One new species and new records of four other species of the parasitic isopod genus Aporobopyrus Nobili, 1906 are reported, all with host records. Aporobopyrus asymmetricus sp. nov. is described infesting Petrolisthes teres Melin, 1939 in Australia, and it can be distinguished from congeners by the asymmetry lateral plates of pleomere 1 and having a pleotelson with distinct lateral plates. Aporobopyrus parvulus (Bourdon, 1983) is recorded from Kiribati, Line Islands, infesting Petrolisthes perdecorus Haig, 1981. Aporobopyrus aff. parvus Shiino, 1939 is recorded from the French Antilles, infesting Petrolisthes caribensis Werding, 1983; it is morphologically close to A. parvus from Japan. Aporobopyrus ryukyuensis Shiino, 1939 is reported from the Philippines infesting Petrolisthes tenkatei de Man, 1893. A new record of A. curtatus (Richardson, 1904) from Florida is also reported from Petrolisthes armatus (Gibbes, 1850). We review hosts and distributions of all Aporobopyrus, and provide a key to its species.

Endemic to temperate northern China, Mongoloniscus sinensis is a soil-dwelling isopod that provides a powerful system for investigating how Pleistocene climatic fluctuations and mountainous barriers have shaped genetic divergence and regional endemism. Through fine-scale phylogeographic and demographic analyses, we explored the evolutionary processes shaping genetic differentiation and biodiversity in this region. We obtained three mitochondrial genes (COI, ND5, and 12S rRNA) in 305 specimens collected from 48 localities spanning the species' distribution. Population structure analyses identified 3 clusters corresponding to geographic locations-East, West, and Midland. The Midland group exhibited the highest genetic diversity, possibly representing ancestral populations, followed by the West group and the lowest in the East group. Limited gene flow was observed between eastern and western populations, likely because of the geographical barrier formed by the Taihang and Luliang Mountains, which restrict genetic exchange. Demographic history analyses showed recent expansion in both East and West groups. Divergence time estimation dated the following splits from the Midland group: West (~0.63 Ma) and East (~0.53 Ma), coinciding with Pleistocene climatic oscillations. Ecological niche modeling revealed that M. sinensis currently occupies a wide climate range with highly suitable areas in northern China, and its distribution during the LGM was affected by the ice age. For the climate variables, the mean temperature of the coldest quarter was the most important variable to determine species distribution, followed by precipitation of the coldest quarter and elevation, indicating that cold adaptability may constrain the species to northern China. As an important geographical barrier, the Qinling Mountains have a diverse climate and habitats, which play a role in limiting the distribution of species.

Accurate identification of species and distributions is essential for developing effective conservation and recovery strategies for threatened taxa. Owing to the extreme shell variation and evolutionary convergence, defining and classifying species based solely on morphology can be a challenging and ambiguous process. The freshwater mussel genus Schistodesmus (Bivalvia, Unionidae), which is endemic to China, has traditionally been considered to comprise only two species: Schistodesmus lampreyanus and Schistodesmus spinosus . In this study, an extensive collection of samples from China was conducted and an integrative taxonomic approach, including shell morphology, soft-body anatomy, molecular systematics and biogeography, was employed to investigate the genus Schistodesmus . The results reveal three cryptic species: Schistodesmus luqiaoensis sp. nov. , Schistodesmus tongpenensis sp. nov. and Schistodesmus xinyuensis sp. nov. , and well-supported phylogenetic relationships are reconstructed based on mitochondrial genomic data. This discovery increases the number of species in the genus to five, thereby substantially improving our understanding of its diversity and systematic relationships. The molecular clock analysis and biogeographical reconstruction based on fossil-calibrated dating indicate that the ancestor of the genus originated in the paleo-Yangtze River Basin during the Eocene (c . 50.74Ma), with species diversification beginning c .18.68Ma in the Early Neogene. The uplift of the Qinghai-Tibet Plateau, along with associated paleoclimate changes and local river capture events, significantly facilitated the diversification process of this group. This study not only reconstructs the species diversity framework of Schistodesmus but also highlights the significance of integrated molecular technologies in addressing morphological convergences and promoting effective species conservation. ZooBank: urn:lsid:zoobank.org:pub:C997B546-CB1D-4050-AC64-2F132739C22C.

