Crustacean Taxa Research Articles

The only terrestrial lineage in the Branchiopoda redefined: a new species of Bryospilus Frey, 1980 (Cladocera: Anomopoda) from India and adaptations of waterfleas to life on land

Abstract Only a small proportion of the world’s crustacean taxa is adapted to limno-terrestrial microhabitats that are disconnected from conventional surface waterbodies. In rare occasions, water films on terrestrial tropical and subtropical vegetation may also harbour specialised cladocerans. Bryospilus Frey, 1980 (Chydoridae) is the only genus within the class Branchiopoda that is specialised to living almost exclusively in water-saturated terrestrial moss patches, leaf litter, and phytotelms. The remarkable waterflea lineage, which has a suite of highly unusual characters within the family, has been found in terrestrial habitats in rainforests of West Africa, South and Central America, and New Zealand. We discovered a new moss-inhabiting chydorid from western India, Bryospilus (Indobryospilus) bharaticus n. sp., the first representative of the genus from the Oriental Region. Its morphology and behaviour are highly unusual for a species of Bryospilus. In comparison to its congeners, the new species can swim and it has significantly less oligomerisation, with three terminal setae on the antennal endopod instead of two and seven exopod setae on the third limb instead of six, among other features. We define a new subgenus Indobryospilus nov. and we amend the genus Bryospilus. The new species is a living evolutionary connection, characterised by a phenotype which provides us with new clues about evolutionary transitions in the only terrestrial branchiopod genus. Our results are informative beyond Cladocera, as the morphology of this species provides insights about the evolution and parallelisms of aquatic crustaceans that have specialised in limno-terrestrial habitats. We revisit the morphology of the genus, the disjunct biogeographical pattern with a potential ancient signature, and discuss the functional adaptations of these cladocerans to life on land, as well as convergences with subterranean lineages. A new key to the world species of Bryospilus species is included.

Zooplankton in brackish water bodies of the plain territory of the Altai territory in the vegetation season of 2022

The zooplankton of three small brackish lakes (Bulatovo, Korostelevskoye and Markovskoye) located in the plain territory of Altai Krai was studied in 2022. Data on the main characteristics of the zooplankton habitat are presented. An assessment of the ecological state of lakes is given based on qualitative and quantitative indicators of zooplankton. The taxonomic composition and main quantitative characteristics of zooplankton in the spring, summer and autumn periods are characterized. Seasonal dynamics of quantitative indicators and changes in the taxonomic composition of zooplankton were noted. The lowest quantitative indicators of zooplankton development were noted in the spring season (April). All identified representatives of zooplankton were cosmopolitans. Common to all lakes are 5 taxa of crustaceans and rotifers (Keratella quadrata, Filinia longiseta, Daphnia magna, Cyclopidae ind., Diaptomidae ind.). In the spring and autumn seasons, copepods dominated in abundance and biomass, reaching 99.9% of the zooplankton population. Differences in the composition of the dominant taxa in the summer season were noted between the lakes. In the lake Bulatovo was dominated in numbers by rotifers due to Brachionus quadridentatus, and in biomass by cladocerans due to Daphnia magna. In the lake Korostelevskoe, the dominant taxonomic group in terms of numbers was copepods, the basis of which were Diaptomidae ind., in terms of biomass — cladocerans due to Diaphanosoma brachiurum. Only in the lake In Markovskoe, copepods — Diaptomidae ind. — dominated in numbers and biomass. The zooplankton of the studied lakes was characterized by a poor species composition, but high summer numbers and biomass (from 342 thou. eq./m3 and 7.13 g/m3 in Lake Markovskoe to 1895 th. eq./m3 and 33.7 g/m3 in Lake Bulatovo). In the summer season, the zooplankton biomass of the lake. Markovskoye belonged to reservoirs of the α-eutrophic type, lakes Bulatovo and Korostelevskoye were of the polytrophic type. The majority of noted species (60%) were indicators of β-mesosaprobic conditions.

