Lower Ordovician synziphosurine reveals early euchelicerate diversity and evolution.

Euchelicerata is a clade of arthropods comprising horseshoe crabs, scorpions, spiders, mites and ticks, as well as the extinct eurypterids (sea scorpions) and chasmataspidids. The understanding of the ground plans and relationships between these crown-group euchelicerates has benefited from the discovery of numerous fossils. However, little is known regarding the origin and early evolution of the euchelicerate body plan because the relationships between their Cambrian sister taxa and synziphosurines, a group of Silurian to Carboniferous stem euchelicerates with chelicerae and an unfused opisthosoma, remain poorly understood owing to the scarce fossil record of appendages. Here we describe a synziphosurine from the Lower Ordovician (ca. 478 Ma) Fezouata Shale of Morocco. This species possesses five biramous appendages with stenopodous exopods bearing setae in the prosoma and a fully expressed first tergite in the opisthosoma illuminating the ancestral anatomy of the group. Phylogenetic analyses recover this fossil as a member of the stem euchelicerate family Offacolidae, which is characterized by biramous prosomal appendages. Moreover, it also shares anatomical features with the Cambrian euarthropod Habelia optata, filling the anatomical gap between euchelicerates and Cambrian stem taxa, while also contributing to our understanding of the evolution of euchelicerate uniramous prosomal appendages and tagmosis.

Distribution pattern of arthropods on the leaf surfaces of Acacia auriculiformis saplings / Padrão de distribuição de artrópodes nas superfícies foliares de plantas de Acacia auriculiformis

Acacia auriculiformis A. Cunn. Ex Benth. (Fabaceae), a non-native pioneer species in Brazil with fast growth and rusticity, is used in restoration programs. Our goal was to assess during a 24-month survey the pattern of arthropods (phytophagous insects, bees, spiders, and predator insects) on the leaf surfaces of A. auriculiformis saplings. Fourteen species of phytophagous, two of bees and eleven of predators were most abundant on the adaxial surface. The values of the ecological indexes (abundance, diversity, and species richness) and the rarefaction, and k-dominance curves of phytophagous, bees and arthropod predators were highest on the adaxial leaf surface of A. auriculiformis. The k-dominance and abundance of Aleyrodidae (Hemiptera) (both leaf surfaces), the native stingless bee Tetragonisca angustula Latreille (Hymenoptera: Apidae) (both leaf surfaces) and the ant Brachymyrmex sp. (adaxial surface) and Pheidole sp. (Hymenoptera: Formicidae) (abaxial surface) were the highest between the taxonomic groups of phytophagous, bees, and predators, respectively on A. auriculiformis saplings. The ecological indexes and rarefaction, abundance, and k-dominance curves of phytophagous insects, bees, and predators were highest on the adaxial leaf surface. The preference of phytophagous insects for the adaxial leaf surface is probably due to the lower effort required to move on this surface. Understanding the arthropod preferences between leaf surfaces may help to develop sampling and pest management plans for the most abundant phytophagous insects on A. auriculiformis saplings. Also, knowledge on the preference pattern of bees and predators may be used to favour their conservation.

Acacia auriculiformis A. Cunn. Ex Benth. (Fabaceae), espécie pioneira com rápido crescimento e rusticidade, é utilizada em programas de recuperação de áreas degradadas. O objetivo deste trabalho foi avaliar, durante 24 meses, o padrão de distribuição de artrópodes (insetos fitófagos, abelhas, aranhas e insetos predadores) nas superfícies foliares de A. auriculiformis. Quatorze espécies de fitófagos, duas de abelhas e onze de predadores foram mais abundantes na superfície adaxial. Índices ecológicos (abundância, diversidade e riqueza de espécies) e curvas de rarefação e dominância-k de fitófagos, abelhas e artrópodes predadores foram maiores na face adaxial de folhas de A. auriculiformis. A dominância-k e a abundância de Aleyrodidae (Hemiptera) (ambas as superfícies foliares), da abelha nativa sem ferrão Tetragonisca angustula Latreille (Hymenoptera: Apidae) (ambas as superfícies foliares) e das formigas Brachymyrmex sp. (superfície adaxial) e Pheidole sp. (Hymenoptera: Formicidae) (superfície abaxial) foram as maiores entre os grupos taxonômicos de fitófagos polinizadores e predadores, respectivamente, em plantas jovens de A. auriculiformis. A abundância, diversidade e riqueza e as curvas de rarefação e dominância-k de artrópodes fitófagos, abelhas e predadores foram maiores nas superfícies adaxiais das folhas dessa árvore. A preferência pela superfície adaxial da folha se deve, provavelmente, ao menor esforço para se movimentarem na mesma. Compreender as preferências dos artrópodes pelas superfícies foliares pode auxiliar no desenvolvimento de planos de amostragem e manejo de pragas em A. auriculiformis. Além disso, o conhecimento da distribuição de abelhas e predadores pode favorecer a conservação desses insetos.

