Species Of Spider Crab Research Articles

New records of spiders of the family Thomisidae (Arachnida: Araneae) from the Caucasus

New records of two crab spider species, Bassaniodes ovadan (Marusik et Logunov, 1995) and Runcinia tarabayevi Marusik et Logunov, 1990, from Azerbaijan are presented. Both species are recorded from the Caucasus for the first time.

The differences in the trophic structure of semi‐enclosed and open coastal communities under the influence of an alien top predator (red king crab in the Barents Sea)

AbstractThe impact of the introduced red king crab (RKC), Paralithodes camtschaticus, in the Barents Sea was mostly studied through its direct predation on native species. This study uses stable isotope analysis of carbon and nitrogen to characterize major trophic groups (including grazing sea urchins) and specifically looks at RKC's trophic position and niche partitioning with the native hermit and spider crab species. To achieve this, we sampled organisms from the food web of a small fjord‐like Zelenaya Inlet on the Murmansk coast in the southwestern Barents Sea and the open sea coast, just outside the inlet for comparison. There, macrophyte‐derived carbon is the major source of organic matter along with the phytoplankton. In general, the fucoid source of primary production was more prominent within the inlet food web compared to the nearby open coastal zone. Isotopic trophic niches calculated using SIBER analysis showed partition between the native hermit and spider crabs suggesting, some degree of trophic segregation between coevolved species. RKCs are clustered together in the center of native decapod species' niches. There were some distinct differences between the feeding habits of RKCs within the inlet and the open sea coastal waters. The subadult RKCs that are present in the inlet throughout the year have a narrower (in the area and specifically in δ15N dimension) niche than the adults from the open sea. The latter have a wider variety of food items due to their migration and may prey on food items from different trophic levels. Sea urchins are an important trophic link transferring the macrophyte carbon to RKC. However, P. camtschaticus may also directly consume plant residues. Despite generally similar calculated trophic levels of decapod species, our isotopic data and literature data on the food composition of Paralithodes camtschaticus in the Barents Sea do not indicate significant RKC's competition with, and predation on, native species of crabs.

Xysticus logunovorum, a replacement name for the preoccupied crab spider Xysticus logunovi Ono & Martens, 2005 (Araneae: Thomisidae)

The replacement name Xysticus logunovorum nomen novum is proposed for the crab spider species Xysticus logunovi Ono & Martens, 2005, which is preoccupied by Xysticus logunovi Seyfulina & Mikhailov, 2004.

The influence of seasonal temperature variation on embryonic development in two species of spider crabs (Majoidea)

The aim of this study was to analyze the ecological influence of seasonal temperature variations on embryonic development in two species of Majoidea. Leurocyclus tuberculosus and Libinia spinosa. These species inhabit stable populations in the San José Gulf (42°25′41″S, 64°08′27″O, Patagonia-Argentina) in a wide depth range and seasonal temperature variations from 8 °C to 18 °C. The influence of seasonal temperatures on embryonic development was examined in ovigerous females of both species, through a bioassay in laboratory conditions at 8 °C, 14 °C, and 18 °C from gastrula to hatching. Additionally, monthly female samplings were conducted for one year, characterizing their spatial depth distribution associated with the seawater temperature in the study area and their ovigerous/non ovigerous condition. Laboratory experimental results showed that duration of incubation increased 67 % in L. tuberculosus and 55% in L. spinosa by a decline in temperature from 18 °C to 8 °C with one diapause period. The embryonic development for the 3 assayed temperatures was divided in five periods. The assayed temperatures did not affect the morphology of the embryo, and its growth during each period did not present significant differences among the different temperatures. Field analysis showed significant differences in the spatial distribution of ovigerous females which were associated to the assessed temperatures along the year. This distribution might modulate the development of embryos leading to two spawnings synchronized with the phyto- and zooplankton peaks in the San José gulf. Finally, ecological and potential impact of ocean warming in these species was also addressed.

