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In this study, the complete mitochondrial (mt) genome sequence of the South China deep‐sea giant isopod Bathynomus sp. was determined, and this study is the first to explore in detail the mt genome of a deep‐sea member of the order Isopoda. This species belongs to the genus Bathynomus, the members of which are saprophagous residents of the deep‐sea benthic environment; based on their large size, Bathynomus is included in the “supergiant group” of isopods. The mt genome of Bathynomus sp. is 14,965 bp in length and consists of 13 protein‐coding genes, two ribosomal RNA genes, only 18 transfer RNA genes, and a noncoding control region 362 bp in length, which is the smallest control region discovered in Isopoda to date. Although the overall genome organization is typical for metazoans, the mt genome of Bathynomus sp. shows a number of derived characters, such as an inversion of 10 genes when compared to the pancrustacean ground pattern. Rearrangements in some genes (e.g., cob, trnT, nad5, and trnF) are shared by nearly all isopod mt genomes analyzed thus far, and when compared to the putative isopod ground pattern, five rearrangements were found in Bathynomus sp. Two tRNAs exhibit modified secondary structures: The TΨC arm is absent from trnQ, and trnC lacks the DHU. Within the class Malacostraca, trnC arm loss is only found in other isopods. Phylogenetic analysis revealed that Bathynomus sp. (Cymothoida) and Sphaeroma serratum (Sphaeromatidea) form a single clade, although it is unclear whether Cymothoida is monophyletic or paraphyletic. Moreover, the evolutionary rate of Bathynomus sp. (dN/dS [nonsynonymous mutational rate/synonymous mutational rate] = 0.0705) is the slowest measured to date among Cymothoida, which may be associated with its relatively constant deep‐sea environment. Overall, our results may provide useful information for understanding the evolution of deep‐sea Isopoda species.

Cerceis biforamina Javed & Yousuf, 1996 is redescribed and illustrated based on material from the Iranian coasts of the Gulf of Oman. This species is distinguished by the smooth pereonites 1–6, pereonite 7 with a row of tubercles and short setae; pleon dorsal surface with multiple prominent tubercles medially; pleotelson with two prominent semilunar tuberculate ridges and clearly trilobed posterior margin. Cerceis insolita Yousuf, 2011 is transferred to genus Cymodoce and synonymised with Cymodoce manorii (Nooruddin, 1965). An extended diagnosis is provided for the genus Cerceis.

Se presenta una lista de los isópodos bentónicos asociados al Área Natural Protegida Arrecife Tuxpan-Lobos, México. Se realizaron muestreos en 11 sitios, entre 5 y 25 m de profundidad, en los meses de junio y julio de 2011. Fueron identificados 1,159 organismos pertenecientes a los subórdenes Asellota Latreille, 1802; Cymothoida Wägele, 1989; Limnoriidea Poore, 2002 y Sphaeromatidea Wägele, 1989; 5 superfamilias, 13 familias, 20 géneros y 31 especies. En este estudio se documentan 10 registros nuevos de isópodos para el Golfo de México: Carpias bermudensis, Joeropsis personatus, Hansenium spathulicarpus, Anthomuda affinis, Mesanthura bivittata, Pendanthura hendleri, Natatolana gracilis, Excorallana oculata, Excorallana quadricornis y Limnoria insulte, así como 16 ampliaciones del ámbito geográfico para esta fauna de crustáceos.

The marine isopod family Serolidae is reviewed for the oceanic regions of the tropical and subtropical southwestern Pacific, namely from off Lord Howe Island, Norfolk Island, northern Coral Sea, New Caledonia and Fiji. Two new genera are established: Sedorolis gen. n., monotypic, from New Caledonia and Myopiarolis gen. n., a widespread Southern Hemisphere genus with 11 (eight described) species. The following new species are described: Heteroserolis pellucida (New Caledonia), Sedorolis simplex (New Caledonia), Myopiarolis koro (Fiji), M. systir (New Caledonia), M. norfanz (Lord Howe Plateau and off Norfolk Island), M. lippa (northern Coral Sea), and Thysanoserolis orbicula (New Caledonia). Keys are provided to the serolid genera and the species of Myopiarolis from the southwestern Pacific. The genus Caecoserolis Wägele, 1994 is redefined and restricted to the type species.

Biremia kensleyi, the second species of its genus and fourth in the Bathynataliidae, is described from the tropical east coast of Australia. Biremia ambocerca Bruce, 1985, also from tropical eastern Australia, is diagnosed and compared with the new species. The family and genus are rediagnosed. Homologies of structures in the mandibles of bathynataliids and serolids are discussed.

