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We are reporting for the first time the presence of the hermit crab Pagurus chevreuxi (Bouvier, 1896) (Paguridae) in the Canary Islands. This finding is based on the collection of three individuals and the sighting of several additional specimens on the coast of Lanzarote. The collection, at coordinates 28°55′N, establishes a new southern distribution limit for this species. The species' geographical distribution aligns perfectly with the typical Atlanto-Mediterranean biogeographic pattern, which is characterized by benthic species showing a clear affinity for warm-temperate waters. [ABSTRACT FROM AUTHOR]

Two new species of amphipods associated with a hermit crab Propagurus obtusifrons were collected from the bottom of a 190–380 m depth in Kumano-nada, central Japan. Metopelloides lowryi sp. nov. is characterized by the short article 2 of antenna 1, the slender mandibular palp with 3 setae, and the oblique palm of gnathopod 2. Isaea concinnoides sp. nov. can be distinguished from its congeners by the short carpus of gnathopod 2, the relatively stout antennae with short setae, and the oval basis of pereopod 5. Both species have prehensile pereopods 3–7 for clinging to the setae of the hermit crab.

Abstract The status of the obscure Pagurus bouvieri (Faxon, 1895), a replacement name proposed for the preoccupied Eupagurus smithii A. Milne-Edwards and Bouvier, 1893, was evaluated. Based on types and numerous unreported museum materials, P. bouvieri is found to be synonymous with Pagurus politus (Smith, 1882) a commonly encountered but infrequently discussed northwestern Atlantic species. The taxonomy and geographic distribution of P. politus is updated with a complete synonymy, redescription, and illustrations. The taxonomy of the northeastern Pacific species Pagurus smithi (Benedict, 1892) is also updated, including a redescription with illustrations.

The hermit crabs of Singapore are relatively well studied in the last few years and 42 species have been reported so far. This paper deals with 31 species of hermit crabs from the families Diogenidae and Paguridae, of which two are described as new: Diogenes pisinnus, new species (Diogenidae), and Pagurus tenuilineatus, new species (Paguridae). Seven species are also newly recorded, Clibanarius ransoni Forest, 1953, Diogenes mixtus Lanchester, 1902, D. spinicarpus Rahayu & Forest, 1995, Pseudopaguristes monoporus (Morgan, 1987), P. hians (Henderson, 1888), Pagurus pitagsaleei McLaughlin, 2002, and P. hedleyi (Lanchester, 1902). Diogenes platyops Rahayu & Forest, 1995, previously synonymised with D. jubatus (Nobili, 1903) is resuscitated based on the live colouration and several morphological characters. Among the specimens identified from the family Diogenidae, the genus Diogenes was the most species-rich with 17 species, while the genera Clibanarius, Dardanus, Paguristes, and Pseudopaguristes were represented only by four, three, one, and two species, respectively. As for the family Paguridae, four species of Pagurus and one species of Spiropagurus, were reported. [ABSTRACT FROM AUTHOR]

Three new species of the pagurid hermit crab genus Catapagurus A. Milne-Edwards, 1880 are described and illustrated on the basis of material from the Bohol Sea, Philippines, collected by the PANGLAO 2004 Marine Biodiversity Project. Catapagurus exilidigitus, new species, appears closest to C. tanimbarensis McLaughlin, 1997 within the C. misakiensis Terao, 1914 species group, but it is readily distinguished from the latter by the wide U-shaped median cleft of the telson. Catapagurus fimbriatus, new species, is notable in having a characteristic fringe of setae on the mesial surfaces of the ambulatory dactyli and propodi of the pereopods 3. Catapagurus latus, new species, appears closest to C. haigae (Asakura, 2001) in the general shape and armature of the ambulatory dactyli within the C. ensifer Henderson, 1888 species group, but might be unique within the group in having a setal cluster on the distoventral portion of each ambulatory propodus. The number of species of Catapagurus known from the Philippines increases to seven. [ABSTRACT FROM AUTHOR]

Se proporciona información preliminar sobre la época de reproducción de las hembras ovíferas de Pagurus villosus, de Caleta Leandro (36°38?36?S; 73°05?25?O). El trabajo se basa en el examen de más de 30.000 especímenes que fueron capturados entre enero de 1969 y noviembre de 1971, cuando invadieron jaulas de madera sumergidas sublitoralmente. También se proporciona información sobre los epibiontes de las conchas de caracol Nassarius (Hima) gayi ocupadas por P. villosus.

Species of the genus Pagurus have diversified into a wide variety of marine habitats across the world. Despite their worldwide abundance, the genus diversity and biogeographical relationship are relatively less understood at species-level. We evaluated the phylogenetic relationship and genetic diversity among the Pagurus species based on publicly available mitochondrial and nuclear markers. While independent analyses of different markers allowed for larger coverage of taxa and produced largely consistent results, the concatenation of 16S and COI partial sequences led to higher confidence in the phylogenetic relationships. Our analyses established several monophyletic species clusters, substantially corresponding to the previously established morphology-based species groups. The comprehensive species inclusion in the molecular phylogeny resolved the taxonomic position of a number of recently described species that had not been assigned to any morpho-group. In mitochondrial markers-based phylogenies, the “Provenzanoi” group was identified as the basal lineage of Pagurus. The divergence time estimation of the major groups of Pagurus revealed that the Pacific species originated and diversified from the Atlantic lineages around 25–51 MYA. The molecular results suggested a higher inter-regional species diversity and complex phylogenetic relationships within the diverse and heterogeneous members of the genus Pagurus. The study presents a comprehensive snapshot of the diversity of pagurid hermit crabs across multiple geographic regions.