DNA barcoding of the spider crab Menaethius monoceros (Latreille, 1825) from the Red Sea, Egypt

BackgroundMost spider crab species inhabiting the Red Sea have not been characterized genetically, in addition to the variation and complexity of morphological identification of some cryptic species. The present study was conducted to verify the identification of two morphotypes of the spider crab Menaethius monoceros (Latreille, 1825) in the family Epialtidae Macleay, 1838, collected from the Red Sea, Egypt. DNA barcoding of two mitochondrial markers, cytochrome oxidase subunit I (COI) and 16S, was used successfully to differentiate between these morphotypes. ResultsDNA barcoding and genetic analyses combined with morphological identification showed that the two morphotypes were clustered together with low genetic distances ranged from 1.1 to 1.7% COI and from 0.0 to 0.06% 16S. Hence, this morphological variation is considered as individual variation within the same species. ConclusionThe present study successively revealed that genetic analyses are important to confirm the spider crab’s identification in case of morphological overlapping and accelerate the accurate identification of small-sized crab species. Also, DNA barcoding for spider crabs is important for better future evaluation and status records along the Red Sea coast.

Description of a new species of deep-sea spider crab from the genus Crocydocinus Lee, Richer de Forges & Ng, 2019, from the south-eastern Arabian Sea (Crustacea: Decapoda: Majoidea: Epialtidae)

A new species of spider crab is described from two male specimens collected from the southeastern Arabian Sea. This species differs from its congeners in the absence of uograstric granule on carapace, the presence of two granules along lateral margin of carapace at branchial region, the presence of granules on P2-P4 dactyli and the constricted distal tip of the male first gonopod.

First record of three species of spider crabs from west coast of India (Crustacea: Decapoda: Brachyura)

The present study records occurrence of three species of spider crabs: Hyastenus hilgendorfi De Man, 1887 (Epialtidae), Hyastenus spinosus A. Milne-Edwards, 1872 (Epialtidae) and Paramaya mulli Ng, Prema & Ravichandran, 2018 (Majidae) for the first time from the west coast of India. These species were earlier reported from coastal areas of east coast of India. The diagnostic characteristics and some remarks on the taxonomy of each species are given in this paper.

Biodiversity Survey of Flower-Visiting Spiders Based on Literature Review and Field Study.

Many arthropods exhibit flower-visiting behavior, including a variety of spider species. However, as spiders are assumed to be strictly predatory, flower-visiting spiders are an often neglected group. We conducted a systematic biodiversity study of flower-visiting spiders based on published papers and field surveys. Most previous studies have focused on the herbivorous behavior of flower-visiting spiders (nectivory or pollinivory) and their effects on host flowers (tritrophic interactions with flower-visiting insects). In our field survey, we utilized standard transect walks (active sampling) and colored pan traps (passive sampling) to investigate species occurrence, diurnal and seasonal variation, and flower color preference of flower-visiting spiders. From the transect walks, crab spider species were found to be the dominant flower-visiting spiders and, based on all spider species, juvenile visitors were significantly more common than adults. Furthermore, in terms of spider number and species richness, tulips were the preferred flower to visit. For the pan traps, wolf spiders were found to be the dominant spider species. No significant differences were observed in the number of spiders caught in different colored pans, suggesting that color may not be an important flower trait in regard to spider preference. To the best of our knowledge, this study is the first to propose the term 'flower-visiting spiders' and conduct a systematic investigation of their diversity. However, this is preliminary research and further studies are required, especially as biodiversity is often closely linked to survey sites and ecotopes.

Can crustacean cuticle preserve a record of chronological age? Investigating the utility of decapod crustacean eyestalks for age determination of two European spider crab species

