METAZOAN PARASITE COMMUNITY OF THE YELLOW SNAPPER LUTJANUS ARGENTIVENTRIS: FACTORS THAT INFLUENCING SPECIES COMPOSITION AND RICHNESS.

A total of 366 individuals of Lutjanus argentiventris (Peters, 1869) were collected over a 5-yr period (October 2018 to June 2022) from Acapulco Bay, Mexico. Parasite communities in Lutjanus argentiventris were quantified and analyzed to determine the main factors that generate changes in species richness and/or species composition over time. The digeneans and copepods were the best-represented parasite groups. The parasite communities were characterized by a high numerical dominance of ectoparasites, mainly isopod larvae. Species richness at the component community level (9-23 species) was similar to the reported richness in other Lutjanus spp. The parasite communities of Lutjanus argentiventris exhibited high variability in species composition, suggesting that each parasite species may respond differently to environmental changes. However, the species richness and diversity were fairly stable over time; therefore, a clear pattern of interannual variation was not observed. Variations in the community structure probably were due to factors such as host traits (e.g., feeding behavior and body size), and possible interannual differences in environmental factors amplified by the occurrence of the anomalous event of La Niña.

New occurrences, mean infestation intensity and prevalence of parasitic isopods (Isopoda, Cymothoida, Bopyridae) associated with Macrobrachium amazonicum (Decapoda, Palaemonidae) from the mouth of the Amazon River.

The Amazon prawn or Macrobrachium amazonicum (Heller, 1862) is widely distributed in South America, occurring in the Orinoco and Amazon rivers, and forms an important source of income for riverside families. This prawn hosts crustacean ectoparasites of the genus Probopyrus (Giard & Bonnier, 1888) (Bopyridae) that infest its gill cavity. The aim of the present study was to report new occurrences of Probopyrus in Amazon prawns caught in the Amazon River. Macrobrachium amazonicum prawns were collected between May 2017 and April 2018, and again from July 2021 to May 2022 in the regions of Ilha de Santana and Rio Mazagão, state of Amapá, Brazil. Among the 5,179 prawn specimens caught, 133 were parasitized by the ectoparasites Probopyrus pandalicola (Packard, 1879), Probopyrus bithynis (Richardson, 1904), Probopyrus floridensis (Richardson, 1904) and Probopyrus palaemoni (Lemos de Castro & Brasil Lima, 1974). These occurrences of P. floridensis and P. palaemoni in M. amazonicum were the first records of this on the northern coast of Brazil. These four ectoparasites are not limited to specific host species or genera, as observed in this study, which reports four species of Probopyrus infesting M. amazonicum.

Description of Sandythoa gen. nov., a fish parasitic branchial cymothoid (Crustacea: Isopoda: Cymothoidae) from the Indian Ocean, with five species including one new species.

The comparative analysis of records of Elthusa samariscii (Shiino, 1951) from Japan and India, alongside corresponding illustrations, indicates that the records of E. samariscii from Samaris cristatus Gray in India represent a distinct and previously undescribed species. This study introduces Sandythoa tiranga gen. and sp. nov., providing comprehensive descriptions of various lifecycle stages, including the female, male, transitional, premanca, and manca larvae. The following combinations of characters identify the genus: cephalon anterior margin with acute rostrum; pleonite 1 is distinctly narrow, not extending laterally; presence of a narrow gap between pleonites; antenna with more than 10 articles; maxilliped with oostegital lobe. Sandythoa tiranga sp. nov. is specifically identified along the southwest coast of India. Furthermore, we propose transferring the following species from Elthusa: Sandythoa arnoglossi (Trilles and Justine 2006) comb. nov.; Sandythoa parabothi (Trilles and Justine, 2004) comb. nov.; Sandythoa samariscii (Shiino, 1951) comb. nov.; Sandythoa moritakii (Saito and Yamauchi, 2016) comb. nov. A revised key to the global marine branchial cymothoid genera is provided.

Ectoparasites of the Critically Endangered green sawfish Pristis zijsron and sympatric elasmobranchs in Western Australia.