A new species, Ceratophysella gracilimucronata sp. nov. from Nan Ling Mountains (Guangdong Province, China), is described. It resembles C. ainu (Yosii, 1972), C. glancei Hammer, 1953 and C. falcifer Cassagnau, 1959 due to the B type chaeotataxy and short and slender mucro. Mitochondrial COI gene sequence of C. gracilimucronata sp. nov. is provided. A key to species of the C. armata group of the Sino-Japanese Region is given.

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.

Background Classification of parasitic bopyrids has traditionally been based on morphological characteristics, but phylogenetic relationships have remained elusive due to limited information provided by morphological data and tendency for loss of morphological features as a result of parasitic lifestyle. Subfamily Argeiinae was separated from Bopyrinae based on morphological evidence, although the assignment of all genera has not been phylogenetically evaluated. Bopyroides hippolytes has been traditionally classified in Bopyrinae, but divergent morphological characters make this assignment questionable. To investigate the relationship of bopyrines, we sequenced the complete mitochondrial genome of B. hippolytes and four mitochondrial genes of two other Bopyrinae. Results The phylogenetic trees based on separate and combined cox1and 18S sequence data recovered Bopyridae as robustly monophyletic, but Bopyrinae as polyphyletic. Bopyroides hippolytes was a close sister to Argeia pugettensis, type species to Argeiinae. Mitochondrial phylogenomics also suggested that B. hippolytes was close to Argeiinae. We also found a novel gene order in B. hippolytes compared to other isopods. Conclusions Bopyroides hippolytes should be excluded from the Bopyrinae and has a close affinity with Argeia pugettensis based on molecular and morphological data. The conserved syntenic blocks of mitochondrial gene order have distinctive characteristics at a subordinal level and may be helpful for understanding the higher taxonomic level relationships of Isopoda.

中国是东亚蚌类（蚌目:蚌超科）物种分布中心,共记录有26属.然而,在世界蚌目框架下,中国仍缺乏一个完整科学的蚌类分类系统.本研究基于多位点分子标记（COI、16S、28S）和线粒体基因组学重构聚焦于蚌超科的蚌目系统发育关系,ML、BI和BEAST系统发育结果均支持蚌科5亚科分类系统,即（（（Ambleminae+Gonideinae）+Rectidentinae）+Unioninae）+Parreysiinae;珍珠蚌科2亚科分类系统,即（Gibbosulinae+Margaritiferinae）;中国蚌类隶属蚌科4亚科（Gonideinae, Rectidentinae, Unioninae, Parreysiinae） 13族和珍珠蚌科两亚科（Gibbosulinae, Margaritiferinae）.基于化石标定的分子钟显示:蚌科物种分化时间为中三叠世（median=232.07 Ma）,其中雕刻蚌亚科（Parreysiinae）起源和物种分化时间早于其他亚科;矩形蚌亚科（Rectidentinae）物种分化时间最晚,为晚白垩世（median=94.72 Ma）;小方蚌亚科（Ambleminae）和隆脊蚌亚科（Gonideinae）最近共同祖先分化于晚侏罗纪世（median=144.69 Ma）,珍珠蚌科起源于晚石炭世（median=312.61 Ma）,物种分化于晚白垩世（median=91.59 Ma）,中国蚌科现生物种最早起源时间可追溯到白垩纪（中国尖嵴蚌（Acuticosta chinensis）, median=114.36 Ma）.蚌超科线粒体基因重排分析显示:蚌超科线粒体基因组有4种基因排列方式（GO）,珍珠蚌科独享一种（GO1）;蚌科中Unioninae和Ambleminae共享一种（GO2）;Gonideinae有2种基因排列方式（GO3和GO4）,其中室蚌（Chamberlainia hainesiana）独享一种（GO4）,其余物种共享一种（GO3）.以往作为高阶元分类的贝壳形态、钩介幼虫形态以及育儿囊类型,并不能作为蚌科属及以上阶元分类依据.本研究重构了世界蚌目聚焦于蚌超科的系统发育关系和进化历史,建立了中国蚌类分类系统,为今后该类群区系多样性研究及资源保护提供了分类依据.

