Geophilomorph Centipedes Research Articles

Découverte de plusieurs géophilomorphes en Martinique, avec la description d’une nouvelle espèce du genre Portoricona (Chilopoda, Geophilomorpha)

Discovery of several geophilomorphs in Martinique, with the description of a new species of the genus Portoricona (Chilopoda, Geophilomorpha). Between 2016 and 2023, hundreds of centipedes have been collected in Martinique by the second author, mainly by soil and litter samples and extracting with Berlese funnels, also by hand collecting. The whole was then identified by the first author over the years. After the examination of the type material of P. adjunta Chamberlin, 1950, and P. socia Chamberlin, 1950, a new species of Portoricona Chamberlin, 1950 (Geophilidae), collected in Martinique island (Lesser Antilles), is described: P. carbetensis n. sp. It is easily distinguishable by the criteria of its anterior sternites and its number of legs. A modern diagnosis of the genus Portoricona is given, with also some morphological complements on the descriptions of P. adjunta and of P. socia after their typical material, and an identification key of the three species. Ityphilus idanus Crabill, 1960 (Schendylidae) and Piestophilus carribeanus (Chamberlin,1915) (Geophilidae) are recorded for the first time in Martinique. Schizonampa barberi Iorio & Coulis, 2019, has been observed in the mountains of pitons du Carbet. A specimen of Piestophilus carribeanus, from an unpubished locality in Cuba, is documented in the collection of the Museum of Comparative Zoology (MCZ) of the Harvard University. After the literature and all our unpublished identifications, eleven geophilomorph centipedes species are recorded in Martinique, taking into account an unknown minute Geophilidae, possibly halophilic. A checklist of the Geophilomorpha of this island is proposed. The diagnosis and the key are translated in English.

On new records of Geophilomorpha (Chilopoda) from Middle Asia

New records of geophilomorph centipedes (Geophilidae, Himantariidae, Mecistocephalidae, and Schendylidae) from Middle Asia are provided. Order Geophilomorpha is new to both the Surxondaryo Region of Uzbekistan and Balkan Region of Turkmenistan. Family Geophilidae, genus Pachymerium C.L. Koch, 1847, and P. ferrugineum (C.L. Koch, 1835) are new to the Issyk-Kul Region of Kyrgyzstan, to the Districts of Republican Subordination of Tajikistan, and to the Surxondaryo Region of Uzbekistan; family Himantariidae, genus Bothriogaster Sseliwanoff, 1879 and B. signata (Kessler, 1874) are new to the Surxondaryo Region of Uzbekistan and to the Balkan Region of Turkmenistan; Krateraspis sselivanovi Titova, 1975 is new to both Uzbekistan and Kyrgyzstan; Escaryus retusidens Attems, 1904 is new to the East Kazakhstan Region of Kazakhstan. All the records are mapped; Tygarrup muminabadicus Titova, 1965 is illustrated.

When SEM becomes a deceptive tool of analysis: the unexpected discovery of epidermal glands with stalked ducts on the ultimate legs of geophilomorph centipedes

BackgroundThe jointed appendage is a key novelty in arthropod evolution and arthropod legs are known to vary enormously in relation to function. Among centipedes, the ultimate legs always are distinctly different from locomotory legs, and different centipede taxa evolved different structural and functional modifications. In Geophilomorpha (soil centipedes), ultimate legs do not participate in locomotion and were interpret to serve a sensory function. They can be sexually dimorphic and in some species, male ultimate legs notably appear “hairy”. It can be assumed that the high abundance of sensilla indicates a pronounced sensory function. This study seeks for assessing the sensory diversity, however, documents the surprising and unique case of an extensive glandular epithelium in the ultimate legs of three phylogenetically distant species.ResultsThe tightly aggregated epidermal glands with stalked ducts – mistakenly thought to be sensilla – were scrutinized using a multimodal microscopic approach comprising histology as well as scanning and transmission electron microscopy in Haplophilus subterraneus. Hence, this is the first detailed account on centipede ultimate legs demonstrating an evolutionary transformation into a “secretory leg”. Additionally, we investigated sensory structures as well as anatomical features using microCT analysis. Contrary to its nomination as a tarsus, tarsus 1 possesses intrinsic musculature, which is an indication that this podomere might be a derivate of the tibia.DiscussionThe presence and identity of ultimate leg associated epidermal glands with stalked ducts is a new discovery for myriapods. A pronounced secretory as well as moderate sensory function in Haplophilus subterraneus can be concluded. The set of characters will improve future taxonomic studies, to test the hypotheses whether the presence of these specialized glands is a common feature in Geophilomorpha, and that tarsus 1 may be a derivate of the tibia. As the number of epidermal glands with stalked ducts is sexually dimorphic, their function might be connected to reproduction or a sex-specific defensive role. Our results, in particular the unexpected discovery of ‘glandular hairs’, may account for a striking example for how deceptive morphological descriptions of epidermal organs may be, if based on non-invasive techniques alone.