This study reports the metazoan ectoparasite fauna of juvenile Critically Endangered green sawfish, Pristis zijsron, and sympatric elasmobranchs in Western Australia. Five parasite taxa were found on 76 screened P. zijsron: Caligus furcisetifer (Copepoda: Caligidae), Dermopristis pterophila (Monogenea: Microbothriidae), Branchellion plicobranchus and Stibarobdella macrothela (Hirudinea: Piscicolidae), and praniza larvae of an unidentified gnathiid isopod. Only C. furcisetifer and D. pterophila were common, exhibiting discrepant site-specificity, with C. furcisetifer occurring mostly on the head and rostrum, and D. pterophila around the pectoral and pelvic fins. Intensity of infection for C. furcisetifer and D. pterophila increased with host total length and was influenced by host sex, but in opposite directions; intensity of C. furcisetifer was greater on female P. zijsron, whereas intensity of D. pterophila was greater on males. In the Ashburton River, likelihood of infection for C. furcisetifer and D. pterophila on P. zijsron increased with time since substantial freshwater discharge events, suggesting decreased salinity impacts both taxa. In addition to P. zijsron, five other sympatric elasmobranch species were opportunistically screened for ectoparasites in the study area: the giant shovelnose ray, Glaucostegus typus, the eyebrow wedgefish, Rhynchobatus palpebratus, the nervous shark, Carcharhinus cautus, the lemon shark, Negaprion acutidens, and the graceful shark, Carcharhinus amblyrhynchoides. Caligus furcisetifer was found on R. palpebratus; no other parasites of P. zijsron were found on other sympatric elasmobranch species. Conversely, Perissopus dentatus (Copepoda: Pandaridae) was found on all three carcharhinids but not on batoid rays (P. zijsron, G. typus or R. palpebratus).

Global distribution patterns and geographic range of Cymothoa Fabricius, 1793 (Isopoda: Cymothoidae) associated with host fish.

Over recent years, fish parasites of the genus Cymothoa Fabricius, 1793, have received increased attention due to both their ecological and their economic importance to aquaculture and fishery. As the studies about Cymothoa have increased this improve our understanding on the host specificity and distribution of these parasites. The aim of this paper was to review the current global geographic distribution, distribution patterns and parasite-host interactions patterns of Cymothoa spp. associated with fish from marine and brackish water bodies around the world. A total of 144 samples were analyzed, from which 23 species of Cymothoa were found parasitizing 84 teleost fish species of 35 families and 20 orders. Most of these parasites were found in the mouth of the host fish, including in wild fish. The highest occurrence of parasites was found in host species belonging to the families Carangidae and Lutjanidae. Host specificity was an important factor in the geographic distribution of Cymothoa species as also environmental temperature. Cymothoa indica, Cymothoa exigua and Cymothoa excisa were the species with lowest specificity for host family and widest geographic distribution.

Finding Nemo! Description of a New Species of Branchial Fish Parasitic Cymothoid, Elthusa Schioedte and Meinert, 1884 (Crustacea: Isopoda), infesting Callionymus filamentosus Valenciennes, 1837 from the Northern Indian Ocean.

PURPOSE: Specimens of Elthusa from trashfish of the Indian SW coast were described as a new parasitic cymothoid, Elthusa nemo sp. nov., (Crustacea: Isopoda). Later, the branchial cavity of the Blotchfin dragonet Callionymus filamentosus Valenciennes, 1837 were documented as its micro- and macro-habitat (host). METHODS: Fresh/live specimens of unidentified cymothoid samples were collected from the trash fishes obtained from Neendakara (08°30.0' N 76°53.30' E) fish landing centre, Kollam district, Kerala state, southwest coast of India. After a long search for the host species, we recovered the isopod from the branchial cavity of the deep-sea fish Callionymus filamentosus Valenciennes, 1837 (Callionymiformes: Callionymidae). The new species is described and illustrated based on ovigerous females. RESULTS: Elthusa nemo sp. nov., has the following sets of combinations of characters: body slightly twisted, elongated, dorsal surfaces smooth, nearly twice as long as greatest width; pleon short, ~ 14% body length, 0.8 times as wide as pereon maximum width; widest at pleonite 2 and narrowest at pleonite 1; only pleonite 1, laterally overlapped by pereonite 7 posterolateral expansion and coxa 7; presence of appendix masculina on pleopod 2; uropods 0.8 times as the length of pleotelson; antenna with two plumose setae on article 4. CONCLUSION: Elthusa nemo sp. nov., is the sixth species of the genus known from Indian waters.