Until recently it was not thought possible to directly and accurately age crustacean species as any calcified structure that could preserve a record of chronological age is lost at moulting. Recent research has suggested that it may be possible to directly infer age from the number of endocuticular bands present within the eyestalks of snow crab (Chionoecetes opilio) and Antarctic krill (Euphausia superba). Using captive-reared Mediterranean spider crabs (Maja squinado), and wild-caught north-east Atlantic spider crabs (Maja brachydactyla), the present study aimed to determine if endocuticular bands of potentially annual periodicity are present within the eyestalks of these brachyurans. Although clear and readable bands were present within the endocuticle of their eyestalks, no bands of potentially annual periodicity were identified. The number of endocuticular bands did not correlate with the known-age of the M. squinado individuals; but did correlate positively with carapace length for both M. squinado and M. brachydactyla, suggesting they form as a result of growth and the size of individuals. It is hypothesised that these endocuticular bands, and potentially those identified by other studies purporting them to be annual growth bands, are in fact lamellae that appear due to the layers of calcite crystal aggregates interspersed with chitin and protein fibres that form the mineral of the cuticle in decapod crustaceans. Further research is needed to determine the processes that control and result in the deposition of crustacean cuticle, particularly during the post-moult period.

Kasagia sudhakari, a new species of deep-sea spider crab (Crustacea: Brachyura: Majidae) from the southeastern Arabian Sea

ABSTRACTKasagia sudhakari, a new species of spider crab, is described from two male specimens from southeastern Arabian Sea. This species differs from its only congener Kasagia arbastoi Richer de Forges & Ng, 2007, from the Philippines in the shape and form of the carapace, shape of the pseudorostral spines, arrangement of the orbital plates (supraorbital eave separated from the postorbital spine), size of the lateral branchial tubercles, as well as structures of the interantennular spine, hepatic lobe, cheliped, ambulatory merus and male first gonopod.

Advantages of social foraging in crab spiders: Groups capture more and larger prey despite the absence of a web

AbstractAmong group‐living spiders, subsocial representatives in the family of crab spiders (Thomisidae) are a special case, as they build protective communal leaf nests instead of extensive communal capture webs. It could thus be inferred that antipredator benefits (e.g., enhanced protection in larger nests) rather than foraging‐related advantages (e.g., capture of more and larger prey) promote sociality in this family. Nonetheless, subsocial crab spiders do share prey, and if this behaviour does not reflect mere food scramble but has a cooperative character, crab spiders may offer insights into the evolution of social foraging applicable to many other cooperative predators that hunt without traps. Here, we performed a comparative laboratory feeding experiment on three of the four subsocial crab spider species—Australomisidia ergandros, Australomisidia socialis and Xysticus bimaculatus—to determine if crab spiders derive advantages from foraging in groups. In particular, we tested artificially composed groups of five sibling spiderlings vs. single siblings in terms of prey capture success and prey size preference. Across species, groups had higher prey capture success (measured in terms of capture rates and capture latency) and were more likely to attack large, sharable prey—dynamics leading to reduced food competition among group members in favour of living and foraging in groups. Within groups, we further compared prey extraction efficiency among the three applied social foraging tactics: producing, scrounging and feeding alone. In A. ergandros, individuals were exceptionally efficient when using the non‐cooperative scrounger tactic, which entails feeding on the prey provided by others. Thus, our multispecies comparison confirms foraging advantages in maintaining a cooperative lifestyle for crab spiders, but also demonstrates the relevance of research into exploitation of cooperative foraging in this family.

Species-specific crab predation on the hydrozoan clinging jellyfish Gonionemus sp. (Cnidaria, Hydrozoa), subsequent crab mortality, and possible ecological consequences.

Here we report a unique trophic interaction between the cryptogenic and sometimes highly toxic hydrozoan clinging jellyfish Gonionemus sp. and the spider crab Libinia dubia. We assessed species–specific predation on the Gonionemus medusae by crabs found in eelgrass meadows in Massachusetts, USA. The native spider crab species L. dubia consumed Gonionemus medusae, often enthusiastically, but the invasive green crab Carcinus maenus avoided consumption in all trials. One out of two blue crabs (Callinectes sapidus) also consumed Gonionemus, but this species was too rare in our study system to evaluate further. Libinia crabs could consume up to 30 jellyfish, which was the maximum jellyfish density treatment in our experiments, over a 24-hour period. Gonionemus consumption was associated with Libinia mortality. Spider crab mortality increased with Gonionemus consumption, and 100% of spider crabs tested died within 24 h of consuming jellyfish in our maximum jellyfish density containers. As the numbers of Gonionemus medusae used in our experiments likely underestimate the number of medusae that could be encountered by spider crabs over a 24-hour period in the field, we expect that Gonionemus may be having a negative effect on natural Libinia populations. Furthermore, given that Libinia overlaps in habitat and resource use with Carcinus, which avoids Gonionemus consumption, Carcinus populations could be indirectly benefiting from this unusual crab–jellyfish trophic relationship.

