Integrative taxonomy of the subfamily Orbioninae (Crustacea: Isopoda) based on mitochondrial and nuclear data with evidence that supports Epicaridea as a suborder.

Epicaridea is a group of isopods with high morphological diversity, reduction and loss of characters, and strong sexual dimorphism due to their parasitic lifestyles but their systematics is not well understood. Despite the use of nuclear and mitochondrial genes to test the phylogeny of many invertebrate groups, few molecular data from epicarideans are known, especially from the subfamily Orbioninae. Species in this group are obligate penaeoid shrimp parasites and the lack molecular data has hampered studies on the phylogeny of Orbioninae. To rectify this, mitochondrial and nuclear genes of 9 orbionine species are sequenced here. Compared to the isopod ground pattern, the sequences of orbionines seem to be more plastic near the control region and major translocations are located between rrns and cob. A phylogenetic analysis based on three data sets showed strong support for a monophyletic Orbioninae and that Epicaridea should be accepted at the rank of a suborder within Isopoda. The monophyly of Parapenaeon and Orbione is in doubt based on morphological and molecular data. The genus Parapenaeon is revised and a new genus Aparapenaeon is erected for Parapenaeon japonica and three closely related species.

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.

The first complete mitochondrial genome of a parasitic isopod supports Epicaridea Latreille, 1825 as a suborder and reveals the less conservative genome of isopods.

The complete mitochondrial genome sequence of the holoparasitic isopod Gyge ovalis (Shiino, 1939) has been determined. The mitogenome is 14,268 bp in length and contains 34 genes: 13 protein-coding genes, two ribosomal RNA, 19 tRNA and a control region. Three tRNA genes (trnE, trnI and trnS1) are missing. Most of the tRNA genes show secondary structures which derive from the usual cloverleaf pattern except for trnC which is characterised by the loss of the DHU-arm. Compared to the isopod ground pattern and Eurydice pulchra Leach, 1815 (suborder Cymothoida Wägele, 1989), the genome of G. ovalis shows few differences, with changes only around the control region. However, the genome of G. ovalis is very different from that of non-cymothoidan isopods and reveals that the gene order evolution in isopods is less conservative compared to other crustaceans. Phylogenic trees were constructed using maxiumum likelihood and Bayesian inference analyses based on 13 protein-coding genes. The results do not support the placement of G. ovalis with E. pulchra and Bathynomus sp. in the same suborder; rather, G. ovalis appears to have a closer relationship to Ligia oceanica (Linnaeus, 1767), but this result suggests a need for more data and further analysis. Nevertheless, these results cast doubt that Epicaridea Latreille, 1825 can be placed as an infraorder within the suborder Cymothoida, and Epicaridea appears to also deserve subordinal rank. Further development of robust phylogenetic relationships across Isopoda Latreille, 1817 will require more genetic data from a greater diversity of taxa belonging to all isopod suborders.

A new genus for Entophilus mirabiledictu Markham & Dworschak, 2005 (Crustacea: Isopoda: Cryptoniscoidea: Entophilidae) with remarks on morphological support for epicaridean superfamilies based on larval characters.

A detailed reexamination of male and female Entophilus mirabiledictu Markham & Dworschak, 2005 (an endoparasite of callianassid shrimp), resulted in recognition of seven female and five male characters that separate the species from its sole congener, E. omnitectus Richardson, 1903 (an endoparasite of munidid squat lobsters). These characters show that the two species are so different as to warrant E. mirabiledictu being placed in its own genus within the Entophilidae. Additionally, a review of the morphological features of entophilid cryptoniscus larvae led to the finding that the number of flagellar segments on the second antenna offers morphological support for a recent molecular phylogeny of epicaridean taxa that rearranged the component families within the two recognised superfamilies. This work highlights the power of using larval characters in testing hypotheses on the evolutionary relationships of epicaridean taxa.

A new genus and species of parasitic isopod (Isopoda: Bopyridae: Orbioninae) from Chinese waters, with a new locality and host record for Orbione halipori Nierstrasz & Brender à Brandis, 1923.