The genus Armadillo Latreille, 1802 (Oniscidea, Armadillidae) from Cyprus, with descriptions of two new species.

The present work aims to morphologically characterize the species of Armadillo from Cyprus. Moreover, two new species of the genus are described, A. konstantinoui sp. nov. from several places along the island, and A. karametae sp. nov. from Pafos region. The circum-Mediterranean species A. officinalis is also redescribed.

Parasitism-Induced Intersexuality in a Sexually Dimorphic Varunid Crab, Ptychognathus ishii (Decapoda: Varunidae).

Although many animals that perform sexual reproduction exhibit sexual dimorphism, individuals with intersex traits between the traits of males and females appear in some species, depending on environmental factors. Ptychognathus ishii, a varunid crab, exhibits distinctive sexual dimorphism in the morphology of its abdomen, chelipeds and setal tufts on the chelipeds. In this study, however, we report for the first time that intersex individuals with intermediate characters between those of males and females were occasionally found in wild populations. Morphological features of intersex individuals are described. Their taxonomic positions are identified based on DNA sequences of part of the mitochondrial cytochrome c oxidase I (COI) gene. It was shown that the intersexuality was induced by entoniscid parasites, because all intersex individuals were parasitized by entoniscid isopods, identified as Entionella sp. The apparent correlation between parasitism and morphological anomalies suggests that the parasitic isopods affect physiological conditions, leading to the feminization of male hosts.

Development and evaluation of a custom bait design based on 469 single-copy protein-coding genes for exon capture of isopods (Philosciidae: Haloniscus).

Transcriptome-based exon capture approaches, along with next-generation sequencing, are allowing for the rapid and cost-effective production of extensive and informative phylogenomic datasets from non-model organisms for phylogenetics and population genetics research. These approaches generally employ a reference genome to infer the intron-exon structure of targeted loci and preferentially select longer exons. However, in the absence of an existing and well-annotated genome, we applied this exon capture method directly, without initially identifying intron-exon boundaries for bait design, to a group of highly diverse Haloniscus (Philosciidae), paraplatyarthrid and armadillid isopods, and examined the performance of our methods and bait design for phylogenetic inference. Here, we identified an isopod-specific set of single-copy protein-coding loci, and a custom bait design to capture targeted regions from 469 genes, and analysed the resulting sequence data with a mapping approach and newly-created post-processing scripts. We effectively recovered a large and informative dataset comprising both short (<100 bp) and longer (>300 bp) exons, with high uniformity in sequencing depth. We were also able to successfully capture exon data from up to 16-year-old museum specimens along with more distantly related outgroup taxa, and efficiently pool multiple samples prior to capture. Our well-resolved phylogenies highlight the overall utility of this methodological approach and custom bait design, which offer enormous potential for application to future isopod, as well as broader crustacean, molecular studies.

Evolutionary history of inversions in directional mutational pressures in crustacean mitochondrial genomes: Implications for evolutionary studies.

Inversions of the origin of replication (ORI) in mitochondrial genomes produce asymmetrical mutational pressures that can cause strong base composition skews. Due to skews often being overlooked, the total number of crustacean lineages that underwent ORI events remains unknown. We analysed skews, cumulative skew plots, conserved sequence motifs, and mitochondrial architecture of all 965 available crustacean mitogenomes (699 unique species). We found indications of an ORI in 159 (22.7%) species, and mapped these to 23 ORI events: 16 identified with confidence and 7 putative (13 newly proposed, and for 5 we improved the resolution). Two ORIs occurred at or above the order level: Isopoda and Copepoda. Shifts in skew plots are not a precise tool for identifying the replication mechanism. We discuss how ORIs can produce mutational bursts in mitogenomes and show how these can interfere with various types of evolutionary studies. Phylogenetic analyses were plagued by artefactual clustering, and ORI lineages exhibited longer branches, a higher number of synonymous substitutions, higher mutational saturation, and higher compositional heterogeneity. ORI events also affected codon usage and protein properties. We discuss how this may have caused erroneous interpretation of data in previous studies that did not account for skew patterns.