Comparative analysis of diet in syntopic geophilomorph species (Chilopoda, Geophilomorpha) using a DNA-based approach

Trophic niche partitioning between potentially competing species within the same coenosis has been little explored for most of the major groups of arthropod soil predators, among which are the geophilomorph centipedes. We performed a comparative study in nature on the diet of three species of Geophilomorpha living in the same site in Southern Europe. Through PCR-based molecular gut content analysis, we estimated trophic niche width and overlap with respect to three common prey groups: lumbricids, collembolans and dipteran larvae. Results show that apparently similar geophilomorph species differ significantly in prey spectrum, with quite different niche widths. Estimates of predator diet overlap gave moderate values, non-significantly different from null expectations. Within-species diet composition does not vary significantly with sex. This work, while providing the first evidence of trophic niche partitioning among coexisting geophilomorph species, contributes to recent progresses in the understanding of intra-guild interactions between predators in the soil food webs.

An exotic species spreads through Europe: Tygarrup javanicus (Chilopoda: Geophilomorpha: Mecistocephalidae) is reported from the Slovakia and the Czech Republic

Abstract Geophilomorph centipedes, due to their soil life style, are frequently transported with plants. This report tries to underline some adaptations that facilitate them being introduced and becoming alien species. Tygarrup javanicus (Attems, 1907), tropical species reported recently from different greenhouses in Central Europe, is used as an example of such a spreading species.

Testing the validity of functional response models using molecular gut content analysis for prey choice in soil predators

Analysis of predator–prey interactions is a core concept of animal ecology, explaining structure and dynamics of animal food webs. Measuring the functional response, i.e. the intake rate of a consumer as a function of prey density, is a powerful method to predict the strength of trophic links and assess motives of prey choice, particularly in arthropod communities. However, due to their reductionist set‐up, functional responses, which are based on laboratory feeding experiments, may not display field conditions, possibly leading to skewed results. Here, we tested the validity of functional responses of centipede predators and their prey by comparing them with empirical gut content data from field‐collected predators. Our predator–prey system included lithobiid and geophilomorph centipedes, abundant and widespread predators of forest soils and their soil‐dwelling prey. First, we calculated the body size‐dependent functional responses of centipedes using a published functional response model in which we included natural prey abundances and animal body masses. This allowed us to calculate relative proportions of specific prey taxa in the centipede diet. In a second step, we screened field‐collected centipedes for DNA of eight abundant soil‐living prey taxa and estimated their body size‐dependent proportion of feeding events. We subsequently compared empirical data for each of the eight prey taxa, on proportional feeding events with functional response‐derived data on prey proportions expected in the gut, showing that both approaches significantly correlate in five out of eight predator–prey links for lithobiid centipedes but only in one case for geophilomorph centipedes. Our findings suggest that purely allometric functional response models, which are based on predator–prey body size ratios are too simple to explain predator–prey interactions in a complex system such as soil. We therefore stress that specific prey traits, such as defence mechanisms, must be considered for accurate predictions.

Shape variation of prey-catching structures in geophilomorph centipedes: A preliminary investigation using geometric morphometrics

Geophilomorph centipedes are common arthropod soil predators, but very little is known about their preying behaviour and their diet. Here we develop an exploratory morpho-functional approach to better understand their feeding habits, based on the morphology of feeding-related structures. Through geometric morphometrics, in a sample of five geophilomorph species, we investigated morphological variation in the three most conspicuous component structures of their prey-catching apparatus. At intra-specific level, we found no strong evidence for sexual dimorphism, left-right directional asymmetries and allometry across adult stages. At inter-specific level, shape differences in the feeding apparatus among the sample species were highly significant and large, even between two congeneric species. We also found a significant covariation between the shapes of the three structures, including those that do not directly articulate with each other, suggesting some degree of morphological integration between the different structures of the prey-catching apparatus. This study suggests the effectiveness and power of geometric morphometrics for the quantitative study of centipede functional morphology and provides a basis for wider comparative investigations on their phenotypic evolution.

