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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

More species of the Agononida incerta complex revealed by molecules and morphology (Crustacea: Decapoda: Anomura: Munididae).

Squat lobsters from Madagascar, Vanuatu, Papua New Guinea, Fiji, eastern Australia and French Polynesia belonging to the Agononida incerta (Henderson, 1888) species complex are described as four new species: A. madagascerta, A. polycerta, A. tasmancerta and A. vanuacerta. This brings to ten the number of species in this complex. All species are morphologically distinguishable only on the basis of the shape of the anterolateral margin of the telson and setation of the dactyli of pereopods 2-4. The morphological delineation of nine of the species and their taxonomic status are robustly supported by phylogenetic analysis of the partial 16S rDNA gene and the partial mitochondrial cytochrome oxidase subunit 1 genes, and in some cases by colour. A phylogenetic analysis of the nine species for which molecular data are available grouped the species in two clades, one of four species with facial spines on the upper surface of pereopod 4 and the other of five species lacking facial spines. 

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. 

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.

Global coordination and standardisation in marine biodiversity through the World Register of Marine Species (WoRMS) and related databases.

The World Register of Marine Species is an over 90% complete open-access inventory of all marine species names. Here we illustrate the scale of the problems with species names, synonyms, and their classification, and describe how WoRMS publishes online quality assured information on marine species. Within WoRMS, over 100 global, 12 regional and 4 thematic species databases are integrated with a common taxonomy. Over 240 editors from 133 institutions and 31 countries manage the content. To avoid duplication of effort, content is exchanged with 10 external databases. At present WoRMS contains 460,000 taxonomic names (from Kingdom to subspecies), 368,000 species level combinations of which 215,000 are currently accepted marine species names, and 26,000 related but non-marine species. Associated information includes 150,000 literature sources, 20,000 images, and locations of 44,000 specimens. Usage has grown linearly since its launch in 2007, with about 600,000 unique visitors to the website in 2011, and at least 90 organisations from 12 countries using WoRMS for their data management. By providing easy access to expert-validated content, WoRMS improves quality control in the use of species names, with consequent benefits to taxonomy, ecology, conservation and marine biodiversity research and management. The service manages information on species names that would otherwise be overly costly for individuals, and thus minimises errors in the application of nomenclature standards. WoRMS' content is expanding to include host-parasite relationships, additional literature sources, locations of specimens, images, distribution range, ecological, and biological data. Species are being categorised as introduced (alien, invasive), of conservation importance, and on other attributes. These developments have a multiplier effect on its potential as a resource for biodiversity research and management. As a consequence of WoRMS, we are witnessing improved communication within the scientific community, and anticipate increased taxonomic efficiency and quality control in marine biodiversity research and management.

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.