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.

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.

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.

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。

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.