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The phylogenetic studies of clam shrimps (Branchiopoda, Crustacea) demonstrated that the significance of several morphological characters for classification of branchiopod shells should be critically re-evaluated. Such a venture is particularly important for integrating the taxonomy of fossil and extant branchiopods. One of the shell characters widely used in the branchiopod classification is the carapace ornamentation pattern. This character might, however, be significantly influenced by intraspecific variability and in particular the sexual dimorphism. In this study we investigate the pattern of ornamentation in extant branchiopods-including differences resulting from sexual dimorphism-in order to assess its value for branchiopod taxonomy. We examined 184 individuals representing 10 living species belonging to 7 genera, 5 families, and 2 suborders from China, and compared with the results of previous studies. Although some differences in ornamentation were related to reproductive modes, the basic ornamentation patterns or combinations were stable within each extant species. We found out that some taxa indeed display sexually dimorphic ornamentations, but their basic ornamentation patterns or combinations are stable within each species so they do not significantly influence the taxonomic identification. Integration of data on fossil and extant taxa indicates that similar ornamentation patterns can be observed on familial level of fossil spinicaudatan branchiopods and indicates therefore that characteristic ornamentation patterns can help to identify these taxa in the fossil record. In light of the new molecular phylogeny, we re-evaluated the phylogenetic relationship between fossil and extant spinicaudatan taxa. The resulting tree suggests: (i) paraphyly of the traditional Eosestherioidea, (ii) an affinity between Ozestheria and Triglypta, and (iii) an affinity between Cyzicus and Diestheria or Aquilonoglypta. [ABSTRACT FROM AUTHOR]

The Permian–Triassic mass extinction was the largest biotic extinction event in the Phanerozoic and affected both marine and continental life. Marine Permian–Triassic transitional sequences can be correlated in many regions, but this has proved difficult for continental successions. A growing number of studies show that spinicaudatans are some of the most common fossils in continental strata and can be used as index fossils for continental stratigraphic division and correlation. Here we document the morphology and biostratigraphic significance of Euestheria gutta based on well‐preserved fossils from southwestern China. It shows strong intraspecific morphological variation, while the most important feature is the strongly convex larval valve and significant finely pitted to weakly reticulated ornamentation on the growth bands. Evidence from palaeobotany, charcoal, and organic carbon isotopes indicated that the continental mass extinction in southwestern China was marked by the catastrophic loss of tropical rainforest vegetation, enhanced wildfire and a negative carbon isotope excursion (CIE) during the P–Tr transition. Meanwhile, abundant E. gutta first appeared at the onset of the negative CIE and just above the horizon of the loss of macroflora. Based on the global geographic distribution of E. gutta and temporal correlation, we conclude that this species existed from the latest Permian to the earliest Triassic, and the occurrence of E. gutta could be used as an index fossil of the continental mass extinction interval or P–Tr transitional beds. [ABSTRACT FROM AUTHOR]

Malformations of crustaceans have been observed in their natural habitats as well as in laboratory studies. Two patterns of morphological abnormalities have been recorded in species of the brine shrimp genus Artemia , including a gynandromorphic pattern and a specimen with three compound eyes. Here we report a hitherto unknown pattern of morphological deformation, viz., a tumour-like abnormality that occurred in the telson skeleton of a specimen of Artemia from China. [ABSTRACT FROM AUTHOR]

Diaphanosoma excisum is the only Cladoceran in tropical freshwaters and parapatrically occurs with Diaphanosoma dubium in the transition between the tropics and subtropics. Here, we present the complete mitochondrial genome (MG) determined by next-generation sequencing and offer a phylogenetic analysis of D. excisum. The MG of D. excisum is 17,615bp in size, including 13 protein-coding genes (PCGs), 2 ribosomal RNA, 23 tRNA, and 2 putative control regions. The MG has a biased AþT of 65.34% for base composition. Compared to D. dubium, the MG of D. excisum has one more tRNA-Met, one unknown extra putative control region and is different in the arrangement of its tRNAs. The MG sequence and tRNA order provide valuable molecular data for understanding the phylogeny and speciation of Diaphanosoma. [ABSTRACT FROM AUTHOR]

The Early Cretaceous Jehol biota of northeastern China contains a diverse group of notostracans, including two genera, Chenops and Jeholops, described here. Chenops is characterized by a combination of an ovate carapace, narrow anal plate, equant distal endites and endopod on the anterior thoracic limbs. In addition to the new species, Chenops yixianensis, the genus also provisionally includes Prolepidurus oblongus Oleynikov, 1968. Jeholops, however, is monotypic, represented by the new species Jeholops hongi. It is characterized by a combination of kazacharthran and notostracan features unique to this taxon. Both new genera are provisionally placed in the taxon Notostraca. More detailed work exploring the morphology of exceptionally-preserved branchiopod crustaceans is needed. The difficulties in placing fossil notostracans into a phylogenetic framework are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The spinicaudatan (conchostracan) Dictyestheria, originally recovered from the Yaojia Formation, is recognized to occur also in the basal part of the overlying Nenjiang Formation. This means that the Dictyestheria elongata (= D. ovata) Zone extends from the Yaojia Formation into the upper Turonian basal part of the First Member of the Nenjiang Formation and underlies the Halysestheria yui Zone at Yaojia Railway Station, Dehui City, Jilin Province, northeast China. The fossil record shows that the basal part of the Halysestheria yui Zone is dominated by Plectestheria songhuaensis in the study area. The diagnoses of Dictyestheria and Plectestheria are revised on the basis of an examination of specimens under a scanning electron microscope. In both genera the radial lirae on the growth bands near the umbo are long and relatively widely spaced. There is a fine reticulum between them in the umbonal part of the carapace and cross-bars occur on the ventral surface. The ornament of both genera indicates that they can be assigned to the family Halysestheriidae rather than to the Jilinestheriidae, in which they have been placed previously. The discovery of serration along the lower margins of growth lines in Plectestheria indicates its close relationship with Orthestheria (Migransia), supporting an interpretation of parallel evolution of O. (Migransia) to Plectestheria in East Asia and Bauruestheria in South America. [Copyright &y& Elsevier]

A detailed morphological study was performed on adult males and females of seven sexual populations of the brine shrimp, Artemia from China. Five populations were collected from the Qinghai-Tibet Plateau, three of which were recorded and investigated for the first time. The measurements of 12 biometrical parameters for males and 13 parameters for females were taken from individuals of each population, raised under standardized culture conditions from nauplii to the adult stage. They were analysed through discriminant analysis and hierarchical cluster analysis, in order to establish relationships among the different populations, as well as to have a tool to assign new sets of data for unknown populations to one of the groups analysed here. The overall percentage of correctly classified cases of females was 87 .32%, a little higher than that of males, which was 84.79%. Our study showed that the Artemia from the Qinghai-Tibet Plateau belong to the "large" types. The results revealed also that the seven populations can clearly be separated into two groups, i.e., high altitude populations and low altitude populations, the former populations belonging to the subspecies Artemia sinica tibetiana Sebastopol, Zhang & Sorgeloos, 1998, the latter belonging to the subspecies Artemia sinica sinica Cai, 1988. [ABSTRACT FROM AUTHOR]