A new genus and species of groundwater isopod of the family Protojaniridae (Isopoda: Asellota: Gnathostenetroidoidea) from southern Chile.

A new asellotan isopod of the family Protojaniridae Fresi, Idato Scipione, 1980 is described from freshwater springs in the Osorno province, Los Lagos region, southern Chile. Wiyufiloides osornoensis gen. sp. n. is the third South American protojanirid species and the first known groundwater isopod in Chile. The new genus and species is principally characterized by the presence of a vestigial antennal scale, a strongly subchelate pereiopod I and the absence of an apical lobe on the protopod of pleopod II. The new taxon is described in detail and figures are given.

New species of Sargassum-boring Limnoria Leach, 1814 (Crustacea, Isopoda, Limnoriidae) from Japan.

A new marine Sargassum-boring species of Limnoria (Limnoriidae) is described on the basis of specimens obtained at Kamogawa-shi, Chiba Prefecture, Japan. Limnoria aspera sp. nov. shares a reduced mandibular palp to a seta, algal-feeding, and the clavate shaped epipod of the maxilliped with the other species of non-mandibular-palp group. L. aspera sp. nov. differs morphologically from the congeneric species by secondary unguis of pereopods and unique carinae of pleonite 5 and pleotelson. We describe the sequences of the mitochondrial COI gene and the nuclear 28S rDNA gene. L. aspera sp. nov. differs by 14.218.0% in p-distance based on COI sequences from other Japanese species, L. furca and L. nagatai.

Two new species of the marine isopod genus emCirolana/em Leach, 1818 (Crustacea: Isopoda: Cirolanidae) from the coast of the western Gulf of Thailand.

Cirolana khamensis sp. nov. and C. parawongat sp. nov. are described from specimens collected in the western Gulf of Thailand at depths of 8 metres and 1 metre, respectively. Both species belong to the Cirolana 'pleonastica-group' with tubercles on the dorsal surfaces, transverse sutures on the pereonites, pleonite 3 not posteriorly produced and pleonite 4 posterolaeral margin rounded. Cirolana khamensis sp. nov. can be distinguished from other species of Cirolana 'pleonastica-group' by lateral margin of uropodal exopod having five robust seatae and a continuous row of plumose marginal setae, pereonites 1-3 each with a single transverse impressed line; antennula peduncle with articles 1 and 2 distinct and articulated peduncle; pleotelson dorsal surface with two sub-median longitudinal carinae, each of which has four prominent tubercles. Cirolana parawongat sp. nov. can be distinguished by pereonites 1-3 without a single transverse impressed line and having nine tubercles on pleonite 4 and 5. A dichotomous key to Cirolana 'pleonastica-group' in South-East Asia region is given.

Six new epigean species of Caecidotea/ (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico.

Six new epigean freshwater species of the genus Caecidotea in Mexico are described. These species were collected in waterbodies located along the Trans-Mexican Volcanic Belt (TMVB) and the eastern slope of the country: Caecidotea buzwilsoni sp. nov., Caecidotea chicoensis sp. nov., Caecidotea alvarezi sp. nov., Caecidotea mintzita sp. nov., Caecidotea zacapuensis sp. nov., and one additional species Caecidotea villalobosi sp. nov. is described from the Papaloapan basin at the Atlantic Slope of Mexico. The taxonomic treatment for each species includes a detailed description, figures of characters of diagnostic importance and comments. We also provide an updated map of Caecidotea records in Mexico. This work substantially increases the number of epigean Caecidotea known to occur in Mexico to 11 species, a new total of 99 species described to North America.

Two new species and a new record of Bopyrinae (Isopoda: Bopyridae) infesting Alpheidae and Hippolytidae, with comments on the genus Bopyrina Kossmann, 1881.