Parasymmetrorbione bicauda n. g., n. sp. is described from Chinese waters infesting two species of Solenocera Lucas (Decapoda: Penaeoidea). The new genus differs from other orbionine genera by the following combination of features: a pronounced asymmetry of coxal and lateral plate development, biramous uropods, tuberculate lateral plates and a digitate internal ridge on oostegite 1. A key to the eight genera of the Orbioninae R. Codreanu, 1967 is presented. Orbione halipori Nierstrasz & Brender à Brandis, 1923 is also recorded from a new Chinese locality and a new host.

A new species and two new records of Minicopenaeon Bourdon, 1981 (Crustacea: Isopoda: Bopyridae) from China.

Three species of the parasitic isopod genus Minicopenaeon Bourdon, 1981 (Crustacea: Isopoda: Bopyridae) are reported from China, one new to science and two new records from mainland China. Minicopenaeon crosnieri (Bourdon, 1979) formerly known from Madagascar, the Philippines and Taiwan, is recorded from Zhejiang province. Minicopenaeon intermedium Bourdon, 1981 previously recorded from the Philippines and Japan, is recorded from China for the first time. The new species Minicopenaeon liuruiyui n. sp. is recorded from the East and South China Seas. As with other species of the genus, females of the new species have rudimentary coxal plates on the second pereomeres on the short side. The new species can be distinguished from other species by the presence of a widely open brood pouch, head with bilobate anterior edge and median concave groove, and male head with curved posterior margin of the pleon. A key to species of Minicopenaeon is provided and the subspecies M. intermedium curvatum Bourdon, 1981 is synonymised with M. intermedium Bourdon, 1981. Metapenaeopsis philippii (Bate, 1881) and M. coniger (Wood-Mason, 1891) are newly recorded as host species for bopyrids.

Nomenclatural and taxonomic changes in parasitic isopods (Isopoda: Epicaridea), including two new families and note on the questionable association between monogeneans and bopyrids.

Several long-standing taxonomic and nomenclatural problems in bopyroid and cryptoniscoid isopods are addressed. Within Bopyroidea we propose five new synonomies, three new combinations, a correction of the spelling of one species and a replacement name for another. In addition, the likely erroneous conclusion that a monogenean is an associate of bopyrids is discussed. Within Cryptoniscoidea, we determined the familial placement of three genera that were previously designated as incertae sedis (Capitoniscus Bourdon, 1972 and Carocryptus Schultz, 1977) or of doubtful affiliation (Cumoechus Hansen, 1916). In total, five species of cryptoniscoids are placed into two new families (Capitoniscidae n. fam. and Cumoechidae n. fam.), each containing at least one species known from both female and cryptoniscus larvae/paedomorphic male stages. Finally, the status of two cryptoniscoid genera is addressed: Gorgoniscus Grygier, 1981 is placed in Hemioniscidae, and Leponiscus Giard, 1887, is synonymized with Hemioniscus Buccholz, 1866.

A review of the endoparasitic isopods (Epicaridea: Entoniscidae) from hermit crabs, including description of the new subfamily Diogenioninae and a new species of Paguritherium Reinhard, 1945 from the Philippines.

Entoniscid isopods (Entoniscidae) are obligate endoparasites of other crustacean species. They have an indirect lifestyle, usually with two hosts and multiple larval stages; as adults they are found living within decapod hosts. Hermit crabs were previously known to be definitive hosts of only two species of entoniscid parasites: Paguritherium alatum, from the east coast of the United States in Pagurus spp. and Diogenion vermifactus from the Red Sea in Diogenes senex. Little beyond the original descriptions of these species has been reported in the literature. Recently, two species of entoniscids were found parasitizing hermit crabs (mostly Calcinus spp.) collected from shallow water coral reef areas in the Philippines. The goal of this study was to describe the morphology of both the adult and larval stages of these entoniscids through light and scanning electron microscopy and compare them to the previously described species that infest hermit crabs. One of these entoniscids is tentatively identified as D. vermifactus, which infested 0.95% (5 of 527) of the hermit crabs sampled. All specimens of D. cf. vermifactus were found in the abdomens of specimens of Calcinus gaimardii, C. minutus, C. pulcher and Pagurojacquesia polymorpha. Examination of D. vermifactus shows that this taxon belongs in its own subfamily: Diogenioninae n. subfam. The second entoniscid is a new species of the genus Paguritherium and infested 0.94% (7 of 744) of the hermit crabs (C. gaimardii and C. latens) sampled. Females of P. manggagaway n. sp. are characterized by a highly vaulted head, a slender body and long pleopods and males by a blunt head and stump-like pereopods covered in scales; the new species can be distinguished from P. alatum based on the specialized fan-like setae on the first five pereopods of the epicaridium larvae. A key to all entoniscid genera is provided.