Abstract Complete mitochondrial genome (mitogenome) provides important information for better understanding of gene rearrangement, molecular evolution and phylogenetic analysis. Currently, only a few Paguridae mitogenomes have been reported. Herein, we described the complete mitogenome of hermit crab Pagurus nigrofascia. The total length was 15,423 bp, containing 13 protein-coding genes (PCGs), two ribosomal RNA, 22 transfer RNA genes, as well as an AT-rich region. The genome composition was highly A + T biased (71.4%), and exhibited a negative AT-skew (−0.006) and GC-skew (−0.138). Eight tRNA genes, two PCGs and an AT-rich region found to be rearranged with respect to the pancrustacean ground pattern gene order. Duplication-random loss and recombination model were adopted to explain the large-scale gene rearrangement events. Two phylogenetic trees of Anomura involving 12 families were constructed. The results showed that all Paguridae species were clustered into one clade except Pagurus longicarpus , which for the first time imposed raises doubt about the morphological taxonomy of this species. Furthermore, the present study found that higher- level phylogenetic relationships within Anomura were controversial, compared with the previous studies. Our results help to better understand gene rearrangements and the evolutionary status of P. nigrofascia and lay foundation for further phylogenetic study of Anomura. Highlights • Complete mitogenome of P. nigrofascia was described. • Large-scale gene rearrangements were identified. • Possible rearrangement mechanisms were discussed. • Phylogenetic trees showed controversial results. [ABSTRACT FROM AUTHOR]

For the first time the occurrence of Porcellanopagurus nihonkaiensis Takeda, 1985 is reported both from Sagami Bay and Otsuchi Bay. The use of an empty shell of a true limpet of the family Lottiidae Gray, 1840 by Porcellanopagurus sp. is herein also reported for the first time. [ABSTRACT FROM AUTHOR]

The population and reproductive characteristics of the hermit crab Pagurus brachiomastus (Thallwitz, 1892) have been examined in Vostok Bay (Peter the Great Bay, Sea of Japan). The average population density of P. brachiomastus was lowest in the spring (2.4 ± 0.6 ind./m2) and highest (3.1 ± 0.4 ind./m2) in the summer; the biomass was 18.24 ± 3.75 and 22.83 ± 2.80 g/m2, respectively. Hermit crabs were found throughout the depth range from 0 to 12 m, but were most numerous at a depth of approximately 5–6 m, with an average population density of 8.3 ± 3.7 ind./m2 and a biomass of 39.09 ± 8.51 g/m2 in the summer. The shield length of males varied from 1.3 to 10.3 mm (on average, 5.3 ± 2.2 mm), that of females varied from 1.3 to 10.6 mm (on average, 4.3 ± 1.5 mm), and that of ovigerous females varied from 1.5 to 8.4 mm (on average, 4.4 ± 1.5 mm). The male to female ratio varied from 0.8 to 3.3 during the observation period, with an average of 1.7. Spawning continued from March through August. The proportion of ovigerous females increased from 8.5% in March to 82.8% in May; embryos in clutches remained in the early stage of development until the second 10-day period of May. Egg development was resumed when the water temperature reached 10°C. Breeding was asynchronous: in June–August, females with late-stage embryos and females with recently laid eggs were observed, indicating the possibility of repeated spawning. The data we obtained showed that the favorable coexistence of P. brachiomastus with other sympatric species in the study area is provided by the spatial dissociation of their clusters and differences in size characteristics, as well as the presence of an embryonic diapause in egg development in part of the females and the possibility of repeated spawning. [ABSTRACT FROM AUTHOR]

Investigation of decapod crustaceans from Paleogene sediments of Mississippi has yielded one new Eocene brachyuran species, Matutites periosus n. sp. and six new Oligocene brachyuran species, Lophoranina lincki n. sp. Notopus adinae n. sp. Calappilia granulosa n. sp. C. perreaulti n. sp. C. gableorum n. sp. and Acanthocarpus osborni n. sp. Other occurrences include previously described caridean shrimp, axiids, pagurids, and raninids. Mesostylus, a callianassid, is described for the first time from Danian deposits, all other occurrences being Late Cretaceous. The Oligocene decapod fauna from Gulf Coastal North America, including localities in Alabama and Mississippi, is most like that of Pacific Coastal Baja California and most different from Pacific coastal localities from Oregon northward. [ABSTRACT FROM AUTHOR]

