Marine parasites remain understudied in South Africa with little information available on their diversity and the effects these parasites may have on their hosts. This is especially true for parasitic copepods within the family Ergasilidae. Among the 4 genera known in Africa, Ergasilus Nordmann, 1832 is the most speciose with 19 reported species. However, this represents only 12% (19/163) of the global diversity. Furthermore, only 5 known African species are reported from marine environments, and only 1 is reported from the South African coastline. Given the rich biodiversity along this coastline, a high marine parasite diversity could be expected from these shores. As a case study, the Evileye blaasop, Amblyrhynchote honckenii (Bloch), a marine and brackish fish species, was screened for parasites along the South African coastline. This resulted in the discovery of 2 species of Ergasilus new to science (Ergasilus arenalbus n. sp. and Ergasilus chintensis n. sp.), which makes them the second and third ergasilid species reported for tetraodontid pufferfishes worldwide. Although genetically distinct, the 2 newly described species clustered in the same subclade within the Ergasilidae based on 18S rDNA, 28S rDNA and COI mtDNA phylogenies. The newly described species differ morphologically from each other, and their respective congeners based on the size and armature of the antenna; body segmentation; and general ornamentation throughout the entire body. The addition of these 2 new species from a single host species indicates that South Africa's marine fishes contain most probably a hidden parasitic copepod diversity that is worth exploring.

The descriptions of two co-occurring cardioid crustaceans from the Ballagan Formation (Tournaisian, Lower Carboniferous) of Chirnside, Scottish Borders, help to resolve the taxonomy of the genus Tealliocaris. Tealliocaris robusta Peach, 1908 is assigned to Schramocaris to form S. robusta (Peach, 1908) comb. nov. on the basis of morphological characters such as the rugosity and position of the branchial carinae as well as the nature of the pleon, and becomes the earliest representative of this genus in Scotland. A new species of Tealliocaris is also recognised from this locality and is described as T. briggsi sp. nov., based on the smooth carapace, lack of pleonic grooves and the number of spines on the scaphocerite and lateral margin of the anterior carapace. The systematic position of the Pendleian specimens identified by Peach (1908) as ‘Tealliocaris robusta var.’ is finally resolved and described as T. weegie sp. nov.

Kelp forests are regarded as important nursery and foraging habitats for commercially important species of finfish and shellfish despite an absence of fishery-independent data in many regions. Here, we conducted targeted surveys at 12 subtidal reefs, distributed across 9° of latitude in the UK, using three complementary techniques (Underwater Visual Census (UVC), Baited Remote Underwater Video (BRUV) and deployment of prawn pots) to quantify the abundance of crustaceans within kelp forests. Commercially important species were recorded at all sites; Cancer pagurus (brown/edible crab) and Necora puber (velvet swimming crab) were the most abundant and commonly observed, although Maja brachydactyla (spider crab), Homarus gammarus (European lobster) and Palaemon serratus (common prawn) were also recorded. The abundance of some species exhibited pronounced regional variability, with higher abundances of C. pagurus within northern regions and, conversely, higher abundances of M. brachydactyla and P. serratus within southern regions. Each sampling technique yielded similar spatial patterns for the most abundant species but had varying sensitivity to some species. Most individuals observed were juvenile or sub-adults, suggesting kelp forests serve as important nursery grounds for commercially and ecologically important crustaceans. Further monitoring efforts, conducted across greater spatiotemporal scales and in different habitat types, are needed to provide a robust baseline against which to detect changes and to inform management and conservation actions.

This paper provides data on diversity, zonation and seasonal fluctuations of decapod crustaceans at the northern Gulf of Oman coast, based on quantitative and qualitative samplings. A total of 75 species belonging to four infraorders, 27 families and 48 genera were identified. These species include 20 new records for the entire Gulf of Oman and 13 new records for its Iranian coast. The mid-intertidal zone showed a higher mean diversity and abundance than high- and low-intertidal zones. The mean diversity and abundance in the high-intertidal zone showed significant differences with the mid- and low-intertidal zones. The indices of species richness (Margalef), diversity (Shannon) and evenness (Pielou) showed significant differences among the intertidal zones. Most of the identified species (>60%) that had high values in their frequency of occurrence and relative abundance showed an overlapping vertical distribution, and were present in all three or just in two of the three defined zones. Other species were found only in one of the three zones (non-overlapping vertical distribution). The decapod community in the mid-intertidal zone showed a higher dissimilarity with the high-intertidal zone than with the low-intertidal. Both abundance and diversity were found to be lowest and highest during south-west and north-east monsoons, respectively. During south-west monsoon, the abundance of decapods declined dramatically, but species diversity and ecological indices did not show any statistically significant difference among the sampling periods.

