搜索结果：Millipedes

Parasitism is one of the primary causes of biotic stress in several taxa, and behaviors resembling self-medication have been documented in numerous species. Anointing involves the application of chemical substances derived from animals, plants, mud, soils, and minerals, often emitting a pungent odor, onto an animal's body. We examined the circumstances surrounding 34 bouts of anointing with millipedes in a group of blond capuchin monkeys (Sapajus flavius) inhabiting an Atlantic Forest fragment in northeastern Brazil. Over 412 h of observation, we collected behavioral data through photographs, video recordings, and ad libitum field notes. We collected and identified the millipedes to the species level. We tested three non-mutually exclusive hypotheses on the function(s) of this behavior: self-medication, social bonding, and opportunistic use. We analyzed data in R using nonparametric tests due to low sample size. Anointing occurred at a rate of 8 episodes every 100 h. Millipedes used during anointing are from species that produce benzoquinone. The behavior was more frequently observed in the inferior strata, during midday, while the group is mostly foraging, in periods of higher rainfall, when millipedes emerge from the ground, and during the high fruit productivity season, when the capuchins' activity budget is less constrained. Although anointing occurred at similar rates in solitary and social contexts, adult males were more actively engaged in anointing bouts, indicating sex difference in this behavior, and a possible social function. The observed pattern suggests anointing is a multifunctional behavior, combining elements of self-medication, opportunity, and social interaction. O parasitismo é uma das principais causas de estresse biótico em diversos táxons, e comportamentos semelhantes à automedicação são documentos em várias espécies. A unção consiste na aplicação de substâncias químicas derivadas de animais, plantas, lama, solos e minerais, frequentemente emitindo um odor forte, sobre o corpo do animal. Examinamos as circunstâncias em torno de 34 episódios de unção com milípedes em um grupo de macacos‐prego‐galego (Sapajus flavius) que habitam um fragmento de Mata Atlântica no nordeste brasileiro. Ao longo de 412 horas de observação, coletamos dados comportamentais por meio de fotografias, gravações de vídeo e notas de campo ad libitum. Coletamos e identificamos os milípedes ao nível de espécie. Testamos três hipóteses não mutuamente exclusivas sobre possíveis funções desse comportamento: automedicação, vínculo social e uso oportunista. Analisamos os dados no R utilizando testes não paramétricos devido ao tamanho amostral reduzido. A unção ocorreu a uma taxa de 8 episódios a cada 100 horas. Os milípedes usados durante as unções são de espécies que excretam benzoquinona. O comportamento foi mais frequentemente observado nos estratos inferiores da vegetação, ao meio‐dia, enquanto o grupo estava principalmente forrageando, em períodos de maior precipitação, quando os milípedes emergem do solo, e durante a estação de alta produtividade de frutos, quando o orçamento de atividades dos macacos é menos restrito. Embora a unção tenha ocorrido em taxas semelhantes em contextos solitários e sociais, os machos adultos estiveram mais ativamente engajados em episódios de unção, indicando uma diferença sexual nesse comportamento e uma possível função social. O padrão observado sugere que a unção é um comportamento multifuncional, combinando elementos de automedicação, oportunismo e interação social.

Arthropods are arguably the most successful group of metazoans, comprising the majority of described animal species. Millipedes belong to the class Diplopoda of arthropods and are vital decomposers of litter and recycle nutrients in the soil ecosystems worldwide. The molecular mechanism of sex determination in millipedes remains unknown. Here, we sequenced and assembled two high-quality genomes of male and female rusty millipedes Trigoniulus corallinus with sizes of 546 Mb (scaffold N50 = 21.9 Mb) and 630 Mb (scaffold N50 = 20.7 Mb), respectively. Whole-genome resequencing was further carried out on 10 males and 10 females, and sequencing depth analyses showed 1 X chromosome and 2 X chromosomes on male and female genome assemblies, suggesting an XX/X0 system. Synteny analyses of T. corallinus with the centipede Strigamia acuminata showed little conservation between their X chromosomes, implying different selection pressures happened on sex chromosomes after their divergence from the myriapod ancestor. The survey of the sex chromosomes of a millipede species provides the first genomic evidence supporting an XX/X0 system in millipedes. It provides a foundational framework for future studies in myriapod genomics and contributes to a broader understanding of arthropod evolution.