Abstract During fieldwork in a small outcrop of the lower Aptian Margas de Forcall Formation at La Cova del Vidre, hitherto known as the type locality of the anomuran Pagurus avellanedai , new decapod crustacean material has been recovered. In this newly recovered lot, two undescribed species of brachyuran have been recognised; there are here described as Rathbunopon tarraconensis n. sp. and Pithonoton lluismariaorum n. sp. In addition, numerous remains of the anomuran P. avellanedai , enable an improvement of the original description of this taxon, and an analysis of associated ammonites from La Cova del Vidre has resulted in precise age calibration for the first time. [ABSTRACT FROM AUTHOR]

A new species of hermit crab, Pagurus fraserorum n. sp. (family Paguridae) is described from rocky subtidal reefs off KwaZulu-Natal, South Africa, and illustrated using both conventional drawings and colour photographs, and via three-dimensional (3D) X-ray micro-computed tomography (μCT). Because of the limitation μCT has in detecting very fine and soft structures, a novel approach of manually drawing setation and spinulation onto the two-dimensional images of the 3D visualizations was used to illustrate the pereopods. In addition, an interactive figure and rotation movie clips in the supplement section complement the species description, and the 3D raw data of the 3D type data are downloadable from the Gigascience Database repository. The new species is the sixth species of Pagurus Fabricius, 1775 reported from South Africa and is closely allied to the Indo-Pacific P. boriaustraliensis Morgen, 1990 and P. pitagsaleei McLaughlin, 2002, from which it differs by its shorter ocular peduncles, by the armature of the carpus of the right cheliped, and also in colouration. This study presents the first description of a hermit crab in which a majority of taxonomic details are illustrated through 3D volume-rendered illustrations. In addition, colour photographs and COI molecular barcodes are provided, and the latter compared to COI sequences of specimens from Western Australia previously identified as P. boriaustraliensis and of specimens of P. pitagsaleei from Taiwan, as well as to three additional South African members of the genus. The South African taxon was confirmed to be genetically distinct from all species tested. [ABSTRACT FROM AUTHOR]

Because of increased human-generated carbon emissions, ocean acidification is beginning to dissolve structures built by calcification, including the shells that all species of hermit crab (Crustacea: Decapoda: Paguroidea) use for protection. Since hermit crabs have been known to non-randomly select shells that best fit, this study explores whether the Atlantic long-clawed hermit crab, Pagurus longicarpus Say, 1817 preferentially chooses sturdier, intact shells when provided a choice between untreated shells (control) and acid-treated shells. Under controlled conditions (i.e., removal of stress from predator presence/effluent and intraspecific competition), not-surprisingly, most P. longicarpus preferred non-acid treated (control) shells by the end of testing period (1 hour) over heavily acid-treated shells; there was no statistical difference between the control shells and lightly acid-treated shells. [ABSTRACT FROM AUTHOR]

Background: Along with the conventional deposition of physical types at natural history museums, the deposition of 3-dimensional (3D) image data has been proposed for rare and valuable museum specimens, such as irreplaceable type material. Findings: Micro computed tomography (µCT) scan data of 5 hermit crab species from South Africa, including rare specimens and type material, depicted main identification characteristics of calcified body parts. However, low-image contrasts, especially in larger (>50 mm total length) specimens, did not allow sufficient 3D reconstructions of weakly calcified and fine characteristics, such as soft tissue of the pleon, mouthparts, gills, and setation. Reconstructions of soft tissue were sometimes possible, depending on individual sample and scanning characteristics. The raw data of seven scans are publicly available for download from the GigaDB repository. Conclusions: Calcified body parts visualized from µCT data can aid taxonomic validation and provide additional, virtual deposition of rare specimens. The use of a nondestructive, nonstaining µCT approach for taxonomy, reconstructions of soft tissue structures, microscopic spines, and setae depend on species characteristics. Constrained to these limitations, the presented dataset can be used for future morphological studies. However, our virtual specimens will be most valuable to taxonomists who can download a digital avatar for 3D examination. Simultaneously, in the event of physical damage to or loss of the original physical specimen, this dataset serves as a vital insurance policy. [ABSTRACT FROM AUTHOR]

Hermit crabs are common and abundant members of the intertidal community and in sublittoral bottoms, where they play a fundamental role in the trophic chain. This study aimed to determine the composition of the hermit crab fauna, to quantify the density in the natural environment, and to register shells use by main species from subtidal boulder fields, in an island off the southeastern Brazilian coast. Monthly samples were taken from March 2010 to February 2011 on boulder fields on Couves Island, Ubatuba, Brazil, during scuba diving daytime sessions. Three hundred and eighty-three crabs were collected by hand, in a quadrat of 20 m² belonging to five species: Calcinus tibicen, Dardanus venosus, Pagurus brevidactylus, Paguristes tortugae, and Petrochirus diogenes. The highest densities were recorded for P. brevidactylus and P. tortugae. Hermit crabs occupied shells of 15 gastropod species. Cerithium atratum, Gemophos auritulus, and Morula nodulosa comprised more than 80% of the occupation. The heterogeneity of boulder fields of Couves Island, composed almost entirely of small refuges and crevices, favors the exploration of hermit crab species recorded here, which are characterized by small size. These results, combined with the findings of further studies, can contribute to the development of effective monitoring programs for decapod crustacean species. [ABSTRACT FROM AUTHOR]