A new species of parasitic isopod (Bopyroidea: Ionidae) infesting burrowing shrimp (Axiidea: Callianassidae) in the tropical eastern Pacific.

A new species of parasitic isopod in the genus Ione Latreille, 1818, infesting the branchial chamber of the intertidal burrowing shrimp Neotrypaea tabogensis (Sakai, 2005) is described on the basis of material collected on the Pacific coast of Costa Rica. Diagnostic features of the new species include: (1) body shape of female asymmetrical with slight left distortion, pereon segments distinct; (2) head of female not fused with first pereomere, posterior margin nearly straight; (3) antenna of female composed of five articles; (4) posterior lamella of barbula of female with two tapered lobes on each side; (5) body of male elongated, clearly segmented dorsally; (6) head of male completely separated from the first pereomere; and (7) maxillipeds absent in male. This is the seventh valid species in the genus Ione and the first record of this genus from the tropical eastern Pacific. A key for identification of species of Ione is also provided.

110-million-years-old fossil suggests early parasitism in shrimps.

Direct evidence of paleo-parasitism in crustaceans is very scarce. Epicaridean isopods are obligatory parasites of crustaceans, including decapods such as crabs, shrimps, and lobsters. Their interaction with hosts is known from fossils as far back as the Jurassic through deformations of the branchial cuticle on the hosts. Their small size and low fossilization potential, outside of those larvae that have been found in amber, makes understanding the group's evolution challenging. Here, we report the oldest evidence of paleo-parasitism in marine shrimps and an imprint of a putative adult parasite that appears to be an epicaridean isopod. Our results suggest that the parasite-host interaction between epicaridean isopods and marine shrimps started at least 110 million years ago, and the Tethys Sea was a possible dispersal pathway for this lineage of parasites during the Jurassic and Cretaceous, as known for other marine organisms through most of the Mesozoic and Cenozoic. The oldest fossil records of bopyrid swellings associated with a large number of decapods from the Jurassic in Europe suggest that the Tethys region was a center of epicaridean distribution as a whole. Recent parasitic isopods found on dendrobranchiate shrimps are restricted to the Indo-Pacific and may represent a relict group of a lineage of parasites more widely distributed in the Mesozoic.

Perezia Microsporidia vs. Perezia Viridiplantae: Homonymy under the ICN with comments on jurisdiction of the ICN or ICZN over nomenclature of the Microsporidia and a brief discussion of this microsporidian genus and its species.

Until recently, the taxon PereziaLéger and Duboscq (1909) (Fungi: Microsporidia) (non-La Gasca, 1811, Viridiplantae: Asteraceae) was a preoccupied name because both it and its senior homonym were regulated under the International Code of Nomenclature of Algae, Fungi, and Plants. This meant that the microsporidian genus name required replacement, as did Pereziidae Loubes [sic], Loubes et al. (1977), as that name was based on a homonymous genus name and therefore illegitimate. However, a recent decision by the ICN to return microsporidians to the auspices of the International Code of Zoological Nomenclature removes this homonymy, but causes a potential problem because current language of the ICZN is not written in a way that allows microsporidians to return to its jurisdiction. Language in the ICZN requires modification in order to avoid microsporidians becoming "code orphans." The species of Perezia Léger and Duboscq are reviewed.