Marine vampires: Persistent, internal associations between bacteria and blood-feeding marine annelids and crustaceans.

Persistent bacterial presence is believed to play an important role in host adaptation to specific niches that would otherwise be unavailable, including the exclusive consumption of blood by invertebrate parasites. Nearly all blood-feeding animals examined so far host internal bacterial symbionts that aid in some essential aspect of their nutrition. Obligate blood-feeding (OBF) invertebrates exist in the oceans, yet symbiotic associations between them and beneficial bacteria have not yet been explored. This study describes the microbiome of 6 phylogenetically-diverse species of marine obligate blood-feeders, including leeches (both fish and elasmobranch specialists; e.g., Pterobdella, Ostreobdella, and Branchellion), isopods (e.g., Elthusa and Nerocila), and a copepod (e.g., Lernanthropus). Amplicon sequencing analysis revealed the blood-feeding invertebrate microbiomes to be low in diversity, compared to host fish skin surfaces, seawater, and non-blood-feeding relatives, and dominated by only a few bacterial genera, including Vibrio (100% prevalence and comprising 39%-81% of the average total recovered 16S rRNA gene sequences per OBF taxa). Vibrio cells were localized to the digestive lumen in and among the blood meal for all taxa examined via fluorescence microscopy. For Elthusa and Branchellion, Vibrio cells also appeared intracellularly within possible hemocytes, suggesting an interaction with the immune system. Additionally, Vibrio cultivated from four of the obligate blood-feeding marine taxa matched the dominant amplicons recovered, and all but one was able to effectively lyse vertebrate blood cells. Bacteria from 2 additional phyla and 3 families were also regularly recovered, albeit in much lower abundances, including members of the Oceanospirillaceae, Flavobacteriacea, Porticoccaceae, and unidentified members of the gamma-and betaproteobacteria, depending on the invertebrate host. For the leech Pterobdella, the Oceanospirillaceae were also detected in the esophageal diverticula. For two crustacean taxa, Elthusa and Lernanthropus, the microbial communities associated with brooded eggs were very similar to the adults, indicating possible direct transmission. Virtually nothing is known about the influence of internal bacteria on the success of marine blood-feeders, but this evidence suggests their regular presence in marine parasites from several prominent groups.

Ecological, physiological and life-history traits correlate with genome sizes in decapod crustaceans

Crustaceans are characterized by some of the most variable genome sizes among animals. Significant relationships between genome size and specific eco-physiological and morphological features have been described in many crustacean taxa, such as Amphipoda, Ostracoda, Cladocera, and Copepoda. A consistent pattern of genome size variation is yet to be found, however, in one of the most specious order of crustaceans, the Decapoda. We investigated how genome size is related to selected eco-physiological and life-history traits in species belonging to this order. We analyzed the respiratory, excretory, and developmental adaptations of 179 decapod species inhabiting shallow marine, deep marine, freshwater, intertidal, and terrestrial habitats. Our results show that the genome size is significantly larger in decapods that have a direct development. Moreover, in Anomura, Astacidea, and Brachyura we found larger genome sizes in species (i) living in freshwater habitats, (ii) using gills as a strictly water-breathing organs, and (iii) presenting a direct development. While species that (i) live in shallow waters, and intertidal and terrestrial habitats, (ii) have some degrees of air-breathing adaptations, namely gills that can exchange oxygen with air if wet or branchiostegal lungs, and (iii) possess an indirect or extended development are characterized by significantly smaller genomes. Our analyses show that developmental complexity affects genome size in decapods, and that multiple eco-physiological and life-history traits correlate with genome size in Anomura, Astacidea, and Brachyura.

Strategies of Invertebrate Osmoregulation: An Evolutionary Blueprint for Transmuting into Fresh Water from the Sea.