An annotated catalogue of Geophilomorph centipedes (Myriapoda, Geophilomorpha) of European Russia

Forty-one species of Geophilomorpha belonging to 17 genera from 6 families are recorded from European Russia. Dicellophilus carniolensis (Koch, 1847) of the family Mecistocephalidae is recorded from the fauna of Russia for the first time. The data of original description, type localities, and the general and local distribution are given for all the species, together with some taxonomic comments. The history of the studies of Geophilomorpha in the region is considered.

Modularity and developmental stability in segmented animals: variation in translational asymmetry in geophilomorph centipedes.

Does a modular body organization present a challenge for developmental control? We investigate the idea of a possible developmental cost of modularity by examining the relationship between modularity and developmental stability in a multi-segmented arthropod taxon: the geophilomorph centipedes. In a sample of eight species, we tested the correlation between developmental stability, estimated from measures of translational fluctuating asymmetry, and the number of trunk segments and some other morphological traits, both at the species and individual levels. We found sizeable differences in size and shape patterns of variation at the level of species. However, we did not find any clear evidence of correlation between fluctuating asymmetry and the number of trunk segments or the other morphological traits considered. Thus, our results provide no support to the idea of a possible trade-off between the cardinality of a modular system and the level of developmental precision in the phenotypic expression of its modules. The results of this exploratory study invite further investigations of patterns of translational fluctuating asymmetry in segmented animals and other modular organisms, as these have the potential to reveal features of developmental stability that cannot be captured by the study of bilateral asymmetry alone.

The complete mitochondrial genome of the geophilomorph centipede Strigamia maritima.

Strigamia maritima (Myriapoda; Chilopoda) is a species from the soil-living order of geophilomorph centipedes. The Geophilomorpha is the most speciose order of centipedes with over a 1000 species described. They are notable for their large number of appendage bearing segments and are being used as a laboratory model to study the embryological process of segmentation within the myriapods. Using a scaffold derived from the recently published genome of Strigamia maritima that contained multiple mitochondrial protein-coding genes, here we report the complete mitochondrial genome of Strigamia, the first from any geophilomorph centipede. The mitochondrial genome of S. maritima is a circular molecule of 14,938 base pairs, within which we could identify the typical mitochondrial genome complement of 13 protein-coding genes and 2 ribosomal RNA genes. Sequences resembling 16 of the 22 transfer RNA genes typical of metazoan mitochondrial genomes could be identified, many of which have clear deviations from the standard ‘cloverleaf’ secondary structures of tRNA. Phylogenetic trees derived from the concatenated alignment of protein-coding genes of S. maritima and >50 other metazoans were unable to resolve the Myriapoda as monophyletic, but did support a monophyletic group of chilopods: Strigamia was resolved as the sister group of the scolopendromorph Scolopocryptos sp. and these two (Geophilomorpha and Scolopendromorpha), along with the Lithobiomorpha, formed a monophyletic group the Pleurostigmomorpha. Gene order within the S. maritima mitochondrial genome is unique compared to any other arthropod or metazoan mitochondrial genome to which it has been compared. The highly unusual organisation of the mitochondrial genome of Strigamia maritima is in striking contrast with the conservatively evolving nuclear genome: sampling of more members of this order of centipedes will be required to see whether this unusual organization is typical of the Geophilomorpha or results from a more recent reorganisation in the lineage leading to Strigamia.

Case 3673Geophilus alpinusMeinert, 1870 (Chilopoda): proposed conservation of the specific name

Abstract. The purpose of this application, under Article 23.9.3 of the Code, is to conserve the specific name Geophilus alpinus Meinert, 1870 for a widespread European species of geophilomorph centipedes. This name, currently in use, is threatened by the subjective synonyms Geophilus impressus C.L. Koch, 1847 and Geophilus palustris C.L. Koch, 1863, which have been disregarded since 1874 and 1882 respectively.