Two new bopyrids, Bopyrinina articulata n. sp. and Bopyrinella asymmetrica n. sp. are described from French Polynesia, the Red Sea, and the Philippines. Bopyrinina articulata n.sp. infests Salmoneus cf. gracilipes Miya, and is distinguishable from other species of this genus by the structure of the maxilliped, pleopods and oostegite 1. Bopyrinella asymmetrica n. sp. is most similar to Bopyrinella albida Shiino, 1958, but females differ from that species because all pereomeres on the short side have round dorsolateral bosses and its pleotelson is greatly distorted. Bopyrina ocellata (Czerniavsky, 1868) is newly recorded from the Western Atlantic, from Florida, USA. Review of the species of Bopyrina revealed that B. choprai Nierstrasz & Brender à Brandis, 1929 and B. sewelli Chopra, 1930 are intermediate in morphology between Bopyrina and Schizobopyrina, the taxonomic assignment of these two species needs further evaluation. Keys to Bopyrinella Nierstrasz & Brender à Brandis, 1925 and Bopyrina Kossmann, 1881 are presented. Hosts and distributions of the seven species of Bopyrinella are summarized.

Infestation of the Parasitic Isopod Mothocya parvostis on Juveniles of the Black Sea Bream Acanthopagrus schlegelii as an Optional Intermediate Host in Hiroshima Bay.

In Hiroshima Bay, parasitic isopods of the genus Mothocya infest the black sea bream Acanthopagrus schlegelii (Bleeker, 1854) and the Japanese halfbeak Hyporhamphus sajori (Temminck and Schlegel, 1846), two fish species that are abundant and commercially important in the Seto Inland Sea of Japan. Immature and mature Mothocya individuals can infect both juveniles and adults of H. sajori, while immature Mothocya are known to parasitize juveniles of A. schlegelii; i.e., no Mothocya parasites are found in adult A. schlegelii. The identification of the immature Mothocya parasitizing juveniles of A. schlegelii remains uncertain, because Mothocya species are morphologically identifiable only based on adult females. Also, the biological/ecological relationship between the hosts and parasites has not been studied. Here, we identified the parasites on A. schlegelii as Mothocya parvostis Bruce, 1986 by molecular sequence analyses along with other parasites obtained from H. sajori, the latter being morphologically confirmed by comparison with paratype materials of M. parvostis as well as the similar congener Mothocya sajori Bruce, 1986. The growth rates of the infected A. schlegelii juveniles from June to September in the years 2013-2015 and 2018 were significantly lower than those of the uninfected ones, suggesting a negative effect of the infection on the hosts. Our data on the prevalence and duration of the infection, as well as the body size gain of the hosts and parasites, corroborate a hypothesis that M. parvostis would utilize A. schlegelii as an optional intermediate host before it reaches the final host, H. sajori.

Isopods Cymothoidae ectoparasites of fish from the Amazon.

Most freshwater species of Cymothoidae are distributed in South America. They have mainly been recorded in the eastern and western regions of the Amazon River basin. However, in this ecosystem, the biodiversity of this group may be greater if the entire Amazon basin is considered. In this regard, the aim of the present study was to provide an updated list of isopod species of the family Cymothoidae that are found in fish in the Brazilian Amazon region and to report on new fish host occurrences and expanded geographical distributions for cymothoid isopods that parasitize fish in the southwestern Brazilian Amazon region. The parasites found in fish specimens were collected, fixed and identified later. We found eight species of Cymothoidae parasitizing different host fish species in the southwestern Amazon region. However, we found 14 species of Cymothoidae throughout the Brazilian Amazon region. Three additional species are thus reported here, which increases the number of species of Cymothoidae in this region to 17. These additional species are also new records for Brazil. Therefore, this study has contribute to expand the knowledge about the distribution and diversity of Cymothoidae in the Amazon basin.

First report of Livoneca guianensis (Isopoda: Cymothoidae) in Leporinus fasciatus (Pisces: Anostomidae) in Brazil.