Among Isopoda suborders the Oniscidea has the highest species richness, and is also the largest terrestrial group in the Crustacea. Terrestrial isopods are an excellent case to study adaptations related to sea-land transition. However, the monophyly of Oniscidea and the relationships of the main lineages has been debated over the last three decades. Aiming to further explore structural features of mitochondrial genome and investigate the phylogenetic relationships within Oniscidea, the mitogenomes and a series of nuclear markers of the oniscids Ligia exotica and Mongoloniscus sinensis were sequenced. The nuclear genome was represented by four nuclear genes analyzed in a separate dataset. The mitogenomes of L. exotica and M. sinensis were 16,018 and 14,978 bp in length, respectively. Both included 13 protein-coding genes, 2 rRNA genes, and 21 and 19 tRNA genes respectively, missing one and three tRNA genes respectively compared to the isopod ground pattern. The M. sinensis mitogenome had higher average A+T content (~75.3%) than any other isopod studied to date. Phylogenetic analyses confirmed the assignment of M. sinesis to Agnaridae, as well as the sister-group relationship of the family with Porcellionidae, one of the more derived Crinochaeta clades. On the other hand, the basal position of Ligia within Oniscidea and the close evolutionary relationship with the aquatic groups Valvifera, Shaperomatida and some Cymothoidea that were included in our analysis, is indicated.

A new species of suborder Oniscidea from northeast China, Mongoloniscus chevronus sp. nov., is described and illustrated. The new species is most related to M. sinensis, only can be distinguished from the latter and other congeners by all pereonites with concave-convex-concave posterior margins, pleon without any decorations. But it can be found new to science by Cox1 gene. A key to all species of genus Mongoloniscus is presented herein.

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.

Three new species of the bopyrid genus Scyracepon Tattersall, 1905 are described from crabs collected on Pacific Islands: Scyracepon polynesiensis n. sp. from the Society Islands, S. pseudoliomerae n. sp. from the Mariana Islands, and S. biglobosus n. sp. from the Line Islands. The first two were found infesting Xanthias lamarckii and Pseudoliomera sp. (Xanthidae), a new host family for species of Scyracepon, and the last was found parasitizing Schizophrys aspera (Majidae). Scyracepon now includes 11 species, all but one known from single collections, infesting 12 host species in 9 brachyuran families. The discovery of three new species, each rare, suggests that crab parasites are undersampled, and further suggests that the low relative diversity of bopyrids known from brachyurans may partly reflect this undersampling. Keys to all species of Scyracepon and to all 31 genera of Keponinae are provided.

Three new species of the parasitic isopod subfamily Hemiarthrinae Markham, 1972 are described. Allodiplophryxus unilateralis n. sp. is described from Western Australia, infesting the palaemonid shrimp Jocaste lucina (Nobili, 1901), and females differ from the only other species in the genus in possessing six pleomeres, an asymmetrical first oostegite and pleopods restricted to the short side of the body. Loki athanus n. sp. is described from Madagascar, infesting the alpheid shrimp Athanas parvus de Man, 1910, and females differ from the only other species in the genus in possessing well-developed lateral plates on pleomere 4 and four pairs of uniramous pleopods. Hemiarthrus alphei n. sp. is described from French Polynesia, infesting the alpheid shrimp Alpheus crinitus Dana, 1852, and females differ from the four other known Hemiarthrus species in having pleomeres with well-developed, symmetrical lateral plates, a barbula with three pairs of projections and a pointed pleotelson. Keys to species of Hemiarthrus and all genera of the Hemiarthrinae are presented.

Abstract Background: Oniscidea is the only truly terrestrial taxon within the Crustacea, and vital to soil formation. However, the monophyly of suborder Oniscidea has been in dispute since 1995, with different studies disagreeing on whether the coastal Ligiidae are included within the suborder. To clarify the phylogenetic hypothesis of suborder Oniscidea, we sequenced the complete mitochondrial genomes of Ligia exotica (Roux, 1828) and Mongoloniscus sinensis (Dollfus, 1901).Results: Like most metazoan, the complete mitogenomes of two species with circular double strands. The structure and characters of mitogenomes of these two species are analyzed. The constructed phylogenetic analyses show that Oniscidea is polyphyletic group, with Ligia being more closely related to marine isopods (Valvifera + Cymothoida + Sphaeromatidea).Conclusions: We elevate the taxonomic status of the family Ligiidae to the suborder Ligiaidea which are with parallel rank with Oniscidea. Ligiaidea is much primitive than other exact terrestrial isopods. Crinocheta are strongly monophyly, family Agnaridae is more closely related to Porcellionidae rather than Armadillididae.