Two new species of the genus Oxytate from China (Araneae: Thomisidae)

Two new crab spider species from China are diagnosed, described and illustrated: Oxytate bicornis sp. nov. from Jiangxi and Oxytate palmata sp. nov. from Guangxi. The total number of the known species of Oxytate from China rises to 13 with the addition of two new species described in the present paper.

The morphology of the male and female reproductive system in two species of spider crabs (Decapoda: Brachyura: Majoidea) and the issue of the velum in majoid reproduction

The reproductive system of spider crabs (Majoidea) has raised considerable interest due to the complexity of female sperm storage organs. In several majoid species, the seminal receptacle has been described as being divided into a dorsal storage chamber and a ventral fertilization chamber separated by a muscular velum. The velum is supposed to control the amount of sperm used for fertilization and to play an important role in sperm competition. Here, we present a study on the reproductive systems of the two majoid species, Mithraculus sculptus (Lamarck, 1818) and Stenorhynchus seticornis (Herbst, 1788) using various morphological techniques such as μCT scans and 3D-reconstructions, complemented by paraffin histology. The male gonopods of the herein investigated species are similar in their general morphology and in the presence and distribution of setae. The tubular first gonopod holding the ejaculatory canal is much longer than the short and stout second gonopod, which is supposed to function as a piston in the transport of sperm into the female ducts. The female reproductive system of M. sculptus and S. seticornis conforms to that of other Eubrachyura in possessing paired ovaries, oviducts, seminal receptacles, vaginae, and vulvae. Based on our 3D-reconstructions we demonstrate that there is no division of the seminal receptacle into two chambers separated by a velum. In contrast to this, we observed a spatially restricted invagination of the seminal receptacle. A comparison of our data with those of previous studies, allows for the conclusion that the invagination of the seminal receptacle may have been misinterpreted and mistaken for a velum by other authors. Thus, the division of the seminal receptacle into two chambers separated by a velum is a character which needs to be re-evaluated.

A new western Atlantic species of Collodes Stimpson (Decapoda, Brachyura, Inachoididae)

A new species of spider crab, Collodes tuerkayi n. sp., is described and illustrated from the Western Atlantic (Puerto Rico and northern Brazil). The new species superficially resembles C. inermis A. Milne-Edwards, 1878, in the general appearance of the body, but is distinguished by the details of the carapace, thoracic sternum and antennal ornamentation and the proportion of the pereopods.

Crab spiders (Thomisidae) attract insect flower‐visitors withoutUVsignalling

1. Crab spiders (Thomisidae) indirectly affect insect flower‐visitor and flowering plant interactions by consuming and altering the behaviour of insects.2. Although one expects insect flower‐visitors to avoid crab spiders actively, some crab spider species are known to attract flower‐visitors. Crab spiders may useUVsignalling to lure potential prey to the flowers they occupy.3. In the present study, a field experiment was conducted to examine the effects of crab spiders occupying three prairie plant species for the insect flower‐visitor community. Pollinating insects were significantly attracted to inflorescences with crab spiders compared to inflorescences without crab spiders for two plant species, and herbivorous insects were attracted to inflorescences with crab spiders for one of these plant species. The two flowering plant species with increased pollinator visitation showed increased seed weights for plants with crab spiders, indicating crab spider presence indirectly increased pollination.4. To test theUVsignalling hypothesis, inflorescences with crab spiders of one plant species were observed under both aUV‐blocking plastic and a clear plastic control. Contrary to our prediction, flower‐visitors were not more likely to land on inflorescences under the clear plastic; theUVsignalling hypothesis was not supported. Other unknown explanations underlie prey attraction to inflorescences with crab spiders.