Three first records of stick insects attacking plants (Inseect: Phasmida) in Tibet / Três primeiros registros de insetos-pau atacando plantas (Inseect: Phasmida) no Tibet

Except for a few stick insects that are economically valuable, most species be considered to be forest pests, so it is extremely important to obtain plant host-use information of more stick insects. In this paper, the plant hosts of three species of stick insects were recorded for the first time. We also discovered these stick insects can feed upon the flowers or leaves of plants. Lopaphus unidentatus (Chen & He, 1995) (Phasmida: Lonchodidae) attacked Hypericum choisianum Wall. ex N. Robson, 1973 (Hypericaceae), Leurophasma dolichocercum Bi, 1995 (Phasmida: Aschiphasmatidae) attacked Antenoron filiforme (Thunb.) Roberty & Vautier, 1964 (Polygonaceae) and Megalophasma granulatum Bi, 1995 (Phasmida: Lonchodidae) attacked Debregeasia orientalis C. J. Chen, 1991 (Urticaceae). Finally, we were lucky enough to also obtain photographs of them mating and feeding.

Exceto por alguns insetos-pau que são economicamente valiosos, a maioria das espécies pode ser considerada praga florestal, por isso é extremamente importante obter informações sobre o uso de hospedeiros de plantas de mais insetos-pau. Neste artigo, as plantas hospedeiras de três espécies de bicho-pau foram registradas pela primeira vez. Também descobrimos que esses bichos-pau podem se alimentar de flores ou folhas de plantas. Lopaphus unidentatus (Chen & He, 1995) (Phasmida: Lonchodidae) atacou a parede de Hypericum choisianum. ex N. Robson, 1973 (Hypericaceae), Leurophasma dolichocercum Bi, 1995 (Phasmida: Aschiphasmatidae) atacou Antenoron filiforme (Thunb.) Roberty & Vautier, 1964 (Polygonaceae) e Megalophasma granulatum Bi, 1995 (Phasmida: Lonchodidae orientaled) atacou Chen, 1991 (Urticaceae). Finalmente, tivemos a sorte de também obter fotos deles se acasalando e se alimentando.

Diversity and Abundance of Predatory Arthropods on Immature and Mature Oil Palm (Elaeis guineensis) Plantations.

BACKGROUND AND OBJECTIVE: Predatory arthropods may play a crucial role in decreasing the pest population that causes a significant loss in oil palm production. In this study, we investigated the diversity of predatory arthropods and their abundance on immature and mature oil palm plantation grown in Aceh Tamiang, Sumatra, Indonesia. MATERIALS AND METHODS: Arthropod predators were collected by using light trap, yellow-pan trap and pitfall trap that were placed on an immature and mature oil palm plantation. Specimens were sorted and identified in the Laboratory. RESULTS: The results showed that there were 674 individuals arthropod predators (insects and spiders) consisted of 7 orders, 22 families and 37 morphospecies collected in the immature plantation. While in mature plantation, arthropod predators found were 740 individuals consisted of 6 orders 23 families and 42 morphospecies. Ants (Hymenoptera: Formicidae) dominated other families regarding morphospecies and individual numbers. There was no significant difference in term of species richness and abundance of predators between both phases of the plantation which implied that the two plantations hosted a similar composition and abundance of predators. The diversity indices of predators calculated in both plantations showed that the predators were categorized as middle level of diversity and middle level of individual distribution, However, the community is unstable. CONCLUSION: Our results suggested that predatory predators were present in similar structure in both phases of oil palm plantations. Efforts to conserve them are needed to enhance their performance as part of a sustainable and environmentally friendly method for controlling pests in oil palm plantation.