The origin of king crabs from a hermit crab ancestor has caused controversy for more than a century. While the phylogenetic position of Lithodidae within the hermit crab family Paguridae has been strengthened in recent years, several key questions regarding the evolution of lithodid crabs have remained unanswered. In particular, it has been debated which hermit crabs constitute the closest extant relatives to lithodid crabs within Paguridae. Also, the relationships of the two lithodid subfamilies, Lithodinae and Hapalogastrinae, are unresolved. Answers to these questions are crucial to the understanding of the origin of king crabs, in particular which factors were the driving forces behind leaving a protective housing, transforming to a crab-like morphology and finally developing a large body size. To address these questions, we constructed the most comprehensive molecular phylogeny of Paguridae and Lithodidae to date. Our analyses revealed a species-rich clade of hermit crabs as closest relatives to lithodid crabs within Paguridae. Hermit crabs included in this clade have a predominantly shallow-water distribution in the North Pacific, agreeing with a proposed origin of lithodid crabs in this region. We suggest that the advances resulting from abandoning a shell-inhabiting lifestyle, rather than constraints of such shelters, played a central role in carcinization in this taxon. Phylogenetic relationships within Lithodidae revealed its two subfamilies to be non-monophyletic. Small-sized, shallow-water taxa are basal in the phylogenetic tree, while an increase in size and subsequent deep-sea distribution occurred later in the evolution of the group. [ABSTRACT FROM AUTHOR]

A new secretive, yet brightly colored hermit crab species of the family Paguridae, Pylopaguropsis mollymullerae sp. n., is fully described based on specimens from the reefs of Bonaire, Lesser Antilles, southern Caribbean Sea. Populations of this new species were discovered and photographed in the Bonaire National Marine Park under a large coral ledge, at a depth of 13.7 m, living in crevices known by scuba divers to serve as den to a pair of "flaming reef lobsters" Enoplometopus antillensis, or a "broad banded moray" Channomuraena vittata. This new species is only the second species of Pylopaguropsis Alcock, 1905 known from the western Atlantic, the 20th named worldwide, and belongs in the teevana group of species of the genus. It is remarkably similar, and herein considered geminate, to the tropical eastern Pacific congener, P. teevana (Boone, 1932), the two being characterized and uniquely different from all other species of the genus, by the striking and deeply excavated, scoop-like ventral surface of the chela of the right cheliped. Minor differences separate this new species from P. teevana in the relative length of the antennal acicles (exceeding the corneas versus not exceeding the corneas in P. teevana); dorsal armature of the right chela (smooth or with scattered minute tubercles versus with numerous small tubercles in P. teevana); surface shape of the lateral face of the dactyl of right pereopod 3 (evenly convex versus flattened in P. teevana); and coloration (red bright red stripes versus brown stripes in P. teevana). The highly visible color pattern of bright red stripes on white background typical of decapods known to have cleaning symbioses with fish, dense setation on the flagella of the antennae, and preference for a crevicular habitat, combined with brief in situ nocturnal observations, suggests the possibility that P. mollymullerae sp. n. engages in "cleaner" activities or functions as a "den commensal" with moray eels. The morphology and possible meaning of the observed behavior is discussed. A tabular summary of the distribution, habitat, and published information on all species of Pylopaguropsis is presented. Supplemental photographs and a video of live P. mollymullerae sp. n. are included. [ABSTRACT FROM AUTHOR]

A new species of the pagurid genus Tomopaguropsis Alcock, 1905 is documented based on specimens collected during the PANGLAO 2005 expedition in deep waters (269-712 m) of the Bohol Sea, the Philippines. This new species, named Tomopaguropsis rahayuae, is the first record of a species of the genus in the Philippines region, and is fully described and illustrated. The most significant morphological character that distinguishes this new species from other congenerics is the symmetrical uropods. The holotype and paratype were found living in scaphopod tusk shells, an unusual type of housing for species of this genus. The morphology and affinities of this new species are discussed. An updated identification key to all species of Tomopaguropsis is also presented. [ABSTRACT FROM AUTHOR]

New records are provided for three species of little-known pagurids. All the material reported was collected by the R/V “El Puma” in the central Gulf of California during the GUAYTEC II cruise. New material is reported for Iridopagurus haigae García-Gómez, 1983, Enallopagurus spinicarpus (Glassell, 1937), and Solenopagurus diomedeae (Faxon, 1893), and these two latter species are redescribed. A new species of hermit crab of the genus Pagurus Fabricius, 1775, is described and illustrated in detail. Among the eastern Pacific species of Pagurus, this new species resembles Pagurus meloi Lemaitre and Cruz Castaño, 2004, P. imarpe Haig, 1974 and P. delsolari Haig, 1974, but differs from these three species in the armature and setation of the chelipeds and second and third pereopods, the shape and armature of the telson, and the number of rows of scales on pereopodal rasp and the presence of a preungual process.

