The venom and telopodal defence systems of the centipede Lithobius forficatus are functionally convergent serial homologues.

BACKGROUND: Evolution of novelty is a central theme in evolutionary biology, yet studying the origins of traits with an apparently discontinuous origin remains a major challenge. Venom systems are a well-suited model for the study of this phenomenon because they capture several aspects of novelty across multiple levels of biological complexity. However, while there is some knowledge on the evolution of individual toxins, not much is known about the evolution of venom systems as a whole. One way of shedding light on the evolution of new traits is to investigate less specialised serial homologues, i.e. repeated traits in an organism that share a developmental origin. This approach can be particularly informative in animals with repetitive body segments, such as centipedes. RESULTS: Here, we investigate morphological and biochemical aspects of the defensive telopodal glandular organs borne on the posterior legs of venomous stone centipedes (Lithobiomorpha), using a multimethod approach, including behavioural observations, comparative morphology, proteomics, comparative transcriptomics and molecular phylogenetics. We show that the anterior venom system and posterior telopodal defence system are functionally convergent serial homologues, where one (telopodal defence) represents a model for the putative early evolutionary state of the other (venom). Venom glands and telopodal glandular organs appear to have evolved from the same type of epidermal gland (four-cell recto-canal type) and while the telopodal defensive secretion shares a great degree of compositional overlap with centipede venoms in general, these similarities arose predominantly through convergent recruitment of distantly related toxin-like components. Both systems are composed of elements predisposed to functional innovation across levels of biological complexity that range from proteins to glands, demonstrating clear parallels between molecular and morphological traits in the properties that facilitate the evolution of novelty. CONCLUSIONS: The evolution of the lithobiomorph telopodal defence system provides indirect empirical support for the plausibility of the hypothesised evolutionary origin of the centipede venom system, which occurred through functional innovation and gradual specialisation of existing epidermal glands. Our results thus exemplify how continuous transformation and functional innovation can drive the apparent discontinuous emergence of novelties on higher levels of biological complexity.

Redescription of the enigmatic myriapod Hanseniellachilensis (Hansen, 1903) (Symphyla, Scutigerellidae) based on scanning electron microscope images of Chilean specimens.

Hanseniellachilensis is the only myriapod of the class Symphyla known from Chile. This garden centipede, or pseudocentipede, was described more than 120 years ago based on morphologically incomplete specimens collected in central Chile, a well-known biodiversity hotspot. In this study, we redescribe this species based on morphologically complete specimens collected near the type locality using scanning electron microscope images. Our study provides the description of diagnostic characters hitherto unknown in this species such as macrochaetae of the tergites and spinnerets of the cerci. We also include a new record from central Chile and discuss the presumed presence of this species in Argentina and Madagascar.

The structural and functional modularity of ovarian follicle epithelium in the pill-millipede Hyleoglomeris japonica Verhoeff, 1936 (Diplopoda: Glomerida: Glomeridae).

Ovarian somatic tissues typically surround developing oocytes and play a crucial role in oogenesis across various metazoans, often displaying structural properties specific to their functions. However, there is an absence of evident structural modularity in the follicle epithelium of Myriapoda. We report here two structurally and developmentally distinct domains within the follicle epithelium of the Japanese pill millipede, Hyleoglomeris japonica. The follicle epithelium of H. japonica exhibits a thick cell mass at the apex of the follicle. These cells harbor abundant rough endoplasmic reticulum, mitochondria, Golgi complexes, and numerous microvilli, indicative of synthetic/secretory activities. Moreover, their height increases as oogenesis progresses. In contrast, another region of the epithelium lacks these features. Our findings highlight the presence of structural and functional modularity in the follicle epithelium of H. japonica. We suggest classifying the follicle epithelium of Myriapoda into three types: homogenous epithelia with enhanced synthetic activities, homogenous epithelia with diminished such activities, and heterogeneous epithelia with varying synthetic activities. These findings prompt a reevaluation of the nature of ovarian somatic tissues in Myriapoda as well as in Arthropoda.

ICTV Virus Taxonomy Profile: Mypoviridae 2023.

Mypoviridae is a family of negative-sense RNA viruses with genomes of about 16.0 kb that have been found in myriapods. The mypovirid genome consists of three monocistronic RNA segments that encode a nucleoprotein (NP), a glycoprotein (GP), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Mypoviridae, which is available at: ictv.global/report/mypoviridae.