Molecular phylogeny and trait evolution in an ancient terrestrial arthropod lineage: Systematic revision and implications for ecological divergence (Collembola, Tomocerinae).

Phylogenetic assessments of functional traits are important for mechanistically understanding the interactions between organisms and environments, but such practices are strongly limited by the availability of phylogenetic frameworks. The tomocerin springtails are an ancient, widespread and ecologically important group of terrestrial arthropods, whereas their phylogeny and trait evolution remained unaddressed. In the present study, we conducted the first comprehensive phylogenetic reconstruction of Tomocerinae, based on a multi-loci molecular dataset covering all major lineages within the subfamily, using Bayesian inference (BI), maximum-likelihood (ML) and maximum-parsimony (MP) approaches. Divergence time was estimated and ancestral character state reconstruction (ACSR) was performed to trace the evolutionary history of five ecomorphological traits correlated with sensory and locomotory functions. Our results support the monophyly of Tomocerinae, and indicate that current classification of Tomocerinae only partially reflects evolutionary relationships, notably the commonest and speciose genus Tomocerus is polyphyletic. The subfamily probably originated in Early Cretaceous and diversified in two Cretaceous and one Eocene radiation events. As indicated by the evolutionary patterns of functional traits, multiple ecological divergences took place during the diversification of Tomocerinae. The study suggests a potential underestimation of ecological divergence and functional diversity in terrestrial arthropods, calls for an update of present trait databases, and demonstrates the value of macroevolutionary knowledge for improving the trait-based ecology. In addition, Tomocerus, Tomocerina and Tritomurus are redefined, a new genus Yoshiicerusgen. n. and new subgenera Coloratomurussubgen. n., Ciliatomurussubgen. n., Striatomurussubgen. n. and Ocreatomurussubgen. n. are described in the appendix.

Phylomitogenomic analyses on collembolan higher taxa with enhanced taxon sampling and discussion on method selection.

Collembola are a basal group of Hexapoda renowned for both unique morphological characters and significant ecological roles. However, a robust and plausible phylogenetic relationship between its deeply divergent lineages has yet to be achieved. We carried out a mitophylogenomic study based on a so far the most comprehensive mitochondrial genome dataset. Our data matrix contained mitogenomes of 31 species from almost all major families of all four orders, with 16 mitogenomes newly sequenced and annotated. We compared the linear arrangements of genes along mitochondria across species. Then we conducted 13 analyses each under a different combination of character coding, partitioning scheme and heterotachy models, and assessed their performance in phylogenetic inference. Several hypothetical tree topologies were also tested. Mitogenomic structure comparison revealed that most species share the same gene order of putative ancestral pancrustacean pattern, while seven species from Onychiuridae, Poduridae and Symphypleona bear different levels of gene rearrangements, indicating phylogenetic signals. Tomoceroidea was robustly recovered for the first time in the presence of all its families and subfamilies. Monophyly of Onychiuroidea was supported using unpartitioned models alleviating LBA. Paronellidae was revealed polyphyletic with two subfamilies inserted independently into Entomobryidae. Although Entomobryomorpha has not been well supported, more than half of the analyses obtained convincing topologies by placing Tomoceroidea within or near remaining Entomobryomorpha. The relationship between elongate-shaped and spherical-shaped collembolans still remained ambiguous, but Neelipleona tend to occupy the basal position in most trees. This study showed that mitochondrial genomes could provide important information for reconstructing the relationships among Collembola when suitable analytical approaches are implemented. Of all the data refining and model selecting schemes used in this study, the combination of nucleotide sequences, partitioning model and exclusion of third codon positions performed better in generating more reliable tree topology and higher node supports than others.

Phylogenomics of the longitarsal Colossendeidae: The evolutionary history of an Antarctic sea spider radiation.