The population of Catapaguroides microps A. Milne-Edwards and Bouvier, 1892 in the Campos Basin was studied with an emphasis on its composition in the Northern and Southern parts of the Basin, the different gender sizes, sex ratio, and size class distribution. Specimens were collected under the "Program for the Environmental Characterization of the deep waters of the Campos Basin" ("Programa de Caracterização Ambiental das Águas Profundas da Bacia de Campos") in February and August 2003. A total of 339 hermit crabs were analyzed. Individual abundance was higher in the North. C. microps shows sexual dimorphism for body size, the males being larger than the females. The sex ratio is skewed in the female's favor (1:0.7), as shown by previous studies on shallow-water populations.A população de Catapaguroides microps A. Milne-Edwards and Bouvier, 1892 da foi analisada com foco na abundância de indivíduos, diferença de tamanho entre machos e fêmeas, razão sexual e distribuição dos indivíduos nas classes de tamanho, ao norte e ao sul da Bacia de Campos. As amostras foram coletadas pelo Programa de Caracterização Ambiental da Bacia de Campos em fevereiro e agosto de 2003. O total de indivíduos analizados foi de 339. A abundância foi maior no norte da Bacia de Campos. Catapaguroides microps mostrou dimorfismo sexual no tamanho do corpo, sendo os machos maiores que as fêmeas. A razão sexual favorece as fêmeas (1:0,7), de forma similar a outros estudos efetuados com populações de águas rasas.

A maioria das espécies de ermitões utiliza conchas vazias de gastrópodes como abrigos móveis. A variação na disponibilidade desse recurso em microambientes distintos pode minimizar interações competitivas em espécies simpátricas, possibilitando sua coexistência. O presente trabalho teve como objetivos caracterizar a ocupação de conchas de gastrópodes por três espécies de ermitões e avaliar a disponibilidade das conchas e a utilização de microambientes pelos ermitões e gastrópodes em uma área infralitorânea no litoral norte do Estado de São Paulo. Para tanto, foram estabelecidos transectos, nos quais foram coletados todos os ermitões, gastrópodes e conchas vazias encontrados, registrando-se o tipo de microambiente utilizado. Em uma sub-amostra, os ermitões foram identificados e classificados quanto às categorias reprodutivas. As conchas utilizadas pelos caranguejos foram identificadas e avaliadas quanto à presença de danos e incrustações. Foram registradas três espécies de ermitão (Paguristes tortugae, Pagurus brevidactylus e Pagurus criniticornis), ocupando 15 espécies de conchas de gastrópodes e uma de escafópode (Dentalium sp.), com danos físicos e incrustação das conchas significativamente diferentes entre as espécies de ermitões. Em relação à utilização de microambientes, P. tortugae e P. brevidactylus foram encontrados principalmente em algas calcárias, enquanto P. criniticornis ocorreu principalmente em areia. Apesar das diferenças de utilização de conchas e microambientes, a grande sobreposição no uso desses recursos, principalmente entre os pagurídeos é um indicativo de que interações competitivas são fatores reguladores importantes para essas populações.

Most species of hermit crabs use the empty shells of gastropods as mobile shelters. The variation of shell availability in different microhabitats can reduce competitive interactions between sympatric species, favoring their coexistence. This work aimed to characterize the occupation of gastropod shells by three species of hermit crabs, and assessing the availability of shells and evaluating the use of microhabitats crabs and gastropods in an infralitoral area on the north coast of São Paulo state. For this purpose, transect lines were established and all hermit crabs, gastropods and empty shells found were collected, recording the type of microhabitat used. In a sub-sample, the hermit crabs were identified and classified into reproductive categories. The shells used by the crabs were identified and evaluated according to physical damage and incrustation. Three species of hermit crabs (Paguristes tortugae, Pagurus brevidactylus and Pagurus criniticornis) were recorded, using 15 species of gastropod shells and one of scaphopod (Dentalium sp.). Physical damage and incrustation of shells were significantly different among the hermit crab species. Considering microhabitat use, P. tortugae and P. brevidactylus were mainly found in calcareous algae, while P. criniticornis mainly occurred in sand substrate. Despite the differences in shell and microhabitat use, the high resource overlap, especially by the pagurids, indicates that competitive interactions are important regulatory factors for these populations.

A new species of pagurid hermit crab, Pagurus liui sp. nov., is described from the South China Sea. It is most closely similar to Pagurus imaii (Yokoya, 1939), but the endopod of the maxillule recurved and the absence of spines on the ventral surface of the propodus of the pereopods can easily distinguish the new species from P. imaii. The new species is placed in the "capillatus" group of Pagurus. [ABSTRACT FROM AUTHOR]

A new species of the genus Turleania McLaughlin, 1997, T. sinensis sp. nov., is described and illustrated. This new species is morphologically similar to T. senticosa, but differs from that species in having nine pairs of quadriserial gills, and in having the ventromesial margin of the ischium of both chelipeds armed with large, prominent spines. This is the tenth species in this genus, and the first record of the genus from the China Sea. An identification key to species of Turleania is provided. [ABSTRACT FROM AUTHOR]

A key for the identification of the zoeae of hermit crabs (Decapoda: Anomura: Paguroidea) in the plankton of Vostok Bay (the Sea of Japan) has been developed based on the external morphology and live coloration of the larvae. The time of hatching and the duration of occurrence of diogenid and pagurid larvae in this area have been determined. [ABSTRACT FROM AUTHOR]