A Review of the Parasitic Isopod Genus Epicepon Nierstrasz & Brender à Brandis, 1931 (Crustacea: Isopoda: Epicaridea), Parasites of Cyclodorippoid Crabs (Crustacea: Decapoda: Brachyura), with Description of a New Species from New Caledonia.

A new species of the parasitic isopod genus Epicepon Nierstrasz & Brender à Brandis, 1931 (Isopoda: Bopyridae) found parasitizing the cyclodorippoid crab host Tymolus hirtipes Tan & Huang, 2000 is described from New Caledonia. Females of Epicepon belema n. sp. can be distinguished from those of the other two species in the genus in length to width ratio, pleopodal endopod morphology, and structure of the barbula. We review the two previously described species of Epicepon from Tymolus Stimpson, 1858 hosts based on type specimens of E. indicum Nierstrasz & Brender à Brandis, 1931 from Indonesia and type specimens plus new material of E. japonicum Nierstrasz & Brender à Brandis, 1931 from Japan. New details previously omitted from the original descriptions and a key to species of Epicepon based on female and male specimens are provided.

New Records of Sand Crabs (Crustacea: Decapoda: Albuneidae and Blepharipodidae) from the Western Pacific with Description of Two New Species of Paralbunea Serène, 1977.

Two new species belonging to the sand crab genus Paralbunea Serène, 1977 are described: one each from the Philippines and Taiwan. Both new species can be distinguished from each other, as well as the five other species of Paralbunea, by characters of the carapace, eyes, and pereopods. Additional new western Pacific locality records are given for two species of spiny sand crabs (Blepharipodidae) and six species of sand crabs (Albuneidae). A key to all seven species of Paralbunea is provided.

Cancrion khanhensis sp. nov. (Crustacea: Isopoda: Entoniscidae) infesting Monomia haanii (Stimpson, 1858) (Crustacea: Brachyura: Portunidae) from Nha Trang Bay, Khanh Hoa, Vietnam, with remarks on larval stages of entoniscids and description of a new family, genus and two new species of hyperparasites infesting entoniscids.

An undescribed entoniscid isopod was found to parasitize Monomia haani, a common portunid crab in Khanh Hoa province of Vietnam. The new species is the eighth in the genus Cancrion, the second species of Cancrion found parasitizing hosts in the family Portunidae, and the first member of the family Entoniscidae to be described from southeast Asia. The cryptoniscius larva of a species of Cancrion is described for the first time. The new entoniscid infests hosts with a prevalence of 10.1% and intensity of 1 or 2 females per host. A new family, genus and species of cryptoniscoid hyperparasite with novel female and cryptoniscus body morphology is also described; this is the first record of a hyperparasite found infesting an entoniscid isopod. The purported cryptoniscus larva of Tiarinion texopallium Shields Ward, 1998 is shown to be that of a hyperparasitic cryptoniscoid isopod closely allied to the new Vietnamese hyperparasite and is described as a new species belonging to the new family and genus.

A new distribution record of Albunea groeningi (Crustacea: Anomura: Decapoda: Albuneidae) from the Digha Coast, West Bengal, India.

Members of the genus Albunea Weber, 1795 (family Albuneidae) are commonly known as sand crabs. Albuneidae contains 59 species belonging to 13 genera (Boyko McLaughlin 2010; WoRMS 2019), of which four genera and nine species are known only as fossils. Most species are relatively uncommon and adapted to living in sandy habitats (Boyko Harvey 1999). Among the 24 species of Albunea, four are known only as fossils (WoRMS 2019). The diversity and distributions of most albuneids were reported by Boyko (2002, 2010).

Rhopalione kali sp. nov., first known epicaridean parasite on the Malaysian pinnotherid crab, Serenotheres besutensis (Serène, 1967).

Species of the bopyrid isopod genus Rhopalione Pérez, 1920, are parasites of Indo-West Pacific pinnotherid crabs. Unlike other bopyrid parasites of brachyurans that occupy the branchial chambers, however, species of Rhopalione (subfamily Pseudioninae) infest the abdominal cavity. Prior to the present study, four species of Rhopalione were recognized: R. atrinicolae Page, 1985 (New Zealand), R. incerta (Bonnier, 1900) (Madagascar), R. sinensis Markham, 1990 (East Asia), and R. uromyzon Pérez, 1920 (Persian Gulf). A fifth species of Rhopalione, from Perhentian Besar, Malaysia, is described herein, parasitic on the pinnotherid crab Serenotheres besutensis (Serène, 1967). Keys are provided to females and males of the species in the genus.