Sea spiders (Pycnogonida) constitute a group of marine benthic arthropods that has a particularly high species diversity in the Southern Ocean. The "longitarsal" group of the sea spider family Colossendeidae is especially abundant in this region. However, this group also includes some representatives from other oceans, which raises the question where the group originates from. Therefore, we here investigated the phylogeny of the group with a hybrid enrichment approach that yielded a dataset of 1607 genes and over one million base pairs. We obtained a well-resolved phylogeny of the group, which is mostly consistent with morphological data. The data support an Antarctic origin of the longitarsal Colossendeidae and multiple dispersal events to other regions, which occurred at different timescales. This scenario is consistent with evidence found in other groups of marine invertebrates and highlights the role of the Southern Ocean as a source for non-Antarctic biota, especially of the deep sea. Our results suggest an initially slow rate of diversification followed by a more rapid radiation possibly correlated with the mid-Miocene cooling of Antarctica, similar to what is found in other taxa.

Edaphic fauna in a vegetation gradient in the Sete Cidades National Park / Fauna edáfica em um gradiente vegetacional no Parque Nacional de Sete Cidades

Abstract The vegetation physionomy and cover can show patterns of diversity and composition of the edaphic community, depending on the quantity and quality of litter in a specific habitat. The objective of this study was to evaluate the effect of the vegetation gradient formed by Graminoid Field (GRF), Cerrado Sensu Stricto (CSS), Cerradão (CRD) and Semideciduous Seasonal Forest (SSF) on density, diversity and composition of the edaphic fauna community in two seasons of the year, in the Sete Cidades National Park (Piauí state). For fauna sampling, a total of eight pitfall traps, distanced 10 m, were placed in each area in the central part of each system, where they remained for seven days. In the wet period, there was a tendency to increase the number of individuals as a function of the complexity of the vegetation formation, with the inverse occurring in the dry period. It was verified an environmental variation of the climatic factors temperature and humidity according to the vegetal formation, contributing to a heterogeneous distribution of the fauna. The GRF formation presented a significantly lower value of average richness only in the dry period. Regarding the variables of diversity and uniformity, they did not show drastic variations in relation to the vegetation gradient studied. The dominant groups in the vegetation gradient were Formicidae, Coleoptera, Aranae, Acari and Collembola, with reduction of the number of Coleoptera in the dry season. Principal component analysis (PCA) revealed greater differences in the composition of the communities between the vegetation formations for the rainy season. At this time, the formations SSF and CRD were associated to a greater diversity of invertebrates than CSS and GRF, demonstrating the influence of the vegetation complexity on the soil fauna community.

Resumo A fisionomia e cobertura vegetal podem mostrar padrões de diversidade e composição da comunidade edáfica, em função da quantidade e qualidade da serapilheira em determinado habitat específico. O presente trabalho teve por objetivo avaliar o efeito do gradiente vegetacional formado por Campo Graminóide (CGR), Cerrado Sensu Stricto (CSS), Cerradão (CRD) e Floresta Estacional Semidecídua (FES) sobre a densidade, diversidade e composição da comunidade da fauna edáfica em duas épocas do ano do Parque Nacional de Sete Cidades (PI). Para amostragem da fauna foram colocadas um total de oito armadilhas do tipo Pit-fall, distanciadas por 10 m, em cada área na parte central de cada sistema, onde permaneceram por sete dias. No período úmido houve uma tendência a aumento do número de indivíduos conforme a complexidade da formação vegetal e o inverso ocorreu no período seco. Verificou-se uma variação ambiental dos fatores climáticos temperatura e umidade conforme a formação vegetal contribuindo para uma distribuição heterogênea da fauna. Apenas no período seco a formação CGR apresentou valor significativamente menor de riqueza média. Em relação às variáveis de diversidade e uniformidade não apresentaram variações drásticas em relação ao gradiente vegetacional estudado. Os grupos dominantes no gradiente vegetacional foram Formicidae, Coleoptera, Aranae, Acari e Collembola, com redução do número de Coleoptera na época seca. Pela análise de componentes principais (ACP) constatou-se maiores diferenças na composição das comunidades entre as formações vegetais para o período chuvoso. Nesta época, as formações vegetais os estádios FES e CRD estiveram associados a uma maior diversidade de invertebrados do que CSS e CGR, demonstrando influência da complexidade vegetacional sobre a comunidade da fauna do solo.