Benchmarking assembly free nanopore read mappers to classify complex millipede gut microbiota via Oxford Nanopore Sequencing Technology.

Millipedes are key players in recycling leaf litter into soil in tropical ecosystems. To elucidate their gut microbiota, we collected millipedes from different municipalities of Puerto Rico. Here we aim to benchmark which method is best for metagenomic skimming of this highly complex millipede microbiome. We sequenced the gut DNA with Oxford Nanopore Technologies' (ONT) MinION sequencer, then analyzed the data using MEGAN-LR, Kraken2 protein mode, Kraken2 nucleotide mode, GraphMap, and Minimap2 to classify these long ONT reads. From our two samples, we obtained a total of 87,110 and 99,749 ONT reads, respectively. Kraken2 nucleotide mode classified the most reads compared to all other methods at the phylum and class taxonomic level, classifying 75% of the reads in the two samples, the other methods failed to assign enough reads to either phylum or class to yield asymptotes in the taxa rarefaction curves indicating that they required more sequencing depth to fully classify this community. The community is hyper diverse with all methods classifying 20-50 phyla in the two samples. There was significant overlap in the reads used and phyla classified between the five methods benchmarked. Our results suggest that Kraken2 nucleotide mode is the most appropriate tool for the application of metagenomic skimming of this highly complex community.

A new species of Illacme from southern California (Siphonophorida, Siphonorhinidae).

The millipede fauna inhabiting deep soil are poorly known. They are small and threadlike, slow moving, lacking pigmentation, and rarely encountered due to their obscure underground way of life. One family, the Siphonorhinidae, encompasses four genera and 12 species in a fragmentary distribution in California, southern Africa, Madagascar, the Malay Archipelago, and Indo-Burma. The family is represented in the Western Hemisphere by a single genus, Illacme Cook & Loomis, 1928 from California, with its closest known relative, Nematozoniumfilum Verhoeff, 1939, from southern Africa. A new species of this family is documented from soil microhabitats in the Los Angeles metropolitan area, Illacmesocal Marek & Shear, sp. nov. Based on this discovery and the recent documentation of other endogean millipede species, we show that these grossly understudied subterranean fauna represent the next frontier of discovery. However, they are threatened by encroaching human settlement and habitat loss, and conservation of this species and other subterranean fauna is of high importance.

Description of the first species of Scutigerella (Symphyla, Scutigerellidae) from China, with mitogenomic and genetic divergence analysis.

Scutigerellasinensis Jin & Bu, sp. nov. from China is described and illustrated. It is characterized by a deeply emarginated posterior margin of tergite 2, less differentiated marginal setae on all tergites, absence of seta a3 around the antennal base, and 6-8 setae on the first tergite. The complete mitochondrial genome of the new species is also analyzed and compared with the mitogenome of Scutigerellacauseyae. In the reconstructed Neighbor-Joining tree based on COI gene sequences, S.sinensissp. nov. clusters with S.causeyae, however, with big distances. The genetic divergence among S.sinensissp. nov. and congeners, species of Hanseniella and Scutigerella, and both families of Symphyla was analyzed using COI gene sequences.

Two new species of the genus Symphylella (Symphyla, Scolopendrellidae) from China and the significance of the frons chaetotaxy.

Symphylellamacrochaeta sp. nov. and Symphylellalongispina sp. nov. from China are described and illustrated. Symphylellamacrochaeta sp. nov. is characterized by 10 extremely long macrosetae arranged as 4/4/2 on the frons, tergites with broad triangular processes, and 4+4 setae on the first tergite. Symphylellalongispina sp. nov. is characterized by a thick and prominent labrum, distinctly long proximal spines on the mandible, eight macrosetae arranged as 4/2/2 on frons, 3+3 setae on first tergite, and narrow triangular processes on the tergites. Detailed comparisons of the new species with similar species are presented. In addition, the frons chaetotaxy of Symphylella is illustrated and discussed for the first time and proposed as a significant diagnostic character for the taxonomic study of the genus.

Sexual selection and predation drive the repeated evolution of stridulation in Heteroptera and other arthropods.