This study describes the daily activity in a simulated high tide situation of four species of hermit crabs (Pagurus criniticornis, Clibanarius antillensis, C. sclopetarius, and C. vittatus) that coexist in an intertidal flat in southeastern Brazil. Observations were done in two-hour intervals during two subsequent days (48 h) in three replicate pools with thirty crabs each. Among species (between and within genera) there was an evident variation in activity patterns, of which three could be distinguished. The circadian activity patterns of C. antillensis and C. vittatus could be characterized as evening and nocturnal, with resting peaks during the morning and afternoon. The circadian activity pattern of C. sclopetarius was characterized by two marked peaks of inactivity, corresponding to dawn and evening, which could represent an intrinsic association with the semi-lunar tidal cycles of the study area. Pagurus criniticornis showed high activity not influenced by day/night conditions during the entire observed period. These activity pattern variations of the studied hermit crabs should be taken into account in designing further experiments. More precise and accurate interspecific behavioral comparisons among species could be achieved in nocturnal experiments, the high activity period of all species.

Pagurus hermit crabs have a well-developed right cheliped (major cheliped) and in some species the major cheliped of males is longer than that of females. This paper describes sex-related differences in major cheliped length and regeneration pattern of the major cheliped in the hermit crab Pagurus filholi. We also examined the function of the major cheliped in male-male competition. Major cheliped length of males was longer than that of females in P. filholi. Males regenerated larger chelipeds than females at the first molt after experimentally induced autotomy. Body size growth in males of the regeneration group was less than that in intact males of the control group while there was no significant difference in body size growth of females between regeneration and control groups. Major cheliped length was included in the best model to explain the outcome of male-male competition and thus sexual selection appears to be a causative factor in the sex-related difference of the major cheliped length. Sex-related differences in the regeneration pattern may reflect differences in evolutionary pressures on males for large major chelipeds and females for large body size. [ABSTRACT FROM AUTHOR]

The emergence of king crabs from a hermit crab-like ancestor is one of the most curious events in decapod evolution. King crabs comprise two taxa, Lithodidae and Hapalogastridae, and while lithodids have formed the focus of various anatomical studies, the internal anatomy of hapalogastrids has never been studied although this group might represent a more ancestral morphological condition within king crabs than lithodids do. To better understand the evolutionary transformation of pagurid-like hermit crabs into king crabs, we studied the hemolymph vascular system and associated organs of representatives of Hapalogaster and present here the first micro-computer tomography data pertaining to the internal anatomy of hapalogastrids. Our results for Hapalogastridae are compared with existing and new data on Paguridae and Lithodidae and are discussed in the light of the process of carcinization or evolutionary transformation into a crab-like habitus. Hapalogaster resembles both pagurids on the one hand and lithodids on the other, not only with regard to external morphological characters but also in terms of certain internal anatomical features. In this and other respects, Hapalogaster represents an evolutionary intermediate form that connects pagurids and lithodids. [ABSTRACT FROM AUTHOR]

Two species of pagurid hermit crab, Diacanthurus ophthalmicus (Ortmann, 1892) and Nematopagurus lepidochirus (Doflein, 1902), which were collected in 2013 from 129 m depth, east of Jeju Island, are now recorded from South Korea for the first time. Diacanthurus ophthalmicus and Nematopagurus lepidochirus are the only members of the genera Diacanthurus and Nematopagurus known from South Korea, respectively. [ABSTRACT FROM AUTHOR]

A new hermit crab species of the family Paguridae, Tomopaguropsis ahkinpechensis sp. n., is described from deep waters (780-827 m) of the Gulf of Mexico. This is the second species of Tomopaguropsis known from the western Atlantic, and the fifth worldwide. The new species is morphologically most similar to a species from Indonesia, T. crinita McLaughlin, 1997, the two having ocular peduncles that diminish in width distally, reduced corneas, dense cheliped setation, and males lacking paired pleopods 1. The calcified plates on the branchiostegite and anterodorsally on the posterior carapace, and the calcified first pleonal somite that is not fused to the last thoracic somite, are unusual paguroid characters. A discussion of the affinities and characters that define this new species is included, along with a key to all five species of Tomopaguropsis. [ABSTRACT FROM AUTHOR]

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We document for the first time the presence of Anapagurus Henderson, 1886 (Paguridae Latreille, 1802) with Anapagurus mamertinus n. sp., from the Pliocene of S. Antonio, Capo Milazzo (Sicily, S Italy). It is the first report of this genus from the Pliocene of Italy, enlarging the knowledge on its distribution in the palaeo-Mediterranean area. Anapagurus was known to date with a. sp. from the Pleistocene of Arda River (Emilia Romagna, N Italy).