This study aimed to report the first record of the occurrence of the parasite Livoneca guianensis in Leporinus fasciatus in Brazil. In September 2019, during surveys of the parasites in 12 specimens of L. fasciatus from the lower Jari River basin, in Amapá State, Brazil, one specimen of L. guianensis was found in the tongue of one host. The prevalence of L. guianensis was 8.3%, and it was observed that this parasite has a geographic distribution restricted to South America, parasitizing fish species from Guyana and Brazil. This study contributed to the first report on the occurrence of L. guianensis for L. fasciatus in Brazil. In addition, increased the knowledge on the geographic distribution of this parasite with morphometric data, which are scarce for this Cymothoidae.

Disrupted architecture and fast evolution of the mitochondrial genome of Argeia pugettensis (Isopoda): implications for speciation and fitness.

BACKGROUND: Argeia pugettensis is an isopod species that parasitizes other crustaceans. Its huge native geographic range spans the Pacific from China to California, but molecular data are available only for a handful of specimens from North-American populations. We sequenced and characterised the complete mitogenome of a specimen collected in the Yellow Sea. RESULTS: It exhibited a barcode (cox1) similarity level of only 87-89% with North-American populations, which is unusually low for conspecifics. Its mitogenome is among the largest in isopods (≈16.5 Kbp), mostly due to a large duplicated palindromic genomic segment (2 Kbp) comprising three genes. However, it lost a segment comprising three genes, nad4L-trnP-nad6, and many genes exhibited highly divergent sequences in comparison to isopod orthologues, including numerous mutations, deletions and insertions. Phylogenetic and selection analyses corroborated that this is one of the handful of most rapidly evolving available isopod mitogenomes, and that it evolves under highly relaxed selection constraints (as opposed to positive selection). However, its nuclear 18S gene is highly conserved, which suggests that rapid evolution is limited to its mitochondrial genome. The cox1 sequence analysis indicates that elevated mitogenomic evolutionary rates are not shared by North-American conspecifics, which suggests a breakdown of cox1 barcoding in this species. CONCLUSIONS: A highly architecturally disrupted mitogenome and decoupling of mitochondrial and nuclear rates would normally be expected to have strong negative impacts on the fitness of the organism, so the existence of this lineage is a puzzling evolutionary question. Additional studies are needed to assess the phylogenetic breadth of this disrupted mitochondrial architecture and its impact on fitness.

A new species of Crinoniscus Pérez, 1900 (Crustacea: Isopoda: Crinoniscidae) parasitising the pedunculate barnacle Heteralepas newmani Buhl-Mortensen & Mifsud (Cirripedia: Heteralepadidae) with notes on its ecology and a review of the genus.

The new species Crinoniscus stroembergi n. sp. belonging to the parasitic isopod family Crinoniscidae Bonnier, 1900, is described from a pedunculate barnacle host collected in the Mediterranean Sea. This is the first species of Crinoniscus Pérez, 1900 described from a host in the genus Heteralepas Pilsbry. The male cryptoniscus larva is distinguished from congeneric species by having a dorsoventrally flattened body with the posterolateral margins of the cephalon scarcely extending beyond the anterior margin of pereomere 1 (in contrast to C. cephalatus Hosie, 2008 with extended margins); articles 1 and 2 of the antennule being subequal in width and the anterodistal angle of antennule article being low and rounded; propodus of pereopods 6 and 7 having a sinuous dorsal margin that is distally narrowing and the posterior margin of the pleotelson being short and rounded. The mature females of species in Crinoniscus are of two basic forms: those with ventrolateral lobes on the pereomeres (C. alepadis (Gruvel, 1901) n. comb., and C. politosummus Hosie, 2008) and those lacking such lobes (C. cephalatus and C. stroembergi n. sp.). The mature females of C. stroembergi n. sp. can be distinguished from other species of Crininiscus based on their lacking lobes on the anterior end. The material examined includes the male and three female developmental stages of the parasite in the host, Heteralepas newmani Buhl-Mortensen & Mifsud. The mouthparts of the immature female are described and the feeding biology and effects on the host are discussed along with a review of feeding modes in species of the Cryptoniscoidea. Leponiscus alepadis is transferred to Crinoniscus; the latter genus now contains five species. A modified diagnosis of Crinoniscus is provided.