Hydrogen cyanide (HCN) is a highly toxic biogenic compound. Unlike most natural defensive chemicals, which are typically lineage-specific, the biosynthesis and liberation of HCN, called "cyanogenesis", occur sporadically among arthropod and plant lineages. This suggests that cyanogenesis has evolved independently numerous times in the animal and plant kingdoms. Although cyanogenesis was identified in millipedes 140 years ago, the cyanogenesis-related enzymes in these arthropods have not yet been fully identified. Here, we report a complete set of cyanogenesis-related enzymes in the millipede Chamberlinius hualienensis based on an analysis combining genome sequencing and biological characterisation. The gene encoding hydroxynitrile lyase, which catalyses the liberation of HCN from (R)-mandelonitrile, and its paralogous genes were clustered, indicating sequential duplication of their coding genes, giving rise to hydroxynitrile lyase in millipedes. We discovered that (R)-mandelonitrile cyanohydrin biosynthesis in C. hualienensis utilises a flavin-dependent monooxygenase (ChuaMOxS) for the initial aldoxime synthesis step, similar to the process in ferns, instead of cytochrome P450 (CYP) as in higher plants and insects. Although a single CYP is responsible for subsequently converting aldoxime into cyanohydrin in plants and insects, the reaction involves two enzymes in millipedes. We found two millipede CYPs (CYP4GL4 and CYP30008A2) that catalyse aldoxime dehydration to produce nitrile, in addition to CYP3201B1, which then catalyses the formation of (R)-mandelonitrile from nitrile. The discovery of cyanogenesis-related enzymes in millipedes demonstrates that cyanogenic millipedes evolved these enzymes independently from plants and insects, providing a deeper understanding of the mechanisms underlying the evolution of metabolic pathways.

Millipedes (class Diplopoda) are vital soil invertebrates that play key roles in litter decomposition and nutrient cycling. However, their phylogenetic relationships remain poorly resolved due to limited genomic resources. In this study, we sequenced and characterized the complete mitochondrial genomes (mitogenomes) of two paradoxosomatid millipedes, Oxidus gracilis (15,034 bp) and Kronopolites swinhoei (15,277 bp). Both mitogenomes contain the typical set of 37 genes, all located on the minor strand (N-strand), and display high AT content. The conserved gene arrangement observed here may represent a molecular synapomorphy for this taxonomic group. Analysis of codon usage revealed that start codons includ ATN (ATA/ATG/ATT), TTG, and GTG, while stop codons consisted of TAN (TAA/TAG/TAT) and an incomplete single T. Relative synonymous codon usage (RSCU) analysis indicated that Leu2, Val, and Gly were the most frequently used codon families, whereas Gln, Cys, and Lys were the least utilized. The tRNA genes formed two distinct clusters, and the rRNAs were flanked by tRNA-Val. The D-loop region was located in a similar position in both species. Phylogenetic reconstruction based on 13 protein-coding genes from 34 diplopod species, using both Bayesian inference and maximum likelihood methods, strongly supported the interordinal relationships among Julida, Spirostreptida, and Spirobolida, and placed O. gracilis and K. swinhoei in distinct clades. Our findings provide valuable mitogenomic data and new phylogenetic insights into Diplopoda, underscoring the importance of expanded taxonomic sampling to further elucidate evolutionary relationships within this ecologically significant group.