Two new species of the pagurid genus Pylopaguropsis Alcock, 1905 are described and illustrated from the Bohol Sea, the Philippines. Pylopaguropsis pygmaeus, new species, resembles P. keijii McLaughlin & Haig, 1989, P. lemaitrei Asakura & Pauly, 2003, P. lewinsohni McLaughlin & Haig, 1989 and P. zebra (Henderson, 1893) in sharing appreciably dissimilar third pereopods and relatively long ocular peduncles, but differs in having corneas not dilated, and fewer corneous spines on the ventral margins of the dactyls of the ambulatory legs. Pylopaguropsis similis, new species, differs from the closely related species P. bellula Osawa & Okuno, 2007, P. furusei Asakura, 2000, P. laevispinosa McLaughlin & Haig, 1989 and P. vicina Komai & Osawa, 2004, by the relatively long, acute spines on the right palm, the lack of additional dorsal spines or spinules on the carpi of the second pereopods and two rows (rather than one) of corneous scales on the propodal rasp of the fourth pereopod. [ABSTRACT FROM AUTHOR]

The pagurid genus Decaphyllus de Saint Laurent, 1968 was represented by fi ve species prior to this study. In this work, six new species of the genus are described and illustrated on the basis of material mainly collected by the PANGLAO 2004 Marine Biodiversity Project, carried out in Bohol, the Philippines, supplemented by a small collection from Japan: D. brevis, D. deliquus, D. litoralis, D. proprius, D. spinulodigitus, and D. tenuis. Affinities of these new species are discussed. Interspecific variation in the development of the arthrobranch gills on the third maxilliped is seen. The genus Decaphyllus is recorded from the Philippines for the fi rst time. The present work increases the number of species of Decaphyllus to 11. [ABSTRACT FROM AUTHOR]

Ten species of the pagurid genus Catapaguroides A. Milne-Edwards & Bouvier, 1892, including eight new to science, are reported from the Bohol Sea, the Philippines, collected by the PANGLAO 2004 Marine Biodiversity Project: C. brevidactylus, new species; C. conicus, new species; C. crassimanus, new species; C. cristimanus de Saint Laurent, 1968; C. hirsutus, new species; C. karubar McLaughlin, 1997; C. levigatus, new species; C. pusillus, new species; C. tenuiclavus, new species; and C. tuber, new species. The sample is rather small, but specimens came from diverse habitats, including coral reefs, underwater caves, and lower sublittoral soft bottoms. This study is the fi rst report of the genus from the Philippines. Affi nities of the eight new species are discussed. Supplemental descriptions and illustrations are also given for C. cristimanus and C. karubar. A list and identifi cation key of all known species of the genus are provided. [ABSTRACT FROM AUTHOR]

The pagurid hermit crab genus Pagurixus Melin, 1939, is widely distributed in shallow waters in tropical to warm temperate seas in the Indo-West to Central Pacifi c. This study deals with a collection made during the PANGLAO 2004 Marine Biodiversity Project. Nine species of the genus were identifi ed, including one new to science: P. concolor Komai & Osawa, 2006, P. formosus Komai, 2010, P. haigae Komai & Osawa, 2007, P. longipes Osawa, Fujita & Okuno, 2006, P. maorus (Nobili, 1906), P. nomurai Komai & Asakura, 1995, P. ruber Komai & Osawa, 2006, P. rubrovittatus Komai, 2010, and P. spiniferore, new species. Of these, all but P. haigae are recorded from the Philippines for the fi rst time, clearly suggesting that the inventory of the shallow coral reef fauna in the area is far from satisfactory. The new species, P. spiniferore, belongs to the P. anceps (Forest, 1954) species group, and is immediately distinguished from all other members of the group by the palm of the right cheliped in the male armed with a row of small spines or spiniform tubercles on each dorsolateral and dorsomesial margin and the presence of spines on the dorsodistal margin of the carpus of the right cheliped. [ABSTRACT FROM AUTHOR]

The hermit crab Pagurus parvispina Komai, 1997 (Decapoda: Paguridae) was found in Vostok Bay (Peter the Great Bay, Sea of Japan) at a depth of 50-65 m. Earlier, this species was recorded from the type locality in northern Japan at a depth of 150-200 m. The finding of P. parvispina in Vostok Bay is its first record in Russian waters and substantially expands the distribution area of this species in the Sea of Japan. Discorsopagurus maclaughlinae Komai, 1995 inhabits Russian waters and was earlier identified as Orthopagurus schmitti (Stevens, 1925); its taxonomical position is discussed. [ABSTRACT FROM AUTHOR]

Pagurus exilis (Benedict, 1892) is an endemic South Atlantic hermit crab with a distribution ranging from Rio de Janeiro State, Brazil, to Buenos Aires Province, Argentina. The present study analyzed the reproduction of two populations at the extremes of this geographical distribution, and compared their reproductive period, fecundity, and changes in egg size and egg volume during the incubation period in order to assess the variability over this latitudinal range. Hermit crabs were collected monthly over a 2-year period. In total, 108 females were analyzed for Brazil (44 non-ovigerous and 64 ovigerous), and 141 for Argentina (87 non-ovigerous and 54 ovigerous). Reproduction in Brazil occurs year-round, with peaks in the fall and winter seasons; in Argentina reproduction occurs only in spring and summer. The Brazilian ovigerous females were significantly larger than the Argentina ones (Brazil: SL = 5.33 ± 1.45 mm; Argentina: SL = 4.15 ± 0.52 mm; P < 0.001). The fecundity was 1447 ± 831 eggs (317 to 2885) in Brazil and 987 ± 711 eggs (114 to 2665) in Argentina, with a trend towards higher fecundity in Brazil. Eggs in the Argentina population were larger than those in Brazil for all the three stages investigated, and no changes in egg volume were found during egg development for both populations. The reproductive traits of the two populations showed some important differences, which may reflect adaptations to local environmental conditions, demonstrating a high plasticity of reproductive features of the species in Brazilian and Argentine waters. The strategy adopted by the Argentina population involves a lower production of larger eggs compared to the population in Brazil; this lower production is associated with reproduction in cold-water regions. [ABSTRACT FROM AUTHOR]