Early marine invertebrates like the Branchiopoda began their sojourn into dilute media some 500 million years ago in the Middle Cambrian. Others like the Mollusca, Annelida, and many crustacean taxa have followed, accompanying major marine transgressions and regressions, shifting landmasses, orogenies, and glaciations. In adapting to these events and new habitats, such invertebrates acquired novel physiological abilities that attenuate the ion loss and water gain that constitute severe challenges to life in dilute media. Among these taxon-specific adaptations, selected from the subcellular to organismal levels of organization, and constituting a feasible evolutionary blueprint for invading freshwater, are reduced body permeability and surface (S) to volume (V) ratios, lowered osmotic concentrations, increased osmotic gradients, increased surface areas of interface epithelia, relocation of membrane proteins in ion-transporting cells, and augmented transport enzyme abundance, activity, and affinity. We examine these adaptations in taxa that have penetrated into freshwater, revealing diversified modifications, a consequence of distinct body plans, morpho-physiological resources, and occupation routes. Contingent on life history and reproductive strategy, numerous patterns of osmotic regulation have emerged, including intracellular isosmotic regulation in weak hyper-regulators and well-developed anisosmotic extracellular regulation in strong hyper-regulators, likely reflecting inertial adaptations to early life in an estuarine environment. In this review, we address osmoregulation in those freshwater invertebrate lineages that have successfully invaded this biotope. Our analyses show that across 66 freshwater invertebrate species from six phyla/classes that have transmuted into freshwater from the sea, hemolymph osmolalities decrease logarithmically with increasing S:V ratios. The arthropods have the highest osmolalities, from 300 to 650 mOsmoles/kg H2O in the Decapoda with 220-320 mOsmoles/kg H2O in the Insecta; osmolalities in the Annelida range from 150 to 200 mOsmoles/kg H2O, and the Mollusca showing the lowest osmolalities at 40-120 mOsmoles/kg H2O. Overall, osmolalities reach a cut-off at ∼200 mOsmoles/kg H2O, independently of increasing S:V ratio. The ability of species with small S:V ratios to maintain large osmotic gradients is mirrored in their putatively higher Na+/K+-ATPase activities that drive ion uptake processes. Selection pressures on these morpho-physiological characteristics have led to differential osmoregulatory abilities, rendering possible the conquest of freshwater while retaining some tolerance of the ancestral medium.

Natural mortality and longevity of the burrowing crayfish Parastacus pugnax (Poeppig, 1835) (Decapoda: Astacidea: Parastacidae)

Abstract Information about longevity and mortality of decapod crustaceans is scarce but is of utmost importance for our understanding of the dynamics of exploited populations. Moreover, such information is crucial for the development of conservation and management strategies. Compared to other crustacean taxa, crayfishes are understudied and under increasing threat of extinction. Particularly, life history data for burrowing crayfishes is highly limited, which is related to their subterranean habitat and collection difficulty. Considering the limited knowledge on mortality and life span in burrowing crayfishes, we studied these two parameters in the burrowing crayfish Parastacus pugnax (Poeppig, 1835), one of six species of Parastacidae in Chile. This species inhabits subterraneous waters in semi-swampy terrain and is heavily exploited for human consumption. We calculated longevity (A0.95) and natural mortality (M) of this species, using growth estimates published in the literature. Longevity was estimated to vary between 8.2 and 12.4 yr. The estimated values for M ranged from 0.241 to 0.611 yr−1, and the medium for the population ranged from 0.37 to 0.57 yr−1. Compared to other crayfishes, parastacids are generally classified as longer-living species, and some can live for decades. Our results suggest that P. pugnax is a medium-age species with a medium-range mortality compared to other parastacids.