Within aquatic habitats, the hyper-abundant Order Crustacea appear to be the predominant host group for members of the Phylum Microsporidia. The musculature, a common site of infection, provides access to biochemical (carbohydrate-rich) and physiological (mitochondria-rich) conditions conducive to prolific parasite replication and maturation. The significant proportion of body plan devoted to skeletal musculature in Crustacea provides the location for a highly efficient intracellular parasite factory. In this study, we utilize histological, ultrastructural and phylogenetic evidence to describe a previously known (Inodosporus octospora) and novel (Ovipleistophora arlo n. sp.) microsporidian parasites infecting the musculature of the common prawn (Palaemon serratus) from the same site, at the same time of year. Despite similar clinical signs of infection, both parasites are otherwise distinct in terms of pathogenesis, morphology and phylogeny. Based upon partial subunit ribosomal RNA (SSU rDNA) sequence, we show that that I. octospora may be identical to a Kabatana sp. previously described infecting two-spot goby (Gobiusculus flavescens) in Europe, or at least that Inodosporus and Kabatana genera are synonyms. In addition, SSU rDNA sequence for O. arlo places it within a distinct clade containing Ovipleistophora mirandellae and Ovipleistophora ovariae, both infecting the oocytes of freshwater fish in Europe. Taken together, our data provide strong evidence for trophic-transfer between crustacean and fish hosts for two different microsporidians within clade 5 of the phylum. Furthermore, it demonstrates that morphologically and phylogenetically distinct microsporidians can infect the same tissues of the same host species to impart clinical signs which mimic infection with the other.

Knowing the determinants of the geographic ranges of parasites is important for understanding their evolutionary ecology, epidemiology and their potential to expand their range. Here we explore the determinants of geographic range in the peculiar case of a parasite species – the microsporidian Hamiltosporidium tvaerminnensis – that has a limited geographic distribution in a wide-spread host – Daphnia magna. We conducted a quantitative trait loci (QTLs) analysis with monoclonal F2D. magna populations originating from a cross between a susceptible northern European genotype and a resistant central European genotype. Contrary to our expectations, long-term persistence turned out to be a quantitative trait across the F2 offspring. Evidence for two QTLs, one epistatic interaction and for further minor QTL was found. This finding contrasts markedly with the previously described bimodal pattern for long-term parasite persistence in natural host genotypes across Europe and leaves open the question of how a quantitative genetic trait could determine the disjunct geographic distribution of the parasite across Europe.

Four species of Pinnotheridae inhabit European marine waters, Afropinnotheres monodi, Nepinnotheres pinnotheres, Pinnotheres pectunculi and Pinnotheres pisum. For these four species there are data available on the morphology of their larval stages as well as DNA markers. This information has allowed us to detect some larvae in plankton samples from the Gulf of Cadiz (SW Iberian Peninsula) that do not belong to any of these European pinnotherid species and to be confirmed by DNA barcoding. In this study these findings are shown as a case of early detection of a newly introduced and unknown species in European marine waters.

Two new species of Clausidium copepods were collected on the bodies of ghost shrimps from the Iranian coast of the Gulf of Oman. Clausidium makranensis sp. nov. and Clausidium sarii sp. nov. are described from the large chelipeds of Neocallichirus natalensis and Corallianassa martensi, respectively. Clausidium makranensis sp. nov. is distinguishable from its congeners by the unique anal somite that is armed with sclerotized hooks on each side. Clausidium sarii sp. nov. can be differentiated from its congeners by the armature and shape of leg 5.

A new species of Trischizostoma collected at depths of 1392–1420 m from western Mexico is described. It represents the first record of the genus in the NE Pacific. The new species is morphologically similar to T. circulare, T. tohokuense and T. richeri. These species all share a large rostrum, expanded eyes and an entire telson. Distinctive characters of the new species include a dorsally unnotched urosomite 1, a subconical coxa 2, a subtriangular propodus of gnathopod 1, a single seta and one protuberance on the palm of gnathopod 2, the presence of 10 spine-teeth in the outer plate of maxilla 1 and of a large, 1-articulate maxilla 1 palp, and the telson with 2 minute simple setae and 2 minute projections distally.

A new species of Mysidium from the eastern tropical Pacific, Mexico, is described, representing the second species of this genus described for the Pacific Ocean and the eighth species reported worldwide. Mysidium pumae sp. nov. is distinguished from the other species of the genus by several characters including: the lanceolate appendix masculina, 3× as long as wide, tapering distally, with a distal tuft of 16 setae and an inner proximal tuft of more than 30 setae, the male pleopod 4 with endopod bearing 3 setae, the exopod with 4 articles, the modified seta from article 3 of the exopod bifid, telson 2.3× as long as wide, distally concave. A table with the main differences among all the known species in the genus is provided.