The embryoid development of Strigamia maritimaand its bearing on post-embryonic segmentation of geophilomorph centipedes

Many arthropods add body segments post-embryonically, including most of the myriapods. However, geophilomorph and scolopendromorph centipedes are epimorphic, i.e. they form all their segments during embryonic time, although this has never been demonstrated directly. Understanding the similarity between embryonic and post-embryonic segmentation is pivotal to understand the possible evolution from anamorphosis to epimorphosis. We have previously demonstrated that in the geophilomorph centipede Strigamia maritima most segments are produced by an oscillatory mechanism operating through waves of expression at double segment periodicity, but that the last-forming (posteriormost) segments are patterned with a different system which might be more similar to post-embryonic segmentation. With a careful analysis of a large number of specimens, I show that the first (“embryoid”) phase of post-embryonic development is clearly distinct from the following ones. It is characterized by more moults than previously reported, allowing me to define and name new stages. I describe these embryoid stages and the first free-leaving stage in detail, providing data on their duration and useful identification characters. At hatching, the prospective last leg-bearing segment is limbless and the genital segments are added in the following stages, indicating a residual anamorphosis in Strigamia segmentation. I demonstrate directly for the first time that at least the leg-bearing segments are in general produced during embryonic life, although in some individuals the external delineation of the last leg-bearing segment may be delayed to post-embryonic time, a possible further residual of anamorphic development. Additionally, I show that the development of the poison claws during this post-embryonic phase may have some element of recapitulation. The data presented in this paper show that the embryoid phase of post-embryonic development of geophilomorph centipedes may represent an extension of embryonic development, possibly in correlation with the evolution of epimorphic development from an anamorphic ancestor, accomplished without completely losing post-embryonic segmentation activity. This continuity in the segmentation process across the embryonic/postembryonic divide may concur to the evolvability of this developmental process.

Geophilomorph centipedes from the Cretaceous amber of Burma

AbstractThe only previously known Mesozoic fossils of the chilopod order Geophilomorpha are two species from the Late Jurassic and Late Cretaceous, both known from single specimens that cannot be assigned with precision to a family. Four specimens from the Late Cretaceous (earliest Cenomanian) amber of Burma include three that can be identified as conspecific, described here as Kachinophilus pereirai gen. nov. sp. nov. These specimens preserve greater morphological detail in comparison with other fossil geophilomorphs: the form and fine features of the head, the maxillary complex, the trunk sternites with associated glandular pores and the ultimate pair of legs defend the assignment of the species to the extant family Geophilidae, and most probably to a derived subgroup including well‐known extant genera such as Ribautia Brölemann, 1909. Confocal laser scanning microscopy supplements examination under incident and transmitted light to document details of high taxonomic relevance in the head and the forcipular segment. The modern appearance of this species and its membership among deeply nested extant clades are consistent with molecular estimates that most of the diversity of crown‐group Geophilomorpha originated before the Late Cretaceous.

Influence of Climate on Segment Number inGeophilus flavus, a Centipede Species Inhabiting Sognefjord in Western Norway

Since in laboratory experiments a relationship between segment number and temperature in geophilomorph centipedes has been proven, we suggest that climatic variation in nature could have a direct effect on segment number. To address this hypothesis we examine the way in which local climatic factors in Sognefjord — air temperature and precipitation both changing along a longitudinal gradient — exert their effect on segment number in Geophilus flavus. Changes in G. flavus segment number along the climatic gradient are similar to that found in previous laboratory experiments with Strigamia maritima, but are even more pronounced. In G. flavus, a 1.5 difference in the mean segment number is found in populations that occur in Sognefjord along a temperature gradient of only about 1.4 °C. In contrast, several degrees centigrade were required to produce a similar increase in the mean segment number in laboratory experiments involving S. maritima.

Early embryonic determination of the sexual dimorphism in segment number in geophilomorph centipedes

BackgroundMost geophilomorph centipedes show intraspecific variability in the number of leg-bearing segments. This intraspecific variability generally has a component that is related to sex, with females having on average more segments than males. Neither the developmental basis nor the adaptive role of this dimorphism is known.ResultsTo determine when this sexual dimorphism in segment number is established, we have followed the development of Strigamia maritima embryos from the onset of segmentation to the first post-embryonic stage where we could determine the sex morphologically. We find that males and females differ in segment number by Stage 6.1, a point during embryogenesis when segment addition pauses while the embryo undergoes large-scale movements. We have confirmed this pattern by establishing a molecular method to determine the sex of single embryos, utilising duplex PCR amplification for Y chromosomal and autosomal sequences. This confirms that male embryos have a modal number of 43 segments visible at Stage 6, while females have 45. In our Strigamia population, adult males have a modal number of 47 leg-bearing segments, and females have 49. This implies that the sexual dimorphism in segment number is determined before the addition of the last leg-bearing segments and the terminal genital segments.ConclusionsSexual dimorphism in segment number is not associated with terminal segment differentiation, but must instead be related to some earlier process during segment patterning. The dimorphism may be associated with a difference in the rate and/or duration of segment addition during the main phase of rapid segment addition that precedes embryonic Stage 6. This suggests that the adaptive role, if any, of the dimorphism is likely to be related to segment number per se, and not to sexual differentiation of the terminal region.

