described), Lucascinus n. gen. (three species), Nasutoplax n. gen. (one species) and Stimpsoplax n. gen. (three species). The genera are distinguished primarily on features of the gonopod 1, interaction of the pleon with the thoracic sternal pleonal cavity, maxilliped 3, male cheliped, propodus-dactylus articulation of the ambulatory pereopods, and degree of fusion of the pleomeres. Species of Halicarcinus s.s. share a short trilobed rostrum, strongly curved gonopod 1 and free pleomeres. Some members of other genera may have a similar rostrum but typically have a long median projection with or without lateral angles or spines variously developed at the anterior margin of a supraocular eave. A lectotype of Hymenicus cookii Filhol, 1885 (now Halicarcinus cookii) is designated. A lectotype of Hymenosoma leachii Guérin, 1832, in Guérin-Méneville 1829-1837 (synonym of Halicarcinus planatus Fabricius, 1775) is selected in the interests of nomenclatural stability. Halicarcinus quoyi (H. Milne Edwards, 1853) is recognised as a senior synonym of the more widely used H. innominatus Richardson, 1949, which is itself a nomen nudum because it was erected without type designation. We also recognise Hymenicus marmoratus Chilton, 1882, as a junior synonym of Halicarcinus varius (Dana, 1851). Species of Rhynchoplax share a curved gonopod 1, falcate dactyli on pereopods 2-5 and fused pleomeres 3-4 in males and 3-5 in females. Species of Micas have a twisted gonopod 1 with the apex bent and only one or two subapical teeth on the dactylus of ambulatory legs. Culexisoma n. gen. is established for Halicarcinus ginowan Naruse & Komai, 2009, and a second species, Culexisoma niugini n. sp., from Papua New Guinea as type species. The genus is unique among these genera in having the male pleon not tightly engaging with the thoracic sternum, maxillipeds 3 not fully covering the buccal cavern and in having a strongly sexually dimorphic rostrum. Species of Lucascinus n. gen. share a male cheliped with 'nut-cracker'-like fingers and free pleomeres in both male and female. Nasutoplax n. gen. differs from others in the erect lateral profile of the rostrum and in gonopod 1 with an unusual subterminal spinulose projection on its posterior face. Stimpsoplax n. gen. has a gonopod 1 with a swollen base and a narrow strongly twisted distal part, tapering distally to a curved apex. Each genus is diagnosed, all species are tabulated, some discussed in more detail, and generic diagnostic characters are illustrated.

Ctenocheloides boucheti n. sp., a new ghost shrimp from Papua New Guinea (Decapoda, Axiidea, Ctenochelidae).

Ctenocheloides boucheti, the third species in this widespread but rare genus, is described from Papua New Guinea. It differs from the others in having more acute distal lobe on the eyestalk, more prominent distal bifid tooth on the cheliped ischium, longer cheliped fingers, shorter telson and the antennular and antennal peduncles reaching similar lengths.

Thermoarcturidae, a new crustacean family of three genera (Isopoda: Valvifera).

A new family Thermoarcturidae of valviferan isopod is erected for three genera, Califarcturus n. gen., Spinarcturus Kensley, 1978 and Thermoarcturus Paul & Menzies, 1971, each represented by one species. All share strong stiff setae on distal articles of pereopods 2-4, uropods with two rami, and a tomentum of fine setae over the cuticle. The members are distinguished from Antarcturidae, Arcturididae, Rectarcturidae and Arcturidae, similar arcturoid families that differ in having rows of filter setae on pereopods 2-4 and usually lack one or more uropodal rami.

Rediagnosis of Callianideidae and its genera (Crustacea: Decapoda: Axiidea), and description of a new species of Heardaxius Sakai, 2011.

Callianideidae and Thomassiniidae, two families of Axiidea, are synonymised and Callianideidae diagnosed. The six genera, Callianidea H. Milne Edwards, 1837, Crosniera Kensley & Heard, 1991, Mictaxius Kensley & Heard, 1991, Heardaxius Sakai, 2011, Paracallianidea Sakai, 1992 and Thomassinia de Saint Laurent, 1979 are diagnosed and all species listed. Garyia Sakai, 2011 is synonymised with Thomassinia. A key to genera is provided. A new species Heardaxius rogerbamberi is described from Papua New Guinea. Thomassinia aimsae Poore, 1997 is newly recorded from Papua New Guinea.

Takereana, a new genus of Idoteidae (Crustacea: Isopoda: Valvifera) from New Zealand.

Takereana n. gen. is erected for the New Zealand species, Idotea festiva Chilton, 1885, which is redescribed. Takereana, Austridotea Poore, 2001 and Idotea Fabricius, 1798 are the only idoteid genera in which both pleonites 1 and 2 are truly articulating. In all other genera of Idoteidae pleonite 2 is variously fused to pleonite 1 and visible only laterally. The new genus differs from Austridotea in that maxillipedal palp articles 2-3 and 4-5 are fused and operculate whereas in Austridotea the palp is of five free articles or has only articles 4-5 fused. All species of Austridotea are smooth with laterally expanded coxae, a quite different habitus from ornamented Takereana festiva. Takereana differs from Idotea in having two uropodal rami rather than one, greater fusion of maxillipedal palp articles, lacking spiniform setae on the pereopods, and unusual narrow pleopods 1. Takereana has an obsolete setose mandibular molar while it is columnar and toothed in both these genera.

Nomenclatural changes in two families of asellote isopods (Acanthaspidiidae and Ischnomesidae).

Iolanthe Beddard, 1886a is shown to be a senior synonyn of Acanthaspidia Stebbing, 1893, the replacement name for the preoccupied Acanthoniscus Sars, 1879 (Isopoda: Asellota: Acanthaspidiidae). Ischnomesus kussakini nom. nov. is erected as a replacement name for Ischnomesus antarcticus (Kussakin, 1982), preoccupied in this combination (Isopoda: Asellota: Ischnomesidae).

A new species of Naxia Latreille, 1825 (Brachyura: Majidae) from deep water off Brazil.

A new species of spider crab, Naxia atlantica n. sp., is described and illustrated from deep waters off São Paulo (southeastern Brazil). The new species can be separated from its congeners by a suite of characters including shapes of the propodi of the walking legs, rostrum and basal antennal article. This is the first record of the genus outside southern Australia and New Zealand.