Ectoparasites of the Nile Rat, Arvicanthis niloticus from Shendi area, Sudan

This study investigated the ectoparasites of the Nile Rat, Arvicanthis niloticus in Shendi area, River Nile State, Sudan. Eighty nine A. niloticus were collected for the first time from the horticultural fields of Shendi, between January to June 2018, and their entire fur was combed thoroughly, using a fine-tooth comb. Any removed ectoparasites were relaxed, mounted and examined under a microscope for morphological identification. Forty two (47.2%) of the collected rats was found infested, with an overall mean intensity of 13.4 (range 2­67) ectoparasites per an infested rat; 10 different species of ectoparasites were identified, including: 2 species of flea ­ Xenopsylla cheopis, Leptopsylla segnis; 3 species of louse ­ Polyplax spinulosa, P. abyssinica, P. serrata; a species of tick ­ Rhipicephalus sp.; 4 species of mite ­ Laelaps agilis, L. nuttalli, Ornitonyssus bacoti, Dermanyssuss gallinae. The most prevalent ectoparasite found was the flea Xenopsylla cheopis, 23.6%, followed by the mite Laelaps nuttalli, 10.1%, while the least was the mite Ornitonyssus bacoti, 1.1%. Significantly higher prevalence and intensity of infestation was found among male rats. Likewise, older rats significantly harbored a higher prevalence and intensity of infestation.

Distribución y fenología de la familia Riodinidae (Lepidoptera: Papilionoidea) en el bosque tropical subcaducifolio de Oaxaca, México / Distribution and phenology of the family Riodinidae (Lepidoptera: Papilionoidea) in the tropical semi-deciduous forest of Oaxaca, Mexico

Resumen La familia Riodinidae es muy diversa en la región Neotropical; en México aún es escaso el conocimiento acerca de la biología de la mayoría de sus especies. Para el presente trabajo, se realizaron recolectas exhaustivas y sistemáticas de Riodinidae en varias localidades de la región Loxicha, Oaxaca, México, particularmente en dos con bosque tropical subcaducifolio. Además se examinaron los registros previos para esa región, en un gradiente altitudinal de los 70 a 2 500 m; la mayoría recolectados por personal del Museo de Zoología (Facultad de Ciencias, UNAM). A partir de la revisión de la base de datos MARIPOSA y del trabajo de campo, se alcanzó la cifra de 4 029 ejemplares de esta región; de los cuales, 2 306 se obtuvieron del bosque tropical subcaducifolio (bts) durante el presente estudio. El total de especies para la región, arrojó un total de 52 especies, distribuidas en 22 géneros y dos subfamilias; la subfamilia Riodininae la más diversa (50 spp.). Mediante estimadores paramétricos se calculó la riqueza de esta familia para las dos localidades de bts estudiadas y en el total de la región; alcanzando valores teóricos mayores al 80 %. Al comparar los resultados con otras listas de especies del Pacífico mexicano, se concluye que en la región Loxicha se encuentra la mayor riqueza de la familia Riodinidae. En el bosque tropical subcaducifolio se efectuaron transectos por dos años, que permitieron distinguir los microhábitats de más de 40 especies, lo cual se ilustra y describe en dibujos y fotografías in situ. En este tipo vegetacional se registra la mayoría de especies de la región Loxicha.

Abstract Riodinidae is very diverse in the Neotropical region; in Mexico the knowledge about the biology of most of its species is still scarce. For the present work, exhaustive and systematic collections of Riodinidae were carried out in 14 localities of the Loxicha region, Oaxaca, Mexico, particularly in two with tropical semi-deciduous forest. In addition, previous records for this region were examined, in an altitude range of 70 to 2 500 m; the majority collected by the staff of the Museo de Zoología (Facultad de Ciencias, UNAM). We obtained 4 029 specimens from the fieldwork and MARIPOSA database, 2 306 of them are present in the tropical semi-deciduous forest (TSF). The total number of species for the region is 52, distributed in 22 genera and two subfamilies; the most diverse subfamily was Riodininae (50 species). Using parametric estimators the richness of the family was calculated for the two locations of TSF studied and the entire region, reaching theoretical values greater than 80 %. When comparing the results with other lists of species of the Mexican Pacific, it is concluded that the Loxicha region harbours the greatest richness of Riodinidae. In the tropical semi-deciduous forest, transects were carried out for two years, allowing microhabitats to be distinguished from more than 40 species, which are described and illustrated with drawings and in situ photographs. In this vegetation type most species of the Loxicha region are recorded. Rev. Biol. Trop. 66(2): 503-558. Epub 2018 June 01.