Popularly known as blue land crab, Cardisoma guanhumi is heavily exploited as food and considered as an important economic resource in Brazil. In recent decades, the species has experienced a sharp population decline by the loss and/or degradation of its natural habitat and overfishing. The present study aimed to investigate the genetic variation and connectivity among 154 specimens of C. guanhumi sampled along the coast of Pernambuco in five different levels of tropical mangroves conservation. Nine ISSR primers were used for assessing the genetic variation of the species. The genetic diversity observed in C. guanhumi was high reinforcing the condition of a resilient species, indicating a good conservation status of this resource in Pernambuco. The hypothesis of panmixia was rejected in favour of a heterogeneous distribution of the genotypes of C. guanhumi (ФST = 0.19) despite the high gene flow observed in the study region. Such difference could be attributed to the candidate loci being under positive selection and differentially distributed between the geographic regions assessed. The genetic structure showed a pattern of fine-scale genetic structuring better fitted to a model of selection-mediated geographic cline. Cluster analysis and candidate loci under positive selection suggested that the populations of C. guanhumi in the North-central and South coasts of Pernambuco might be different management units and must be managed independently. In conclusion, exhaustion of natural stocks upon which fishing is totally dependent will lead to serious ecological and sociocultural impacts.

Sampling in subtidal waters of the Persian Gulf revealed a new species of ghost shrimp from the family Gourretiidae. Gourretia qeshmensis sp. nov. resembles G. sinica from the South China Sea and G. manihinae from Tanzania. Gourretia qeshmensis sp. nov. differs from these two species by characters of the ischium of the large cheliped, pereopod 3, exopod of the uropod and maxilliped 3.

We report for the first time the association of some caridean shrimps with the octocoral Carijoa riisei (Cnidaria: Clavulariidae) and the sponge Dragmacidon reticulatum (Porifera: Axinellidae), in estuaries from north-eastern Brazil. The alpheid shrimp Synalpheus apioceros, Synalpheus fritzmuelleri, Alpheus formosus, Alpheus carlae and the palaemonid Cuapetes americanus are reported in association with Carijoa riisei. The latter two species, plus the alpheid Alpheus buckupi, are recorded in association with D. reticulatum.

The rare pilumnoid crab, Dentoxanthus iranicus Stephensen, 1946 (Galenidae), is recorded from Gujarat state in India for the first time. Originally described from a small female (Gulf of Oman), and subsequently reported twice from Pakistan on the basis of two males and a female, the species is not well known and has never been described to modern standards. On the basis of the present male specimen from India, as well as a previously unreported male specimen from Pakistan, the species is redescribed and its systematics discussed.

Parasites have a major impact on global finfish and shellfish aquaculture, having significant effects on farm production, sustainability and economic viability. Parasite infections and impacts can, according to pathogen and context, be considered to be either unpredictable/sporadic or predictable/regular. Although both types of infection may result in the loss of stock and incur costs associated with the control and management of infection, predictable infections can also lead to costs associated with prophylaxis and related activities. The estimation of the economic cost of a parasite event is frequently complicated by the complex interplay of numerous factors associated with a specific incident, which may range from direct production losses to downstream socio-economic impacts on livelihoods and satellite industries associated with the primary producer. In this study, we examine the world's major marine and brackish water aquaculture production industries and provide estimates of the potential economic costs attributable to a range of key parasite pathogens using 498 specific events for the purposes of illustration and estimation of costs. This study provides a baseline resource for risk assessment and the development of more robust biosecurity practices, which can in turn help mitigate against and/or minimise the potential impacts of parasite-mediated disease in aquaculture.

The decapod Crustacea from Ascension Island are reported upon on the basis of major expeditions undertaken during 2008 and 2012, including several minor additional collections made in other years. Two species, Gnathophyllum americanum and Corallianassa longiventris are new records for the island bringing the total known marine decapod fauna to 75 species, of which 11 are currently endemic to Ascension Island.

Three specimens of Platyscelus armatus (Crustacea: Amphipoda: Hyperiidea: Platyscelidae) are reported from coastal waters of the Canary Islands, Spain; these are the first records from these waters. The specimens were collected south-west of Tenerife and El Hierro Islands during the ‘CETOBAPH 2012' (April 2012) oceanographic cruise. Morphological and morphometric measurements of the specimens, geographical and bathymetric distribution of this species and a key to species of the genus reported in the Canary Islands are provided.

Eriocheir sinensis is an invasive species that spread in European waters as the result of human activity. The captures from the Portuguese population took place in September 2013 in the Tagus Estuary and were dominated by the medium-sized individuals at the beginning of their reproducing cycle (n=192).

Selwynia, is regarded as a senior subjective synonym of Aphanodactylus (Crustacea: Brachyura: Pinnotheroidea: Aphanodactylidae). This synonymy does not affect the family name Aphanodactylidae. A diagnosis is provided for Selwynia laevis and this species is re-described.

Three brachyuran species of the family Xanthidae, Atergatis ocyroe, Macromedaeus voeltzkowi and Macromedaeus quinquedentatus are recorded from the Iranian coast of the Gulf of Oman. These specimens were collected in 2009 and 2010 from the Iranian waters of the Gulf of Oman. Among these species, A. ocyroe is a new record for the Gulf of Oman and M. quinquedentatus is a new record for the Iranian coast. This is the second record of M. voeltzkowi from the Iranian coast, whereas there is still no record from the Arabian coast of the Gulf of Oman. The diagnostic characteristics of the species and some taxonomic remarks are reported upon in this paper.