ALGUNAS ESPECIES DE MAJIDAE (CRUSTACEA: BRACHYURA) DE LA BAHIA DE PISCADERA (CURASAO) Y COMPARACIONES CON LAS ESPECIES DEL CARIBE COLOMBIANO

The present paper contains a list of 16 species of spider crabs (Majidae: Brachyura) that were collected at Piscadera Bay, Curasao, Only one of the species (Stenorhynchus seticornis) had previously been reported from this place (Rathbun, 1925). Five of the species reported herein appear to be new for Curasao.

A new species of Sunipea Griffin & Tranter, 1986 (Crustacea: Brachyura:Inachidae) and a redescription of Sunipea indicus (Alcock, 1895).

A new species of spider crab, Sunipea callistus, n. sp., from Cape Guardafui, Somali Republic, is described and illustrated. Sunipea indicus (Alcock, 1895) is also redescribed and figured. Sunipea callistus n. sp. differs from S. indicus in the structures of the carapace, third maxillipeds, thoracic sternum, male abdomen, and chelipeds. Despite a number of characteristics that separate both species, these differences are more pronounced in males and are less evident in females. A diagnosis for the genus is provided.

The Application of DNA Barcodes for the Identification of Marine Crustaceans from the North Sea and Adjacent Regions.

During the last years DNA barcoding has become a popular method of choice for molecular specimen identification. Here we present a comprehensive DNA barcode library of various crustacean taxa found in the North Sea, one of the most extensively studied marine regions of the world. Our data set includes 1,332 barcodes covering 205 species, including taxa of the Amphipoda, Copepoda, Decapoda, Isopoda, Thecostraca, and others. This dataset represents the most extensive DNA barcode library of the Crustacea in terms of species number to date. By using the Barcode of Life Data Systems (BOLD), unique BINs were identified for 198 (96.6%) of the analyzed species. Six species were characterized by two BINs (2.9%), and three BINs were found for the amphipod species Gammarus salinus Spooner, 1947 (0.4%). Intraspecific distances with values higher than 2.2% were revealed for 13 species (6.3%). Exceptionally high distances of up to 14.87% between two distinct but monophyletic clusters were found for the parasitic copepod Caligus elongatus Nordmann, 1832, supporting the results of previous studies that indicated the existence of an overlooked sea louse species. In contrast to these high distances, haplotype-sharing was observed for two decapod spider crab species, Macropodia parva Van Noort & Adema, 1985 and Macropodia rostrata (Linnaeus, 1761), underlining the need for a taxonomic revision of both species. Summarizing the results, our study confirms the application of DNA barcodes as highly effective identification system for the analyzed marine crustaceans of the North Sea and represents an important milestone for modern biodiversity assessment studies using barcode sequences.

Colour change ability and its effect on prey capture success in female Misumenoides formosipes crab spiders

1. Changing between white and yellow body colour in certain crab spider species has been interpreted as an adaptation for matching the background colour where they hunt and thereby remaining cryptic to prey and/or their own predators. The potential costs and benefits of colour change in female Misumenoides formosipes Walckenaer were investigated via assessment of prey opportunities and capture success, in conjunction with the tendency for and rate of colour change on different backgrounds.2. It was tested whether being matched or mismatched to their background affected foraging by moving females between white and yellow inflorescences. Female colour was quantified in digital photos using the Lab colour space component of Adobe photoshop, providing the first empirical assessment of the rate of colour change for a crab spider species.3. Insect visits (potential prey) on inflorescences with and without spiders and prey capture success with females matched and mismatched to their background were quantified.4. Yellow females abandoned white inflorescences, whereas white females remained on and underwent colour change on yellow inflorescences. This difference supported the notion that the costs of colour change differ depending on the starting colour. Female departures from white flowers were apparently not due to a lack of insect visitation, as white inflorescences had higher visitation rates than did yellow inflorescences, even in the presence of spiders.5. An increase in the prey capture success of females who transitioned from white to yellow body colour on a yellow background supported the hypothesis that colour matching functions to deceive prey.