Acoustic and substrate-borne vibrations are among the most widely used signalling modalities in animals. Arthropods display a staggering diversity of vibroacoustic organs generating acoustic sound and/or substrate-borne vibrations, and are fundamental to our broader understanding of the evolution of animal signalling. The primary mechanism that arthropods use to generate vibroacoustic signals is stridulation, which involves the rubbing together of opposing body parts. Although stridulation is common, its behavioural context and evolutionary drivers are often hard to pinpoint, owing to limited synthesis of empirical observations on stridulatory species. This is exacerbated by the diversity of mechanisms involved and the sparsity of their description in the literature, which renders their documentation a challenging task. Here, we present the most comprehensive review to date on the systematic distribution and behavioural context of stridulation. We use the megadiverse heteropteran insects as a model, together with multiple arthropod outgroups (arachnids, myriapods, and selected pancrustaceans). We find that stridulatory vibroacoustic signalling has evolved independently at least 84 times and is present in roughly 20% of Heteroptera, representing a remarkable case of convergent evolution. By studying the behavioural context of stridulation across Heteroptera and 189 outgroup lineages, we find that predation pressure and sexual selection are the main behaviours associated with stridulation across arthropods, adding further evidence for their role as drivers of large-scale signalling and morphological innovation in animals. Remarkably, the absence of tympanal ears in most Heteroptera suggests that they typically cannot detect the acoustic component of their stridulatory signals. This demonstrates that the adoption of new signalling modalities is not always correlated with the ability to perceive those signals, especially when these signals are directed towards interspecific receivers in defensive contexts. Furthermore, by mapping their morphology and systematic distribution, we show that stridulatory organs tend to evolve in specific body parts, likely originating from cleaning motions and pre-copulatory displays that are common to most arthropods. By synthesising our understanding of stridulation and stridulatory organs across major arthropod groups, we create the necessary framework for future studies to explore their systematic and behavioural significance, their potential role in sensory evolution and innovation, and the biomechanics of this mode of signalling.

Re-evaluating and dating myriapod diversification with phylotranscriptomics under a regime of dense taxon sampling.

Recent transcriptomic studies of myriapod phylogeny have been based on relatively small datasets with <40 myriapod terminals and variably supported or contradicted the traditional morphological groupings of Progoneata and Dignatha. Here we amassed a large dataset of 104 myriapod terminals, including multiple species for each of the four myriapod classes. Across the tree, most nodes are stable and well supported. Most analyses across a range of gene occupancy levels provide moderate to strong support for a deep split of Myriapoda into Symphyla + Pauropoda (=Edafopoda) and an uncontradicted grouping of Chilopoda + Diplopoda (=Pectinopoda nov.), as in other recent transcriptome-based analyses; no analysis recovers Progoneata or Dignatha as clades. As in all recent multi-locus and phylogenomic studies, chilopod interrelationships resolve with Craterostigmus excluded from Amalpighiata rather than uniting with other centipedes with maternal brood care in Phylactometria. Diplopod ordinal interrelationships are largely congruent with morphology-based classifications. Chilognathan clades that are not invariably advocated by morphologists include Glomerida + Glomeridesmida, such that the volvation-related characters of pill millipedes may be convergent, and Stemmiulida + Polydesmida more closely allied to Juliformia than to Callipodida + Chordeumatida. The latter relationship implies homoplasy in spinnerets and contradicts Nematophora. A time-tree with nodes calibrated by 25 myriapod and six outgroup fossil terminals recovers Cambrian-Ordovician divergences for the deepest splits in Myriapoda, Edafopoda and Pectinopoda, predating the terrestrial fossil record of myriapods as in other published chronograms, whereas age estimates within Chilopoda and Diplopoda overlap with or do not appreciably predate the calibration fossils. The grouping of Chilopoda and Diplopoda is recovered in all our analyses and is formalized as Pectinopoda nov., named for the shared presence of mandibular comb lamellae. New taxonomic proposals for Chilopoda based on uncontradicted clades are Tykhepoda nov. for the three blind families of Scolopendromorpha that share a "sieve-type" gizzard, and Taktikospina nov. for Scolopendromorpha to the exclusion of Mimopidae.

An anatomical and ultrastructural study of the eye of the luminescent millipede Paraspirobolus lucifugus (Gervais 1836) (Diplopoda, Spirobolida, Spiroboleliidae).