The nuclear ssu rRNA gene of several isopods (Crustacea, Peracarida) was sequenced to study its phylogenetic information content. Several areas had to be cut out of the alignment of 31 isopod sequences and selected outgroup arthropod sequences due to the lack of alignable patterns. The final alignment had 2,533 positions and 43 sequences. The length of the isopod nuclear ssu rRNA genes varies between 2,098 and 3,402 bp. In some clades the gene length increases; in others like the cymothoids and bopyrids, long deletions occur. Some insertions are specific for major groups (e.g., amphipods, isopods). Most elongation areas evolve rapidly and are not alignable among higher taxa. Information content is visualized with spectra of supporting positions. Only a few groups are unambiguously supported with a signal distinctly higher than background noise. The results of maximum parsimony analyses are congruent with major aspects of earlier hypotheses on isopod phylogeny. Some contradictions are discussed. The latter are mainly based on a lack of reliable information. A major monophyletic group found in the molecular phylogenies and also supported by distinct morphological characters is named Scutocoxifera tax. nov., composed of the Oniscidea, Valvifera, Sphaeromatidea, Anthuridea, and Cymothoida. SEM photographs are presented to document the apomorphic state of the coxa in the Scutocoxifera.

Isopods are one of the key marine groups that radiated extensively in the southern high-latitude regions, and it is widely assumed that they did so essentially through the Cenozoic era. Nevertheless, palaeontological evidence is now beginning to accumulate which suggests that some at least of the key isopod taxa may be of considerably greater antiquity. In particular, Schweglerella strobli Polz from the Early Tithonian Plattenkalk of Solnhofen, southern Germany indicates that the suborder Sphaeromatidea is of at least Late Jurassic ancestry, and possibly much older. Schweglerella strobli is phylogenetically close to both the Bathynataliidae and Serolidae, but is here placed in a new family, Schweglerellidae. Like the decapods, the early phylogenetic history of the isopods may be characterized by a considerable macroevolutionary lag. Perhaps a number of major marine invertebrate groups underwent a Mesozoic phase of widespread dispersal when the Pangaean margins were still largely intact and climates globally more equable? The subsequent radiation of groups such as the sphaeromatidean isopods may have been largely contingent upon the Cenozoic thermal isolation of the Southern Ocean.

Ancinus jarocho n. sp. described from mesolittoral zone of sandy beaches in Veracruz State, Mexico, is the eighth species of the genus and the second record for the Gulf of Mexico coast. The new species is characterized by an antennular flagellum of 11–16 articles, single aesthetasc in 9 distal flagellar articles, uropodal endopod styliform, lightly arched and shortest than pleotelson, male pleopod 5 exopod with the distomesial margin serrated, with minutes spines. Ancinus jarocho n. sp. is morphologically similar to A. granulatus, which has a truncate pleotelson apex, densely granulated body surface and eyes on elevated swellings.

Cymodoce brucei sp. nov. is described from the intertidal zone of the Iranian coast of the Oman Sea. This species can be distinguished from all other Cymodoce in the Western Indian Ocean region, by a pleotelson with a large prominent tongue-like projection in midline of the posterior margin. The status of Cerceis manorii Nooruddin, 1965, and Cymodoce spinula Yousuf & Javed, 2001 both from Pakistan (Karachi) is determined and Cymodoce manorii (Nooruddin, 1965) comb. nov. is established.

Exosphaeroides quirosi is described from a karstic stream and its associated cave sink located 390 m above sea level and 23.5 km inland from the east coast of Espiritu Santo (Vanuatu, SW Pacific ocean). This is the first purely freshwater sphaeromatid isopod reported from an oceanic island, and is a new example of colonization of an oceanic island freshwater habitat by a typically marine taxon. E. quirosi differs from any other representative of the family in the peculiar condition displayed by the exopod of pleopod 4, which has a falcate outline, is distinctly longer than the corresponding endopod, and has the medial margin of the proximal segment produced into a foliaceous endite. Seemingly, the sexual dimorphism expressed in the presence/absence of a setulose fringe on the pereopods has not been recorded in any other sphaeromatid. Even though the peculiar pleopod 4 and the fusion pattern of pleonites-with complete incorporation of pleonite 1 to rest of pleonites - could suggest a new genus to accommodate the new species, it is included here in the broad Exosphaeroma s. I. cluster, from which most freshwater sphaeromatids seem to derive. This is done with the caveat that it is incertae sedis in Exosphaeroides until such time as a comprehensive revision of Exosphaeroma and related genera has been undertaken. E. quirosi appears to be a Exosphaeroma-derived species with an unusual pleopod 4 and fusion of pleonite 1 to the remainder of the pleon; these features being here regarded as species-level apomorphies within a morphologically diverse genus. Copyright ©2007 Magnolia Press.

Heterodina Schotte & Kensley, 2005 is revised with Heterodina qeshmensis sp. nov., described from the subtidal zone of the Qeshm Island, southern Iran. Heterodina qeshmensis sp. nov. is characterized by: unornamented dorsal surfaces, wide and anteriorly concave epistome, and the appendix masculina with sub-parallel margins and not extending beyond the distal margin of the endopod. A key to the species is provided. The penial processes of Heterodina mccaini Schotte & Kensley, 2005 is also re-illustrated.