Review of the large branchiopod crustacean fauna of Qatar (Anostraca, Notostraca, Spinicaudata) and adjacent countries

The large branchiopod crustaceans (Anostraca, Notostraca, and Spinicaudata) of Qatar have only been examined recently. Although 15 nominal species have been reported for the Arabian Peninsula, there is confusion surrounding the determinations of previously collected taxa from Qatar, and the validity of some spinicaudatan taxa is in question. Most spinicaudatan clam shrimp taxa are poorly described; some lack type material or the type material has been lost. We provide a review of the taxa from Qatar and some records from adjacent Saudi Arabia. We recognise five large branchiopod crustacean taxa from Qatar (two anostracans, one notostracan, and two spinicaudatans) and provide new locality records from Umm Alshkoot and correct some previous literature statements. In addition, we comment on the likelihood of another ten taxa to occur in or near Qatar.

Molecular ecology of the fiddler crab Austruca perplexa (H. Milne Edwards, 1852): genetic divergence along a major biogeographical barrier, Wallace’s Line

Abstract Genetic diversity and population structure in the fiddler crab Austruca perplexa were investigated to acquire a better understanding of the evolutionary history of the species. Nucleotide sequence analysis was performed from a polymerase chain reaction-amplified fragment of the mitochondrial DNA control region. A 691 bp nucleotide sequence was obtained from 618 specimens collected from 13 sites across Japan, Taiwan, the Philippines, Indonesia and Australia. Haplotype diversity ranged from 0.8 to 0.99, and nucleotide diversity values were lower (range, 0.30–1.9%) than those reported previously for other crustacean taxa. Gene flow was evident within populations in Japan and western Indonesia, but absent among all other populations, including eastern Indonesia. This pattern conforms to the one observed in many other marine taxa across the major biogeographical region referred to as Wallacea. The population pairwise fixation index (FST) and FSTP-values were high and significant among many sites, implying that gene flow is restricted among most of the geographical regions sampled here. We hypothesize that physical oceanic barriers coupled with a short pelagic larval duration are responsible for creating the patterns we found. Strong evidence for population structure in a species that has relatively high dispersal potential, resulting in among-population differentiation, is a potential driver of evolutionary novelty. Our results provide a foundation for developing better conservation strategies for this widespread intertidal species.

Adding pieces to the puzzle: insights into diversity and distribution patterns of Cumacea (Crustacea: Peracarida) from the deep North Atlantic to the Arctic Ocean.

The Nordic Seas have one of the highest water-mass diversities in the world, yet large knowledge gaps exist in biodiversity structure and biogeographical distribution patterns of the deep macrobenthic fauna. This study focuses on the marine bottom-dwelling peracarid crustacean taxon Cumacea from northern waters, using a combined approach of morphological and molecular techniques to present one of the first insights into genetic variability of this taxon. In total, 947 specimens were assigned to 77 morphologically differing species, representing all seven known families from the North Atlantic. A total of 131 specimens were studied genetically (16S rRNA) and divided into 53 putative species by species delimitation methods (GMYC and ABGD). In most cases, morphological and molecular-genetic delimitation was fully congruent, highlighting the overall success and high quality of both approaches. Differences were due to eight instances resulting in either ecologically driven morphological diversification of species or morphologically cryptic species, uncovering hidden diversity. An interspecific genetic distance of at least 8% was observed with a clear barcoding gap for molecular delimitation of cumacean species. Combining these findings with data from public databases and specimens collected during different international expeditions revealed a change in the composition of taxa from a Northern Atlantic-boreal to an Arctic community. The Greenland-Iceland-Scotland-Ridge (GIS-Ridge) acts as a geographical barrier and/or predominate water masses correspond well with cumacean taxa dominance. A closer investigation on species level revealed occurrences across multiple ecoregions or patchy distributions within defined ecoregions.

New genus and four new species of anthuroid isopods (Crustacea: Peracarida) from southern Mexican Pacific

Anthuroid Isopoda are a poorly studied crustacean taxon in the Tropical Eastern Pacific, barely 21 species recorded, while to the southern Mexican Pacific, only eight species have been recorded. This study aims to increase knowledge of the species that inhabit the region. One hundred and one specimens from seven localities of the coast of Guerrero and Oaxaca were examined. Four new species were identified, belonging to three genera and two families: Negoescuanthura bastidai n. gen., n. sp., Colanthura gabinae n. sp., Paranthura amorensis n. sp. and P. tientai n. sp. A new genus is established, Negoescuanthura, very close to the genus Accalathura; the former is characterized by sucker-like cuticular structures on the antennal peduncle, while the latter lack these structures.