海胆的叉棘是海胆御敌、清除体表异物的重要器官，其形状在海胆的分类上具有重要意义。本文通过扫描电子显微镜对西太平洋海山区柔海胆科软海胆属Araeosoma、兜海胆属Sperosoma和革海胆属Hygrosoma的叉棘形态与结构特征进行研究，并提供了柔海胆科属的检索表。结果表明：柔海胆有三种常见的叉棘形式，三叉叉棘、三叶叉棘和指状叉棘。三叉叉棘和三叶叉棘在3个属中均存在，指状叉棘只在软海胆属中存在，三叶叉棘和指状叉棘的超微结构变化比较细微，三叉叉棘的超微结构特征具有明显的种属间差异。建议将叉棘的种类和结构作为柔海胆科的分类依据。

Background: Oniscidea is the only truly terrestrial taxon within the Crustacea, and vital to soil formation. However, the monophyly of suborder Oniscidea has been in dispute since 1995, with different studies disagreeing on whether the coastal Ligiidae are included within the suborder. To clarify the phylogenetic hypothesis of suborder Oniscidea, we sequenced the complete mitochondrial genomes of Ligia exotica (Roux, 1828) and Mongoloniscus sinensis (Dollfus, 1901).Results: Like most metazoan, the complete mitogenomes of two species with circular double strands. The structure and characters of mitogenomes of these two species are analyzed. The constructed phylogenetic analyses show that Oniscidea is polyphyletic group, with Ligia being more closely related to marine isopods (Valvifera + Cymothoida + Sphaeromatidea).Conclusions: We elevate the taxonomic status of the family Ligiidae to the suborder Ligiaidea which are with parallel rank with Oniscidea. Ligiaidea is much primitive than other exact terrestrial isopods. Crinocheta are strongly monophyly, family Agnaridae is more closely related to Porcellionidae rather than Armadillididae.

作者对蟹鳃虱亚科（Keponinae）的研究进展进行概述，且阐述“海蛄虾转变”过程中该亚科的演化过程，从形态特征推测该亚科是相对较早演化出来的。基于蟹鳃虱亚科的形态特征，作者比较各属之间的特征差异并制作检索表，总结蟹鳃虱亚科31属98种的模式产地分布，发现物种主要集中分布在印度尼西亚等一些暖水区域，同1986年Markham推测鳃虱科的分布中心为印度-西太平洋热带，亚热带等观点一致。另外，对中国各海域内发现蟹鳃虱亚科14属的基本形态特征描述，并总结属内物种的地理分布。

Two new records of the rare parasitic isopod genus Parioninella are described. Parioninella liuruiyui n. sp. represents the first record of the genus from Australia and the first bopyrid described from the porcelain crab Pachycheles pisoides (Heller, 1865). The female of the new species differs from other described species in lacking eyes, produced into pair of anterolateral flaps, the brood pouch completely covered by oostegites, while the male lacks pigmentation. Parioninella astridae Nierstrasz & Brender à Brandis, 1930 is recorded from Mindoro, Philippines, in Pachycheles sculptus (H. Milne Edwards, 1837). An identification key to the three Parioninella species is provided.

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.

中华蒙潮虫Mongoloniscus sinensis（Dollfus,1901）隶属于甲壳动物亚门Crustacea等足目Isopoda潮虫亚目Oniscidea,中国特有种。为了探究中华蒙潮虫的种群遗传分化和系统进化关系,采用PCR对采自华北地区10个地理种群89只个体线粒体2个基因COⅠ和ND5进行联合分析。结果表明:1)中华蒙潮虫COⅠ部分基因长604 bp,ND5部分基因长615 bp,拼接序列长1 219 bp,T、C、A和G含量分别为41.0%、11.2%、30.8%和17.0%,具有显著的A+T偏倚;变异位点503个（占总核苷酸序列的41.3%）,序列间的转换/颠换比值为2.8。2)89只个体共45种单倍型,单倍型多样性0.964,核苷酸多样性0.005 6,整体遗传多样性水平中等;单倍型H1、H15、H16、H21、H41为2～3个种群共享单倍型。3)联合基因（COⅠ+ND5）系统发育树表明,最早出现的是华北以北地区（山西大同、河北石家庄）,最晚分化出的是华北以南地区（山西临汾、陕西西安未央区、河南新乡）,演化路线为从北向南,个别种群单倍型未按地理来源形成明显的簇群。4)平均遗传分化指数为0.513,基因流为0.24;分子变异分析结果表明,种群的变异与分化主要来自种群内部,错配分布呈多峰,结合中性检验（Tajima’s D=-1.429;Fu’s F s =6.499）,发现中华蒙潮虫近期未经历扩张,但种群内部分化显著,增长平稳。本研究首次基于线粒体多基因联合分析了中华蒙潮虫种群遗传多样性。

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.