The phylum Nematoda includes species adapted to nearly every environment on Earth, ranging from free-living forms to parasites of plants and animals. Parasitism has evolved multiple times independently within the phylum, and the suborder Spirurina is particularly notable because all of its members are obligate animal parasites. In this study, we conducted a molecular phylogenetic analysis of Spirurina, integrating ancestral state reconstruction (ASR) to clarify higher-level relationships and to trace the evolutionary origins of parasitism. Our analysis suggested that the parasitic origin of Spirurina, which arose from free-living nematodes within Rhabditida that had adapted to terrestrial environments, is bifurcated. One is associated with early-dividing lineages of aquatic invertebrates (Gnathostomatomorpha and Seuratoidea), while the other is associated with millipedes belonging to a large terrestrial clade that includes the suborders Oxyuridomorpha, Rhigonematomorpha, Ascaridomorpha, Camallanomorpha, and Spiruromorpha. Comparative examination of life cycles across infraorders indicates that parasitic strategies evolved from simple, single-host infection cycles to complex life cycles requiring intermediate hosts. These complex cycles appear to have originated in freshwater environments, where copepods and other crustaceans served as ancestral intermediate hosts in aquatic lineages. Importantly, our findings identify millipedes as a pivotal ancestral host group that shaped the early terrestrial evolution of parasitism within Spirurina. Together, these findings provide a comprehensive framework for understanding the evolutionary pathways that gave rise to the remarkable diversity of parasitic strategies within Spirurina.

Fossil evidence indicates that millipedes were the first animals adapted to life on land about 425 million years ago, becoming the very first land animals and beating vertebrates by a staggering 50 million years.1,2 These multi-legged arthropods provide a vital ecological role in forests by decomposing coarse organic matter and contributing to the formation of nutrient-rich soils.3,4 To date, 14,232 species have been described, with at least as many still awaiting discovery.5 Despite their ecological significance and ancient origins in the Ordovician, the evolutionary relationships among millipedes have remained unresolved, and a synthesis of the 16 orders that comprise the class Diplopoda had never been attempted. In this study, we analyzed the last two remaining unsampled orders, Siphonocryptida and Siphoniulida, two rare paleoendemics whose placement had been unresolved until now. Our results show that all extant diplopod orders except one were present by the end of the Jurassic, that millipedes evolved potent terpenoid alkaloid chemical defenses 261 million years ago, and that Siphonocryptida is a derived lineage of Polyzoniida. Early millipede lineages possessed sophisticated sensory structures, including compound eyes and Tömösváry organs, which were repeatedly lost over 459 million years of diversification. These findings provide a robust framework for understanding the evolution of the earliest fully terrestrial animals and support ongoing efforts to discover and describe thousands of new millipede species.

Less well known in the parasitological community than in the entomological community are the wonderfully complex systems of army ants and the multitude of taxa that associate with them, collectively termed guests. Guests include vertebrates such as antbirds, but also a diversity of arthropods such as beetles, flies, wasps, millipedes, thysanurans, and collembolans. In addition, a wide variety of mites live on the bodies of army ants and appear to have become modified in form to conform with a particular site on their ant host. The nature of the relationships between army ants and many of their guest taxa remains to be definitively determined. Nonetheless, relationships involving commensalism, mutualism, parasitism, parasitoidism, and phoresy have all been described. The Carl W. and Marian E. Rettenmeyer Army Ant Guest Collection (AAGC) is largely the result of 55 yr of fieldwork (from 1951 to 2004) by the Rettenmeyers in the jungles of Central and South America. It was donated to the Biodiversity Research Collection at the University of Connecticut in 2016 and has since been stabilized and almost fully digitized. This multifaceted resource includes specimens of army ants and their guests housed in 7,310 vials and 278 jars of ethanol, 5,500 microscope slides of guests, and 108 Cornell-style drawers of pinned specimens. We estimate that it includes over 2,000,000 specimens representing 40 species of army ants and their numerous species of guests and prey. Ancillary material includes data from, and images of, 6,246 Kodachrome slides and 9,500 field cards that provide detailed observations on the members of these systems in the field. An online database consisting of 4 modules (i.e., Specimens, Colonies, Kodachromes, and Field Cards) provides digital access to these materials. Because of its interconnected and detailed nature, the AAGC can serve as an unprecedented resource not only for expanding understanding of multiple aspects of the associations between army ants and their guests, but also for helping to inform fundamental questions about the evolution of interspecific interactions and, of primary interest to this audience, parasitism and parasitoidism.