Crustacea biodiversity in tubes of Ceriantharia (Cnidaria; Anthozoa), including the description of a novel species of Amphipoda from southeastern Brazil

ABSTRACT This study investigates ceriantharian tubes to better understand the biodiversity of marine benthic crustaceans. The inner and outer surfaces of eight tubes of Ceriantharia from the northern coast of the state of São Paulo, Brazil, were analyzed. We observed 14 taxa of crustaceans, including one novel species, Podocerus carmelina sp. nov. We also report two new location records for previously known species and provide an identification key for Podocerus species with type localities in the Atlantic Ocean. The new species can be easily differentiated from its congeners by the following features: pereonite 3 with weak dorsal carina; gnathopod 2 carpus indistinct, almost entirely fused to propodus, propodus bearing several facial short plumose setae, palm defined by a proximal blunt projection, with a subtriangular tooth medially, a ‘u-shaped’ concavity and a crenulated lobe distally; pereonite 4 elongated, about 2.2 × deeper than wide; pereonites 5–6 anteroventral corner with a subacute projection; coxa 5 anteroventral corner with a notch, forming an acute spine; telson dorsal lobe with three stout setae, with naked lateral margins; uropod 2 outer ramus with one subapical long and stout plumose seta. Publication LSID: lsid:zoobank.org:act:B733959C-C1E7-464B-88FB-AF5D2C6347F8

Rediscovery of the horseshoe shrimp Lightiella serendipita Jones, 1961 (Cephalocarida: Hutchinsoniellidae) in San Francisco Bay, California, USA, with a key to the worldwide species of Cephalocarida

Abstract Lightiella serendipita Jones, 1961 was first discovered in San Francisco Bay, California in 1953, but it had not been observed since 1988. In 2017, a total of 13 adult L. serendipita specimens were found as part of a study in central San Francisco Bay, nearly doubling the total number of specimens ever collected. We measured vertical distribution of macroinvertebrates and environmental variables, including grain size and chemical composition of sediment samples, to evaluate potential features associated with the habitat of the species. Specimens were generally found in sediments with low organic matter (1.7–3%), high sulfate concentrations (594.6–647 ppm SO4), fine grain size (12.8–36.2% sand, 35.6–58% silt, 22.8–37.6% clay) and were mostly found in deep core sections (4–10 cm). Specimens were also consistently observed in cores containing tube-forming Polychaeta (i.e., Sabaco elongatus (Verrill, 1873) and Capitellidae), suggesting L. serendipita may have a commensal relationship with sedentary polychaetes, as do other cephalocaridans such as Lightiella incisaGooding, 1963. We provide a scanning electron micrograph of L. serendipita and the first complete key to the species in class Cephalocarida to help elucidate the taxonomy of this rare crustacean taxon. The perceived absence of L. serendipita in previous surveys of the Bay may be attributable to its rarity; however, additional research is needed to fully understand habitat requirements and population size of this unique endemic species.

Diet composition of starry smooth‐hound Mustelus asterias and methodological considerations for assessing the trophic level of predatory fish