A New Species of Pararrhopalites Bonet & Tellez (Collembola, Symphypleona, Sminthuridae) from Iron Caves in Brazil.

A second species of the genus Pararrhopalites is described from caves inserted in iron ore lithology. Both species present a particular sensory organ in the interantennal region. The new species, Pararrhopalites ubiquum n.sp., has a wider distribution and it is not restricted to a single cave, as it is the case of Pararrhopalites sideroicus Zeppelini & Brito, in Fla Entomol 97(4):1733-1744, 2014, being found even in the Mesovoid Shallow Substratum. An update to the previously published identification key is presented.

Cytochrome P450 diversity in the tree of life.

Sequencing in all areas of the tree of life has produced >300,000 cytochrome P450 (CYP) sequences that have been mined and collected. Nomenclature has been assigned to >41,000 CYP sequences and the majority of the remainder has been sorted by BLAST searches into clans, families and subfamilies in preparation for naming. The P450 sequence space is being systematically explored and filled in. Well-studied groups like vertebrates are covered in greater depth while new insights are being added into uncharted territories like horseshoe crab (Limulus polyphemus), tardigrades (Hypsibius dujardini), velvet worm (Euperipatoides_rowelli), and basal land plants like hornworts, liverworts and mosses. CYPs from the fungi, one of the most diverse groups, are being explored and organized as nearly 800 fungal species are now sequenced. The CYP clan structure in fungi is emerging with 805 CYP families sorting into 32 CYP clans. >3000 bacterial sequences are named, mostly from terrestrial or freshwater sources. Of 18,379 bacterial sequences downloaded from the CYPED database, all are >43% identical to named CYPs. Therefore, they fit in the 602 named P450 prokaryotic families. Diversity in this group is becoming saturated, however 25% of 3305 seawater bacterial P450s did not match known P450 families, indicating marine bacterial CYPs are not as well sampled as land/freshwater based bacterial CYPs. Future sequencing plans of the Genome 10K project, i5k and GIGA (Global Invertebrate Genomics Alliance) are expected to produce more than one million cytochrome P450 sequences by 2020. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone.

Evolutionary origin of type IV classical cadherins in arthropods.

BACKGROUND: Classical cadherins are a metazoan-specific family of homophilic cell-cell adhesion molecules that regulate morphogenesis. Type I and type IV cadherins in this family function at adherens junctions in the major epithelial tissues of vertebrates and insects, respectively, but they have distinct, relatively simple domain organizations that are thought to have evolved by independent reductive changes from an ancestral type III cadherin, which is larger than derived paralogs and has a complicated domain organization. Although both type III and type IV cadherins have been identified in hexapods and branchiopods, the process by which the type IV cadherin evolved is still largely unclear. RESULTS: Through an analysis of arthropod genome sequences, we found that the only classical cadherin encoded in chelicerate genomes was the type III cadherin and that the two type III cadherin genes found in the spider Parasteatoda tepidariorum genome exhibited a complex yet ancestral exon-intron organization in arthropods. Genomic and transcriptomic data from branchiopod, copepod, isopod, amphipod, and decapod crustaceans led us to redefine the type IV cadherin category, which we separated into type IVa and type IVb, which displayed a similar domain organization, except type IVb cadherins have a larger number of extracellular cadherin (EC) domains than do type IVa cadherins (nine versus seven). We also showed that type IVa cadherin genes occurred in the hexapod, branchiopod, and copepod genomes whereas only type IVb cadherin genes were present in malacostracans. Furthermore, comparative characterization of the type IVb cadherins suggested that the presence of two extra EC domains in their N-terminal regions represented primitive characteristics. In addition, we identified an evolutionary loss of two highly conserved cysteine residues among the type IVa cadherins of insects. CONCLUSIONS: We provide a genomic perspective of the evolution of classical cadherins among bilaterians, with a focus on the Arthropoda, and suggest that following the divergence of early arthropods, the precursor of the insect type IV cadherin evolved through stepwise reductive changes from the ancestral type III state. In addition, the complementary distributions of polarized genomic characters related to type IVa/IVb cadherins may have implications for our interpretations of pancrustacean phylogeny.

Cambrian suspension-feeding lobopodians and the early radiation of panarthropods.