The two forward-looking eyes and their ultrastructural organization of an 18 mm long adult bioluminescent female millipede (Paraspirobolus lucifugus) were investigated by transmission electron microscopy and energy-dispersive X-ray spectroscopy. Each eye contained approximately 23 ommatidia with 50-60 µm wide and 80 um thick corneal lenses that contained calcium and silicon and proximally ended in truncated flat surfaces of around 20 µm in diameter. A maximally 28 µm thick and 25 µm long rhabdom, made up of at least 12-14 retinula cells and a 4 µm thick sleeve of screening pigment granules in a light-adapted position was present. Compared with the eyes of non-luminescent julid millipede species, those of P. lucifugus share their basic anatomy, but also exhibit features like the wide possible binocular frontal visual overlap, somewhat narrower interommatidial angles combined with relatively larger rhabdoms, which suggests that P. lucifugus has more efficient eyes and makes greater use of its photoreceptors. P. lucifugus is negatively phototactic and strictly nocturnal and its activity rhythm is apparently governed by a circadian clock.

Novel mitochondrial gene rearrangements pattern in the millipede Polydesmus sp. GZCS-2019 and phylogenetic analysis of the Myriapoda.

The subphylum Myriapoda included four extant classes (Chilopoda, Symphyla, Diplopoda, and Pauropoda). Due to the limitation of taxon sampling, the phylogenetic relationships within Myriapoda remained contentious, especially for Diplopoda. Herein, we determined the complete mitochondrial genome of Polydesmus sp. GZCS-2019 (Myriapoda: Polydesmida) and the mitochondrial genomes are circular molecules of 15,036 bp, with all genes encoded on + strand. The A+T content is 66.1%, making the chain asymmetric, and exhibits negative AT-skew (-0.236). Several genes rearrangements were detected and we propose a new rearrangement model: "TD (N\R) L + C" based on the genome-scale duplication + (non-random/random) loss + recombination. Phylogenetic analyses demonstrated that Chilopoda and Symphyla both were monophyletic group, whereas Pauropoda was embedded in Diplopoda to form the Dignatha. Divergence time showed the first split of Myriapoda occurred between the Chilopoda and other classes (Wenlock period of Silurian). We combine phylogenetic analysis, divergence time, and gene arrangement to yield valuable insights into the evolutionary history and classification relationship of Myriapoda and these results support a monophyletic Progoneata and the relationship (Chilopoda + (Symphyla + (Diplopoda + Pauropoda))) within myriapod. Our results help to better explain the gene rearrangement events of the invertebrate mitogenome and lay the foundation for further phylogenetic study of Myriapoda.

Six new species of Aphilodon centipedes (Geophilidae: Aphilodontinae) from Brazil

After recent sampling in the Southeast and Northeast of Brazil, six new species of Aphilodon are described and illustrated based on males and females. From the Atlantic Forest biome, Aphilodon foraminis n. sp., A. aiuruocae n. sp., A. acutus n. sp. and A. rectitibia n. sp. were registered in the state of Rio de Janeiro. Aphilodon cangaceiro n. sp. is the first record of Aphilodontinae for the state of Piauí and was sampled in the Caatinga biome. Aphilodon bahianus n. sp. is the first species of Aphilodontinae known for the state of Bahia, being registered from the Atlantic Forest and in the Caatinga biomes. Additionally, some morphological characteristics of all known species of Aphilodon and their distributions are compared.

A new species of Mecophilus (Geophilidae: Aphilodontinae), with the first report of the genus from the state of Rio de Janeiro, Brazil

Mecophilus carioca n. sp. is described based on males and females recently sampled in the Parque Nacional de Itatiaia, and is the first record of the genus from the state of Rio de Janeiro, Brazil. The specimens were analyzed in both light microscopy and scanning electron microscopy, and photos and schematic illustrations are provided. The known distribution of the three species of Mecophilus are presented in a map.

A new amphibious species of the genus emScolopendra/em Linnaeus, 1758 (Scolopendromorpha, Scolopendridae) from the Ryukyu Archipelago and Taiwan.