The stomach contents of 640 starry smooth-hound Mustelus asterias from the north-east Atlantic were examined. The diet was dominated by crustaceans (98.8% percentage of index of relative importance, %IRI), with the two main prey species being hermit crab Pagurus bernhardus (34% IRI) and flying crab Liocarcinus holsatus (15% IRI). Ontogenetic dietary preferences showed that smaller individuals [20-69 cm total length (LT ) n = 283] had a significantly lower diversity of prey than larger individuals (70-124 cm LT , n = 348); however, 18 prey species were found exclusively in smaller individuals and eight prey taxa were found exclusively in larger individuals. Larger commercially important brachyurans such as edible crab Cancer pagurus and velvet swimming crab Necora puber were more prevalent in the diet of larger individuals. Specimens from the North Sea ecoregion had a lower diversity of prey types for a given sample size than fish from the Celtic Seas ecoregion. Whilst cumulative prey curves did not reach an asymptote, this was primarily due to the high taxonomic resolution utilized and 95% of the diet was described by just seven crustacean taxa. The trophic level (TL) was calculated as 4.34 when species-level prey categories were used. This fine-scale taxonomic resolution resulted in a TL estimate close to a whole level above that estimated using wider taxonomic groupings. This large bias has important methodological implications for TL studies based on categorized prey data, particularly those of predatory fish.

Crustacean remains from the Yuka mammoth raise questions about non-analogue freshwater communities in the Beringian region during the Pleistocene

Frozen permafrost Pleistocene mammal carcasses with soft tissue remains are subject to intensive study and help elucidate the palaeoenvironment where these animals lived. Here we present an inventory of the freshwater fauna and flora found in a sediment sample from the mummified Woolly Mammoth carcass found in August 2010, from the Oyogos Yar coast near the Kondratievo River in the Laptev Sea region, Sakha (Yakutia) Republic, NE Russia. Our study demonstrates that the waterbody where the carcass was buried could be characterized as a shallow pond or lake inhabited mainly by taxa which are present in this area today, but additionally by some branchiopod crustacean taxa currently absent or unusual in the region although they exist in the arid zone of Eurasia (steppes and semi-deserts). These findings suggest that some “non-analogue” crustacean communities co-existed with the “Mammoth fauna”. Our findings raise questions about the nature of the waterbodies that existed in Beringia during the MIS3 climatic optimum when the mammoth was alive.

Genetic evidence against monophyly of Oniscidea implies a need to revise scenarios for the origin of terrestrial isopods

Among the few crustacean taxa that managed to inhabit terrestrial environments, Oniscidea includes the most successful colonizers in terms of species richness and abundance. However, neither morphological traits nor molecular markers have definitively resolved phylogenetic relationships among major Oniscidea clades or established the monophyly of the taxon. Herein, we employed the highly conserved, nuclear protein-coding genes Sodium-Potassium Pump (NAK) and Phosphoenolpyruvate Carboxykinase (PEPCK), along with the traditionally used 18 s and 28 s ribosomal RNA genes, in an attempt to clarify these questions. Our dataset included sequences representing all major Oniscidea clades and closely related aquatic taxa, as suggested by previous studies. We applied Bayesian Inference and Maximum Likelihood methods and produced a robust and fully resolved phylogenetic tree that offers strong evidence against the monophyly of Oniscidea. The amphibious genus Ligia appears to be more closely related to representatives of marine suborders, while the phylogenetic pattern of the remaining Oniscidea implies a complex history of the transition from the marine environment to land. With the exception of the basal clade, all other established major clades have been recovered as monophyletic, even though relationships within these clades call for a revised interpretation of morphological characters used in terrestrial isopod taxonomy.

Molecular taxonomy of endemic coastal Ligia isopods from the Hawaiian Islands: re-description of L. hawaiensis and description of seven novel cryptic species.