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Abstract: The evolutionary history of the Anomura has long been controversially discussed. One aspect that has received little attention is the dissimilarity in physiological tolerances of the related families Paguridae and Lithodidae to environmental conditions, and how this may have determined the divergence and radiation of the families into different distribution ranges, in particular with regard to the limited penetration of the deep sea by the Paguridae. This study investigates the physiological tolerances of the temperate shallow-water hermit crab, Pagurus cuanensis, to various temperature (5, 10, 15, 20°C) and pressure regimes (1 to 100atm) by measuring the standard metabolic rate (SMR) and behavioural changes. SMR was primarily affected by temperature, with a notably low rate at 5°C throughout all pressures. Behaviour was affected by pressure, with an increase in pressure from 50 to 100 atmospheres (atm) resulting in reduced activity. It is suggested that this species can tolerate hydrostatic pressures greater than those found in its natural bathymetric range. It is discussed that a lack of physiological cold tolerance and ecological factors, such as the need to find gastropod shells for protection, are the principal restrictions maintaining P. cuanensis to a maximum depth of approximately 250m. We hypothesize that temperate shallow-water invertebrates could indeed be able to penetrate greater depths as continental shelf waters warm up in the course of global climate change. [Copyright &y& Elsevier]

Specimens belonging to the pagurid genus Pagurixus Melin, 1939 collected during various French expeditions made in the Indo-West Pacific were studied. Additional material from other sources is also included. Fifteen species have been identified, of which eight are new: Pagurixus aurantiaca sp. nov., P. cavicarpus sp. nov., P. crosnieri sp. nov., P. formosus sp. nov., P. icelus sp. nov., P. pilosus sp. nov., P. rubrovittatus sp. nov., and P. sculptus sp. nov. Pagurixus anceps (Forest, 1954) is redescribed on the basis of the syntypes and supplemental material from various localities. New locality records are reported for the following seven species: P. concolor Komai and Osawa, 2006, P. dissimilis Osawa and Komai, 2007, P. fasciatus Komai and Myorin, 2005, P. haigae Komai and Osawa, 2007, P. maorus (Nobili, 1906), P. nomurai Komai and Asakura, 1995, and P. ruber Komai and Osawa, 2006. An identification key to all known species is provided. [ABSTRACT FROM AUTHOR]

Four shallow-water hermit crab species, Clibanarius boschmai Buitendijk, 1937, C. cruentatus (H. Milne Edwards, 1848), Paguritta vittata Komai & Nishi, 1996, and Pagurixus nomurai Komai & Asakura, 1995, are recorded from Taiwan for the first time. The addition of the four species increases the number of Taiwanese hermit crabs to 138 species in 39 genera. The poorly known species, Clibanarius boschmai, is diagnosed on the basis of the syntypes and Taiwanese specimens. Although two deep-water pagurids, Chanopagurus atopos Lemaitre, 2003 and Tomopaguroides valdiviae (Balss, 1911), have already been reported from Taiwan, additional specimens obtained provide supplemental information on these poorly known species. The discovery of a male specimen of C. atopos also requires an emendation of the diagnosis of the genus Chanopagurus Lemaitre, 2003. Color photographs are provided for all these species. [ABSTRACT FROM AUTHOR]

Species of the genus Pagurus have diversified into a wide variety of marine habitats across the world. Despite their worldwide abundance, the genus diversity and biogeographical relationship are relatively less understood at species-level. We evaluated the phylogenetic relationship and genetic diversity among the Pagurus species based on publicly available mitochondrial and nuclear markers. While independent analyses of different markers allowed for larger coverage of taxa and produced largely consistent results, the concatenation of 16S and COI partial sequences led to higher confidence in the phylogenetic relationships. Our analyses established several monophyletic species clusters, substantially corresponding to the previously established morphology-based species groups. The comprehensive species inclusion in the molecular phylogeny resolved the taxonomic position of a number of recently described species that had not been assigned to any morpho-group. In mitochondrial markers-based phylogenies, the "Provenzanoi" group was identified as the basal lineage of Pagurus. The divergence time estimation of the major groups of Pagurus revealed that the Pacific species originated and diversified from the Atlantic lineages around 25–51 MYA. The molecular results suggested a higher inter-regional species diversity and complex phylogenetic relationships within the diverse and heterogeneous members of the genus Pagurus. The study presents a comprehensive snapshot of the diversity of pagurid hermit crabs across multiple geographic regions. [ABSTRACT FROM AUTHOR]