Segment number, body length, and latitude in geophilomorph centipedes: a ‘converse-Bergmann’ pattern

There is a negative relationship between trunk segment number and latitude among geophilomorph centipedes in general. A similar relationship is known to exist within the most intensively-studied geophilomorph species, Strigamia maritima, and also within several other species from this group. Previously, it was considered that this relationship did not involve body length; instead, individuals of S. maritima with more segments were considered to be more finely subdivided (not longer) than those with fewer segments. This incorrect interpretation arose from the difficulty of reliably separating post-embryonic stages and thus of making a simple and direct comparison. In the present study, we build on recent work that facilitates such comparisons; and we show conclusively that individuals with more segments are longer. Our finding means that it is now possible to connect the work on S. maritima in particular, and on geophilomorph centipedes in general, with the debate about Bergmann's ‘rule’: the proposal that body size increases with increasing latitude. There is a clear ‘converse-Bergmann’ pattern, as has been found in several other taxa. We propose an adaptive hypothesis that may explain why geophilomorphs show this pattern. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ••, ••–••.

Algerophilus, a neglected lineage of Western Mediterranean centipedes (Chilopoda: Geophilidae)

Among the diverse geophilomorph centipedes inhabiting the Mediterranean region, we recognise and describe a morpho-logically distinct lineage that has long been misunderstood and neglected. This lineage, which deserves to be treated as adistinct genus (Algerophilus Brolemann, 1925), is broadly similar to Geophilus Leach, 1814 and Tuoba Chamberlin, 1920,but differs from them mainly in the more elongate head and forcipular segment and the coxal pores clustered into elonga-ted pouches. All published and new records are from Western Mediterranean regions including the Baetic Mountains, Ibi-za, the Atlantic Moroccan coastal plain, and the Tell Atlas. A single species A. hispanicus (Meinert, 1870) (=Nesogeophilus mateui Machado, 1953, syn. n.) is recognised on morphological characters, but some geographical varia-tion has been detected in the relative elongation of antennae and forcipules and in the number of trunk segments. The evo-lutionary distinctness and geographical distribution highlighted here for Algerophilus mirror those of other divergent lineages of soil arthropods that are endemic to the Western Mediterranean region.

Cases of trunk segmental anomalies in the geophilomorph centipedes Clinopodes flavidus C.L. Koch and clinopodes trebevicensis (Verhoeff) (Chilopoda: Geophilomorpha)

We describe and analyze two examples of naturally occurring morphological anomalies in the geophilomorph centipedes. Recorded abnormalities include a supernumerary hemisclerite in an adult female specimen of Clinopodes flavidus C.L. Koch, and an even number of leg-bearing segments in a subadult male specimen of Clinopodes trebevicensis (Verhoeff). The morphological complexity of these defects makes them hard to explain as the result of healing or regeneration. They are most probably congenital and are interpreted as the effects of perturbation of different morphogenetic processes occurring at different phases of development of the segments in a given trunk region.

An early temperature‐sensitive period for the plasticity of segment number in the centipede Strigamia maritima

Geophilomorph centipedes show variation in segment number (a) between closely related species and (b) within and between populations of the same species. We have previously shown for a Scottish population of the coastal centipede Strigamia maritima that the temperature of embryonic development is one of the factors that affects the segment number of hatchlings, and hence of adults, as these animals grow epimorphically--that is, without postembryonic addition of segments. Here, we show, using temperature-shift experiments, that the main developmental period during which embryos are sensitive to environmental temperature is surprisingly early, during blastoderm formation and before, or very shortly after, the onset of segmentation.

Demonstration of a heritable component of the variation in segment number in the centipede Strigamia maritima

Here we address the question of how arthropod segment number may evolve by reporting the results of further work on the model system Strigamia maritima. Recently, we showed that there was a plastic component of the variation in segment number within this species; now we demonstrate that there is also a heritable component. This is important because it enables a connection to be made between the known latitudinal trend among species of geophilomorph centipedes (more segments at lower latitudes) and the parallel trend within them. This latter trend is best documented in S. maritima but is also known in several other species. However, while a general connection between the inter- and intraspecific trends can now be made, deciding upon a specific hypothesis of the nature of the selection involved is still problematic. We provide two alternative hypotheses, one based on the temperature-related plasticity in segment number being adaptive, the other based on it being nonadaptive.