Past phylogeographic work has shown Ligia hawaiensis, a coastal isopod species endemic to the Hawaiian Islands, to be a paraphyletic complex of several highly genetically divergent yet morphologically cryptic lineages. Despite the need for a taxonomic revision of this species, the lack of morphological differentiation has proven an impediment to formally describe new Ligia species in the region. Molecular characters and species delimitation approaches have been successfully used to formally describe cryptic species in other crustacean taxa, suggesting they may aid taxonomic revisions of L. hawaiensis. Herein, various distance- and tree-based molecular species delimitation approaches are applied on a concatenated dataset comprised of both mitochondrial and nuclear gene sequences of L. hawaiensis and L. perkinsi, a terrestrial species endemic to the Hawaiian archipelago. Results of these analyses informed a taxonomic revision leading to the redescription of L. hawaiensis and the description of seven new cryptic species on the basis of molecular characters: L. dante, L. eleluensis, L. honu, L. kamehameha, L. mauinuiensis, L. pele, and L. rolliensis. These coastal Ligia species from the Hawaiian archipelago appear to be largely limited to single islands, where they appear largely constrained to volcanic rift zones suggesting allopatric events at local scales may drive diversification for poorly dispersing organisms in the Hawaiian coastlines. Additional work remains needed to fully assess the role of said events; however, the description of these novel species underscore their potential to aid in studies of local diversification of marine organisms in Hawai‘i. Lastly, this represents the first application of molecular taxonomic approaches to formally describe genetic lineages found in Ligia isopods as species, underscoring the promise these methods hold to taxonomic revisions in other species in the genus shown to harbor cryptic genetic lineages.

Do active‐dispersing insects dominate the invertebrate fauna of rock pools in the wet–dry tropics, Kimberley, Australia?

Abstract Invertebrate assemblages of tropical freshwater rock pools (FRPs) are poorly known compared with temperate regions, where FRPs contain specialized, endemic taxa of high conservation value. Invertebrates were sampled from pristine FRPs in the Morgan River catchment in the Australian wet–dry tropics in the 2015 and 2016 wet seasons. Taxa were classified as either active or passive dispersers and by functional feeding groups. A range of physical variables were examined to identify associations with invertebrate assemblages. Forty‐seven taxa were identified from FRPs; most were actively dispersing predatory insects, primarily Coleoptera and Hemiptera. Five adult insect species were found in most pools; other taxa were rare and scattered across FRPs. Two previously undescribed species of Spinicaudata were collected, but few crustacean taxa were recorded, and passively dispersing taxa were rare. Species accumulation curves indicated that had more pools been sampled, more taxa would have been collected in 2015, but in 2016 most species were collected. There was no pattern in FRP assemblages related to any physical variable, but the assemblages in pools were correlated between sampling times. An opportunistic and mobile assemblage composed mostly of actively dispersing predatory insects may explain the absence of relationships with measured variables. Low hydrological stability in the wet–dry tropics may be associated with low taxon richness. The dominance of actively dispersing insects is in contrast with FRP assemblages in temperate and arid regions. Studies of a wider range of FRPs from tropical regions are required to determine whether the fauna of these Kimberley FRPs are typical, and to fully describe short‐range endemic species across the Kimberley and elsewhere. The FRPs have conservation value as habitat for endemic, specialist rock‐pool taxa, contributing to regional species pools. At present, a lack of knowledge of endemic FRP specialist species in tropical regions, including the Kimberley, impedes our ability to protect and conserve these species from disturbance.

Guidelines for RNA-seq projects: applications and opportunities in non-model decapod crustacean species

Next-generation sequencing (NGS) has dramatically changed the way biological research is being conducted in the post-genomic era, and they have only been utilized widely over the recent decade for studies of non-model decapod crustacean species, predominantly by sequencing the transcriptome of various tissues across different life stages. Next-generation sequencing can now provide a rapid, cost-effective solution for discovery of genetic markers crucial in many applications that would previously have otherwise taken years to develop. Sequencing of the entire transcriptome (referred to as RNA sequencing; RNA-seq) is one of the most popular NGS tools. RNA-seq studies of non-model species in crustacean taxa, however, have faced some problems, including a lack of “good” experimental study design, a relative paucity of gene annotations, combined with limited knowledge of genomic technologies and analyses. The aim of the current review is to assist crustacean biologists to develop a better appreciation for the applications and scope of RNA-seq analysis, understand the basic requirements for optimal RNA-seq studies and provide an overview of each step, from RNA-seq experimental design to bioinformatics approaches to data analysis. Insights that have resulted from RNA-seq studies across a wide range of non-model decapod species are also summarized.