Two new species of Bathycopea Tattersall, 1905 are described from Japan. Bathycopea oculata sp. nov. differs from its congeners in having laterally rounded pleonite 1, well-developed eye lobes with 43–57 ommatidia, uropod about 4–4.7 times as long as wide, blunt and broadly rounded distal corner of carpus of pereopod 1, and the propodus of male pereopod 2 about 2.9 times as long as carpus. Bathycopea dicarina sp. nov. is distinctive in having pleotelson with two dorsal carinae and the merus and carpus of male pereopod 2 slightly longer than ischium. Bathycopea parallela Birstein, 1963 is redescribed using newly collected specimens from the region of the type locality. A key to species of the genus is provided.

Exosphaeroma waitemata sp. nov. is described from the Waitamata Estuary, Auckland, northern North Island; it is characterised by the setose pereopods and body margins, setose uropod rami with distally acute exopods, and males with coxae 6 posteriorly extended and acute; the species is regarded as incertae sedis. A new genus and new species of Sphaeromatidae, Makarasphaera amnicosa gen. nov., sp. nov. is described from maritime freshwater streams and seeps from the Wellington and Wairarapa region of the southern North Island of New Zealand. The genus characterised by the thickened ventrolateral margins of pereonite 1, head deeply immersed in pereonite 1, elongate penial processes, short and mesially produced pleopod 1 peduncle, flask-shaped appendix masculina, pleopods 4 and 5 without thickened ridges, pleopod 5 with reduced scale patches, and the pleon with only one short suture running to the poster margin.

Paradella tiffany sp. nov., from the high intertidal of Baja California, Mexico, is described and figured. It is the first record of a species of Paradella with a posteriorly-directed median process on pereonite 7, this character distinguishing males of the species from all other species in the genus and all other sphaeromatids known from the East Pacific. A further unique character, in the male only, is the presence of short, stout and rigid plumose marginal setae on the distal margin of the pleopod 1 endopod.

The history of the systematics of isopod suborders is summarised. Several authors have suggested that the traditional suborder Flabellifera is paraphyletic and includes one or more of the suborders Gnathiidea, Epicaridea and Anthuridea. Two suborders, Cymothoida and Sphaeromatidea, have been proposed as replacement taxa for the Flabellifera, but it has not been possible on the basis of phylogenetic analyses to elucidate significant relationships between the suborders and families. Morphological characters are used to explore relationships between 35 genus-, family- and suborder-level taxa of flabelliferan Isopoda in a cladistic analysis (using Phreatoicidea and Asellota as outgroups) and to derive a new classification. The analysis did not find a synapomorphy for 'Flabellifera' sensu lato, but recognises two diverging clades of 'long-tailed' isopods. Members of the Oniscidea are not part of either clade. Nor are the Tainisopidea, a new suborder erected for members of the family Tainisopidae. The Tainisopidea has many synapomorphies and plesiomorphic features, but does not share characters with either clade. The first clade comprises Phoratopidea (for Phoratopus remex) and sister-taxa Cymothoida and Limnoriidea. Representatives of these suborders have uropodal rami ventral to the pleotelson and articulating from side-to-side inside the branchial space. The new suborder, Phoratopidea, is for one species with unique, broad articles of pereopods 3 and 4 with reduced dactyls. It lacks the synapomorphies of the following two suborders. In members of the suborder Cymothoida, the mandibular molar is either a flat triangular blade, reduced to a conical process, or absent, and the maxillipedal endite is rarely longer than palp article 1 (or is absent), distally tapering and has few setae. The suborder Limnoriidea is diagnosed as lacking the mandibular molar, and the non-tapering, slender (except in Keuphylia) maxillipedal endite reaches to at least the distal margin of palp article 4. Members of the second clade share a vaulted pleotelson enclosing a branchial chamber defined by ventrolateral ridges and uropods lateral to the pleotelson margin that fold down alongside the branchial space. It comprises two suborders. Members of the Sphaeromatidea have pleonite 1 much narrower than pleonite 2 and a reduced (or absent) right lacinia mobilis fused to the spine row. They lack operculiform uropods, which characterise Valvifera. The suborder Anthuridea is reduced to superfamily rank and Epicaridea is reduced to two superfamilies within Cymothoida. Unambiguous relationships between most families are resolved, but Sphaeromatidae is suspected to be paraphyletic, Paravireia is placed as the most plesiomorphic of the Sphaeromatoidea and a new family, Basserolidae, is proposed. The Tainisopidea includes freshwater taxa in a relictual environment. The sole species of Phoratopidea is marine, rare, and its ecology is unknown. The Cymothoida are most diverse in tropical regions. Members of the most plesiomorphic family, the Cirolanidae, are mobile predators or scavengers and the more derived families are ectoparasites on fishes and other crustaceans. Members of the Limnoriidea are mainly tropical and at least one family is herbivorous. The Valvifera and Sphaeromatidea are benthic, with respiratory pleopods in a branchial chamber. They are most diverse in the temperate southern hemisphere, and most are detritivores.