With fossil records dating back to the Silurian/Late Ordovician, millipedes stand out as one of the earliest terrestrial animal groups. Their limited vagility and high endemism make them valuable tools for formulating and testing biogeographic hypotheses, including those related to macro-vicariance events. Among the order Polydesmida, the family Chelodesmidae displays an intriguing transatlantic distribution, suggesting a Gondwanan origin. Despite this, the evolutionary relationships and biogeography of the family remain largely unknown. In this study, we explore areas of endemism (AEs) for Chelodesmidae using endemicity analysis (NDM/VNDM), utilising a data set of 1512 records for 725 species. NDM/VNDM analyses identified 135 areas of endemism, which were consolidated into 10 generalised areas. These overlapping patterns revealed common areas of endemism, including Central Africa, Western-Central Africa, Western Africa, West Indies, Northern Amazon, Northern Andes, Guiana Shield, Southern Amazon, America Platina and the Southeastern Mountain Range. This study represents the first explicit assessment of endemism patterns in the family using a quantitative methodology and underscores its significance for further research on Gondwanan distribution patterns.

BACKGROUND: Arthropod segmentation involves not only embryonic patterning but also postembryonic segment addition through molting, a process known as anamorphosis. In millipedes (class Diplopoda), which universally undergo anamorphosis, new segmental units also known as “rings” are added anterior to the telson, yet the morphogenetic mechanisms underlying this process remain poorly understood. Here, we investigate ring addition during anamorphosis in the millipede Niponia nodulosa (Polydesmida, Cryptodesmidae), focusing on epidermal and muscular organization. Using X-ray micro-computed tomography and microscopic histological analysis, we reconstructed the sequence of tissue changes preceding molting. RESULTS: Our results show that a local invagination of the epidermis between the telson and the penultimate ring establishes a ring primordium, whose subsequent development gives rise to a new ring. In stadia where multiple rings are added with one molt, a corresponding number of ring primordia appeared. In addition, the muscle originally linking the penultimate ring to the telson detaches and reattaches to the newly added ring, while additional muscles differentiate within the new ring to form novel connections with the telson. These coordinated changes occur rapidly before molting, enabling ring addition within the restricted posterior body region. CONCLUSIONS: We provided a detailed three-dimensional description of the morphological changes accompanying ring addition. Epidermal morphogenesis and muscular rearrangement are thought to enable the addition of new rings while maintaining the functional integrity of the posterior body, including defecation. This study establishes a histological and morphological basis for understanding segmentation during postembryonic development in arthropods and paves the way for future developmental investigations.

The order Glomerida (pill millipedes) represents a group of terrestrial invertebrates of high ecological and taxonomic significance, yet its diversity and distribution in China remain poorly documented. Employing an integrative taxonomic approach that combines traditional morphological examination with COI gene sequence analysis, this study describes a new species of the genus Rhopalomeris, R. dinghushan sp. nov., collected from Dinghushan National Nature Reserve, Guangdong Province. This discovery represents the first formal record of the genus Rhopalomeris from China, thereby filling in a major distributional gap for this endemic Oriental genus and extending its known range north of Indochina to southern China. Phylogenetic analyses based on COI sequences, using maximum likelihood and Bayesian inference, reveal that the genus as currently circumscribed seems to be polyphyletic. The new species, R. dinghushan sp. nov., forms a well-supported clade together with Peplomeris magna, challenging the current generic delimitation and highlighting the need for a comprehensive revision of the genus.