BACKGROUND: Arthropoda, Tardigrada and Onychophora evolved from lobopodians, a paraphyletic group of disparate Palaeozoic vermiform animals with soft legs. Although the morphological diversity that this group encompasses likely illustrates the importance of niche diversification in the early radiation of panarthropods, the ecology of lobopodians remains poorly characterized. RESULTS: Here we describe a new luolishaniid taxon from the middle Cambrian Burgess Shale (Walcott Quarry) in British Columbia, Canada, whose specialized morphology epitomizes the suspension-feeding ecology of this clade, and is convergent with some modern marine animals, such as caprellid crustaceans. This species possesses two long pairs and four shorter pairs of elongate spinose lobopods at the front, each bearing two slender claws, and three pairs of stout lobopods bearing single, strong, hook-like anterior-facing claws at the back. The trunk is remarkably bare, widening rearwards, and, at the front, extends beyond the first pair of lobopods into a small "head" bearing a pair of visual organs and a short proboscis with numerous teeth. Based on a critical reappraisal of character coding in lobopodians and using Bayesian and parsimony-based tree searches, two alternative scenarios for early panarthropod evolution are retrieved. In both cases, hallucigeniids and luolishaniids are found to be extinct radiative stem group panarthropods, in contrast to previous analyses supporting a position of hallucigeniids as part of total-group Onychophora. Our Bayesian topology finds luolishaniids and hallucigeniids to form two successive clades at the base of Panarthropoda. Disparity analyses suggest that luolishaniids, hallucigeniids and total-group Onychophora each occupy a distinct region of morphospace. CONCLUSIONS: Hallucigeniids and luolishaniids were comparably diverse and successful, representing two major lobopodian clades in the early Palaeozoic, and both evolved body plans adapted to different forms of suspension feeding. A Bayesian approach to cladistics supports the view that a semi-sessile, suspension-feeding lifestyle characterized the origin and rise of Panarthropoda from cycloneuralian body plans.

Expression of segment polarity genes in brachiopods supports a non-segmental ancestral role of engrailed for bilaterians.

The diverse and complex developmental mechanisms of segmentation have been more thoroughly studied in arthropods, vertebrates and annelids-distantly related animals considered to be segmented. Far less is known about the role of "segmentation genes" in organisms that lack a segmented body. Here we investigate the expression of the arthropod segment polarity genes engrailed, wnt1 and hedgehog in the development of brachiopods-marine invertebrates without a subdivided trunk but closely related to the segmented annelids. We found that a stripe of engrailed expression demarcates the ectodermal boundary that delimits the anterior region of Terebratalia transversa and Novocrania anomala embryos. In T. transversa, this engrailed domain is abutted by a stripe of wnt1 expression in a pattern similar to the parasegment boundaries of insects-except for the expression of hedgehog, which is restricted to endodermal tissues of the brachiopod embryos. We found that pax6 and pax2/5/8, putative regulators of engrailed, also demarcate the anterior boundary in the two species, indicating these genes might be involved in the anterior patterning of brachiopod larvae. In a comparative phylogenetic context, these findings suggest that bilaterians might share an ancestral, non-segmental domain of engrailed expression during early embryogenesis.

Venomous and poisonous arthropods: identification, clinical manifestations of envenomation, and treatments used in human injuries

Abstract This review presents the main species of venomous and poisonous arthropods, with commentary on the clinical manifestations provoked by the toxins and therapeutic measures used to treat human envenomations. The groups of arthopods discussed include the class Arachnida (spiders and scorpions, which are responsible for many injuries reported worldwide, including Brazil); the subphylum Myriapoda, with the classes Chilopoda and Diplopoda (centipedes and millipedes); and the subphylum Hexapoda, with the class Insecta and the orders Coleoptera (beetles), Hemiptera (stink bugs, giant water bugs, and cicadas), Hymenoptera (ants, wasps, and bees), and Lepidoptera (butterflies and moths).

The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa.