Peptidergic signaling in the tadpole shrimp Triops newberryi: A potential model for investigating the roles played by peptide paracrines/hormones in adaptation to environmental change

Peptides are the largest/most diverse class of molecules used by animals for chemical communication, and with their cognate receptors, are key players in modulating physiological/behavioral control systems, including those involved in adaptation to environmental change. Crustaceans have long served as models for investigating peptidergic control of physiology/behavior, and members of Notostraca, an ancient branchiopod order, have recently been proposed as models for investigating the genetic/physiological underpinnings of ecoresponsiveness; nothing is currently known about the genes/proteins underlying peptidergic signaling in any member of this crustacean taxon. Transcriptome mining is a powerful tool for peptidome prediction in crustaceans, and all large-scale discovery of crustacean peptide receptors has been achieved via transcriptomics. Here, in silico transcriptome mining was used to elucidate the peptidergic signaling systems of the tadpole shrimp Triops newberryi, a member of Notostraca. Transcripts encoding putative precursor proteins and/or receptors for 28 peptide families were identified within the T. newberryi dataset. The deduced precursor proteins included those for allatostatin A, allatostatin B, allatostatin C, allatotropin, bursicon, CCHamide, crustacean cardioactive peptide, crustacean hyperglycemic hormone, diuretic hormone 44, ecdysis-triggering hormone, eclosion hormone, elevenin, FMRFamide-like peptide, glycoprotein hormone, GSEFLamide, inotocin, insulin-like peptide, neuroparsin, neuropeptide F, orcokinin/orcomyotropin, proctolin, pyrokinin/periviscerokinin, SIFamide, sulfakinin and tachykinin-related peptide; 117 distinct mature peptides were predicted from the collective set of deduced pre/preprohormones. Transcripts encoding putative receptors for most of the abovementioned peptide groups were also identified from the T. newberryi assembly, as were those for several families for which no precursors were found, i.e., corazonin, RYamide and short neuropeptide F. This is the first description of a peptidome and peptide receptors from any member of the Notostraca, and as such, provide a foundation for beginning to investigate the roles played by peptidergic signaling systems in T. newberryi and other notostracans, including how they may contribute to modulating organism-environment interactions.

Dietary habits of the polkadot skate Dipturus chinensis in the East China Sea

We investigated the dietary habits of the polkadot skate, Dipturus chinensis (Japanese name: Gangi-ei), in the East China Sea by analyzing the stomach contents of 529 individuals. Of these, 18 (3.40%) had empty stomachs. The mean and maximum fullness indices (FIs) were 0.67% and 6.12%, respectively. The mean FI of female skates > 500 mm in total length (TL) was higher than that of males and smaller females. The most dominant prey category was crustaceans, which included shrimps, crabs, and anomurans, followed by fishes. Cephalopods were additionally observed. Dipturus chinensis fed on a wide variety of crustacean taxa, and among them, Caridea and Galatheidae were particularly common. Fishes that could be identified were mostly demersal fishes, such as Callionymidae, Triglidae, and Rajidae. Some juvenile D. chinensis were also observed, indicating that cannibalism occurs in this species. Even though dental sexual dimorphism was observed in large size classes (mainly > 500 mm TL), the diet of males and females significantly overlapped. Size-related dietary shifts from small crustaceans, such as shrimps and anomurans, to relatively fast-swimming prey, such as fishes, crabs, and cephalopods, were observed in all seasons. The composition of these prey categories varied among seasons. Shannon–Wiener diversity indices calculated for each size class ranged from 2.01 to 2.51, indicating D. chinensis are generalist predators. As size increased, trophic level increased from 3.58 to 3.85, indicating that larger specimens are at a slightly higher trophic level than smaller specimens. These results suggest that D. chinensis are middle-trophic-level generalist predators that utilize diverse prey depending on their size and the season, and thus play an influential role in the demersal ecosystem of the East China Sea.