In Japan and Taiwan, five valid species of the genus Scolopendra Linnaeus, 1758 have been described: S. morsitans Linnaeus, 1758, S. subspinipes Leach, 1816, S. mutilans Koch, 1878, S. japonica Koch, 1878, and S. multidens Newport, 1844. Recently, an undetermined species was found in the Ryukyu Archipelago and Taiwan. Using molecular phylogenetic analyses with mitochondrial COI and 16S rRNA and nuclear 28S rRNA and 18S rRNA genes as well as conventional morphological examination, we successfully discriminated this sixth species as an independent lineage from S. subspinipes, S. mutilans, and other named congeners from East and Southeast Asia. Therefore, the species was described as S. alcyona Tsukamoto Shimano, sp. nov. Several situational evidences suggest that this species prefers streamside environments and exhibits amphibious behavior.

A new giant species of the millipede genus emPrionopetalum/em Attems, 1909 from Mt. Kilimanjaro, Tanzania (Diplopoda, Spirostreptida, Odontopygidae).

A new large species of the millipede genus Prionopetalum Attems, 1909, P. nessiae sp. nov. from Mt. Kilimanjaro, Tanzania, is described, with SEM imaging and illustrations of relevant taxonomic characters, and mapped. Comments on the significance of sternum 9 in descriptions of Odontopygidae, and on the intrageneric differences in Prionopetalum, are included.

Two new species of the genus Dasongius (Myriapoda, Pauropoda, Pauropodidae) from China.

Two new species of the family Pauropodidae: Dasongius liupanensis sp. n. and D. spatulatus sp. n. are described from China. Both of them have non-furcate setae on the collum segment, long setae p and q on the antennae, 6+6 setae on tergite II, furcate setae on the coxa, cylindrical setae on the trochanter of leg 9, and two appendages on the anal plate; these features are distinct from other congeners. The new species can be distinguished by the shape of the tergum of the pygidium, shape of the anal plate, as well as the shape of setae a1, a2, st and b1 on the pygidium. In addition, all species of the genus Dasongius are compared in detail.

The millipede family Striariidae Bollman, 1893: III. Four new species of Striaria Bollman, 1888 (Diplopoda, Chordeumatida, Striariidae) from Idaho, USA.

The millipede genus Striaria Bollman, 1888 heretofore had been thought to be confined to the Appalachian region of eastern North America, is replaced in western North America by species of the genus Amplaria Chamberlin, 1941. Collections from northern Idaho show that this is not the case, and that at least four species of Striaria occur in the west. These species are described herein as Striaria aculeata n. sp., S. bombillus n. sp., S. vagabundus n. sp. and S. orator n. sp.

A new Rhopalomeris species (Diplopoda: Glomerida: Glomeridae), and notes on the phylogenetic relationships between glomeridans in Vietnam.

A new pill millipede, Rhopalomeris nagao sp. nov., is described from Vietnam. It is recognized by the following combination of characters: antennal tip with numerous sensory cones; telopods with short prefemoral and femoral trichosteles, with long, straight and acute tuberculiform femoral process, and with shorter lobuliform tibial process; syncoxial lobe being slightly concave medially, syncoxial horns being longer than lobe. A fragment of the cytochrome c oxidase subunit I (COI) gene is also provided for the new species. The K2P genetic distance of the COI between the new species and other Vietnamese glomeridans is from 10.7% to 16.9%. Two genera, Hyperglomeris and Hyleoglomeris, are considered to be non-monophyletic, but more data and samples will be needed for confirmation.

Description of Hypocambala zizhongi sp. nov. and the new combination, Glyphiulus polytrichus (Golovatch et al., 2011) comb. nov., based on morphological and molecular data (Spirostreptida: Cambalidea: Cambalopsidae).

The recent delimitation of the cambalopsid genera Hypocambala and Glyphiulus is debatable. The focus of controversy is whether the presence of crests on the trunk rings is an appropriate key character dividing these two genera. To address this issue, we conducted a molecular phylogenetic analysis including species with or without crests belonging to Hypocambala and species with crests belonging to Glyphiulus. The results of the phylogenetic analysis suggest that cambalopsids with crests are monophyletic and sister to a species without crests. Hypocambala polytricha, a cambalopsid with crests that is in a clade with crested Glyphiulus species, should be transferred to Glyphiulus. Therefore, a new combination is proposed, Glyphiulus polytrichus comb. nov. In addition, a discussion on the boundary between these two genera and a description of a new species, Hypocambala zizhongi sp. nov., are provided.