BACKGROUND: Eurypterids are a diverse group of chelicerates known from ~250 species with a sparse Ordovician record currently comprising 11 species; the oldest fully documented example is from the Sandbian of Avalonia. The Middle Ordovician (Darriwilian) fauna of the Winneshiek Lagerstätte includes a new eurypterid species represented by more than 150 specimens, including some juveniles, preserved as carbonaceous cuticular remains. This taxon represents the oldest described eurypterid, extending the documented range of the group back some 9 million years. RESULTS: The new eurypterid species is described as Pentecopterus decorahensis gen. et sp. nov.. Phylogenetic analysis places Pentecopterus at the base of the Megalograptidae, united with the two genera previously assigned to this family by the shared possession of two or more pairs of spines per podomere on prosomal appendage IV, a reduction of all spines except the pair on the penultimate podomere of appendage V, and an ornamentation of guttalate scales, including angular scales along the posterior margin of the dorsal tergites and in longitudinal rows along the tergites. The morphology of Pentecopterus reveals that the Megalograptidae are representatives of the derived carcinosomatoid clade and not basal eurypterids as previously interpreted. CONCLUSIONS: The relatively derived position of megalograptids within the eurypterids indicates that most eurypterid clades were present by the Middle Ordovician. Eurypterids either underwent an explosive radiation soon after their origination, or earlier representatives, perhaps Cambrian in age, remain to be discovered. The available instars of Pentecopterus decorahensis suggest that eurypterids underwent extreme appendage differentiation during development, a potentially unique condition among chelicerates. The high degree of appendage specialization in eurypterids is only matched by arachnids within chelicerates, supporting a sister taxon relationship between them.

A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids.

Euchelicerates were a major component of Palaeozoic faunas, but their basal relationships are uncertain: it has been suggested that Xiphosura-xiphosurids (horseshoe crabs) and similar Palaeozoic forms, the synziphosurines-may not represent a natural group. Basal euchelicerates are rare in the fossil record, however, particularly during the initial Ordovician radiation of the group. Here, we describe Winneshiekia youngae gen. et sp. nov., a euchelicerate from the Middle Ordovician (Darriwilian) Winneshiek Lagerstätte of Iowa, USA. Winneshiekia shares features with both xiphosurans (a large, semicircular carapace and ophthalmic ridges) and dekatriatan euchelicerates such as chasmataspidids and eurypterids (an opisthosoma of 13 tergites). Phylogenetic analysis resolves Winneshiekia at the base of Dekatriata, as sister taxon to a clade comprising chasmataspidids, eurypterids, arachnids, and Houia. Winneshiekia provides further support for the polyphyly of synziphosurines, traditionally considered the stem lineage to xiphosurid horseshoe crabs, and by extension the paraphyly of Xiphosura. The new taxon reveals the ground pattern of Dekatriata and provides evidence of character polarity in chasmataspidids and eurypterids. The Winneshiek Lagerstätte thus represents an important palaeontological window into early chelicerate evolution.

Stemmiulus brasiliensis n. sp., a new species of millipede from Brazilian iron ore caves (Diplopoda: Stemmiulida: Stemmiulidae).

A new species of Stemmiulus Gervais, 1844 is described from Amazonian iron ore caves located in Pará State, Brazil. The new species differs from the other Brazilian species by gonopod morphology, especially the angiocoxite and colpocoxite, and for the first pairs of legs of males. A key for the species of Stemmiulus found in Brazil is included.

Molecular phylogeny supports S-chaetae as a key character better than jumping organs and body scales in classification of Entomobryoidea (Collembola).

The jumping organ (furcula) is the most characteristic structure among collembolans, and it is of great taxonomical values at higher levels. The largest superfamily Entomobryoidea is traditionally classified into four families only by the morphology of the furcula. Actually, many taxa among these families are strikingly similar in morphology without considering furcula. The phylogeny of Entomobryoidea was reconstructed here based on mitochondrial and ribosomal fragments. This indicated that both Paronellidae and Cyphoderidae were ingroups within Entomobryidae with the former polyphyletic. Topology tests, which used the likelihood and Bayesian approaches, also rejected the traditional hypotheses relying on furcula morphology. Further ancestral state reconstructions have revealed that traditional taxonomical characters, i.e., furcula and body scales, had multiple independent origins in Entomobryoidea whereas tergal specialized chaetae (S-chaetae) exhibited strong phylogenetic signals. By integrating both molecular and morphological evidence, the results of this study drastically undermine the present classification of Entomobryoidea. Tergal S-chaetotaxic pattern in combination with other characters are more reasonable in taxonomy at suprageneric levels than convergent furcula. This study provides new insights of the jumping organ, which could be adaptively modified during evolution of Collembola.