New hosts and localities for species of Cancricepon Giard Bonnier, 1887 Isopoda: Epicaridea: Bopyridae) with description of two new species and comments on the relationship between Cancricepon and Trapezicepon Bonnier, 1900.

The genus Cancricepon Giard Bonnier, 1887 is recorded for the first time from Australia, the Maldives, Papua New Guinea and Taiwan. Four species of Cancricepon are reported here, and two are new to science. Cancricepon choprae (Nierstrasz Brender à Brandis, 1925) is reported from the Gulf of Mexico on the Florida coast, infesting a new host, Micropanope cf. sculptipes Stimpson, 1871. Cancricepon castroi n. sp. is described from Australia, the Maldives, Japan and Papua New Guinea parasitizing coral crabs of the family Trapeziidae. Cancricepon cf. multituberosum An, Yu Williams, 2012 is recorded from a specimen of Leptodius affinis (De Haan, 1835) from Taiwan. Specimens previously misidentified as C. choprae parasitizing Scalopidia spinosipes Stimpson, 1858, from China are described as C. beibusinus n. sp. All known hosts and localities of species of Cancricepon are summarized, and a key to the species in the genus is provided. The similarities between species of Cancricepon and the type species of Trapezicepon Bonnier, 1900, are discussed and Trapezicepon thalamitae Markham, 1985, is transferred to Scyracepon Tattersall, 1905.

A new species of Pseudione Kossmann, 1881 (Crustacea, Isopoda, Bopyridae) parasitizing the squat lobster Munida microphthalma A. Milne-Edwards, 1880 in the Southwestern Atlantic.

A new species of Pseudione Kossmann, 1881, is described from 21 parasitized individuals of the squat lobster Munida microphthalma A. Milne-Edwards, 1880, collected in Brazilian waters of the southwestern Atlantic Ocean. The new species belongs to the Pseudione "crénéles" group sensu Bourdon (1976). The number of specimens obtained as well as the life history stage diversity of the type series, consisting of mature females, mature males, subadult males and cryptoniscus larvae, are unusually large for bopyrid isopod type series.

Parasites (Isopoda: Epicaridea and Nematoda) from ghost and mud shrimp (Decapoda: Axiidea and Gebiidea) with descriptions of a new genus and a new species of bopyrid isopod and clarification of Pseudione Kossmann, 1881.

Ghost and mud shrimps in Axiidea and Gebiidea are hosts to parasitic epicaridean isopods, including species in Bopyridae and Ionidae. These isopods can reach high prevalence levels on their mud shrimp hosts and may strongly influence host ecology and biology. Currently, 54 species of bopyrids and eight species of ionids are known to parasitize ghost and mud shrimps. We present new taxonomic data on three species of ionids and ten species of bopyrids (nine previously described and one new to science), as well as on an undescribed species of nematode from an axiidean host. New locality and host records are given for all species. Our analysis of new material and review of museum specimens includes the description of the new species Acrobelione halimedae n. sp. from Austinogebia spinfrons (Haswell, 1881). We also provide an improved definition for the genus Pseudione Kossmann, 1881, based on morphological characters found in both sexes, and resolution of the type species, P. callianassae Kossmann, 1881. In our revision of Pseudione we erect a new genus, Robinione, and placed two species therein: R. overstreeti (Adkison Heard, 1995) and R. brattstroemi (Stuardo, Vega Cespedes, 1986). In addition, two other species are removed from Pseudione: P. compressa (Shiino, 1964) is moved to Ionella Bonnier, 1900, and P. panopei Pearse, 1947 is considered a synonym of Progebiophilus upogebiae (Hay, 1917). Bopyrid isopods represent a large, diverse taxon and our findings help clarify the taxonomy of those species found on ghost and mud shrimps.